Martin Jack Blaser, M.D.

The seroprevalence of Helicobacter pylori and its relationship to malaria in Ugandan children
Gupta V.; Perez-Perez G.I.; Dorsey G.; Rosenthal P.J.; Blaser M.J.
2012 ;106(1):35-42, Transactions of the Royal Society of Tropical Medicine & Hygiene
Helicobacter pylori epidemiology in sub-Saharan Africa, particularly among children, has been little investigated. A secondary endpoint of our study was to examine for associations between the seroprevalence of H. pylori and the incidence of malaria. We explored H. pylori prevalence by measuring serum IgG antibodies to H. pylori whole cell and cytotoxin-associated gene A (CagA) antigens by ELISA in a longitudinal cohort of 200 Ugandan children, aged 1-10 years at enrollment, in whom malaria incidence was followed over 572 person-years. First-sample seroprevalence for H. pylori -specific IgG (63%) and for the H. pylori protein CagA (78.5%) were both high, and they were positively associated with advancing age (per each 1-year age increase, OR (95% CI): 1.60 (1.39-1.85), P< 0.001). We observed nearly universal prevalence of CagA+ H. pylori by the age of 10 years in Kampala and found no evidence that H. pylori-positivity is protective against malaria. 2011 Royal Society of Tropical Medicine and Hygiene
— id: 147750, year: 2012, vol: 106, page: 35, stat: Journal Article,

Antibiotic overuse: Stop the killing of beneficial bacteria
Blaser, Martin
2011 Aug 25;476(7361):393-394, Nature
— id: 136953, year: 2011, vol: 476, page: 393, stat: Journal Article,

Deconstructing a lethal foodborne epidemic
Blaser, Martin J
2011 Nov 10;365(19):1835-1836, New England journal of medicine
— id: 146224, year: 2011, vol: 365, page: 1835, stat: Journal Article,

Detecting a bacterial protein to understand cancer risk
Blaser, Martin J
2011 Sep;57(9):1331-1332, Clinical chemistry
— id: 138105, year: 2011, vol: 57, page: 1331, stat: Journal Article,

Farm microbiome and childhood asthma
Chen, Yu; Blaser, Martin J
2011 May 19;364(20):1972-1973, New England journal of medicine
— id: 140485, year: 2011, vol: 364, page: 1972, stat: Journal Article,

Helicobacter pylori and the birth cohort effect: evidence for stabilized colonization rates in childhood
den Hoed, Caroline M; Vila, Anne J; Holster, Ingrid L; Perez-Perez, Guillermo I; Blaser, Martin J; de Jongste, Johan C; Kuipers, Ernest J
2011 Oct;16(5):405-409, Helicobacter
Background: The prevalence of Helicobacter pylori has declined over recent decades in developed countries. The increasing prevalence with age is largely because of a birth cohort effect. We previously observed a decline in H. pylori prevalence in 6- to 8-year-old Dutch children from 19% in 1978 to 9% in 1993. Knowledge about birth-cohort-related H. pylori prevalence is relevant as a predictor for the future incidence of H. pylori-associated conditions. Aim: The aim of this study was to investigate whether the birth cohort effect of H. pylori observed between 1978 and 1993 continued in subsequent years. Methods: Anti-H. pylori IgG antibodies and anti-CagA IgG antibodies were determined in serum samples obtained in 2005/2006 from 545 Dutch children aged 7-9 years who participated in the Prevention and Incidence of Asthma and Mite Allergy birth cohort. The H. pylori and CagA antibodies were determined by enzyme-linked immunosorbent assays that have been extensively validated in children, with a 94% sensitivity for H. pylori colonization and a 92.5% sensitivity for colonization with a cagA-positive strain. Results: Of the 545 children (M/F 300/245), most (91.5%) were of Dutch descent. The H. pylori positivity rate was 9% (95% CI 6.6-11.4%). The prevalence of CagA antibodies was 0.9% (95% CI 0.1-1.6%). No significant differences were demonstrated in H. pylori and cagA prevalence in relation to gender or ethnicity. Conclusion: The prevalence of H. pylori in childhood has remained stable in the Netherlands from 1993 to 2005, suggesting a stabilization of the previously decreasing trend in subsequent birth cohorts. This finding may reflect stabilization in determinants such as family size, housing, and hygienic conditions (or offset by day care). If confirmed in other populations in developed countries, it implies that colonization with H. pylori will remain common in the coming decades. Remarkably however, the rate of colonization with cagA(+) H. pylori strains has become very low, consistent with prior observations that cagA(+) strains are disappearing in Western countries
— id: 137846, year: 2011, vol: 16, page: 405, stat: Journal Article,

Development of the human gastrointestinal microbiota and insights from high-throughput sequencing
Dominguez-Bello, Maria Gloria; Blaser, Martin J; Ley, Ruth E; Knight, Rob
2011 May;140(6):1713-1719, Gastroenterology
Little was known about the development of the gastrointestinal (GI) tract microbiota, until recently, because of difficulties in obtaining sufficient sequence information from enough people or time points. Now, with decreased costs of DNA sequencing and improved bioinformatic tools, we can compare GI tract bacterial communities among individuals, of all ages from infancy to adulthood. Some key recent findings are that the initial bacterial community, even in the GI tract, depends strongly on delivery mode; that the process of early development of the microbiota is highly unstable and idiosyncratic; that the microbiota differs considerably among children from different countries; and that older adults have substantially different GI tract communities than younger adults, indicating that the GI tract microbiota can change throughout life. We relate these observations to different models of evolution including the evolution of senescence and suggest that probiotics be selected based on patient age. Studies of the microbiota in older people might tell us which probiotics could increase longevity. Drug metabolism varies among individuals with different microbial communities, so age- and region-specific clinical trials are required to ensure safety and efficacy
— id: 133417, year: 2011, vol: 140, page: 1713, stat: Journal Article,

The effect of H. pylori eradication on meal-associated changes in plasma ghrelin and leptin
Francois, Fritz; Roper, Jatin; Joseph, Neal; Pei, Zhiheng; Chhada, Aditi; Shak, Joshua R; de Perez, Asalia Z Olivares; Perez-Perez, Guillermo I; Blaser, Martin J
2011 ;11:37-37, BMC gastroenterology
ABSTRACT: BACKGROUND: Appetite and energy expenditure are regulated in part by ghrelin and leptin produced in the gastric mucosa, which may be modified by H. pylori colonization. We prospectively evaluated the effect of H. pylori eradication on meal-associated changes in serum ghrelin and leptin levels, and body weight. METHODS: Veterans referred for upper GI endoscopy were evaluated at baseline and >/=8 weeks after endoscopy, and H. pylori status and body weight were ascertained. During the first visit in all subjects, and during subsequent visits in the initially H. pylori-positive subjects and controls, blood was collected after an overnight fast and 1 h after a standard high protein meal, and levels of eight hormones determined. RESULTS: Of 92 enrolled subjects, 38 were H. pylori-negative, 44 H. pylori-positive, and 10 were indeterminate. Among 23 H. pylori-positive subjects who completed evaluation after treatment, 21 were eradicated, and 2 failed eradication. After a median of seven months following eradication, six hormones related to energy homeostasis showed no significant differences, but post-prandial acylated ghrelin levels were nearly six-fold higher than pre-eradication (p = 0.005), and median integrated leptin levels also increased (20%) significantly (p < 0.001). BMI significantly increased (5 +/- 2%; p = 0.008) over 18 months in the initially H. pylori-positive individuals, but was not significantly changed in those who were H. pylori-negative or indeterminant at baseline. CONCLUSIONS: Circulating meal-associated leptin and ghrelin levels and BMI changed significantly after H. pylori eradication, providing direct evidence that H. pylori colonization is involved in ghrelin and leptin regulation, with consequent effects on body morphometry
— id: 132313, year: 2011, vol: 11, page: 37, stat: Journal Article,

Novel gastric helicobacters and oral campylobacters are present in captive and wild cetaceans
Goldman, Cinthia G; Matteo, Mario J; Loureiro, Julio D; Almuzara, Marisa; Barberis, Claudia; Vay, Carlos; Catalano, Mariana; Heredia, Sergio Rodriguez; Mantero, Paula; Boccio, Jose R; Zubillaga, Marcela B; Cremaschi, Graciela A; Solnick, Jay V; Perez-Perez, Guillermo I; Blaser, Martin J
2011 Aug 26;152(1-2):138-145, Veterinary microbiology
The mammalian gastric and oral mucosa may be colonized by mixed Helicobacter and Campylobacter species, respectively, in individual animals. To better characterize the presence and distribution of Helicobacter and Campylobacter among marine mammals, we used PCR and 16S rDNA sequence analysis to examine gastric and oral samples from ten dolphins (Tursiops gephyreus), one killer whale (Orcinus orca), one false killer whale (Pseudorca crassidens), and three wild La Plata river dolphins (Pontoporia blainvillei). Helicobacter spp. DNA was widely distributed in gastric and oral samples from both captive and wild cetaceans. Phylogenetic analysis demonstrated two Helicobacter sequence clusters, one closely related to H. cetorum, a species isolated from dolphins and whales in North America. The second related cluster was to sequences obtained from dolphins in Australia and to gastric non-H. pylori helicobacters, and may represent a novel taxonomic group. Dental plaque sequences from four dolphins formed a third cluster within the Campylobacter genus that likely represents a novel species isolated from marine mammals. Identification of identical Helicobacter spp. DNA sequences from dental plaque, saliva and gastric fluids from the same hosts, suggests that the oral cavity may be involved in transmission. These results demonstrate that Helicobacter and Campylobacter species are commonly distributed in marine mammals, and identify taxonomic clusters that may represent novel species
— id: 136497, year: 2011, vol: 152, page: 138, stat: Journal Article,

Role of luxS in Bacillus anthracis growth and virulence factor expression (vol 1, pg 72, 2010)
Jones, Marcus B.; Peterson, Scott N.; Benn, Rosslyn; Braisted, John C.; Jarrahi, Behnam; Shatzkes, Kenneth; Ren, Dacheng; Wood, Thomas K.; Blaser, Martin J.
2011 MAR-APR ;2(2):172-172, Virulence
— id: 135630, year: 2011, vol: 2, page: 172, stat: Journal Article,

Campylobacter capsule and lipooligosaccharide confer resistance to serum and cationic antimicrobials
Keo, Thormika; Collins, Jennifer; Kunwar, Pratima; Blaser, Martin J; Iovine, Nicole M
2011 Jan 1;2(1):30-40, Virulence
The innate immune system plays a critical role in host defense against mucosal bacteria. Campylobacter jejuni is a major cause of human gastroenteritis that usually resolves spontaneously within several days, suggesting that innate mechanisms are important to control the infection. However, the specific means by which this occurs is not well understood. While diarrheal isolates of C. jejuni usually are susceptible to human serum, we found that a systemic strain of C. jejuni, isolated from the cerebrospinal fluid of an infant with meningitis, is relatively more resistant to human serum, the Bactericidal/Permeability-Increasing Protein (BPI), an endogenous cationic antimicrobial protein, and the cationic peptide antibiotic polymyxin B. To test the hypothesis that the surface properties of this strain contributed to its ability to withstand these innate host defenses, we constructed isogenic mutants in capsule (kpsM) and lipooligosaccharide (waaF) and complemented these mutants by insertion of the complementation construct in trans into hipO, a chromosomal locus. We found that capsule expression was essential for serum resistance, whereas lipooligosaccharide played no substantial role. In contrast, the lipooligosaccharide mutant showed increased sensitivity to polymyxin B, alpha-defensins, cathelicidins, and BPI. These findings suggest that the polysaccharides of C. jejuni strains contribute differently to resistance against host innate immunity; whereby capsule is more important for resisting human complement and lipooligosaccharide is more important for protection against killing mediated by cationic antimicrobial peptides and proteins
— id: 123208, year: 2011, vol: 2, page: 30, stat: Journal Article,

Structure of the human gastric bacterial community in relation to Helicobacter pylori status
Maldonado-Contreras, Ana; Goldfarb, Kate C; Godoy-Vitorino, Filipa; Karaoz, Ulas; Contreras, Monica; Blaser, Martin J; Brodie, Eoin L; Dominguez-Bello, Maria G
2011 Apr;5(4):574-579, ISME journal
The human stomach is naturally colonized by Helicobacter pylori, which, when present, dominates the gastric bacterial community. In this study, we aimed to characterize the structure of the bacterial community in the stomach of patients of differing H. pylori status. We used a high-density 16S rRNA gene microarray (PhyloChip, Affymetrix, Inc.) to hybridize 16S rRNA gene amplicons from gastric biopsy DNA of 10 rural Amerindian patients from Amazonas, Venezuela, and of two immigrants to the United States (from South Asia and Africa, respectively). H. pylori status was determined by PCR amplification of H. pylori glmM from gastric biopsy samples. Of the 12 patients, 8 (6 of the 10 Amerindians and the 2 non-Amerindians) were H. pylori glmM positive. Regardless of H. pylori status, the PhyloChip detected Helicobacteriaceae DNA in all patients, although with lower relative abundance in patients who were glmM negative. The G2-chip taxonomy analysis of PhyloChip data indicated the presence of 44 bacterial phyla (of which 16 are unclassified by the Taxonomic Outline of the Bacteria and Archaea taxonomy) in a highly uneven community dominated by only four phyla: Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Positive H. pylori status was associated with increased relative abundance of non-Helicobacter bacteria from the Proteobacteria, Spirochetes and Acidobacteria, and with decreased abundance of Actinobacteria, Bacteroidetes and Firmicutes. The PhyloChip detected richness of low abundance phyla, and showed marked differences in the structure of the gastric bacterial community according to H. pylori status
— id: 134261, year: 2011, vol: 5, page: 574, stat: Journal Article,

Microbiome and malignancy
Plottel, Claudia S; Blaser, Martin J
2011 Oct 4;10(4):324-335, Cell Host & Microbe
Current knowledge is insufficient to explain why only a proportion of individuals exposed to environmental carcinogens or carrying a genetic predisposition to cancer develop disease. Clearly, other factors must be important, and one such element that has recently received attention is the human microbiome, the residential microbes including Bacteria, Archaea, Eukaryotes, and viruses that colonize humans. Here, we review principles and paradigms of microbiome-related malignancy, as illustrated by three specific microbial-host interactions. We review the effects of the microbiota on local and adjacent neoplasia, present the estrobolome model of distant effects, and discuss the complex interactions with a latent virus leading to malignancy. These are separate facets of a complex biology interfacing all the microbial species we harbor from birth onward toward early reproductive success and eventual senescence
— id: 139747, year: 2011, vol: 10, page: 324, stat: Journal Article,

Genotypic and Phenotypic Variation of Lewis Antigen Expression in Geographically Diverse Helicobacter pylori Isolates
Pohl, Mary Ann; Zhang, William; Shah, Sunny N; Sanabria-Valentin, Edgardo L; Perez-Perez, Guillermo I; Blaser, Martin J
2011 Dec;16(6):475-481, Helicobacter
Background: Helicobacter pylori are a persistent colonizer of the human gastric mucosa, which can lead to the development of peptic ulcer disease and gastric adenocarcinomas. However, H. pylori can asymptomatically colonize a host for years. One factor that has been hypothesized to contribute to such persistence is the production of Lewis (Le) antigens in the lipopolysaccharide layer of the bacterial outer membrane as a form of molecular mimicry, because humans also express these antigens on their gastric mucosa. Humans and H. pylori both are polymorphic for Le expression, which is driven in H. pylori by variation at the Le synthesis loci. In this report, we sought to characterize Le genotypic and phenotypic variation in geographically diverse H. pylori isolates. Materials and Methods: From patients undergoing endoscopy in 29 countries, we determined Le phenotypes of 78 H. pylori strains and performed genotyping of the galT and beta-(1,3)galT loci in 113 H. pylori strains. Results: Le antigen phenotyping revealed a significant (p < .0001) association between type 1 (Le(a) and Le(b) ) expression and strains of East Asian origin. Genotyping revealed a significant correlation between strain origin and the size of the promoter region upstream of the Le synthesis gene, galT (p < .0001). Conclusion: These results indicate that the heterogeneity of human Le phenotypes is reflected in their H. pylori colonizing strains and suggest new loci that can be studied to assess the variation of Le expression
— id: 141081, year: 2011, vol: 16, page: 475, stat: Journal Article,

De minimis risk: a proposal for a new category of research risk
Rhodes, Rosamond; Azzouni, Jody; Baumrin, Stefan Bernard; Benkov, Keith; Blaser, Martin J; Brenner, Barbara; Dauben, Joseph W; Earle, William J; Frank, Lily; Gligorov, Nada; Goldfarb, Joseph; Hirschhorn, Kurt; Hirschhorn, Rochelle; Holzman, Ian; Indyk, Debbie; Jabs, Ethylin Wang; Lackey, Douglas P; Moros, Daniel A; Philpott, Sean; Rhodes, Matthew E; Richardson, Lynne D; Sacks, Henry S; Schwab, Abraham; Sperling, Rhoda; Trusko, Brett; Zweig, Arnulf
2011 Nov;11(11):1-7, American journal of bioethics : AJOB
— id: 142151, year: 2011, vol: 11, page: 1, stat: Journal Article,

Association Between Oral Health And Gastric Precancerous Lesions
Salazar CR; Francois F; Li Y; Corby P; Hays R; Leung C; Bedi S; Segers S; Queiroz E; Sun J; Wang B; Ho H; Craig R; Cruz G; Blaser MJ; Perez-Perez G; Hayes RB; Dasanayake A; Pei Z; Chen Y
2011 Dec 1;:399-403 #, Carcinogenesis
Although recent studies have suggested that tooth loss is positively related to the risk of gastric non-cardia cancer, the underlying oral health conditions potentially responsible for the association remain unknown. We investigated whether clinical and behavioral measures of oral health are associated with the risk of gastric precancerous lesions. We conducted a cross sectional study of 131 patients undergoing upper gastrointestinal endoscopy. Cases were defined as those with gastric precancerous lesions including intestinal metaplasia or chronic atrophic gastritis on the basis of standard biopsy review. A validated structured questionnaire was administered to obtain information on oral health behaviors. A comprehensive clinical oral health examination was performed on a subset of 91 patients to evaluate for periodontal disease and dental caries experience. A total of 41 (31%) cases of gastric precancerous lesions were identified. Compared to non-cases, cases were significantly more likely to not floss their teeth (Odds Ratio [OR] = 2.89, 95% Confidence Interval [CI]: 1.09-7.64), adjusting for age, sex, race, BMI, smoking status, educational attainment and Helicobacter pylori status in serum. Among participants who completed the oral examination, cases (n=28) were more likely to have a higher percentage of sites with gingival bleeding than non-cases (OR = 2.63, 95% CI: 1.37-5.05 for a standard deviation increase in bleeding sites [equivalent to 19.7%]), independent of potential confounders. Our findings demonstrate that specific oral health conditions and behaviors such as gingival bleeding and tooth flossing are associated with gastric precancerous lesions
— id: 147670, year: 2011, vol: , page: 399, stat: Journal Article,

Minimum information about a marker gene sequence (MIMARKS) and minimum information about any (x) sequence (MIxS) specifications
Yilmaz P; Kottmann R; Field D; Knight R; Cole JR; Amaral-Zettler L; Gilbert JA; Karsch-Mizrachi I; Johnston A; Cochrane G; Vaughan R; Hunter C; Park J; Morrison N; Rocca-Serra P; Sterk P; Arumugam M; Bailey M; Baumgartner L; Birren BW; Blaser MJ; Bonazzi V; Booth T; Bork P; Bushman FD; Buttigieg PL; Chain PS; Charlson E; Costello EK; Huot-Creasy H; Dawyndt P; Desantis T; Fierer N; Fuhrman JA; Gallery RE; Gevers D; Gibbs RA; Gil IS; Gonzalez A; Gordon JI; Guralnick R; Hankeln W; Highlander S; Hugenholtz P; Jansson J; Kau AL; Kelley ST; Kennedy J; Knights D; Koren O; Kuczynski J; Kyrpides N; Larsen R; Lauber CL; Legg T; Ley RE; Lozupone CA; Ludwig W; Lyons D; Maguire E; Methe BA; Meyer F; Muegge B; Nakielny S; Nelson KE; Nemergut D; Neufeld JD; Newbold LK; Oliver AE; Pace NR; Palanisamy G; Peplies J; Petrosino J; Proctor L; Pruesse E; Quast C; Raes J; Ratnasingham S; Ravel J; Relman DA; Assunta-Sansone S; Schloss PD; Schriml L; Sinha R; Smith MI; Sodergren E; Spor A; Stombaugh J; Tiedje JM; Ward DV; Weinstock GM; Wendel D; White O; Whiteley A; Wilke A; Wortman JR; Yatsunenko T; Glockner FO
2011 May 6;29(5):415-420, Nature biotechnology
Here we present a standard developed by the Genomic Standards Consortium (GSC) for reporting marker gene sequences-the minimum information about a marker gene sequence (MIMARKS). We also introduce a system for describing the environment from which a biological sample originates. The 'environmental packages' apply to any genome sequence of known origin and can be used in combination with MIMARKS and other GSC checklists. Finally, to establish a unified standard for describing sequence data and to provide a single point of entry for the scientific community to access and learn about GSC checklists, we present the minimum information about any (x) sequence (MIxS). Adoption of MIxS will enhance our ability to analyze natural genetic diversity documented by massive DNA sequencing efforts from myriad ecosystems in our ever-changing biosphere
— id: 134266, year: 2011, vol: 29, page: 415, stat: Journal Article,

Harnessing the power of the human microbiome
Blaser, Martin J
2010 Apr 6;107(14):6125-6126, Proceedings of the National Academy of Sciences of the United States of America
— id: 109043, year: 2010, vol: 107, page: 6125, stat: Journal Article,

Helicobacter pylori and esophageal disease: wake-up call?
Blaser, Martin J
2010 Dec;139(6):1819-1822, Gastroenterology
— id: 134409, year: 2010, vol: 139, page: 1819, stat: Journal Article,

Serum pepsinogens and Helicobacter pylori in relation to the risk of esophageal squamous cell carcinoma in the alpha-tocopherol, beta-carotene cancer prevention study
Cook, Michael B; Dawsey, Sanford M; Diaw, Lena; Blaser, Martin J; Perez-Perez, Guillermo I; Abnet, Christian C; Taylor, Philip R; Albanes, Demetrius; Virtamo, Jarmo; Kamangar, Farin
2010 Aug;19(8):1966-1975, Cancer epidemiology biomarkers & prevention
BACKGROUND: Helicobacter pylori can induce gastric atrophy in humans, which in turn increases gastric cancer risk. Whether H. pylori and gastric atrophy also affect the risk of esophageal squamous cell carcinoma (ESCC), however, remains unresolved. METHODS: We performed a nested case-control study within the prospective Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study to assess these relationships. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study is composed of 29,133 Finnish male smokers, ages 50 to 69 years, who were recruited during 1985-1988. Using baseline sera, we assessed H. pylori status (via immunoglobulin G antibodies against whole-cell and CagA antigens) and gastric atrophy status [via the biomarkers pepsinogen I (PGI) and pepsinogen II (PGII)] in 79 ESCC cases and 94 controls. Logistic regression with adjustment for age, date of blood draw, education, cigarette smoking, alcohol, body mass index, and fruit and vegetable intake was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). RESULTS: Gastric atrophy (PGI/PGII <4) was associated with ESCC (OR, 4.58; 95% CI, 2.00-10.48). There was no evidence for an association between H. pylori and ESCC (OR, 0.94; 95% CI, 0.40-2.24). CONCLUSIONS: These results could be explained by misclassification of H. pylori status due to serologic amnesia, ESCC risk being dependent on the functional consequences or interactions of H. pylori rather than the infection per se, gastric atrophy having a different histogenesis in ESCC without being primarily dependent on H. pylori acquisition, or a lack of statistical power to detect an effect. IMPACT: Validation of these results may warrant mechanistic studies to determine the route of association between gastric atrophy and ESCC
— id: 134354, year: 2010, vol: 19, page: 1966, stat: Journal Article,

Genetic Relationships among Reptilian and Mammalian Campylobacter fetus Strains Determined by Multilocus Sequence Typing
Dingle, KE; Blaser, MJ; Tu, ZC; Pruckler, J; Fitzgerald, C; van Bergen, MAP; Lawson, AJ; Owen, RJ; Wagenaar, JA
2010 MAR ;48(3):977-980, Journal of clinical microbiology
Reptile Campylobacter fetus isolates and closely related strains causing human disease were characterized by multilocus sequence typing. They shared similar to 90% nucleotide sequence identity with classical mammalian C. fetus, and there was evidence of recombination among members of these two groups. The reptile group represents a possible separate genomospecies capable of infecting humans
— id: 108316, year: 2010, vol: 48, page: 977, stat: Journal Article,

Quantitation of major human cutaneous bacterial and fungal populations
Gao, Zhan; Perez-Perez, Guillermo I; Chen, Yu; Blaser, Martin J
2010 Oct;48(10):3575-3581, Journal of clinical microbiology
Because the human skin microbiota may play roles in the causation or modification of skin diseases, we sought to provide initial quantitative analysis from different cutaneous locations. We developed quantitative PCRs to enumerate the total bacterial and fungal populations, as well as the most common bacterial and fungal genera present in six locales, in eight healthy subjects. We used a set of primers and TaqMan MGB probes based on the bacterial 16S rRNA and fungal internally transcribed spacer region, as well as bacterial genus-specific probes for Propionibacterium, Corynebacterium, Streptococcus, and Staphylococcus and a fungal genus-specific probe for Malassezia. The extent of human DNA contamination of the specimen was determined by quantitating the human housekeeping GAPDH gene. The highest level of 16S rRNA copies of bacteria was present in the axilla (4.44 +/- 0.18 log(10) copies/mul [mean +/- standard error of the mean]), with normalization based on GAPDH levels, but the other five locations were similar to one another (range, 2.48 to 2.89 log(10) copies/mul). There was strong symmetry between the left and right sides. The four bacterial genera accounted for 31% to 59% of total bacteria, with the highest percent composition in the axilla and the lowest in the forearm. Streptococcus was the most common genus present on the forehead and behind the ear. Corynebacterium spp. were predominant in the axilla. Fungal levels were 1 to 2 log(10) lower than for bacteria, with Malassezia spp. accounting for the majority of fungal gene copies. These results provide the first quantitation of the site and host specificities of major bacterial and fungal populations in human skin and present simple methods for their assessment in studies of disease
— id: 114044, year: 2010, vol: 48, page: 3575, stat: Journal Article,

Role of luxS in Bacillus anthracis growth and virulence factor expression
Jones, Marcus B; Peterson, Scott N; Benn, Rosslyn; Braisted, John C; Jarrahi, Behnam; Shatzkes, Kenneth; Ren, Dacheng; Wood, Thomas K; Blaser, Martin J
2010 Mar-Apr;1(2):72-83, Virulence
Quorum-sensing (QS), the regulation of bacterial gene expression in response to changes in cell density, involves pathways that synthesize signaling molecules (auto-inducers). The luxS/AI-2-mediated QS system has been identified in both gram-positive and gram-negative bacteria. Bacillus anthracis, the etiological agent of anthrax, possesses genes involved in luxS/AI-2-mediated QS, and deletion of luxS in B. anthracis Sterne strain 34F2 results in inhibition of AI-2 synthesis and a growth defect. In the present study, we created a DeltaluxS B. anthracis strain complemented in trans by insertion of a cassette, including luxS and a gene encoding erythromycin resistance, into the truncated plcR regulator locus. The complemented DeltaluxS strain has restored AI-2 synthesis and wild-type growth. A B. anthracis microarray study revealed consistent differential gene expression between the wild-type and DeltaluxS strain, including downregulation of the B. anthracis S-layer protein gene EA1 and pXO1 virulence genes. These data indicate that B. anthracis may use luxS/AI-2-mediated QS to regulate growth, density-dependent gene expression and virulence factor expression
— id: 133762, year: 2010, vol: 1, page: 72, stat: Journal Article,

Helicobacter pylori CagA Phosphorylation Status Determines the gp130-activated SHP2/ERK and JAK/STAT Signal Transduction Pathways in Gastric Epithelial Cells
Lee, IO; Kim, JH; Choi, YJ; Pillinger, MH; Kim, SY; Blaser, MJ; Lee, YC
2010 MAY 21 ;285(21):16042-16050, Journal of biological chemistry
The Helicobacter pylori protein CagA may undergo tyrosine phosphorylation following its entry into human gastric epithelial cells with downstream effects on signal transduction. Disruption of the gp130 receptor that modulates the balance of the SHP2/ERK and JAK/STAT pathways enhanced peptic ulceration and gastric cancer in gp130 knock-out mice. In this study, we evaluated the effect of translocated CagA in relation to its tyrosine phosphorylation status on the gp130-mediated signal switch between the SHP2/ERK and JAK/STAT3 pathways. We showed that in the presence of CagA, SHP2 was recruited to gp130. Phosphorylated CagA showed enhanced SHP2 binding activity and ERK1/2 phosphorylation, whereas unphosphorylated CagA showed preferential STAT3 activation. These findings indicate that the phosphorylation status of CagA affects the signal switch between the SHP2/ERK and JAK/STAT3 pathways through gp130, providing a novel mechanism to explain H. pylori signaling
— id: 109777, year: 2010, vol: 285, page: 16042, stat: Journal Article,

Host-Interactive Genes in Amerindian Helicobacter pylori Diverge from Their Old World Homologs and Mediate Inflammatory Responses
Mane, SP; Dominguez-Bello, MG; Blaser, MJ; Sobral, BW; Hontecillas, R; Skoneczka, J; Mohapatra, SK; Crasta, OR; Evans, C; Modise, T; Shallom, S; Shukla, M; Varon, C; Megraud, F; Maldonado-Contreras, AL; Williams, KP; Bassaganya-Riera, J
2010 JUN ;192(12):3078-3092, Journal of bacteriology
Helicobacter pylori is the dominant member of the gastric microbiota and has been associated with an increased risk of gastric cancer and peptic ulcers in adults. H. pylori populations have migrated and diverged with human populations, and health effects vary. Here, we describe the whole genome of the cag-positive strain V225d, cultured from a Venezuelan Piaroa Amerindian subject. To gain insight into the evolution and host adaptation of this bacterium, we undertook comparative H. pylori genomic analyses. A robust multiprotein phylogenetic tree reflects the major human migration out of Africa, across Europe, through Asia, and into the New World, placing Amerindian H. pylori as a particularly close sister group to East Asian H. pylori. In contrast, phylogenetic analysis of the host-interactive genes vacA and cagA shows substantial divergence of Amerindian from Old World forms and indicates new genotypes (e.g., VacA m3) involving these loci. Despite deletions in CagA EPIYA and CRPIA domains, V225d stimulates interleukin-8 secretion and the hummingbird phenotype in AGS cells. However, following a 33-week passage in the mouse stomach, these phenotypes were lost in isolate V225-RE, which had a 15-kb deletion in the cag pathogenicity island that truncated CagA and eliminated some of the type IV secretion system genes. Thus, the unusual V225d cag architecture was fully functional via conserved elements, but the natural deletion of 13 cag pathogenicity island genes and the truncation of CagA impaired the ability to induce inflammation
— id: 109966, year: 2010, vol: 192, page: 3078, stat: Journal Article,

Longitudinal Analysis of Serological Responses of Adults to Helicobacter pylori Antigens
Perez-Perez, Guillermo I; Maw, Anna M; Feingold-Link, Lani; Gunn, Jennifer; Bowers, Andrea L; Minano, Cecilia; Rautelin, Hilpi; Kosunen, Timo U; Blaser, Martin J
2010 Sep 15;202(6):916-923, Journal of infectious diseases
Because Helicobacter pylori persist for decades in the human stomach, the aim of this study was to examine the long-term course of H. pylori-specific serum immunoglobulin G (IgG) responses with respect to subclass and antigenic target. We studied paired serum samples obtained in 1973 and in 1994 in Vammala, Finland, from 64 healthy H. pylori-positive adults and from other healthy control subjects. H. pylori serum immunoglobulin A, IgG, and IgG subclass responses were determined by antigen-specific enzyme-linked immunosorbent assays. H. pylori-specific IgG1 and IgG4 subtype responses from 47 subjects were similar in 1973 and 1994, but not when compared with unrelated persons. H. pylori-specific IgG1:IgG4 ratios among the participants varied >1000-fold; however, 57 (89.1%) of 64 subjects had an IgG1:IgG4 ratio >1.0, consistent with a predominant IgG1 (Th1) response. Furthermore, ratios in individual hosts were stable over the 21-year period ([Formula: see text]; [Formula: see text]). The immune response to heat shock protein HspA was unchanged in 49 (77%) of the 64 subjects tested; of the 15 whose serostatus changed, all seroconverted and were significantly younger than those whose status did not change. These findings indicate that H. pylori-specific antibody responses are host-specific with IgG1:IgG4 ratios stable over 21 years, IgG1 responses predominating, and HspA seroconversion with aging
— id: 111828, year: 2010, vol: 202, page: 916, stat: Journal Article,

Streptococcus gallolyticus subspecies pasteurianus (biotype II/2), a newly reported cause of adult meningitis
Sturt, Amy S; Yang, Liying; Sandhu, Kuldip; Pei, Zhiheng; Cassai, Nicholas; Blaser, Martin J
2010 Jun;48(6):2247-2249, Journal of clinical microbiology
We report the first case of adult meningitis confirmed to be due to Streptococcus gallolyticus subsp. pasteurianus. Phenotypically reported as Streptococcus bovis biotype II/2, 16S rRNA sequencing revealed S. gallolyticus subsp. pasteurianus. Because of taxonomic uncertainties, S. gallolyticus subsp. pasteurianus may be an underrecognized agent of systemic infections
— id: 133500, year: 2010, vol: 48, page: 2247, stat: Journal Article,

Pre-symptomatic Influenza Transmission, Surveillance, and School Closings: Implications for Novel Influenza A (H1N1)
Webb, G. F.; Hsieh, Y-H.; Wu, J.; Blaser, M. J.
2010 FEB ;5(3):191-205, Mathematical modelling of natural phenomena. MMNP
Early studies of the novel swine-origin 2009 influenza A (H1N1) epidemic indicate clinical attack rates in children much higher than in adults. Non-medical interventions such as school closings are constrained by their large socio-economic costs. Here we develop a mathematical model to ascertain the roles of pre-symptomatic influenza transmission as well as symptoms surveillance of children to assess the utility of school closures. Our model analysis indicates that school closings are advisable when pre-symptomatic transmission is significant or when removal of symptomatic children is inefficient. Our objective is to provide a rational basis for school closings decisions dependent on virulence characteristics and local surveillance implementation, applicable to the current epidemic and future epidemics
— id: 124114, year: 2010, vol: 5, page: 191, stat: Journal Article,

Coadaptation of Helicobacter pylori and humans: ancient history, modern implications
Atherton, JC; Blaser, MJ
2009 SEP ;119(9):2475-2487, Journal of clinical investigation
Humans have been colonized by Helicobacterpylori for at least 50,000 years and probably throughout their evolution. H. pylori has adapted to humans, colonizing children and persisting throughout life. Most strains possess factors that subtly modulate the host environment, increasing the risk of peptic ulceration, gastric adenocarcinoma, and possibly other diseases. H. pylori genes encoding these and other factors rapidly evolve through mutation and recombination, changing the bacteria-host interaction. Although immune and physiologic responses to H. pylori also contribute to pathogenesis, humans have evolved in concert with the bacterium, and its recent absence throughout the life of many individuals has led to new human physiological changes. These may have contributed to recent increases in esophageal adenocarcinoma and, more speculatively, other modern diseases
— id: 102461, year: 2009, vol: 119, page: 2475, stat: Journal Article,

Helicobacter pylori Genome Plasticity
Baltrus, D A; Blaser, M J; Guillemin, K
2009 ;6:75-90, Genome dynamics
Helicobacter pylori, a Gram-negative pathogen associated with ulcers, chronic gastritis, and gastric cancers, has been a resident of the human stomach since early human history [1]. This association has only recently begun to erode with the advent of antibiotics and modern lifestyles, but even today H. pylori colonizes approximately half the world's population. To have remained a successful colonizer of humans during thousands of years of association, populations of H. pylori must have been able to survive and adapt to countless evolutionary challenges within and between hosts. As a species, H. pylori possesses one of the most fluid genomes within the prokaryotic kingdom [2], a characteristic that has likely aided its continued success. H. pylori exhibits exceptionally high rates of DNA point mutations, intragenomic recombination (facilitated by repetitive elements common in H. pylori genomes), and intergenomic recombination (mediated by natural transformation), all of which contribute to the high genomic variability between isolates. Previous reviews have focused on these processes as agents of evolutionary change within H. pylori [2-8]. The mechanisms of both mutation and natural transformation, and the evolutionary processes that retain genetic variation generated by these mechanisms, dictate the extent to which each contributes to genomic diversity in the context of different bacterial population structures [9-13]. Unlike well-studied evolutionary systems, such as Salmonella and Escherichia coli, H. pylori is notable in its lack of an environmental reservoir outside of human and other primate stomachs, suggesting that between-host survival is a relatively weak determinant of selection pressures [14, 15]. Given that H. pylori exist largely as distinct host-associated populations, it is possible to begin to model the evolutionary mechanisms that affect the long-term persistence of this species. In this chapter, we consider how the attributes of H. pylori's natural history as a long-term resident of the human stomach and the specific mechanisms of mutation and genetic exchange in this organism have shaped the H. pylori genome. We begin with a survey of genome plasticity in H. pylori. We then discuss mechanisms of mutation and natural transformation in H. pylori and examine experimental evidence for the generation of genomic changes within populations. Finally, we consider how different models of H. pylori population structure affect the relative contributions of mutation and recombination to the evolutionary success of this organism. By bridging evolutionary studies with investigations of pathogenesis from a molecular perspective, we hope to shed new light on how H. pylori has and continues to evolve with its human hosts
— id: 133757, year: 2009, vol: 6, page: 75, stat: Journal Article,

What are the consequences of the disappearing human microbiota?
Blaser, Martin J; Falkow, Stanley
2009 Dec;7(12):887-894, Nature reviews. Microbiology
Humans and our ancestors have evolved since the most ancient times with a commensal microbiota. The conservation of indicator species in a niche-specific manner across all of the studied human population groups suggests that the microbiota confer conserved benefits on humans. Nevertheless, certain of these organisms have pathogenic properties and, through medical practices and lifestyle changes, their prevalence in human populations is changing, often to an extreme degree. In this Essay, we propose that the disappearance of these ancestral indigenous organisms, which are intimately involved in human physiology, is not entirely beneficial and has consequences that might include post-modern conditions such as obesity and asthma
— id: 105338, year: 2009, vol: 7, page: 887, stat: Journal Article,

Reply to raj et Al
Chen, Yu; Blaser, Martin J
2009 Mar 15;199(6):915-916, Journal of infectious diseases
— id: 95157, year: 2009, vol: 199, page: 915, stat: Journal Article,

Helicobacter pylori in health and disease
Cover, Timothy L; Blaser, Martin J
2009 May;136(6):1863-1873, Gastroenterology
Helicobacter pylori is highly adapted for colonization of the human stomach and is present in about half of the human population. When present, H pylori is usually the numerically dominant gastric microorganism. H pylori typically does not cause any adverse effects, but it is associated with an increased risk of noncardia gastric adenocarcinoma, gastric lymphoma, and peptic ulcer. Disorders such as esophageal diseases and childhood-onset asthma were recently reported to occur more frequently in individuals who lack H pylori than in H pylori-positive persons. In this review, we discuss biologic factors that allow H pylori to colonize the human stomach, mechanisms by which H pylori increases the risk of peptic ulcer disease and noncardia gastric adenocarcinoma, and potential benefits that H pylori might confer to humans
— id: 133687, year: 2009, vol: 136, page: 1863, stat: Journal Article,

Natural transformation of helicobacter pylori involves the integration of short DNA fragments interrupted by gaps of variable size
Lin, Edward A; Zhang, Xue-Song; Levine, Steven M; Gill, Steven R; Falush, Daniel; Blaser, Martin J
2009 Mar;5(3):e1000337-e1000337, PLoS pathogens
Helicobacter pylori are gram-negative bacteria notable for their high level of genetic diversity and plasticity, features that may play a key role in the organism's ability to colonize the human stomach. Homeologous natural transformation, a key contributor to genomic diversification, has been well-described for H. pylori. To examine the mechanisms involved, we performed restriction analysis and sequencing of recombination products to characterize the length, fragmentation, and position of DNA imported via natural transformation. Our analysis revealed DNA imports of small size (1,300 bp, 95% confidence limits 950-1850 bp) with instances of substantial asymmetry in relation to selectable antibiotic-resistance markers. We also observed clustering of imported DNA endpoints, suggesting a possible role for restriction endonucleases in limiting recombination length. Additionally, we observed gaps in integrated DNA and found evidence suggesting that these gaps are the result of two or more separate strand invasions. Taken together, these observations support a system of highly efficient short-fragment recombination involving multiple recombination events within a single locus
— id: 95156, year: 2009, vol: 5, page: e1000337, stat: Journal Article,

Diversity of 23S rRNA genes within individual prokaryotic genomes
Pei, Anna; Nossa, Carlos W; Chokshi, Pooja; Blaser, Martin J; Yang, Liying; Rosmarin, David M; Pei, Zhiheng
2009 ;4(5):e5437-e5437, PLoS ONE
BACKGROUND: The concept of ribosomal constraints on rRNA genes is deduced primarily based on the comparison of consensus rRNA sequences between closely related species, but recent advances in whole-genome sequencing allow evaluation of this concept within organisms with multiple rRNA operons. METHODOLOGY/PRINCIPAL FINDINGS: Using the 23S rRNA gene as an example, we analyzed the diversity among individual rRNA genes within a genome. Of 184 prokaryotic species containing multiple 23S rRNA genes, diversity was observed in 113 (61.4%) genomes (mean 0.40%, range 0.01%-4.04%). Significant (1.17%-4.04%) intragenomic variation was found in 8 species. In 5 of the 8 species, the diversity in the primary structure had only minimal effect on the secondary structure (stem versus loop transition). In the remaining 3 species, the diversity significantly altered local secondary structure, but the alteration appears minimized through complex rearrangement. Intervening sequences (IVS), ranging between 9 and 1471 nt in size, were found in 7 species. IVS in Deinococcus radiodurans and Nostoc sp. encode transposases. T. tengcongensis was the only species in which intragenomic diversity >3% was observed among 4 paralogous 23S rRNA genes. CONCLUSIONS/SIGNIFICANCE: These findings indicate tight ribosomal constraints on individual 23S rRNA genes within a genome. Although classification using primary 23S rRNA sequences could be erroneous, significant diversity among paralogous 23S rRNA genes was observed only once in the 184 species analyzed, indicating little overall impact on the mainstream of 23S rRNA gene-based prokaryotic taxonomy
— id: 106442, year: 2009, vol: 4, page: e5437, stat: Journal Article,

Host-dependent Lewis (Le) antigen expression in Helicobacter pylori cells recovered from Leb-transgenic mice
Pohl, Mary Ann; Romero-Gallo, Judith; Guruge, Janaki L; Tse, Doris B; Gordon, Jeffrey I; Blaser, Martin J
2009 Dec 21;206(13):3061-3072, Journal of experimental medicine
Variation of surface antigen expression is a mechanism used by microbes to adapt to and persist within their host habitats. Helicobacter pylori, a persistent bacterial colonizer of the human stomach, can alter its surface Lewis (Le) antigen expression. We examined H. pylori colonization in mice to test the hypothesis that host phenotype selects for H. pylori (Le) phenotypes. When wild-type and Le(b)-expressing transgenic FVB/N mice were challenged with H. pylori strain HP1, expressing Le(x) and Le(y), we found that bacterial populations recovered after 8 mo from Le(b)-transgenic, but not wild-type, mice expressed Le(b). Changes in Le phenotype were linked to variation of a putative galactosyltransferase gene (beta-(1,3)galT); mutagenesis and complementation revealed its essential role in type I antigen expression. These studies indicate that H. pylori evolves to resemble the host's gastric Le phenotype, and reveal a bacterial genetic locus that is subject to host-driven selection pressure
— id: 105979, year: 2009, vol: 206, page: 3061, stat: Journal Article,

Repeat-associated plasticity in the Helicobacter pylori RD gene family
Shak, Joshua R; Dick, Jonathan J; Meinersmann, Richard J; Perez-Perez, Guillermo I; Blaser, Martin J
2009 Nov;191(22):6900-6910, Journal of bacteriology
The bacterium Helicobacter pylori is remarkable for its ability to persist in the human stomach for decades without provoking sterilizing immunity. Since repetitive DNA can facilitate adaptive genomic flexibility via increased recombination, insertion, and deletion, we searched the genomes of two H. pylori strains for nucleotide repeats. We discovered a family of genes with extensive repetitive DNA that we have termed the H. pylori RD gene family. Each gene of this family is composed of a conserved 3' region, a variable mid-region encoding 7 and 11 amino acid repeats, and a 5' region containing one of two possible alleles. Analysis of five complete genome sequences and PCR genotyping of 42 H. pylori strains revealed extensive variation between strains in the number, location, and arrangement of RD genes. Furthermore, examination of multiple strains isolated from a single subject's stomach revealed intrahost variation in repeat number and composition. Despite prior evidence that the protein products of this gene family are expressed at the bacterial cell surface, enzyme-linked immunosorbent assay and immunoblot studies revealed no consistent seroreactivity to a recombinant RD protein by H. pylori-positive hosts. The pattern of repeats uncovered in the RD gene family appears to reflect slipped-strand mispairing or domain duplication, allowing for redundancy and subsequent diversity in genotype and phenotype. This novel family of hypervariable genes with conserved, repetitive, and allelic domains may represent an important locus for understanding H. pylori persistence in its natural host
— id: 104893, year: 2009, vol: 191, page: 6900, stat: Journal Article,

Genetic Variation in a4GnT in Relation to Helicobacter pylori Serology and Gastric Cancer Risk
Zheng, ZL; Jia, YB; Hou, LF; Persson, C; Yeager, M; Lissowska, J; Chanock, SJ; Blaser, M; Chow, WH; Ye, WM
2009 OCT ;14(5):120-125, Helicobacter
Background: Helicobacter pylori, a known risk factor of gastric cancer, rarely colonize the deeper portion of normal gastric glands, where the mucus is rich in alpha-1,4-linked N-acetylglucosamine capped O-glycans, that strongly inhibit H. pylori growth in vitro. Materials and methods: We investigated the association between genetic variation in the O-glycan transferase encoding gene (a4GnT) and H. pylori infection and gastric cancer risk using a Polish population-based case-control study (273 gastric cancer patients and 377 controls). Results: A haplotype at the rs2622694-rs397266 locus was associated with H. pylori infection, with the A-A haplotype associated with a higher risk compared with the most frequent G-G haplotype (odds ratio 2.30; 95% confidence interval 1.35-3.92). The association remained significant after correction for multiple tests (global p value: nominal 0.002, empirical 0.045). Neither this haplotype nor the tagSNPs were associated with overall gastric cancer risk. Conclusion: a4GnT genetic variation may be relevant to H. pylori infection, but not to gastric cancer risk
— id: 102302, year: 2009, vol: 14, page: 120, stat: Journal Article,

Disappearing microbiota: Helicobacter pylori protection against esophageal adenocarcinoma
Blaser, Martin J
2008 Oct;1(5):308-311, Cancer prevention research (Philadelphia, Pa.)
— id: 95158, year: 2008, vol: 1, page: 308, stat: Journal Article,

Understanding microbe-induced cancers
Blaser, Martin J
2008 Jun;1(1):15-20, Cancer prevention research (Philadelphia, Pa.)
Microbes are important causes of human cancers, and our estimation of their significance continues to grow as cancer biology is better dissected. A classification system is proposed that highlights common and proposed microbe-induced pathways toward oncogenesis, with an emphasis on types of targeted cells and host-microbial interactions. The central principles that underlie oncogenesis induced by the many diverse microbes and the major mechanisms involved are outlined. The phenomenon of microbe-induced cancers raises a number of important biological questions, the solving of which may inform other fields, including aging and degenerative disorders. Finally, our challenge for the future is to better understand the steps in microbe-induced cancers to optimize both prevention and therapy
— id: 93570, year: 2008, vol: 1, page: 15, stat: Journal Article,

Does Helicobacter pylori protect against asthma and allergy?
Blaser, Martin J; Chen, Yu; Reibman, Joan
2008 May;57(5):561-567, Gut: journal of the British Society of Gastroenterology
The microbes that persistently colonize their vertebrate hosts are not accidental (1). Although highly numerous and diverse, there is specificity by site and substantial conservation between individuals. The genus Helicobacter includes spiral, highly motile, urease-positive, gram-negative bacteria that colonize the stomach in many mammals. Each mammal has one or more dominant Helicobacter species and they are highly, if not exclusively, host species-specific (2). Such observations are consistent with the hypothesis that when ancestral mammals diverged from reptiles about 150 million years ago, they contained ancestral helicobacters, which then diverged as their hosts changed. According to this hypothesis, helicobacters represent ancestral biota (flora) in the mammalian stomach. The human-adapted strain is H. pylori (3), which has not been reproducibly observed in any animals other than humans and other primates (3)
— id: 76054, year: 2008, vol: 57, page: 561, stat: Journal Article,

Viral commensalism in humans?
Blaser, Martin J; Valentine, Fred T
2008 Jul 1;198(1):1-3, Journal of infectious diseases
— id: 79202, year: 2008, vol: 198, page: 1, stat: Journal Article,

Helicobacter pylori Colonization Is Inversely Associated with Childhood Asthma
Chen, Yu; Blaser, Martin J
2008 Aug 15;198(4):553-560, Journal of infectious diseases
Background. @nbsp; Asthma, a serious health problem worldwide, is becoming more common. Colonization with Helicobacter pylori, a major human indigenous (commensal) microbe, during early life may be relevant to the risk of childhood asthma. Methods. @nbsp; We conducted cross-sectional analyses, using data from 7412 participants in the National Health and Nutrition Examination Survey (NHANES) 1999-2000, to assess the association between H. pylori and childhood asthma. Results. @nbsp; H. pylori seropositivity was inversely associated with onset of asthma before 5 years of age and current asthma in children aged 3-13 years. Among participants 3-19 years of age, the presence of H. pylori was inversely related to ever having had asthma (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.45-1.06), and the inverse association with onset of asthma before 5 years of age was stronger (OR, 0.58; 95% CI, 0.38-0.88). Among participants 3-13 years of age, H. pylori positivity was significantly inversely associated with current asthma (OR, 0.41; 95% CI, 0.24-0.69). H. pylori seropositivity also was inversely related to recent wheezing, allergic rhinitis, and dermatitis, eczema, or rash. Conclusions. @nbsp; This study is the first to report an inverse association between H. pylori seropositivity and asthma in children. The findings indicate new directions for research and asthma prevention
— id: 80354, year: 2008, vol: 198, page: 553, stat: Journal Article,

Do you have a probiotic in your future?
Dominguez-Bello, Maria G; Blaser, Martin J
2008 Jul;10(9):1072-1076, Microbes & infection
The possibility of using microbes to maintain health, and to prevent or treat disease is a topic as old as microbiology. However, one factor impeding the introduction of effective probiotics has been our very limited understanding of the composition of the human microbiome, as well as the biological requirements for these organisms. With advances in understanding the microbiome and its metagenome in humans and other mammals, we now can build a more robust scientific basis to develop probiotic strategies. Increasing knowledge of intramicrobial competition and cooperation, as well as host-microbe cross-signaling, will facilitate design of new probiotics and the modeling of their deployment, leading to eventual clinical trials
— id: 95159, year: 2008, vol: 10, page: 1072, stat: Journal Article,

Association of Helicobacter pylori infection and diet on the risk of gastric cancer: a case-control study in Hawaii
Epplein, Meira; Nomura, Abraham M Y; Hankin, Jean H; Blaser, Martin J; Perez-Perez, Guillermo; Stemmermann, Grant N; Wilkens, Lynne R; Kolonel, Laurence N
2008 Oct;19(8):869-877, Cancer causes & control. ccc
OBJECTIVE: The risk factors most strongly associated with gastric cancer are the gastric bacteria Helicobacter pylori and diet. Utilizing data from a case-control study among residents in Hawaii, we examined the association of diet, presence of H. pylori, and non-cardia gastric cancer risk. METHODS: Serum taken at diagnosis for cases (n = 212) and at interview for controls (n = 336) was assayed for IgG antibodies to H. pylori group antigens and to a recombinant fragment of the cytotoxin-associated antigen A (CagA) protein, and subjects completed food frequency questionnaires. Risk measures were calculated using logistic regression. The likelihood ratio test was used to assess interactions. RESULTS: Inverse associations were found between gastric cancer risk and increasing intake of several micronutrients and vegetables among all individuals. For H. pylori/CagA-positive subjects, significant trends were present for total, green, and yellow vegetables, while a significant trend was present only for yellow vegetables among H. pylori/CagA-negative individuals. For intestinal gastric cancer, there was a suggestion that intake of vegetables, especially cruciferous vegetables, had a stronger protective effect for the H. pylori/CagA-positive group. CONCLUSIONS: Diet may play a greater role in the etiology of non-cardia gastric cancer among individuals with evidence of H. pylori infection than among those without
— id: 79187, year: 2008, vol: 19, page: 869, stat: Journal Article,

The association of gastric leptin with oesophageal inflammation and metaplasia
Francois, F; Roper, J; Goodman, A J; Pei, Z; Ghumman, M; Mourad, M; de Perez, A Z Olivares; Perez-Perez, G I; Tseng, C-H; Blaser, M J
2008 Jan;57(1):16-24, Gut: journal of the British Society of Gastroenterology
BACKGROUND: Gastro-oesophageal reflux disease complications may reflect imbalances between protective and injurious factors. Through its effects on cell growth, leptin may influence oesophageal mucosal homeostasis. AIMS: To determine whether leptin receptors are present in the oesophagus, and whether serum or gastric leptin levels are associated with oesophageal inflammation and metaplasia. METHODS: From patients referred for upper endoscopy, biopsies were obtained from the stomach and distal oesophagus, and serum samples were collected. Patients were classified as having normal, inflamed or Barrett's oesophagus. Quantitative immunohistochemistry was performed on representative sections, and leptin levels in plasma and gastric biopsy samples were determined by specific immunoassay. RESULTS: Of 269 individuals enrolled, 105 were Helicobacter pylori-negative. Of the 88 patients with complete oesophageal biopsies, 44 were normal, 24 were inflamed and 20 were Barrett's oesophagus. Receptors for leptin were highly expressed on oesophageal epithelial cells, with similar density and staining pattern in all three conditions, and plasma and antral leptin levels did not differ significantly. Patients with Barrett's had significantly (p = 0.01) higher fundic leptin levels (median 202 (interquartile range 123-333) pg/mg) compared with normal (126 (78-221) pg/mg) or inflamed (114 (76-195) pg/mg) oesophagus. In multivariate analysis, for every twofold increase in fundic leptin, the odds of having Barrett's was 3.4 times (95% CI 1.5 to 7.6) higher compared with having a normal oesophagus. CONCLUSIONS: Leptin receptor expression on oesophageal epithelial cells provides a pathway for leptin-mediated signal transduction. Variation in gastric leptin production could contribute to differential oesophageal healing and metaplasia progression
— id: 75709, year: 2008, vol: 57, page: 16, stat: Journal Article,

Substantial alterations of the cutaneous bacterial biota in psoriatic lesions
Gao, Zhan; Tseng, Chi-hong; Strober, Bruce E; Pei, Zhiheng; Blaser, Martin J
2008 ;3(7):e2719-e2719, PLoS ONE
For psoriasis, an idiopathic inflammatory disorder of the skin, the microbial biota has not been defined using cultivation-independent methods. We used broad-range 16S rDNA PCR for archaea and bacteria to examine the microbiota of normal and psoriatic skin. From 6 patients, 19 cutaneous samples (13 from diseased skin and 6 from normal skin) were obtained. Extracted DNA was subjected to the broad range PCR, and 1,925 cloned products were compared with 2,038 products previously reported from healthy persons. Using 98% sequence identity as a species boundary, 1,841 (95.6%) clones were similar to known bacterial 16S rDNA, representing 6 phyla, 86 genera, or 189 species-level operational taxonomic unit (SLOTU); 84 (4.4%) clones with <98% identity probably represented novel species. The most abundant and diverse phylum populating the psoriatic lesions was Firmicutes (46.2%), significantly (P<0.001) overrepresented, compared to the samples from uninvolved skin of the patients (39.0%) and healthy persons (24.4%). In contrast, Actinobacteria, the most prevalent and diverse phylum in normal skin samples from both healthy persons (47.6%) and the patients (47.8%), was significantly (P<0.01) underrepresented in the psoriatic lesion samples (37.3%). Representation of Propionibacterium species were lower in the psoriatic lesions (2.9+/-5.5%) than from normal persons (21.1+/-18.2%; P<0.001), whereas normal skin from the psoriatic patients showed intermediate levels (12.3+/-21.6%). We conclude that psoriasis is associated with substantial alteration in the composition and representation of the cutaneous bacterial biota
— id: 86553, year: 2008, vol: 3, page: e2719, stat: Journal Article,

Bacterial community in the crop of the hoatzin, a neotropical folivorous flying bird
Godoy-Vitorino, Filipa; Ley, Ruth E; Gao, Zhan; Pei, Zhiheng; Ortiz-Zuazaga, Humberto; Pericchi, Luis R; Garcia-Amado, Maria A; Michelangeli, Fabian; Blaser, Martin J; Gordon, Jeffrey I; Dominguez-Bello, Maria G
2008 Oct;74(19):5905-5912, Applied & environmental microbiology
The hoatzin is unique among known avian species because of the fermentative function of its enlarged crop. A small-bodied flying foregut fermenter is a paradox, and this bird provides an interesting model to examine how diet selection and the gut microbiota contribute to maximizing digestive efficiency. Therefore, we characterized the bacterial population in the crop of six adult hoatzins captured from the wild. A total of 1,235 16S rRNA gene sequences were grouped into 580 phylotypes (67% of the pooled species richness sampled, based on Good's coverage estimator, with C(ACE) and Chao1 estimates of 1,709 and 1,795 species-level [99% identity] operational taxonomic units, respectively). Members of 9 of the approximately 75 known phyla in Bacteria were identified in this gut habitat; the Firmicutes were dominant (67% of sequences, belonging to the classes Clostridia, Mollicutes, and Bacilli), followed by the Bacteroidetes (30%, mostly in the order Bacteroidales), Proteobacteria (1.8%), and Lentisphaerae, Verrucomicrobia, TM7, Spirochaetes, Actinobacteria, and Aminanaerobia (all <0.1%). The novelty in this ecosystem is great; 94% of the phylotypes were unclassified at the 'species' level and thus likely include novel cellulolytic lineages
— id: 95160, year: 2008, vol: 74, page: 5905, stat: Journal Article,

Reactive nitrogen species contribute to innate host defense against Campylobacter jejuni
Iovine, Nicole M; Pursnani, Seema; Voldman, Alex; Wasserman, Gregory; Blaser, Martin J; Weinrauch, Yvette
2008 Mar;76(3):986-993, Infection & immunity
Campylobacter jejuni, a gram-negative, invasive organism, is a common cause of food-borne bacterial diarrheal disease. However, the relationship between C. jejuni and the innate immune system is not well described. To better characterize host defense against C. jejuni, we investigated the ability of nitric oxide/reactive nitrogen species to kill two strains of C. jejuni. C. jejuni viability was measured after exposure to reactive nitrogen species produced biochemically as acidified nitrite and by bone marrow-derived macrophages. We report that acidified nitrite caused a 3-log-increased kill of C. jejuni (P < 0.05) at doses that did not affect the viability of Salmonella enterica serovar Typhimurium. Expression of NOS2, the gene responsible for the production of inducible nitric oxide, was increased >100-fold in murine macrophages after incubation with C. jejuni (P < 0.001). These macrophages effected a 2-log-increased kill of C. jejuni over 24 h compared to that by NOS2-/- macrophages unable to produce nitric oxide (P < 0.05). These findings suggest that the mammalian host upregulates the production of nitric oxide in response to exposure to C. jejuni and that nitric oxide and reactive nitrogen species comprise part of the innate defense mechanisms that contribute to the resolution of C. jejuni infection
— id: 76388, year: 2008, vol: 76, page: 986, stat: Journal Article,

Repair and antirepair DNA helicases in Helicobacter pylori
Kang, Josephine; Blaser, Martin J
2008 Jun;190(12):4218-4224, Journal of bacteriology
Orthologs of RecG and RuvABC are highly conserved among prokaryotes; in Escherichia coli, they participate in independent pathways that branch migrate Holliday junctions during recombinational DNA repair. RecG also has been shown to directly convert stalled replication forks into Holliday junctions. The bacterium Helicobacter pylori, with remarkably high levels of recombination, possesses RecG and RuvABC homologs, but in contrast to E. coli, H. pylori RecG limits recombinational repair. We now show that the RuvABC pathway plays the prominent, if not exclusive, repair role. By introducing an E. coli resolvase (RusA) into H. pylori, the repair and recombination phenotypes of the ruvB mutant but not the recG mutant were improved. Our results indicate that RecG and RuvB compete for Holliday junction structures in recombinational repair, but since a classic RecG resolvase is absent from H. pylori, deployment of the RecG pathway is lethal. We propose that evolutionary loss of the H. pylori RecG resolvase provides an 'antirepair' pathway allowing for selection of varied strains. Such competition between repair and antirepair provides a novel mechanism to maximize fitness at a bacterial population level
— id: 79203, year: 2008, vol: 190, page: 4218, stat: Journal Article,

Rate heterogeneity in the evolution of Helicobacter pylori and the behavior of homoplastic sites
Meinersmann, Richard J; Romero-Gallo, Judith; Blaser, Martin J
2008 Sep;8(5):593-602, Infection, Genetics & Evolution
Helicobacter pylori are bacteria with substantial inter-strain variability and phylogenetic reconstructions of sequence data from the organism have common homoplastic sites. Although frequent recombination events have been proposed to contribute to the variation, the effects of nucleotide substitution rate heterogeneities on the reconstruction of H. pylori genealogies have not been studied. We analyzed the substitution pattern of a housekeeping gene, a homologue of the ribonuclease reductase gene (rnr), to characterize rate heterogeneities between 11 H. pylori isolates. Evidence of limited recombination was demonstrated by the Sawyer's runs test, but the homoplasy test and site-by-site compatibility tests indicated frequent recombination events. Within the 1935 nucleotide gene, 292 sites were polymorphic with an average pair-wise difference of 5.01%. Xia's distances for amino acids at non-synonymous codon substitution sites were smaller at homoplastic sites than at sites that were not homoplastic. Transitions were significantly more common among homoplastic than among non-homoplastic nucleotide substitutions. Simulations of evolution with or without recombination indicated the transition/transversion ratio is expected to be higher in homoplastic sites with no recombination. Despite evidence of recombination, analyses of the rnr genealogy does not show a random tree but rather base substitution behaviors characteristic of both recombination and substitution saturation at some sites. Analyses of sequences in the H. pylori multilocus sequence-typing database provided similar evidence for substitution saturation in multiple housekeeping genes
— id: 95161, year: 2008, vol: 8, page: 593, stat: Journal Article,

Campylobacter
Nachamkin, Irving; Blaser, Martin J
Washington DC : ASM Press, 2008,
— id: 2004, year: 2008, vol: , page: , stat: ,

Analysis of Malassezia microbiota in healthy superficial human skin and in psoriatic lesions by multiplex real-time PCR
Paulino, Luciana C; Tseng, Chi-Hong; Blaser, Martin J
2008 May;8(3):460-471, FEMS yeast research
Yeasts from the genus Malassezia are members of the normal biota of human skin, and may play a role in dermatopathology. Our previous study of the fungal microbiota from healthy subjects and from patients with psoriasis using clone library analysis revealed the presence of five Malassezia species and four uncharacterized phylotypes. We now compared the Malassezia microbiota from six healthy body locations and two psoriatic lesions, and evaluated its stability over time using multiplex real-time PCR. Samples from each body location were obtained monthly, for 4 months. Dual-labeled probes were designed to recognize four Malassezia sp. and two uncharacterized groups, and a genus-specific probe was also developed. A good correspondence was obtained between real-time PCR data and clone library analyses. Malassezia restricta was the most abundant species in the majority of samples, and high amounts of Malassezia globosa were also detected. The uncharacterized phylotype 1 was usually detected in lower proportions, nevertheless it was present in most samples. The microbiota was host-specific and relatively stable over time. In accordance with our previous observations, no significant dichotomy between samples from healthy skin and from psoriatic lesions was found; the samples clustered according to the subject, rather than health status
— id: 79204, year: 2008, vol: 8, page: 460, stat: Journal Article,

Asthma is inversely associated with Helicobacter pylori status in an urban population
Reibman, Joan; Marmor, Michael; Filner, Joshua; Fernandez-Beros, Maria-Elena; Rogers, Linda; Perez-Perez, Guillermo I; Blaser, Martin J
2008 ;3(12):e4060-e4060, PLoS ONE
BACKGROUND: Microbial exposures have been suggested to confer protection from allergic disorders and reduced exposures to gastrointestinal microbiota have been proposed as an explanation for the increase in asthma prevalence. Since the general prevalence of Helicobacter pylori has been decreasing, we hypothesized that H. pylori serostatus would be inversely related to the presence of asthma. METHODS: Adults were recruited to participate in the New York University (NYU)/Bellevue Asthma Registry in New York City. Adult asthma cases (N = 318) and controls (N = 208) were identified and serum IgG antibodies to H. pylori whole cell antigens or the immunodominant CagA antigen were measured. RESULTS: As expected, the asthma cases and controls differed with respect to atopy and lung function. Seropositivity to H. pylori or CagA antigen was present in 47.1% of the total case and control study population. Asthma was inversely associated with CagA seropositivity (OR = 0.57, 95% CI = 0.36-0.89). Median age of onset of asthma (doctor's diagnosis) was older (21 years) among individuals with CagA+ strains than among H. pylori- individuals (11 years) (p = 0.006). CONCLUSION: These data are consistent with the hypothesis that colonization with CagA+ H. pylori strains is inversely associated with asthma and is associated with an older age of asthma onset in an urban population. The data suggest H. pylori as a marker for protection
— id: 91964, year: 2008, vol: 3, page: e4060, stat: Journal Article,

Leptin and ghrelin in relation to Helicobacter pylori status in adult males
Roper, Jatin; Francois, Fritz; Shue, Peter L; Mourad, Michelle S; Pei, Zhiheng; Olivares de Perez, Asalia Z; Perez-Perez, Guillermo I; Tseng, Chi-Hong; Blaser, Martin J
2008 Jun;93(6):2350-2357, Journal of clinical endocrinology & metabolism
Context: Leptin and ghrelin, hormones involved in human energy homeostasis, are both produced in the stomach. Objective: We sought to determine whether the presence of Helicobacter pylori affects local and systemic levels of leptin and ghrelin. Design: Prospective Setting: Veterans Affairs outpatient endoscopy center Patients: 256 patients referred for upper endoscopy Outcomes: We obtained fasting serum, fundic and antral biopsies, and gastric juice. Based on histological, biochemical and serological assays, patients were categorized as H. pylori+ or H. pylori-. Leptin and total ghrelin levels in serum, gastric biopsies and gastric juice were determined by specific ELISAs. Results: Of the 256 subjects, 120 were H. pylori+ and 96 were H. pylori-; 40 patients of indeterminant status were excluded. Serum and fundic leptin levels correlated with Body Mass Index in the H. pylori+ (R=0.35, p<0.0001 and R=0.35, p<0.0001, respectively) and H. pylori- (R=0.65, p<0.0001 and R=0.41, p<0.0001, respectively) groups, but H. pylori+ subjects had significantly lower serum leptin levels [median 2.2 ng/ml, IQR (0.9-4.6) vs. 4.0 ng/ml, (1.7-7.2); p=0.0003]. Serum ghrelin levels were similar in the H. pylori+ and H. pylori- groups [median 1651 pg/ml, IQR (845-2247) vs. 1629 pg/ml, (992-2886); p=0.23]. H. pylori status did not significantly affect gastric biopsy leptin and ghrelin levels. Ghrelin levels in gastric juice varied over 4 log10 (<80-776,000 pg/ml) and correlated with gastric juice pH in the H. pylori+ group (R=0.68, p<0.0001). Conclusions: These findings provide evidence that H. pylori status affects leptin and ghrelin homeostasis, presumably via intragastric interactions
— id: 78624, year: 2008, vol: 93, page: 2350, stat: Journal Article,

The Effect of Laparoscopic Gastric Banding Surgery on Plasma Levels of Appetite-Control, Insulinotropic, and Digestive Hormones
Shak, Joshua R; Roper, Jatin; Perez-Perez, Guillermo I; Tseng, Chi-hong; Francois, Fritz; Gamagaris, Zoi; Patterson, Carlie; Weinshel, Elizabeth; Fielding, George A; Ren, Christine; Blaser, Martin J
2008 Sep;18(9):1089-1096, Obesity surgery
BACKGROUND: We hypothesized that laparoscopic adjustable gastric banding (LAGB) reduces weight and modulates ghrelin production, but largely spares gastrointestinal endocrine function. To examine this hypothesis, we determined plasma concentrations of appetite-control, insulinotropic, and digestive hormones in relation to LAGB. METHODS: Twenty-four patients undergoing LAGB were prospectively enrolled. Body mass index (BMI) was measured and blood samples obtained at baseline and 6 and 12 months post-surgery. Plasma concentrations of leptin, acylated and total ghrelin, pancreatic polypeptide (PP), insulin, glucose-dependent insulinotropic peptide (GIP), active glucagon-like peptide-1 (GLP-1), gastrin, and pepsinogens I and II were measured using enzyme-linked immunoassays. RESULTS: Median percent excess weight loss (%EWL) over 12 months was 45.7% with median BMI decreasing from 43.2 at baseline to 33.8 at 12 months post-surgery (p < 0.001). Median leptin levels decreased from 19.7 ng/ml at baseline to 6.9 ng/ml at 12 months post-surgery (p < 0.001). In contrast, plasma levels of acylated and total ghrelin, PP, insulin, GIP, GLP-1, gastrin, and pepsinogen I did not change in relation to surgery (p > 0.05). Pepsinogen II levels were significantly lower 6 months after LAGB but returned to baseline levels by 12 months. CONCLUSIONS: LAGB yielded substantial %EWL and a proportional decrease in plasma leptin. Our results support the hypothesis that LAGB works in part by suppressing the rise in ghrelin that normally accompanies weight loss. Unchanged concentrations of insulinotropic and digestive hormones suggest that gastrointestinal endocrine function is largely maintained in the long term
— id: 78623, year: 2008, vol: 18, page: 1089, stat: Journal Article,

The equilibria that allow bacterial persistence in human hosts
Blaser, Martin J; Kirschner, Denise
2007 Oct 18;449(7164):843-849, Nature
We propose that microbes that have developed persistent relationships with human hosts have evolved cross-signalling mechanisms that permit homeostasis that conforms to Nash equilibria and, more specifically, to evolutionarily stable strategies. This implies that a group of highly diverse organisms has evolved within the changing contexts of variation in effective human population size and lifespan, shaping the equilibria achieved, and creating relationships resembling climax communities. We propose that such ecosystems contain nested communities in which equilibrium at one level contributes to homeostasis at another. The model can aid prediction of equilibrium states in the context of further change: widespread immunodeficiency, changing population densities, or extinctions
— id: 75392, year: 2007, vol: 449, page: 843, stat: Journal Article,

Early-life family structure and microbially induced cancer risk
Blaser, Martin J; Nomura, Abraham; Lee, James; Stemmerman, Grant N; Perez-Perez, Guillermo I
2007 Jan;4(1):e7-e7, PLoS medicine
BACKGROUND: Cancer may follow exposure to an environmental agent after many decades. The bacterium Helicobacter pylori, known to be acquired early in life, increases risk for gastric adenocarcinoma, but other factors are also important. In this study, we considered whether early-life family structure affects the risk of later developing gastric cancer among H. pylori+ men. METHODS AND FINDINGS: We examined a long-term cohort of Japanese-American men followed for 28 y, and performed a nested case-control study among those carrying H. pylori or the subset carrying the most virulent cagA+ H. pylori strains to address whether family structure predicted cancer development. We found that among the men who were H. pylori+ and/or cagA+ (it is possible to be cagA+ and H. pylori- if the H. pylori test is falsely negative), belonging to a large sibship or higher birth order was associated with a significantly increased risk of developing gastric adenocarcinoma late in life. For those with cagA+ strains, the risk of developing gastric cancer was more than twice as high (odds ratio 2.2; 95% confidence interval 1.2-4.0) among those in a sibship of seven or more individuals than in a sibship of between one and three persons. CONCLUSIONS: These results provide evidence that early-life social environment plays a significant role in risk of microbially induced malignancies expressing five to eight decades later, and these findings lead to new models to explain these interactions
— id: 79193, year: 2007, vol: 4, page: e7, stat: Journal Article,

Inverse Associations of Helicobacter pylori With Asthma and Allergy
Chen, Yu; Blaser, Martin J
2007 Apr 23;167(8):821-827, Archives of internal medicine
BACKGROUND: Acquisition of Helicobacter pylori, which predominantly occurs before age 10 years, may reduce risks of asthma and allergy. METHODS: We evaluated the associations of H pylori status with history of asthma and allergy and with skin sensitization using data from 7663 adults in the Third National Health and Nutrition Examination Survey. Adjusted odds ratios (ORs) for currently and ever having asthma, allergic rhinitis, allergy symptoms in the previous year, and allergen-specific skin sensitization were computed comparing participants seropositive for cagA(-) or cagA(+) strains of H pylori with those without H pylori. RESULTS: The presence of cagA(+) H pylori strains was inversely related to ever having asthma (OR, 0.79; 95% confidence interval [CI], 0.63-0.99), and the inverse association of cagA positivity with childhood-onset (age </=15 years) asthma was stronger (OR, 0.63; 95% CI, 0.43-0.93) than that with adult-onset asthma (OR, 0.97; 95% CI, 0.72-1.32). Colonization with H pylori, especially with a cagA(+) strain, was inversely associated with currently (OR, 0.77; 95% CI, 0.62-0.96) or ever (OR, 0.77; 95% CI, 0.62-0.94) having a diagnosis of allergic rhinitis, especially for childhood onset (OR, 0.55; 95% CI, 0.37-0.82). Consistent inverse associations were found between H pylori colonization and the presence of allergy symptoms in the previous year and sensitization to pollens and molds. CONCLUSION: These observations support the hypothesis that childhood acquisition of H pylori is associated with reduced risks of asthma and allergy
— id: 71638, year: 2007, vol: 167, page: 821, stat: Journal Article,

Another perfect storm: Shigella, men who have sex with men, and HIV
Daskalakis, Demetre C; Blaser, Martin J
2007 Feb 1;44(3):335-337, Clinical infectious diseases
— id: 78759, year: 2007, vol: 44, page: 335, stat: Journal Article,

Characterization of Campylobacter fetus strains originating in reptiles and closely related human strains by multilocus sequence typing
Dingle, KE; Blaser, MJ; Tu, ZC; Pruckler, J; Fitzgerald, C; Van Bergen, MA; Lawson, AJ; Owen, RJ; Wagenaar, JA
2007 JAN ;54(1):76-76, Zoonoses & public health
— id: 87168, year: 2007, vol: 54, page: 76, stat: Journal Article,

Molecular analysis of human forearm superficial skin bacterial biota
Gao, Zhan; Tseng, Chi-hong; Pei, Zhiheng; Blaser, Martin J
2007 Feb 20;104(8):2927-2932, Proceedings of the National Academy of Sciences of the United States of America
The microbial ecology of human skin is complex, but little is known about its species composition. We examined the diversity of the skin biota from the superficial volar left and right forearms in six healthy subjects using broad-range small subunit rRNA genes (16S rDNA) PCR-based sequencing of randomly selected clones. For the initial 1,221 clones analyzed, 182 species-level operational taxonomic units (SLOTUs) belonging to eight phyla were identified, estimated as 74.0% [95% confidence interval (C.I.), approximately 64.8-77.9%] of the SLOTUs in this ecosystem; 48.0 +/- 12.2 SLOTUs were found in each subject. Three phyla (Actinobacteria, Firmicutes, and Proteobacteria) accounted for 94.6% of the clones. Most (85.3%) of the bacterial sequences corresponded to known and cultivated species, but 98 (8.0%) clones, comprising 30 phylotypes, had <97% similarity to prior database sequences. Only 6 (6.6%) of the 91 genera and 4 (2.2%) of the 182 SLOTUs, respectively, were found in all six subjects. Analysis of 817 clones obtained 8-10 months later from four subjects showed additional phyla (numbering 2), genera (numbering 28), and SLOTUs (numbering 65). Only four (3.4%) of the 119 genera (Propionibacteria, Corynebacteria, Staphylococcus, and Streptococcus) were observed in each subject tested twice, but these genera represented 54.4% of all clones. These results show that the bacterial biota in normal superficial skin is highly diverse, with few well conserved and well represented genera, but otherwise low-level interpersonal consensus
— id: 71419, year: 2007, vol: 104, page: 2927, stat: Journal Article,

Serological Assays for Identification of Human Gastric Colonization by Helicobacter pylori Strains Expressing VacA m1 or m2
Ghose, Chandrabali; Perez-Perez, Guillermo I; Torres, Victor J; Crosatti, Marialuisa; Nomura, Abraham; Peek, Richard M Jr; Cover, Timothy L; Francois, Fritz; Blaser, Martin J
2007 Apr;14(4):442-450, Clinical & vaccine immunology
The Helicobacter pylori vacA gene encodes a secreted protein (VacA) that alters the function of gastric epithelial cells and T lymphocytes. H. pylori strains containing particular vacA alleles are associated with differential risk of disease. Because the VacA midregion may exist as one of two major types, m1 or m2, serologic responses may potentially be used to differentiate between patients colonized with vacA m1- or vacA m2-positive H. pylori strains. In this study, we examined the utility of specific antigens from the m regions of VacA as allele-specific diagnostic antigens. We report that serological responses to P44M1, an H. pylori m1-specific antigen, are observed predominantly in patients colonized with m1-positive strains, whereas responses to VacA m2 antigens, P48M2 and P55M2, are observed in patients colonized with either m1- or m2-positive strains. In an Asian-American population, serologic responses to VacA m region-specific antigens were not able to predict the risk of development of gastric cancer
— id: 71774, year: 2007, vol: 14, page: 442, stat: Journal Article,

Helicobacter pylori and oesophageal and gastric cancers in a prospective study in China
Kamangar, F; Qiao, YL; Blaser, MJ; Sun, XD; Katki, H; Fan, JH; Perez-Perez, GI; Abnet, CC; Zhao, P; D Mark, S; Taylor, PR; Dawsey, SM
2007 JAN 15 ;96(1):172-176, British journal of cancer
In a cohort of 29 584 residents of Linxian, China, followed from 1985 to 2001, we conducted a case - cohort study of the magnitude of the association of Helicobacter pylori seropositivity with cancer risk in a random sample of 300 oesophageal squamous cell carcinomas, 600 gastric cardia adenocarcinomas, all 363 diagnosed gastric non-cardia adenocarcinomas, and a random sample of the entire cohort (N = 1050). Baseline serum was evaluated for IgG antibodies to whole-cell and CagA H. pylori antigens by enzyme-linked immunosorbent assay. Risks of both gastric cardia and non-cardia cancers were increased in individuals exposed to H. pylori ( Hazard ratios (HRs) and 95% confidence intervals 1.64; 1.26 - 2.14, and 1.60; 1.15 - 2.21, respectively), whereas risk of oesophageal squamous cell cancer was not affected (1.17; 0.88 - 1.57). For both cardia and non-cardia cancers, HRs were higher in younger individuals. With longer time between serum collection to cancer diagnosis, associations became stronger for cardia cancers but weaker for non-cardia cancers. CagA positivity did not modify these associations. The associations between H. pylori exposure and gastric cardia and non-cardia adenocarcinoma development were equally strong, in contrast to Western countries, perhaps due to the absence of Barrett's oesophagus and oesophageal adenocarcinomas in Linxian, making all cardia tumours of gastric origin, rather than a mixture of gastric and oesophageal malignancies
— id: 70170, year: 2007, vol: 96, page: 172, stat: Journal Article,

Plastic cells and populations: DNA substrate characteristics in Helicobacter pylori transformation define a flexible but conservative system for genomic variation
Levine, Steven M; Lin, Edward A; Emara, Walid; Kang, Josephine; DiBenedetto, Michael; Ando, Takafumi; Falush, Daniel; Blaser, Martin J
2007 Nov;21(13):3458-3467, FASEB journal
Helicobacter pylori, bacteria that colonize the human gastric mucosa, are naturally competent for transformation by exogenous DNA, and show a panmictic population structure. To understand the mechanisms involved in its horizontal gene transfer, we sought to define the interval required from exposure to substrate DNA until DNA uptake and expression of a selectable phenotype, as well as the relationship of transforming fragment length, concentration, homology, symmetry, and strandedness, to the transformation frequency. We provide evidence that natural transformation in H. pylori differs in efficiency among wild-type strains but is saturable and varies with substrate DNA length, symmetry, strandedness, and species origin. We show that H. pylori cells can be transformed within one minute of contact with DNA, by DNA fragments as small as 50 bp, and as few as 5 bp on one flank of a selectable single nucleotide mutation is sufficient substrate for recombination of a transforming fragment, and that double-stranded DNA is the preferred (1000-fold >single-stranded) substrate. The high efficiency of double-stranded DNA as transformation substrate, in conjunction with strain-specific restriction endonucleases suggests a model of short-fragment recombination favoring closest relatives, consistent with the observed H. pylori population biology
— id: 75362, year: 2007, vol: 21, page: 3458, stat: Journal Article,

Helicobacter pylori and intestinal parasites are not detrimental to the nutritional status of Amerindians
Marini, Elisabetta; Maldonado-Contreras, Ana L; Cabras, Stefano; Hidalgo, Glida; Buffa, Roberto; Marin, Aura; Floris, Giovanni; Racugno, Walter; Pericchi, Luis R; Castellanos, Maria E; Groschl, Michael; Blaser, Martin J; Dominguez-Bello, Maria G
2007 Mar;76(3):534-540, American journal of tropical medicine & hygiene
Gastrointestinal parasites have evolved with humans and colonize many asymptomatic subjects. We investigated the influence of microbial gastrointestinal colonization on the nutritional status of rural Amerindians (40 males and 61 females). Helicobacter pylori was detected by 13C-breath test, and intestinal parasites were detected in fecal specimens. Body morphometry and bioelectrical impedance measurements were measured. Although Amerindians showed low height and weight for age, they had an adequate body mass index, morphometric parameters, and cell mass. Intestinal parasites were detected in 99% of the subjects, with no detrimental effect on nutritional parameters. Helicobacter pylori was present in 82% of adults and half the children, and was positively correlated with improved nutritional status. Despite the high prevalence of gastrointestinal microbes often associated with disease, the studied population of Amerindians had a body morphometry and composition indicative of good nutritional status, and improved in children positive for gastric H. pylori
— id: 79205, year: 2007, vol: 76, page: 534, stat: Journal Article,

The language used by Helicobacter pylori to regulate human cells
Pillinger, Michael H; Blaser, Martin J
2007 Jul 1;196(1):6-9, Journal of infectious diseases
— id: 73298, year: 2007, vol: 196, page: 6, stat: Journal Article,

Helicobacter pylori stimulates gastric epithelial cell MMP-1 secretion via CagA-dependent and -independent ERK activation
Pillinger, Michael H; Marjanovic, Nada; Kim, Seok-Yong; Lee, Yong-Chan; Scher, Jose U; Roper, Jatin; Abeles, Aryeh M; Izmirly, Peter I; Axelrod, Matthew; Pillinger, Mara Y; Tolani, Sonia; Dinsell, Victoria; Abramson, Steven B; Blaser, Martin J
2007 Jun 29;282(26):18722-18731, Journal of biological chemistry
Because the mechanisms of Helicobacter pylori-induced gastric injury are incompletely understood, we examined the hypothesis that H. pylori induces matrix metalloproteinase-1 (MMP-1) secretion, with potential to disrupt gastric stroma. We further tested the role of CagA, an H. pylori virulence factor, in MMP-1 secretion. Co-incubation of AGS cells with Tx30a, an H. pylori strain lacking the cagA virulence gene, stimulated MMP-1 secretion, confirming cagA-independent secretion. Co-incubation with strain 147C (cagA(+)) resulted in CagA translocation into AGS cells and increased MMP-1 secretion relative to Tx30a. Transfection of cells with the recombinant 147C cagA gene also induced MMP-1 secretion, indicating that CagA can independently stimulate MMP-1 secretion. Co-incubation with strain 147A, containing a cagA gene that lacks an EPIYA tyrosine phosphorylation motif, as well as transfection with 147A cagA, yielded an MMP-1 secretion intermediate between no treatment and 147C, indicating that CagA tyrosine phosphorylation regulates cellular signaling in this model system. H. pylori induced activation of the MAP kinase ERK, with CagA-independent (early) and dependent (later) components. MEK inhibitors UO126 and PD98059 inhibited both CagA-independent and -dependent MMP-1 secretion, whereas p38 inhibition enhanced MMP-1 secretion and ERK activation, suggesting p38 negative regulation of MMP-1 and ERK. These data indicate H. pylori effects on host epithelial MMP-1 expression via ERK, with p38 playing a potential regulatory role
— id: 73947, year: 2007, vol: 282, page: 18722, stat: Journal Article,

Role of futC slipped strand mispairing in Helicobacter pylori Lewisy phase variation
Sanabria-Valentin, Edgardo; Colbert, Marie-Teresa C; Blaser, Martin J
2007 Nov-Dec;9(14-15):1553-1560, Microbes & infection
The O antigen of the Helicobacter pylori lipopolysaccharide is composed of repeating units of fucosylated Lewis (Le) antigens. The alpha(1,2)-fucosyltransferase (futC) of H. pylori, which catalyzes the conversion of Le(x) to Le(y) by addition of fucose, is subject to slipped-strand mispairing involving a homonucleotide (poly-C) tract. To explore the distribution of Le phenotypes within H. pylori cells grown in vitro, 379 single colonies of strain J166 were examined for Le expression. Two major populations with reciprocal Le(x)/Le(y) phenotypes were identified. Phenotypes correlated with futC frame status, suggesting that strain J166 represents a mixed population with respect to futC poly-C tract length, which was confirmed by a translational reporter. After hundreds of generations in vitro, phenotypes did not change significantly, indicating that the observed J166 Le diversity reflects the founding population. Since slipped-strand mispairing in the futC poly-C tract was postulated to explain the Le(y) phenotypic change observed in J166 derivative strain 98-169 isolated 10 months after rhesus monkey challenge, in trans complementation with in-frame futC was performed. Le(y) synthesis was restored and Le(x) expression was reciprocally lowered. From these studies, we confirmed the principal role of futC slipped-strand mispairing in Le antigenic variation in vitro and in vivo
— id: 76143, year: 2007, vol: 9, page: 1553, stat: Journal Article,

Role of futC slipped strand mispairing in Helicobacter pylori Lewis(y) phase variation during rhesus monkey challenge
Sanabria-Valentin, EL; Blaser, MJ
2007 JAN ;54(1):57-57, Zoonoses & public health
— id: 87167, year: 2007, vol: 54, page: 57, stat: Journal Article,

Fasting gastric leptin levels are elevated in diabetics independent of BMI
Young, B; Roper, H; Mourad, M; Olivares de Perez, AZ; Perez-Perez, GI; Pei, ZH; Blaser, MJ; Francois, F
2007 SEP ;102(6):S163-S163, American journal of gastroenterology
— id: 74153, year: 2007, vol: 102, page: S163, stat: Journal Article,

Molecular analysis of the bacterial microbiota in the human stomach
Bik, Elisabeth M; Eckburg, Paul B; Gill, Steven R; Nelson, Karen E; Purdom, Elizabeth A; Francois, Fritz; Perez-Perez, Guillermo; Blaser, Martin J; Relman, David A
2006 Jan 17;103(3):732-737, Proceedings of the National Academy of Sciences of the United States of America
The microbiota of the human stomach and the influence of Helicobacter pylori colonization on its composition remain largely unknown. We characterized bacterial diversity within the human gastric mucosa by using a small subunit 16S rDNA clone library approach and analyzed 1,833 sequences generated by broad-range bacterial PCR from 23 gastric endoscopic biopsy samples. A diverse community of 128 phylotypes was identified, featuring diversity at this site greater than previously described. The majority of sequences were assigned to the Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Fusobacteria phyla. Ten percent of the phylotypes were previously uncharacterized, including a Deinococcus-related organism, relatives of which have been found in extreme environments but not reported before in humans. The gastric clone libraries from 19 subjects contained H. pylori rDNA; however, only 12 of these subjects tested positive for H. pylori by conventional laboratory methods. Statistical analysis revealed a large degree of intersubject variability of the gastric ecosystem. The presence of H. pylori did not affect the composition of the gastric community. This gastric bacterial rDNA data set was significantly different from sequence collections of the human mouth and esophagus described in other studies, indicating that the human stomach may be home to a distinct microbial eco-system. The gastric microbiota may play important, as-yet-undiscovered roles in human health and disease
— id: 62128, year: 2006, vol: 103, page: 732, stat: Journal Article,

Wei chang dao gan ran = [Infections of the gastroenterological tract]
Blaser, Martin J
Bei jing : Ren min wei sheng chu ban she, 2006,
— id: 2042, year: 2006, vol: , page: , stat: ,

Microbes adapt to inner space
Blaser, Martin J
2006 Sep;12(9):994-996, Nature medicine
— id: 79208, year: 2006, vol: 12, page: 994, stat: Journal Article,

Pandemics and preparations
Blaser, Martin J
2006 Nov 1;194 Suppl 2:S70-S72, Journal of infectious diseases
— id: 79206, year: 2006, vol: 194 Suppl 2, page: S70, stat: Journal Article,

Who are we? Indigenous microbes and the ecology of human diseases
Blaser, Martin J
2006 Oct;7(10):956-960, EMBO reports
— id: 69595, year: 2006, vol: 7, page: 956, stat: Journal Article,

Mechanisms for Helicobacter pylori CagA-induced cyclin D1 expression that affect cell cycle
Chang, Ya-Jen; Wu, Ming-Shiang; Lin, Jaw-Town; Pestell, Richard G; Blaser, Martin J; Chen, Ching-Chow
2006 Nov;8(11):1740-1752, Cellular microbiology
Particular Helicobacter pylori genotypes differentially induce epithelial cell proliferation, but the mechanisms are not characterized. We explored the effect of H. pylori CagA on expression of cyclin D1, an important cell cycle regulator. H. pylori-induced cell survival and cyclin D1 expression were attenuated in a cagA mutant. AP1 and cAMP response element (CRE), but not NF-kappaB, were involved in the induced cyclin D1 expression. Diminished mitogen-activated protein kinase (MAPK) activation, especially involving p38, with downstream effects on AP1 and CRE activation, was observed for the cagA mutant. In total, these data show that cagA+ H. pylori strains are enhanced in their ability to activate MAPKs and downstream transcription factors, increasing cyclin D1 expression, G1-S phase progression, and host cell survival, explaining both the preferential survival of affected host cells, and the enhanced oncogenesis by these bacteria
— id: 79210, year: 2006, vol: 8, page: 1740, stat: Journal Article,

Infection, cancer and prevention: report of the 19th International Symposium of the Foundation for Promotion of Cancer Research
Emura, Fabian; Saito, Daizo; Kakizoe, Tadao; Blaser, Martin J
2006 Nov;36(11):745-755, Japanese journal of clinical oncology
— id: 79207, year: 2006, vol: 36, page: 745, stat: Journal Article,

Improving Helicobacter pylori eradication regimens
Francois, Fritz; Blaser, Martin J
2006 Jan 17;144(2):140-141, Annals of internal medicine
— id: 62127, year: 2006, vol: 144, page: 140, stat: Journal Article,

Antimutator role of the DNA glycosylase mutY gene in Helicobacter pylori
Huang, Shuyan; Kang, Josephine; Blaser, Martin J
2006 Sep;188(17):6224-6234, Journal of bacteriology
Helicobacter pylori has a highly variable genome with ongoing diversification via inter- and intragenomic recombination and spontaneous mutation. DNA repair genes modulating mutation and recombination rates that influence diversification have not been well characterized for H. pylori. To examine the role of putative base excision repair ung and mutY glycosylase and xthA apurinic/apyrimidinic endonuclease genes in H. pylori, mutants of each were constructed in strain JP26 by allelic exchange. Spontaneous mutation frequencies of JP26 mutY mutants, assessed by rifampin resistance, were consistently higher (26-fold) than that of the wild type, whereas the ung and xthA mutants showed smaller increases. In trans complementation of the JP26 mutY mutant restored spontaneous mutation frequencies to wild-type levels. In cross-species studies, H. pylori mutY complemented an Escherichia coli mutY mutant and vice versa. In contrast, the ung and mutY mutants did not show higher frequencies of intergenomic recombination or greater sensitivity to UV-induced DNA damage than the wild type. The H. pylori mutY open reading frame contains an eight-adenine homonucleotide tract; we provide evidence that this is subject to slipped-strand mispairing, leading to frameshifts that eliminate gene function. Our findings indicate that H. pylori possesses phase-variable base excision repair, consistent with a tension between repair and mutation
— id: 68780, year: 2006, vol: 188, page: 6224, stat: Journal Article,

Opposing risks of gastric cardia and noncardia gastric adenocarcinomas associated with Helicobacter pylori seropositivity
Kamangar, Farin; Dawsey, Sanford M; Blaser, Martin J; Perez-Perez, Guillermo I; Pietinen, Pirjo; Newschaffer, Craig J; Abnet, Christian C; Albanes, Demetrius; Virtamo, Jarmo; Taylor, Philip R
2006 Oct 18;98(20):1445-1452, Journal of the National Cancer Institute
BACKGROUND: Colonization with Helicobacter pylori is a risk factor for gastric adenocarcinoma, but the magnitude of this association and its relationship to anatomic location of the cancer, duration of follow-up, age at diagnosis, histologic subtype, and H. pylori strain differences are less clear. We conducted a prospective nested case-control study of H. pylori serology to address these questions. METHODS: Case and control subjects were selected from the 29,133 50- to 69-year-old males recruited into the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. At baseline, detailed demographic data and a serum sample were collected. From 1985 to 1999, 243 incident cases of gastric adenocarcinoma were diagnosed in cohort members. Serum samples from 234 case subjects (173 with noncardia gastric cancers and 61 with gastric cardia cancers) and 234 age-matched control subjects were assayed for antibodies against H. pylori whole-cell and CagA antigens. We fit conditional logistic regression models to estimate the unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association of H. pylori seropositivity, defined as seropositivity to either whole-cell or CagA antigens, with noncardia gastric and gastric cardia cancers. All statistical tests were two-sided. RESULTS: H. pylori seropositivity was strongly associated with the risk of noncardia gastric cancer (adjusted OR = 7.9, 95% CI = 3.0 to 20.9) but was inversely associated with the risk of gastric cardia cancer (adjusted OR = 0.31, 95% CI = 0.11 to 0.89). H. pylori seropositivity rates did not vary statistically significantly by length of follow-up, age at diagnosis, or histologic subtype. A calculation of rates showed that the absolute risks of noncardia gastric and cardia gastric adenocarcinomas in the H. pylori-positive participants of this cohort would be 63 and 12 per 100,000 person-years, respectively, whereas corresponding rates in H. pylori-negative participants would be 8 and 37 per 100,000 person-years, respectively. CONCLUSION: H. pylori is a strong risk factor for noncardia gastric cancer but is inversely associated with the risk of gastric cardia cancer. These findings bolster the hypothesis that decreasing H. pylori prevalence during the past century may have contributed to lower rates of noncardia cancer and higher rates of cardia cancer in Western countries
— id: 79194, year: 2006, vol: 98, page: 1445, stat: Journal Article,

A paradigm for direct stress-induced mutation in prokaryotes
Kang, Josephine M; Iovine, Nicole M; Blaser, Martin J
2006 Dec;20(14):2476-2485, FASEB journal
Environmental stresses may lead to selection for hypermutator bacterial cells, which have an increased chance of generating beneficial variants. With stress removal, cost of mutation exceeds the fitness advantage, selecting against hypermutators. Hypermutators arise through several mechanisms, including inactivation of mismatch repair genes (MMR) or induction of error-prone polymerases. Helicobacter pylori may provide an alternative mechanism of stress-induced mutagenesis, since it lacks the MMR genes and error-prone polymerases found in other bacterial species, and possesses an endogenously high mutation frequency. In this study, we expose H. pylori strains to reactive oxygen species and reactive nitrogen species, stressors found in their natural environment. These exposures directly resulted in elevated rates of spontaneous point mutation, deletion between direct repeats, and intergenomic recombination. We demonstrate that these effects are transient and do not involve selection for hypermutator strains. That H. pylori possesses direct repeats in regions where potential gene rearrangements can occur suggests a mechanism for targeted mutation in response to stress that avoids the deleterious fitness costs of fixed hypermutation. These studies provide a new paradigm for adaptation under increased selective pressures that may be present in other prokaryotes
— id: 69607, year: 2006, vol: 20, page: 2476, stat: Journal Article,

Bacterial populations as perfect gases: genomic integrity and diversification tensions in Helicobacter pylori
Kang, Josephine; Blaser, Martin J
2006 Nov;4(11):826-836, Nature reviews. Microbiology
Microorganisms that persist in single hosts face particular challenges. Helicobacter pylori, an obligate bacterial parasite of the human stomach, has evolved a lifestyle that features interstrain competition and intraspecies cooperation, both of which involve horizontal gene transfer. Microbial species must maintain genomic integrity, yet H. pylori has evolved a complex nonlinear system for diversification that exists in dynamic tension with the mechanisms for ensuring fidelity. Here, we review these tensions and propose that they create a dynamic pool of genetic variants that is sufficiently genetically diverse to allow H. pylori to occupy all of the potential niches in the stomach
— id: 69084, year: 2006, vol: 4, page: 826, stat: Journal Article,

UvrD helicase suppresses recombination and DNA damage-induced deletions
Kang, Josephine; Blaser, Martin J
2006 Aug;188(15):5450-5459, Journal of bacteriology
UvrD, a highly conserved helicase involved in mismatch repair, nucleotide excision repair (NER), and recombinational repair, plays a critical role in maintaining genomic stability and facilitating DNA lesion repair in many prokaryotic species. In this report, we focus on the UvrD homolog in Helicobacter pylori, a genetically diverse organism that lacks many known DNA repair proteins, including those involved in mismatch repair and recombinational repair, and that is noted for high levels of inter- and intragenomic recombination and mutation. H. pylori contains numerous DNA repeats in its compact genome and inhabits an environment rich in DNA-damaging agents that can lead to increased rearrangements between such repeats. We find that H. pylori UvrD functions to repair DNA damage and limit homologous recombination and DNA damage-induced genomic rearrangements between DNA repeats. Our results suggest that UvrD and other NER pathway proteins play a prominent role in maintaining genome integrity, especially after DNA damage; thus, NER may be especially critical in organisms such as H. pylori that face high-level genotoxic stress in vivo
— id: 67539, year: 2006, vol: 188, page: 5450, stat: Journal Article,

Helicobacter pylori CagA transfection of gastric epithelial cells induces interleukin-8
Kim, Seok-Yong; Lee, Yong-Chan; Kim, Hyong Kyu; Blaser, Martin J
2006 Jan;8(1):97-106, Cellular microbiology
To determine the effect of Helicobacter pylori CagA expression on interleukin-8 (IL-8) induction in AGS cells, cagA and five of its fragments from strains 147A and 147C that vary in the 3' repeat region were cloned into the eukaryotic expression plasmid pSP65SRalpha. IL-8, but not RANTES or IL-Ibeta, levels were increased in AGS cells transfected with 147A-cagA and to a greater extent with 147C-cagA, compared with negative controls. The 5' b fragment from the two strains had similar effects, but the 3' d and e fragments from 147C CagA had greater effects than those from 147A-CagA. When the Western CagA-specific sequence (WSS) of 147C-cagA was replaced with East Asian CagA-specific sequence (ESS) and cloned into pSP65SRalpha as an East/West chimera, there was no significant effect on IL-8 production. Use of specific inhibitors indicates that Src kinase activation, and the mitogen-activated protein (MAP) kinase and NF-kappaB pathways are the major intermediates for CagA effects on IL-8 induction, but the p38 MAP kinase pathway has little effect. These results indicate a direct CagA effect on IL-8 induction by gastric epithelial cells, and indicate signal pathway loci that can be targeted for amelioration
— id: 79212, year: 2006, vol: 8, page: 97, stat: Journal Article,

Role of the small Rho GTPases Racl and Cdc42 in epithelial cell invasion of Campylobacter jejuni 81-176
Krause-Gruszczynska, M; Rohde, M; Hartig, R; Schmidt, G; Miller, WG; Blaser, MJ; Konig, W; Backert, S
2006 SEP ;296(2):167-167, International journal of medical microbiology : IJMM
— id: 70623, year: 2006, vol: 296, page: 167, stat: Journal Article,

Deregulation of SHP-2 affecting signal transduction switch by Helicobacter pylori oncoprotein CagA
Lee, I; Kim, J; Ryu, E; Choi, Y; Cheon, J; Lee, Y; Kim, S; Blaser, M
2006 AUG ;11(4):394-395, Helicobacter
— id: 68676, year: 2006, vol: 11, page: 394, stat: Journal Article,

Molecular analysis of fungal microbiota in samples from healthy human skin and psoriatic lesions
Paulino, Luciana C; Tseng, Chi-Hong; Strober, Bruce E; Blaser, Martin J
2006 Aug;44(8):2933-2941, Journal of clinical microbiology
Psoriasis, a common cutaneous disease of unknown etiology, may be triggered by infections, including those due to fungi. Since the fungal community of human skin is poorly characterized, we aimed to analyze the mycological microbiota in healthy skin and psoriatic lesions. Twenty-five skin samples from five healthy subjects (flexor forearm) and three patients with psoriasis were analyzed using broad-range 18S ribosomal DNA (rDNA) and 5.8S rDNA/internal transcribed spacer 2 (ITS2) Malassezia-specific PCR primers. Broad-range PCR analysis indicated that most organisms resembled Malassezia. Malassezia-specific 5.8S/ITS2 analysis of 1,374 clones identified five species and four unknown phylotypes, potentially representing new species. The species distribution appears largely host specific and conserved in different sites of healthy skin. In three subjects, the Malassezia microbiota composition appeared relatively stable over time. Samples of Malassezia microbiota from healthy skin and psoriatic lesions were similar in one patient but substantially different in two others. These data indicate the predominance of Malassezia organisms in healthy human skin, host-specific variation, stability over time, and as yet, no consistent patterns differentiating psoriatic skin from healthy skin
— id: 66657, year: 2006, vol: 44, page: 2933, stat: Journal Article,

Specific geographic genotypes among Helicobacter pylori strains
Perez-Perez, GI; Andersson, M; Olivares, AZ; Gonzalez, EG; Padilla, FB; Torres, J; Blaser, MJ
2006 AUG ;11(4):342-342, Helicobacter
— id: 68671, year: 2006, vol: 11, page: 342, stat: Journal Article,

Stability and variability of cagA and its correlation with disease outcome
Perez-Perez, GI; Wong, C; Olivares, AZ; Gonzalez, EG; Padilla, FB; Blaser, MJ
2006 AUG ;11(4):333-333, Helicobacter
— id: 68670, year: 2006, vol: 11, page: 333, stat: Journal Article,

Evidence of host-virus co-evolution in tetranucleotide usage patterns of bacteriophages and eukaryotic viruses
Pride, David T; Wassenaar, Trudy M; Ghose, Chandrabali; Blaser, Martin J
2006 ;7:8-8, BMC genomics
BACKGROUND: Virus taxonomy is based on morphologic characteristics, as there are no widely used non-phenotypic measures for comparison among virus families. We examined whether there is phylogenetic signal in virus nucleotide usage patterns that can be used to determine ancestral relationships. The well-studied model of tail morphology in bacteriophage classification was used for comparison with nucleotide usage patterns. Tetranucleotide usage deviation (TUD) patterns were chosen since they have previously been shown to contain phylogenetic signal similar to that of 16S rRNA. RESULTS: We found that bacteriophages have unique TUD patterns, representing genomic signatures that are relatively conserved among those with similar host range. Analysis of TUD-based phylogeny indicates that host influences are important in bacteriophage evolution, and phylogenies containing both phages and their hosts support their co-evolution. TUD-based phylogeny of eukaryotic viruses indicates that they cluster largely based on nucleic acid type and genome size. Similarities between eukaryotic virus phylogenies based on TUD and gene content substantiate the TUD methodology. CONCLUSION: Differences between phenotypic and TUD analysis may provide clues to virus ancestry not previously inferred. As such, TUD analysis provides a complementary approach to morphology-based systems in analysis of virus evolution
— id: 79211, year: 2006, vol: 7, page: 8, stat: Journal Article,

Host Lewis phenotype-dependent Helicobacter pylori Lewis antigen expression in rhesus monkeys
Wirth, Hans-Peter; Yang, Manqiao; Sanabria-Valentin, Edgardo; Berg, Douglas E; Dubois, Andre; Blaser, Martin J
2006 Jul;20(9):1534-1536, FASEB journal
Both human and H. pylori populations are polymorphic for the expression of Lewis antigens. Using an experimental H. pylori challenge of rhesus monkeys of differing Lewis phenotypes, we aimed to determine whether H. pylori populations adapt their Lewis phenotypes to those of their hosts. After inoculation of four monkeys with a mixture of seven strains identified by RAPD-polymerase chain reaction, H. pylori Lewis expression was followed in 86 isolates obtained over 40 wk. Host Lewis(a/b) secretion status was characterized by immunological assays. Fingerprints of the predominating strain (J166) were identical in all four animals after 40 wk, but its Lewis phenotype had substantial variability in individual hosts. At 40 wk, J166 populations from two Lewis(a-b+) animals predominantly expressed Lewis(y). In contrast, J166 populations had switched to a Lewis(x) dominant phenotype in the two Lewis(a+b-) animals; a frame shift in futC, regulating conversion of Lewis(x) to Lewis(y), accounted for the phenotypic switch. The results indicate that individual cells in H. pylori populations can change Lewis phenotypes during long-term colonization of natural hosts to resemble those of their hosts, providing evidence for host selection for bacterial phenotypes
— id: 68992, year: 2006, vol: 20, page: 1534, stat: Journal Article,

4-Hydroxyphenylacetate decarboxylases: properties of a novel subclass of glycyl radical enzyme systems
Yu, Lihua; Blaser, Martin; Andrei, Paula I; Pierik, Antonio J; Selmer, Thorsten
2006 Aug 8;45(31):9584-9592, Biochemistry
The 4-hydroxyphenylacetate decarboxylases from Clostridium difficile and Clostridium scatologenes, which catalyze the formation of p-cresol, form a distinct group of glycyl radical enzymes (GREs). Cresol formation provides metabolic toxicity, which allows an active suppression of other microbes and may provide growth advantages for the producers in highly competitive environments. The GRE decarboxylases are characterized by a small subunit, which is not similar to any protein of known function in the databases, and provides unique properties that have not been observed in other GREs. Both decarboxylases are functional hetero-octamers (beta(4)gamma(4)), which contain iron-sulfur centers in addition to the glycyl radical prosthetic group. The small subunit is responsible for metal binding and is also involved in the regulation of the enzymes' oligomeric state and activity, which are triggered by reversible serine phosphorylation of the glycyl radical subunits. Biochemical data suggest that the iron-sulfur centers of the decarboxylases could be involved in the radical dissipation of previously activated enzymes in the absence of substrate. The cognate activating enzymes differ from their Pfl and Nrd counterparts in that up to two iron-sulfur centers, in addition to the characteristic SAM cluster, were found. Biochemical data suggested that these [4Fe-4S] centers are involved in the electron transfer to the SAM cluster but do not directly participate in the reductive cleavage of SAM. These data imply a tight regulation of p-cresol formation, which is necessary in order to avoid detrimental effects of the toxic product on the producers
— id: 79209, year: 2006, vol: 45, page: 9584, stat: Journal Article,

Local and systemic immune and inflammatory responses to Helicobacter pylori strains
Bhat, Niranjan; Gaensbauer, James; Peek, Richard M; Bloch, Karen; Tham, Kyi-Toe; Blaser, Martin J; Perez-Perez, Guillermo
2005 Dec;12(12):1393-1400, Clinical & diagnostic laboratory immunology
Colonization with Helicobacter pylori eventuates in varied clinical outcomes, which relate to both bacterial and host factors. Here we examine the relationships between cagA status, serum and gastric juice antibody responses, and gastric inflammation in dyspeptic patients. Serum, gastric juice, and gastric biopsy specimens were obtained from 89 patients undergoing endoscopy. H. pylori colonization and cagA status were determined by histology, culture, and PCR methods, and acute inflammation and chronic inflammation in the gastric mucosa were scored by a single pathologist. Serum and gastric juice antibodies to H. pylori whole-cell and CagA antigens were determined by enzyme-linked immunosorbent assay. Relationships between variables were sequentially analyzed using univariate and multivariate statistical methods. Of the 89 subjects, 62 were colonized by H. pylori. By univariate analyses, levels of serum immunoglobulin G (IgG) and IgA and gastric juice IgA antibodies against whole-cell and CagA antigens each were significantly higher in the H. pylori-positive group than in the H. pylori-negative group (P<0.001). H. pylori and CagA sero-positivities were both significantly associated with enhanced inflammation in gastric antrum and body (P<0.02). The presence of gastric juice antibodies to H. pylori antigens was associated with more severe gastric inflammation. However, in multivariate analyses, only the presence of serum antibodies against CagA and, to a lesser extent, whole-cell antigens remained significantly associated with acute and chronic inflammation in antrum and body (P<0.05). Thus, serum antibody response to CagA correlates with severity of gastric inflammation. Furthermore, given the relationships demonstrated by multivariate analysis, determination of gastric juice antibodies may provide a better representation of serum, rather than secretory, immune response
— id: 79197, year: 2005, vol: 12, page: 1393, stat: Journal Article,

An endangered species in the stomach
Blaser, Martin J
2005 Feb;292(2):38-45, Scientific american
— id: 48225, year: 2005, vol: 292, page: 38, stat: Journal Article,

The biology of cag in the Helicobacter pylori-human interaction
Blaser, Martin J
2005 May;128(5):1512-1515, Gastroenterology
— id: 79218, year: 2005, vol: 128, page: 1512, stat: Journal Article,

Theodore E. Woodward Award: Global warming and the human stomach: microecology follows macroecology
Blaser, Martin J
2005 ;116:65-75, Transactions of the American Clinical & Climatological Association
Just as there have been 20th century changes in our 'macroecology,' including global warming, there have been alterations in our 'microecology,' involving the microbial populations that colonize the human body. Helicobacterpylori, an ancient inhabitant of the human stomach, has been disappearing over the course of the 20th century. As such, by comparing H. pylori+ and H. pylori- persons, the consequences of its colonization can be determined. The presence of H. pylori is associated with increased risk for development of gastric cancer and peptic ulceration, and with decreased risk for gastroesophageal reflux disease (GERD) and its sequelae, including esophageal adenocarcinoma. The disappearance of H. pylori (especially cag+ strains), possibly contributing to the risk of these esophageal diseases, may be an indicator for changing human microecology
— id: 64204, year: 2005, vol: 116, page: 65, stat: Journal Article,

Determinants of virulence for the parasite Nosema whitei in its host Tribolium castaneum
Blaser, Martin; Schmid-Hempel, Paul
2005 Jul;89(3):251-257, Journal of invertabrate pathology
For many parasites, especially those that obligately kill the host for transmission, host age is crucially important to determine success. Here, we have experimentally investigated this relationship with the microsporidian parasite, Nosema whitei, in its host, the Red Flour Beetle, Tribolium castaneum. We find that infection is only possible in young larvae and that spore load at the time of transmission (i.e., host death) correlates with host body size. The data suggested that an infection by N. whitei prolongs the life span of the infected larva and prevents them from pupation. Together, virulence to the host and success for the parasite is mainly determined by the host age at infection. The patterns are consistent with theoretical predictions for obligate killer parasites
— id: 79217, year: 2005, vol: 89, page: 251, stat: Journal Article,

Analysis of hopQ alleles in East Asian and Western strains of Helicobacter pylori
Cao, Ping; Lee, Kerry Jo; Blaser, Martin J; Cover, Timothy L
2005 Oct 1;251(1):37-43, FEMS microbiology letters
Helicobacter pylori hopQ (omp27) alleles exhibit a high level of genetic diversity, and certain hopQ genotypes have been associated with an increased risk for peptic ulcer disease. In this study, we analyzed hopQ alleles in H. pylori strains from East Asia and the United States. Phylogenetic analysis indicated the presence of two highly divergent families of hopQ alleles, without evidence of extensive recombination. Type I hopQ alleles from Western and Asian H. pylori strains were similar, and markedly different from type II hopQ alleles. Analyses of synonymous and non-synonymous nucleotide substitutions suggested that there is a positive selection for HopQ amino acid diversity. Type II hopQ alleles were identified commonly in Western H. pylori strains, but rarely in East Asian strains. Nearly all of the East Asian strains analyzed were cagA-positive and contained type I hopQ alleles. Geographic variation in the genetic characteristics of H. pylori strains may be a factor contributing to geographic variation in gastric cancer incidence
— id: 79216, year: 2005, vol: 251, page: 37, stat: Journal Article,

Internal medicine residency training in the 21st century: aligning requirements with professional needs
Charap, Mitchell H; Levin, Richard I; Pearlman, R Ellen; Blaser, Martin J
2005 Sep;118(9):1042-1046, American journal of medicine
— id: 58700, year: 2005, vol: 118, page: 1042, stat: Journal Article,

Helicobacter pylori and overweight status in the United States: data from the Third National Health and Nutrition Examination Survey
Cho, Ilseung; Blaser, Martin J; Francois, Fritz; Mathew, Jomol P; Ye, Xiang Y; Goldberg, Judith D; Bini, Edmund J
2005 Sep 15;162(6):579-584, American journal of epidemiology
Obesity is an important public health problem in the United States. Because of its potential effects on gastric leptin homeostasis, Helicobacter pylori may play a role in regulating body weight. The authors' aim in this study was to examine the association between H. pylori colonization and overweight status. Nonpregnant participants in the Third National Health and Nutrition Examination Survey (1988-1994) aged > or = 20 years who had had H. pylori testing performed and body mass index (weight (kg)/height (m2)) measured were studied. Overweight was defined as a body mass index greater than or equal to 25. On the basis of serologic results, the participants were categorized into three H. pylori status groups: H. pylori-positive and cytotoxin-associated gene A (cagA)-positive (H. pylori+ cagA+), H. pylori-positive and cagA-negative (H. pylori+ cagA-), and H. pylori-negative (H. pylori-). Of the 7,003 subjects with complete body mass index and H. pylori data, 2,634 (weighted percentage, 22.9%) were H. pylori+ cagA+, 1,385 (15.1%) were H. pylori+ cagA-, and 2,984 (62.0%) were H. pylori-. The adjusted odds of being overweight were 1.17 (95% confidence interval: 0.98, 1.39; p = 0.075) for the H. pylori+ cagA+ group and 0.99 (95% confidence interval: 0.80, 1.22; p = 0.92) for the H. pylori+ cagA- group in comparison with H. pylori- subjects. Serum leptin levels did not differ significantly between the three H. pylori groups. In this US population-based study, there was no significant association between H. pylori colonization, cagA+ strains of H. pylori, and being overweight
— id: 58658, year: 2005, vol: 162, page: 579, stat: Journal Article,

Are iron-scavenging parasites protective against malaria?
Dominguez-Bello, Maria G; Blaser, Martin J
2005 Feb 15;191(4):646-646, Journal of infectious diseases
— id: 48226, year: 2005, vol: 191, page: 646, stat: Journal Article,

Fluoroquinolone use in food animals - Response
Iovine, NM; Blaser, MJ
2005 NOV ;11(11):1790-1790, Emerging infectious diseases
— id: 58902, year: 2005, vol: 11, page: 1790, stat: Journal Article,

Inhibition of Bacillus anthracis growth and virulence-gene expression by inhibitors of quorum-sensing
Jones, Marcus B; Jani, Rachana; Ren, Dacheng; Wood, Thomas K; Blaser, Martin J
2005 Jun 1;191(11):1881-1888, Journal of infectious diseases
Density-dependent gene expression, quorum sensing (QS), involves the synthesis and detection of low-molecular-weight molecules known as autoinducers. Inhibitors of bacterial QS systems offer potential treatment of infections with highly virulent or multidrug-resistant agents. We studied the effects on Bacillus anthracis growth and the virulence gene (pagA, lef, and cya) expression of the QS inhibitor (5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone, which is naturally synthesized by the marine alga Delisea pulchra, as well as a related compound and synthetic derivatives. Growth of B. anthracis Sterne strain was substantially reduced in the presence of each furanone in a dose-dependent manner. When furanones were added to midlog-phase cultures of B. anthracis strains with LacZ reporters in pagA, lef, or cya, growth was inhibited, and expression of these virulence genes was inhibited to a proportionately greater extent. These data suggest that use of QS inhibitors could represent novel therapies for anthrax
— id: 55981, year: 2005, vol: 191, page: 1881, stat: Journal Article,

Structural and functional divergence of MutS2 from bacterial MutS1 and eukaryotic MSH4-MSH5 homologs
Kang, Josephine; Huang, Shuyan; Blaser, Martin J
2005 May;187(10):3528-3537, Journal of bacteriology
MutS homologs, identified in nearly all bacteria and eukaryotes, include the bacterial proteins MutS1 and MutS2 and the eukaryotic MutS homologs 1 to 7, and they often are involved in recognition and repair of mismatched bases and small insertion/deletions, thereby limiting illegitimate recombination and spontaneous mutation. To explore the relationship of MutS2 to other MutS homologs, we examined conserved protein domains. Fundamental differences in structure between MutS2 and other MutS homologs suggest that MutS1 and MutS2 diverged early during evolution, with all eukaryotic homologs arising from a MutS1 ancestor. Data from MutS1 crystal structures, biochemical results from MutS2 analyses, and our phylogenetic studies suggest that MutS2 has functions distinct from other members of the MutS family. A mutS2 mutant was constructed in Helicobacter pylori, which lacks mutS1 and mismatch repair genes mutL and mutH. We show that MutS2 plays no role in mismatch or recombinational repair or deletion between direct DNA repeats. In contrast, MutS2 plays a significant role in limiting intergenomic recombination across a range of donor DNA tested. This phenotypic analysis is consistent with the phylogenetic and biochemical data suggesting that MutS1 and MutS2 have divergent functions
— id: 55800, year: 2005, vol: 187, page: 3528, stat: Journal Article,

Mechanisms of disease: Inflammation and the origins of cancer
Moss, Steven F; Blaser, Martin J
2005 Feb;2(2):90-97, Nature clinical practice. Oncology
Many common cancers develop as a consequence of years of chronic inflammation. Increasing evidence indicates that the inflammation may result from persistent mucosal or epithelial cell colonization by microorganisms; including hepatitis B virus and hepatitis C virus, which can cause hepatocellular cancer; human papilloma virus subtypes, which cause cervical cancer, and the bacterium Helicobacter pylori, which can cause gastric cancer. At present, the cause of other chronic inflammatory conditions associated with increased cancer risk, such as ulcerative colitis, is obscure. Particular microbial characteristics as well as the type of the inflammatory response contribute to clinical outcomes via influence on epithelial cell and immune responses. Persistent inflammation leads to increased cellular turnover, especially in the epithelium, and provides selection pressure that result in the emergence of cells that are at high risk for malignant transformation. Cytokines, chemokines, free radicals, and growth factors modulate microbial populations that colonize the host. Thus, therapeutic opportunities exist to target the causative microbe, the consequent inflammatory mediator, or epithelial cell responses. Such measures could be of value to reduce cancer risk in inflammation-associated malignancies
— id: 79213, year: 2005, vol: 2, page: 90, stat: Journal Article,

Helicobacter pylori, pepsinogen, and gastric adenocarcinoma in Hawaii
Nomura, Abraham M Y; Kolonel, Laurence N; Miki, Kazumasa; Stemmermann, Grant N; Wilkens, Lynne R; Goodman, Marc T; Perez-Perez, Guillermo I; Blaser, Martin J
2005 Jun 15;191(12):2075-2081, Journal of infectious diseases
BACKGROUND: The objective was to investigate the association of Helicobacter pylori and serum pepsinogen (PG) levels with gastric adenocarcinoma. METHODS: Serum obtained from 299 patients at the time of cancer diagnosis and from 336 population-based control subjects was tested for PG I, PG II, and antibodies to H. pylori and to CagA. RESULTS: Subjects with low PG I levels or low PG I/II ratios were at increased risk for cardia and noncardia gastric cancer, whereas those with H. pylori or CagA seropositivity had an elevated risk for noncardia cancer only. Subjects seropositive for either H. pylori or CagA who had low PG I levels had the highest odds ratio (OR) (9.21 [95% confidence interval {CI}, 4.95-17.13]) for noncardia cancer, compared with subjects with neither factor. Elevated risks were also found among subjects with only 1 factor (OR, 5.40 [95% CI, 2.61-11.20] for low PG I level only; OR, 4.86 [95% CI, 5.90-8.13] for H. pylori or CagA seropositivity only). This pattern persisted when PG I/II ratio replaced PG I level and when CagA seropositivity alone replaced H. pylori immunoglobulin G or CagA seropositivity. CONCLUSIONS: The results suggest that persons with both H. pylori or CagA seropositivity and a low PG I level or PG I/II ratio are highly susceptible to development of noncardia gastric cancer
— id: 64080, year: 2005, vol: 191, page: 2075, stat: Journal Article,

Bacterial biota in reflux esophagitis and Barrettos esophagus
Pei, Zhiheng; Yang, Liying; Peek, Richard M; Jr Levine, Steven M; Pride, David T; Blaser, Martin J
2005 Dec 14;11(46):7277-7283, World journal of gastroenterology : WJG
AIM: To identify the bacterial flora in conditions such as Barrettos esophagus and reflux esophagitis to determine if they are similar to normal esophageal flora. METHODS: Using broad-range 16S rDNA PCR, esophageal biopsies were examined from 24 patients [9 with normal esophageal mucosa, 12 with gastroesophageal reflux disease (GERD), and 3 with Barrettos esophagus]. Two separate broad-range PCR reactions were performed for each patient, and the resulting products were cloned. In one patient with Barrettos esophagus, 99 PCR clones were analyzed. RESULTS: Two separate clones were recovered from each patient (total = 48), representing 24 different species, with 14 species homologous to known bacteria, 5 homologous to unidentified bacteria, and 5 were not homologous (<97% identity) to any known bacterial 16S rDNA sequences. Seventeen species were found in the reflux esophagitis patients, 5 in the Barrettos esophagus patients, and 10 in normal esophagus patients. Further analysis concentrating on a single biopsy from an individual with Barrettos esophagus revealed the presence of 21 distinct bacterial species. Members of four phyla were represented, including Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria. Microscopic examination of each biopsy demonstrated bacteria in intimate association with the distal esophageal epithelium, suggesting that the presence of these bacteria is not transitory. CONCLUSION: These findings provide evidence for a complex, residential bacterial population in esophageal reflux-related disorders. While much of this biota is present in the normal esophagus, more detailed comparisons may help identify potential disease associations
— id: 61597, year: 2005, vol: 11, page: 7277, stat: Journal Article,

Seroprevalence of Helicobacter pylori in New York City populations originating in East Asia
Perez-Perez, Guillermo Ignacio; Olivares, Asalia Zuni; Foo, F Yeong; Foo, Sun; Neusy, Andre J; Ng, Christopher; Holzman, Robert S; Marmor, Michael; Blaser, Martin J
2005 Sep;82(3):510-516, Journal of urban health
Helicobacter pylori prevalence is higher in developing countries than in industrialized countries, and within the latter, higher among immigrants than among nativeborn residents. Using a point-prevalence survey, we sought to identify risk factors for H. pylori seropositivity in US urban East Asian-born populations. At a clinic in New York City, we consecutively enrolled 194 East Asian-born adults, who then responded to a survey and provided a blood sample. Assays were performed to detect IgG antibodies against whole cell (WC) and cytotoxin associated gene A (CagA) antigens of H. pylori. For this group (mean age 50.2+/-14.7 years), the mean period of residence in the United States was 11.9+/-7.7 years. The total H. pylori seroprevalence was 70.1%, with highest (81.4%) in Fujianese immigrants. Multiple logistic regression analysis indicated an independent association of H. pylori seropositivity with Fujianese origin [odds ratios (OR) =2.3, 95% confidence interval (95% CI) =1.05-5.0] and inverse associations with period in the United States (OR per year of residency in the United States =0.95, 95% CI =0.91-0.99) and with a history of dyspepsia (OR for a history of stomach pain =0.52, 95% CI =0.3-1.0). We conclude that H. pylori is highly prevalent among recent East Asian immigrants, especially among Fujianese. The protective effects of history of dyspepsia and duration in the United States suggest that these may be markers for antibiotic therapies.
— id: 58190, year: 2005, vol: 82, page: 510, stat: Journal Article,

Matrix metalloproteinase secretion by gastric epithelial cells is regulated by E prostaglandins and mitogen-activated protein kinases
Pillinger, Michael H; Marjanovic, Nada; Kim, Seok-Yong; Scher, Jose U; Izmirly, Peter; Tolani, Sonia; Dinsell, Victoria; Lee, Yong-Chan; Blaser, Martin J; Abramson, Steven B
2005 Mar 18;280(11):9973-9979, Journal of biological chemistry
Since matrix metalloproteinases (MMP) play roles in inflammatory tissue injury, we asked whether MMP secretion by gastric epithelial cells may contribute to gastric injury in response to signals involved in H. pylori-induced inflammation and/or cyclooxygenase inhibition. TNF-alpha, IL-1beta and epidermal growth factor (EGF) stimulated gastric cell MMP-1 secretion, indicating that MMP-1 secretion occurs in inflammatory as well as non-inflammatory situations. MMP-1 secretion required activation of the mitogen-activated protein kinase (MAPK) Erk, and subsequent protein synthesis, but was downregulated by the alternate MAPK, p38. In contrast, secretion of MMP-13 was stimulated by TNF-alpha/IL-1beta but not EGF, was Erk-independent and mediated by p38. MMP-13 secretion was more rapid (peak 6 h) than MMP-1 (peak = 30 h) and only partly depended on protein synthesis, suggesting initial release of a pre-existing MMP-13 pool. Therefore, MMP-1 and MMP-13 secretion are differentially regulated by MAPKs. MMP-1 secretion was regulated by E prostaglandins (PGEs) in an Erk-dependent manner. PGEs enhanced Erk activation and MMP-1 secretion in response to EGF, but inhibited Erk and MMP-1 when TNF-alpha/IL-1beta were the stimuli, indicating that the effects of PGEs on gastric cell responses are context-dependent. These data show that secretion of MMPs is differentially regulated by MAPKs, and suggest mechanisms through which H pylori infection and/or cyclooxygenase inhibition may induce epithelial cell signaling to contribute to gastric ulcerogenesis
— id: 48227, year: 2005, vol: 280, page: 9973, stat: Journal Article,

Bacterial diarrhea in HIV-infected patients: why Clostridium difficile, and why now?
Sivapalasingam, Sumathi; Blaser, Martin J
2005 Dec 1;41(11):1628-1630, Clinical infectious diseases
— id: 64405, year: 2005, vol: 41, page: 1628, stat: Journal Article,

Persistence of resistant Staphylococcus epidermidis after single course of clarithromycin
Sjolund, Maria; Tano, Eva; Blaser, Martin J; Andersson, Dan I; Engstrand, Lars
2005 Sep;11(9):1389-1393, Emerging infectious diseases
We examined how a common therapy that includes clarithromycin affects normally colonizing Staphylococcus epidermidis. Samples from the nostrils of 5 patients receiving therapy were collected before, immediately after, 1 year after, and 4 years after treatment. From each patient and sample, S. epidermidis strains were isolated and analyzed for clarithromycin susceptibility and presence of the erm(C) gene. We show that macrolide-resistant strains of S. epidermidis were selected during therapy and that the same resistant strain may persist for 4 years, in the absence of further antimicrobial treatment
— id: 79214, year: 2005, vol: 11, page: 1389, stat: Journal Article,

Role of dprA in transformation of Campylobacter jejuni
Takata, Tohru; Ando, Takafumi; Israel, Dawn A; Wassenaar, Trudy M; Blaser, Martin J
2005 Nov 1;252(1):161-168, FEMS microbiology letters
The role of a dprA ortholog (Cj0634) in Campylobacter jejuni transformation was phenotypically assessed using two strains. C. jejuni strain 11168 was naturally competent for transformation by chromosomal DNA, while efficiency decreased 100-fold in a Cj0634::aphA mutant, whereas C. jejuni strain 480 was not naturally competent. C. jejuni strain 480 but not 11168 could be electro-transformed by shuttle plasmid pRY111, an effect completely abolished by Cj0634 interruption. Complementation of the Cj0634 mutation in C. jejuni strain 480 in trans with vectors containing the dprA homologs from C. jejuni, Helicobacter pylori, or Haemophilus influenzae, completely (for Cj0634) or partially (H. pylori>H. influenzae) restored electro-transformation. Thus, C. jejuni expresses a DprA ortholog that functionally most closely resembles that of H. pylori and is involved in DNA transformation
— id: 79215, year: 2005, vol: 252, page: 161, stat: Journal Article,

Genetic divergence of Campylobacter fetus strains of mammal and reptile origins
Tu, Zheng-Chao; Eisner, William; Kreiswirth, Barry N; Blaser, Martin J
2005 Jul;43(7):3334-3340, Journal of clinical microbiology
Campylobacter fetus is a gram-negative bacterial pathogen of both humans and animals. Two subspecies have been identified, Campylobacter fetus subsp. fetus and Campylobacter fetus subsp. venerealis, and there are two serotypes, A and B. To further investigate the genetic diversity among C. fetus strains of different origins, subspecies, and serotypes, we performed multiple genetic analyses by utilizing random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and DNA-DNA hybridization. All 10 primers used for the RAPD analyses can distinguish C. fetus strains of reptile and mammal origin, five can differentiate between C. fetus subsp. fetus and C. fetus subsp. venerealis strains, and four showed differences between type A and type B isolates from mammals. PFGE with SmaI and SalI digestion showed varied genome patterns among different C. fetus strains, but for mammalian C. fetus isolates, genome size was well conserved (mean, 1.52 +/- 0.06 Mb for SmaI and 1.52 +/- 0.05 Mb for SalI). DNA-DNA hybridization demonstrated substantial genomic-homology differences between strains of mammal and reptile origin. In total, these data suggest that C. fetus subsp fetus strains of reptile and mammal origin have genetic divergence more extensive than that between the two subspecies and that between the type A and type B strains. Combining these studies with sequence data, we conclude that there has been substantial genetic divergence between Campylobacter fetus of reptile and mammal origin. Diagnostic tools have been developed to differentiate among C. fetus isolates for taxonomic and epidemiologic uses
— id: 57719, year: 2005, vol: 43, page: 3334, stat: Journal Article,

Mechanisms Underlying Campylobacter fetus Pathogenesis in Humans: Surface-Layer Protein Variation in Relapsing Infections
Tu, Zheng-Chao; Gaudreau, Christiane; Blaser, Martin J
2005 Jun 15;191(12):2082-2089, Journal of infectious diseases
Campylobacter fetus causes gastrointestinal and systemic infections in humans. Although relapse is common despite antibiotic treatment, the mechanisms are not well understood. The surface-layer proteins (SLPs) of C. fetus, which are critical in virulence, undergo high-frequency phenotypic switching due to recombination of sap homologues, resulting in antigenic variation. To investigate the mechanisms involved in relapsing C. fetus infections, we compared SLP variation in 4 pairs of C. fetus strains that infect humans; initial and follow-up isolations were performed 20 days to 34 months apart. Of the 4 pairs of strains, 2 had antigenic variation, and another provided evidence for selection for SLP-positive populations. Southern hybridization indicated recombination underlying the SLP variation and up-regulation. The fourth pair had the same SLP antigenic profile and sap homologue hybridization pattern, which is consistent with latency of the original strain in a privileged locus. In total, these findings indicate that relapse may reflect at least 3 differing pathogenetic pathways
— id: 55980, year: 2005, vol: 191, page: 2082, stat: Journal Article,

Functional Adaptation of BabA, the H. pylori ABO Blood Group Antigen Binding Adhesin
Aspholm-Hurtig, Marina; Dailide, Giedrius; Lahmann, Martina; Kalia, Awdhesh; Ilver, Dag; Roche, Niamh; Vikstrom, Susanne; Sjostrom, Rolf; Linden, Sara; Backstrom, Anna; Lundberg, Carina; Arnqvist, Anna; Mahdavi, Jafar; Nilsson, Ulf J; Velapatino, Billie; Gilman, Robert H; Gerhard, Markus; Alarcon, Teresa; Lopez-Brea, Manuel; Nakazawa, Teruko; Fox, James G; Correa, Pelayo; Dominguez-Bello, Maria Gloria; Perez-Perez, Guillermo I; Blaser, Martin J; Normark, Staffan; Carlstedt, Ingemar; Oscarson, Stefan; Teneberg, Susann; Berg, Douglas E; Boren, Thomas
2004 Jul 23;305(5683):519-522, Science
Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations
— id: 43533, year: 2004, vol: 305, page: 519, stat: Journal Article,

You may have this stomach bug and not even know it
Blaser MJ
2004 ;18(7):7-11, Bottom Line/Health
H. pylori is found in 30% of Americans. New research suggests that its effect on your health may be much more complex than once believed
— id: 48032, year: 2004, vol: 18, page: 7, stat: Journal Article,

Bacteria and diseases of unknown cause: hemolytic-uremic syndrome
Blaser, Martin J
2004 Feb 1;189(3):552-555, Journal of infectious diseases
— id: 42604, year: 2004, vol: 189, page: 552, stat: Journal Article,

Helicobacter pylori persistence: biology and disease
Blaser, Martin J; Atherton, John C
2004 Feb;113(3):321-333, Journal of clinical investigation
Helicobacter pylori are bacteria that have coevolved with humans to be transmitted from person to person and to persistently colonize the stomach. Their population structure is a model for the ecology of the indigenous microbiota. A well-choreographed equilibrium between bacterial effectors and host responses permits microbial persistence and health of the host but confers risk of serious diseases, including peptic ulceration and gastric neoplasia
— id: 42598, year: 2004, vol: 113, page: 321, stat: Journal Article,

A three-component clinical model to predict reflux-related histopathology
Francois, F; Bini, EJ; Perez-Perez, GI; Yee, HT; Blaser, MJ
2004 ;126(4):A324-A324, Gastroenterology
— id: 108227, year: 2004, vol: 126, page: A324, stat: Journal Article,

Antibiotics in animal feed and spread of resistant Campylobacter from poultry to humans
Iovine, Nicole M; Blaser, Martin J
2004 Jun;10(6):1158-1159, Emerging infectious diseases
— id: 43534, year: 2004, vol: 10, page: 1158, stat: Journal Article,

Antimicrobial resistance in Campylobacter
Iovine, Nicole M; Blaser, Martin J
2004 Jul;10(7):1346-1346, Emerging infectious diseases
— id: 44758, year: 2004, vol: 10, page: 1346, stat: Journal Article,

Effect of host species on recG phenotypes in Helicobacter pylori and Escherichia coli
Kang, Josephine; Tavakoli, Don; Tschumi, Ariane; Aras, Rahul A; Blaser, Martin J
2004 Nov;186(22):7704-7713, Journal of bacteriology
Recombination is a fundamental mechanism for the generation of genetic variation. Helicobacter pylori strains have different frequencies of intragenomic recombination, arising from deletions and duplications between DNA repeat sequences, as well as intergenomic recombination, facilitated by their natural competence. We identified a gene, hp1523, that influences recombination frequencies in this highly diverse bacterium and demonstrate its importance in maintaining genomic integrity by limiting recombination events. HP1523 shows homology to RecG, an ATP-dependent helicase that in Escherichia coli allows repair of damaged replication forks to proceed without recourse to potentially mutagenic recombination. Cross-species studies done show that hp1523 can complement E. coli recG mutants in trans to the same extent as E. coli recG can, indicating that hp1523 has recG function. The E. coli recG gene only partially complements the hp1523 mutation in H. pylori. Unlike other recG homologs, hp1523 is not involved in DNA repair in H. pylori, although it has the ability to repair DNA when expressed in E. coli. Therefore, host context appears critical in defining the function of recG. The fact that in E. coli recG phenotypes are not constant in other species indicates the diverse roles for conserved recombination genes in prokaryotic evolution
— id: 47826, year: 2004, vol: 186, page: 7704, stat: Journal Article,

Infectious agents and cancer: criteria for a causal relation
Pagano, Joseph S; Blaser, Martin; Buendia, Marie-Annick; Damania, Blossom; Khalili, Kamel; Raab-Traub, Nancy; Roizman, Bernard
2004 Dec;14(6):453-471, Seminars in cancer biology
Infectious agents, mainly viruses, are among the few known causes of cancer and contribute to a variety of malignancies worldwide. The agents and cancers considered here are human papillomaviruses (cervical carcinoma); human polyomaviruses (mesotheliomas, brain tumors); Epstein-Barr virus (B-cell lymphoproliferative diseases and nasopharyngeal carcinoma); Kaposi's Sarcoma Herpesvirus (Kaposi's Sarcoma and primary effusion lymphomas); hepatitis B and hepatitis C viruses (hepatocellular carcinoma); Human T-cell Leukemia Virus-1 (T-cell leukemias); and helicobacter pylori (gastric carcinoma), which account for up to 20% of malignancies around the globe. The criteria most often used in determining causality are consistency of the association, either epidemiologic or on the molecular level, and oncogenicity of the agent in animal models or cell cultures. However use of these generally applied criteria in deciding on causality is selective, and the criteria may be weighted differently. Whereas for most of the tumor viruses the viral genome persists in an integrated or episomal form with a subset of viral genes expressed in the tumor cells, some agents (HBV, HCV, helicobacter) are not inherently oncogenic, but infection leads to transformation of cells by indirect means. For some malignancies the viral agent appears to serve as a cofactor (Burkitt's lymphoma-EBV; mesothelioma - SV(40)). For others the association is inconsistent (Hodgkin's Disease, gastric carcinomas, breast cancer-EBV) and may either define subsets of these malignancies, or the virus may act to modify phenotype of an established tumor, contributing to tumor progression rather than causing the tumor. In these cases and for the human polyomaviruses the association with malignancy is less consistent or still emerging. In contrast despite the potent oncogenic properties of some strains of human adenovirus in tissue culture and animals the virus has not been linked with any human cancers. Finally it is likely that more agents, most likely viruses, both known and unidentified, have yet to be implicated in human cancer. In the meantime study of tumorigenic infectious agents will continue to illuminate molecular oncogenic processes
— id: 79219, year: 2004, vol: 14, page: 453, stat: Journal Article,

Bacterial biota in the human distal esophagus
Pei, Zhiheng; Bini, Edmund J; Yang, Liying; Zhou, Meisheng; Francois, Fritz; Blaser, Martin J
2004 Mar 23;101(12):4250-4255, Proceedings of the National Academy of Sciences of the United States of America
The esophagus, like other luminal organs of the digestive system, provides a potential environment for bacterial colonization, but little is known about the presence of a bacterial biota or its nature. By using broad-range 16S rDNA PCR, biopsies were examined from the normal esophagus of four human adults. The 900 PCR products cloned represented 833 unique sequences belonging to 41 genera, or 95 species-level operational taxonomic units (SLOTU); 59 SLOTU were homologous with culture-defined bacterial species, 34 with 16S rDNA clones, and two were not homologous with any known bacterial 16S rDNA. Members of six phyla, Firmicutes, Bacteroides, Actinobacteria, Proteobacteria, Fusobacteria, and TM7, were represented. A large majority of clones belong to 13 of the 41 genera (783/900, 87%), or 14 SLOTU (574/900, 64%) that were shared by all four persons. Streptococcus (39%), Prevotella (17%), and Veilonella (14%) were most prevalent. The present study identified approximately 56-79% of SLOTU in this bacterial ecosystem. Most SLOTU of esophageal biota are similar or identical to residents of the upstream oral biota, but the major distinction is that a large majority (82%) of the esophageal bacteria are known and cultivable. These findings provide evidence for a complex but conserved bacterial population in the normal distal esophagus
— id: 42671, year: 2004, vol: 101, page: 4250, stat: Journal Article,

Conservation and diversity of sap homologues and their organization among Campylobacter fetus isolates
Tu, Zheng-Chao; Hui, John; Blaser, Martin J
2004 Mar;72(3):1715-1724, Infection & immunity
Campylobacter fetus surface layer proteins (SLPs), encoded by sapA homologues, are important in virulence. In wild-type C. fetus strain 23D, all eight sapA homologues are located in the 54-kb sap island, and SLP expression reflects the position of a unique sapA promoter in relation to the sapA homologues. The extensive homologies in the sap island include both direct and inverted repeats, which allow DNA rearrangements, deletion, or duplication; these elements confer substantial potential for genomic plasticity. To better understand C. fetus sap island diversity and variation mechanisms, we investigated the organization and distribution of sapA homologues among 18 C. fetus strains of different subspecies, serotypes, and origins. For all type A strains, the boundaries of the sap island were relatively consistent. A 187-bp noncoding DNA insertion near the upstream boundary of the sap island was found in two of three reptile strains studied. The sapA homologue profiles were strain specific, and six new sapA homologues were recognized. Several homologues from reptile strains are remarkably conserved in relation to their corresponding mammalian homologues. In total, the observed differences suggest that the sap island has evolved differing genotypes that are plastic, perhaps enabling colonization of varied niches, in addition to antigenic variation
— id: 42586, year: 2004, vol: 72, page: 1715, stat: Journal Article,

Campylobacter fetus of Reptile Origin as a Human Pathogen
Tu, Zheng-Chao; Zeitlin, Gary; Gagner, Jean-Pierre; Keo, Thormika; Hanna, Bruce A; Blaser, Martin J
2004 Sep;42(9):4405-4407, Journal of clinical microbiology
A Campylobacter species was isolated from blood from a febrile patient with precursor T-cell acute lymphoblastic leukemia, and after antibiotic treatment, a similar bacterium was isolated from blood 37 days later. Although phenotypic testing did not definitively identify the organisms, molecular analysis indicated that they were the same strain of Campylobacter fetus subsp. fetus and were of reptile origin
— id: 44757, year: 2004, vol: 42, page: 4405, stat: Journal Article,

Distinguishing human ethnic groups by means of sequences from Helicobacter pylori: lessons from Ladakh
Wirth, Thierry; Wang, Xiaoyan; Linz, Bodo; Novick, Richard P; Lum, J Koji; Blaser, Martin; Morelli, Giovanna; Falush, Daniel; Achtman, Mark
2004 Apr 6;101(14):4746-4751, Proceedings of the National Academy of Sciences of the United States of America
The history of mankind remains one of the most challenging fields of study. However, the emergence of anatomically modern humans has been so recent that only a few genetically informative polymorphisms have accumulated. Here, we show that DNA sequences from Helicobacter pylori, a bacterium that colonizes the stomachs of most humans and is usually transmitted within families, can distinguish between closely related human populations and are superior in this respect to classical human genetic markers. H. pylori from Buddhists and Muslims, the two major ethnic communities in Ladakh (India), differ in their population-genetic structure. Moreover, the prokaryotic diversity is consistent with the Buddhists having arisen from an introgression of Tibetan speakers into an ancient Ladakhi population. H. pylori from Muslims contain a much stronger ancestral Ladakhi component, except for several isolates with an Indo-European signature, probably reflecting genetic flux from the Near East. These signatures in H. pylori sequences are congruent with the recent history of population movements in Ladakh, whereas similar signatures in human microsatellites or mtDNA were only marginally significant. H. pylori sequence analysis has the potential to become an important tool for unraveling short-term genetic changes in human populations
— id: 63880, year: 2004, vol: 101, page: 4746, stat: Journal Article,

Evolutionary history of hrgA, which replaces the restriction gene hpyIIIR in the hpyIII locus of Helicobacter pylori
Ando, T; Aras, R A; Kusugami, K; Blaser, M J; Wassenaar, T M
2003 Jan;185(1):295-301, Journal of bacteriology
A recently identified Helicobacter pylori gene, hrgA, was previously reported to be present in 70 (33%) of 208 strains examined (T. Ando, T. M. Wassenaar, R. M. Peek, R. A. Aras, A. I. Tschumi, L.-J. Van Doorn, K. Kusugami, and M. J. Blaser, Cancer Res. 62:2385-2389, 2002). Sequence analysis of nine such strains indicated that in each strain hrgA replaced hpyIIIR, which encodes a restriction endonuclease and which, together with the gene for its cognate methyltransferase, constitutes the hpyIII locus. As a consequence of either the hrgA insertion or independent mutations, hpyIIIM function was lost in 11 (5%) of the 208 strains examined, rendering chromosomal DNA sensitive to MboI digestion. The evolutionary history of the locus containing either hpyIII or hrgA was reconstructed. By homologous recombination involving flanking sequences, hrgA and hpyIIIR can replace one another in the hpyIII locus, and there is simultaneous replacement of several flanking genes. These findings, combined with the hpyIM/iceA2 locus discovered previously, suggest that the two most strongly conserved methylase genes of H. pylori, hpyIIIM and hpyIM, are both preceded by alternative genes that compete for presence at their loci
— id: 34574, year: 2003, vol: 185, page: 295, stat: Journal Article,

Plasticity of repetitive DNA sequences within a bacterial (Type IV) secretion system component
Aras, Rahul A; Fischer, Wolfgang; Perez-Perez, Guillermo I; Crosatti, MariaLuisa; Ando, Takafumi; Haas, Rainer; Blaser, Martin J
2003 Nov 3;198(9):1349-1360, Journal of experimental medicine
DNA rearrangement permits bacteria to regulate gene content and expression. In Helicobacter pylori, cagY, which contains an extraordinary number of direct DNA repeats, encodes a surface-exposed subunit of a (type IV) bacterial secretory system. Examining potential DNA rearrangements involving the cagY repeats indicated that recombination events invariably yield in-frame open reading frames, producing alternatively expressed genes. In individual hosts, H. pylori cell populations include strains that produce CagY proteins that differ in size, due to the predicted in-frame deletions or duplications, and elicit minimal or no host antibody recognition. Using repetitive DNA, H. pylori rearrangements in a host-exposed subunit of a conserved bacterial secretion system may permit a novel form of antigenic evasion
— id: 42650, year: 2003, vol: 198, page: 1349, stat: Journal Article,

Extensive repetitive DNA facilitates prokaryotic genome plasticity
Aras, Rahul A; Kang, Josephine; Tschumi, Ariane I; Harasaki, Yasuaki; Blaser, Martin J
2003 Nov 11;100(23):13579-13584, Proceedings of the National Academy of Sciences of the United States of America
Prokaryotic genomes are substantially diverse, even when from closely related species, with the resulting phenotypic diversity representing a repertoire of adaptations to specific constraints. Within the microbial population, genome content may not be fixed, as changing selective forces favor particular phenotypes; however, organisms well adapted to particular niches may have evolved mechanisms to facilitate such plasticity. The highly diverse Helicobacter pylori is a model for studying genome plasticity in the colonization of individual hosts. For H. pylori, neither point mutation, nor intergenic recombination requiring the presence of multiple colonizing strains, is sufficient to fully explain the observed diversity. Here we demonstrate that H. pylori has extensive, nonrandomly distributed repetitive chromosomal sequences, and that recombination between identical repeats contributes to the variation within individual hosts. That H. pylori is representative of prokaryotes, especially those with smaller (<2 megabases) genomes, that have similarly extensive direct repeats, suggests that recombination between such direct DNA repeats is a widely conserved mechanism to promote genome diversification
— id: 39007, year: 2003, vol: 100, page: 13579, stat: Journal Article,

Natural variation in populations of persistently colonizing bacteria affect human host cell phenotype
Aras, Rahul A; Lee, Yongchan; Kim, Sung-Kook; Israel, Dawn; Peek, Richard M Jr; Blaser, Martin J
2003 Aug 15;188(4):486-496, Journal of infectious diseases
The highly diverse bacterium Helicobacter pylori, which persistently colonizes the human stomach, provides models to study the role of genome plasticity in host adaptation. Within H. pylori populations from 2 colonized individuals, intragenomic recombination between cagA DNA repeat sequences leads to deletion or duplication of tyrosine phosphorylation sites in the CagA protein, which is injected by a type IV secretion system into host cells. Experimental coculture of gastric epithelial cells with the strains containing these naturally occurring CagA phosphorylation site variants induced markedly divergent host cell morphologic responses. Mutants were constructed in which a phosphorylation site was either added or deleted in the expressed CagA protein; coculture studies confirmed that the naturally occurring differences in CagA phosphorylation are responsible for the observed phenotypic variation. These findings indicate that within an individual host, intragenomic recombination between H. pylori repetitive DNA produces strain variants differing in their signals to host cells
— id: 39118, year: 2003, vol: 188, page: 486, stat: Journal Article,

Great Teachers - Cancer, Ulcer, and Helicobacter: To Have or to Have Not?
Blaser, Martin
[S.l.] : NIH, 2003,
— id: 1429, year: 2003, vol: , page: , stat: ,

Campylobacter fetus bacteremia in a patient with adult T cell leukemia
Chuman, Yoshiko; Takata, Tohru; Sameshima, Hisako; Takeuchi, Shogo; Takatsuka, Yoshifusa; Makino, Torahiko; Blaser, Martin J; Utsunomiya, Atae
2003 Jun 1;36(11):1497-1498, Clinical infectious diseases
— id: 43540, year: 2003, vol: 36, page: 1497, stat: Journal Article,

Population attributable risks of esophageal and gastric cancers
Engel, Lawrence S; Chow, Wong-Ho; Vaughan, Thomas L; Gammon, Marilie D; Risch, Harvey A; Stanford, Janet L; Schoenberg, Janet B; Mayne, Susan T; Dubrow, Robert; Rotterdam, Heidrun; West, A Brian; Blaser, Martin; Blot, William J; Gail, Mitchell H; Fraumeni, Joseph F Jr
2003 Sep 17;95(18):1404-1413, Journal of the National Cancer Institute
BACKGROUND: Several risk factors have been identified for esophageal adenocarcinoma, gastric cardia adenocarcinoma, esophageal squamous cell carcinoma, and noncardia gastric adenocarcinoma, but no study has comprehensively examined their contributions to the cancer burden in the general population. Herein, we estimate the population attributable risks (PARs) for various risk factors observed in a multicenter population-based case-control study. METHODS: We calculated PARs by using 293 patients with esophageal adenocarcinoma, 261 with gastric cardia adenocarcinoma, 221 with esophageal squamous cell carcinoma, 368 with noncardia gastric adenocarcinoma, and 695 control subjects. We included smoking for all four tumor types and Helicobacter pylori infection for noncardia gastric adenocarcinoma as established causal risk factors as well as several other factors for which causality is under evaluation. RESULTS: Ever smoking, body mass index above the lowest quartile, history of gastroesophageal reflux, and low fruit and vegetable consumption accounted for 39.7% (95% confidence interval [CI] = 25.6% to 55.8%), 41.1% (95% CI = 23.8% to 60.9%), 29.7% (95% CI = 19.5% to 42.3%), and 15.3% (95% CI = 5.8% to 34.6%) of esophageal adenocarcinomas, respectively, with a combined PAR of 78.7% (95% CI = 66.5% to 87.3%). Ever smoking and body mass index above the lowest quartile were responsible for 45.2% (95% CI = 31.3% to 59.9%) and 19.2% (95% CI = 4.9% to 52.0%) of gastric cardia adenocarcinomas, respectively, with a combined PAR of 56.2% (95% CI = 38.1% to 72.8%). Ever smoking, alcohol consumption, and low fruit and vegetable consumption accounted for 56.9% (95% CI = 36.6% to 75.1%), 72.4% (95% CI = 53.3% to 85.8%), and 28.7% (95% CI = 11.1% to 56.5%) of esophageal squamous cell carcinomas, respectively, with a combined PAR of 89.4% (95% CI = 79.1% to 95.0%). Ever smoking, history of gastric ulcers, nitrite intake above the lowest quartile, and H. pylori infection were responsible for 18.3% (95% CI = 6.5% to 41.8%), 9.7% (95% CI = 5.4% to 16.8%), 40.7% (95% CI = 23.4% to 60.7%), and 10.4% (95% CI = 0.3% to 79.6%) of noncardia gastric adenocarcinomas, respectively, with a combined PAR of 59.0% (95% CI = 16.2% to 91.4%). CONCLUSION: In this population, a few known risk factors account for a majority of esophageal and gastric cancers. These results suggest that the incidence of these cancers may be decreased by reducing the prevalence of smoking, gastroesophageal reflux, and being overweight and by increasing the consumption of fruits and vegetables
— id: 79220, year: 2003, vol: 95, page: 1404, stat: Journal Article,

Traces of human migrations in Helicobacter pylori populations
Falush, Daniel; Wirth, Thierry; Linz, Bodo; Pritchard, Jonathan K; Stephens, Matthew; Kidd, Mark; Blaser, Martin J; Graham, David Y; Vacher, Sylvie; Perez-Perez, Guillermo I; Yamaoka, Yoshio; Megraud, Francis; Otto, Kristina; Reichard, Ulrike; Katzowitsch, Elena; Wang, Xiaoyan; Achtman, Mark; Suerbaum, Sebastian
2003 Mar 7;299(5612):1582-1585, Science
Helicobacter pylori, a chronic gastric pathogen of human beings, can be divided into seven populations and subpopulations with distinct geographical distributions. These modern populations derive their gene pools from ancestral populations that arose in Africa, Central Asia, and East Asia. Subsequent spread can be attributed to human migratory fluxes such as the prehistoric colonization of Polynesia and the Americas, the neolithic introduction of farming to Europe, the Bantu expansion within Africa, and the slave trade
— id: 34570, year: 2003, vol: 299, page: 1582, stat: Journal Article,

Do GERD symptoms predict Helicobacter pylori colonization?
Francois, F; Bini, EJ; Perez-Perez, GI; Blaser, MJ
2003 ;124(4):A624-A624, Gastroenterology
— id: 108237, year: 2003, vol: 124, page: A624, stat: Journal Article,

Relationship of Helicobacter pylori and strain characteristics to esophageal pathology
Francois, F; Bini, EJ; Perez-Perez, GI; Yee, HT; Blaser, MJ
2003 ;124(4):A55-A55, Gastroenterology
— id: 108235, year: 2003, vol: 124, page: A55, stat: Journal Article,

Role of S-layer protein antigenic diversity in the immune responses of sheep experimentally challenged with Campylobacter fetus subsp. fetus
Grogono-Thomas, R; Blaser, M J; Ahmadi, M; Newell, D G
2003 Jan;71(1):147-154, Infection & immunity
Surface layer proteins (SLPs) are essential for induction of abortion by Campylobacter fetus subsp. fetus in experimentally challenged ewes. These proteins are encoded by multiple sap genes and vary in size and antigenicity. The role of SLP antigenic variation during experimental ovine infection was investigated. Following subcutaneous challenge, the SLPs were highly antigenic, and antibodies were detected in serum, milk, bile, and urine. Fecal anti-SLP antibodies were detected only in animals challenged orally. Ewes challenged with wild-type strain 23D with variable SLPs developed detectable circulating anti-SLP immunoglobulin G (IgG) antibodies by 2 weeks postchallenge. In contrast, ewes challenged with mutants of 23D that had fixed expression of a single SLP developed antibodies within 1 week postchallenge, suggesting that antigenic variation in SLPs may delay the host antibody response. Although not statistically significant, the data from challenge experiments in which vaccinated ewes were used suggested that SLP-expressing vaccines could protect animals from abortion and that this effect was independent of the SLP expressed, indicating involvement of conserved epitopes in the SLP. The conserved 184-amino-acid N-terminal region of the SLP, identified from previously published sequences, was epitope mapped with rabbit anti-SLP antisera by using overlapping synthetic 20-mer peptides. Two putative epitopes were identified at amino acids 81 to 110 and 141 to 160. Amino acids 81 to 100 also bound serum IgG antibodies from experimentally challenged sheep. Conserved antigenic regions of the SLP that induce protective immune responses may enable development of synthetic vaccine candidates for C. fetus subsp. fetus-associated ovine abortion
— id: 34572, year: 2003, vol: 71, page: 147, stat: Journal Article,

Detection of a luxS-signaling molecule in Bacillus anthracis
Jones, Marcus B; Blaser, Martin J
2003 Jul;71(7):3914-3919, Infection & immunity
Quorum-sensing regulation of density-dependent genes has been described for numerous bacterial species. The partially annotated genome sequence of Bacillus anthracis contains an open reading frame (BA5047) predicted to encode an ortholog of luxS, required for synthesis of the quorum-sensing signaling molecule autoinducer-2 (AI-2). To determine whether B. anthracis produces AI-2, the Vibrio harveyi luminescence bioassay was used. Cell-free conditioned media from vaccine (Sterne) strain 34F(2) induced luminescence in V. harveyi reporter strain BB170, indicating its production of AI-2. Cloned BA5047, expressed in Escherichia coli DH5 alpha cells, restored AI-2 activity to these cells. To evaluate whether BA5047 is essential for AI-2 synthesis, it was deleted through allelic exchange with marker rescue; the resulting mutant had no functional luxS activity and had reduced growth in vitro. In the wild-type strain, AI-2 activity was greatest during the exponential phase of growth. In total, these data indicate that BA5047 is a functional luxS ortholog in B. anthracis necessary for growth-phase-specific AI-2 expression. Thus, B. anthracis may utilize extracellular signaling molecules to regulate density-dependent gene expression
— id: 39188, year: 2003, vol: 71, page: 3914, stat: Journal Article,

Helicobacter pylori and TT virus prevalence in Japanese children
Kato, Seiichi; Okamoto, Hiroaki; Nishino, Yoshikazu; Oyake, Yasuo; Nakazato, Yutaka; Okuda, Masumi; Fujisawa, Takuji; Iinuma, Kazuie; Blaser, Martin J
2003 ;38(12):1126-1130, Journal of gastroenterology
BACKGROUND: The major transmission route of Helicobacter pylori, oral-oral or fecal-oral, remains to be established. TT virus (TTV), a recently discovered microbe that is prevalent in healthy persons, is believed to be mainly transmitted by nonparenteral routes. The purpose of this study was to test the hypothesis that these two microorganisms have a common mode of transmission. METHODS: We investigated the seroprevalence of H. pylori and TTV in a cross-sectional study of 454 healthy Japanese children from birth to age 15 years, living in five different geographic areas. Determination of H. pylori status was based on the presence of specific serum IgG and IgA antibodies, determined using enzyme immunoassays. TTV DNA was detected and the titer was determined using semiquantitative polymerase chain reaction with heminested primers. RESULTS: The overall prevalences of H. pylori and TTV were 12.2% and 21.6%, respectively. An age-related increase of prevalence was shown for H. pylori ( P < 0.001), but not for TTV ( P = 0.23). Titers of TTV DNA significantly decreased with age (P = 0.02). There were significant geographic differences in TTV prevalence ( P < 0.001), but not in H. pylori seroprevalence (P = 0.33). There was no true correlation between the prevalence of these two organisms (Phi coefficient = -0.02 and P = 0.66). CONCLUSIONS: Although Japanese children frequently acquire both H. pylori and TTV, especially in early childhood, their acquisition appears to be independent
— id: 43536, year: 2003, vol: 38, page: 1126, stat: Journal Article,

Use of an open-reading frame-specific Campylobacter jejuni DNA microarray as a new genotyping tool for studying epidemiologically related isolates
Leonard, Edward E 2nd; Takata, Tohru; Blaser, Martin J; Falkow, Stanley; Tompkins, Lucy S; Gaynor, Erin C
2003 Feb 15;187(4):691-694, Journal of infectious diseases
Findings from use of an open-reading frame-specific Campylobacter jejuni DNA microarray to investigate genetic diversity among clinical isolates associated with 5 independent clusters of infection were compared with data from random amplified polymeric DNA (RAPD) and Penner serotyping analyses. The DNA microarray provides a highly specific epidemiological typing tool for analysis of C. jejuni isolates and reveals both divergent and highly conserved gene classes among isolates
— id: 43541, year: 2003, vol: 187, page: 691, stat: Journal Article,

Promoter analysis of Helicobacter pylori genes with enhanced expression at low pH
McGowan, Catherine C; Necheva, Antoaneta S; Forsyth, Mark H; Cover, Timothy L; Blaser, Martin J
2003 Jun;48(5):1225-1239, Molecular microbiology
To identify Helicobacter pylori genes with expression that is enhanced under low pH conditions, we used subtractive hybridization methodology. We identified 28 acid-induced genes, of which 18 have known or putative functions. Six pairs of genes were co-transcribed. Primer extension analysis identified single or multiple transcriptional start points (tsp) for 14 of the 22 loci. Sequence analysis of the -10 regions upstream of the tsps revealed consensus motifs for multiple RNA polymerase sigma factors present in H. pylori (sigma80, sigma54 and sigma28). No sequences resembling the -35 Escherichia coli consensus sequence (TTGACA) were present upstream of any of the genes. Both increased gene transcription and decreased mRNA decay contribute to the observed increase in H. pylori transcript abundance at acid pH. These studies document the complex response of H. pylori to environmental pH changes, and provide insight into mechanisms used for intragastric survival
— id: 43539, year: 2003, vol: 48, page: 1225, stat: Journal Article,

Transient and persistent Helicobacter pylori colonization in Native American children
Perez-Perez, Guillermo I; Sack, R Bradley; Reid, Raymond; Santosham, Mathuram; Croll, Janne; Blaser, Martin J
2003 Jun;41(6):2401-2407, Journal of clinical microbiology
Helicobacter pylori is chiefly acquired in childhood, but the exact timing of acquisition is not well understood. The main goal of this study was to assess H. pylori acquisition in a pediatric population. We studied two cohorts of Native American children: a birth cohort of 50 children and 58 older children (mean age, 53 months). We measured serum immunoglobulin G (IgG), IgM, and IgA antibodies to H. pylori whole-cell antigen and IgG antibodies to CagA. Among 44 birth cohort children monitored for more than 12 months, 24 (54.5%) had seroconversions, 7 (15.9%) were transient, and 17 (38.6%) were persistent. Among the older children, 49 (84.5%) of the 58 children were monitored for 1 year; 34 (69.4%) had H. pylori antibodies at study entry. During the next year, 7 (20.6%) children seroreverted, and of 15 initially negative children, 5 (33.3%) seroconverted. In both groups, evaluation of CagA antibodies increased the sensitivity of H. pylori detection. Serum pepsinogen I (PGI) levels in H. pylori-negative children rose significantly until age 6 months and remained constant for the next 19 months. At the time of H. pylori seroconversion, PGI peaked to levels significantly higher than in the never-seroconverted (P = 0.02) and the pre-seroconverted (P = 0.03) children, but then declined to levels paralleling those of H. pylori-negative children. Thus, H. pylori acquisition, accompanied by a transient PGI increase, was frequent in this population, especially in the second and third years of life, but often was brief
— id: 39203, year: 2003, vol: 41, page: 2401, stat: Journal Article,

Evolutionary implications of microbial genome tetranucleotide frequency biases
Pride, David T; Meinersmann, Richard J; Wassenaar, Trudy M; Blaser, Martin J
2003 Feb;13(2):145-158, Genome research
We compared nucleotide usage pattern conservation for related prokaryotes by examining the representation of DNA tetranucleotide combinations in 27 representative microbial genomes. For each of the organisms studied, tetranucleotide usage departures from expectations (TUD) were shared between related organisms using both Markov chain analysis and a zero-order Markov method. Individual strains, multiple chromosomes, plasmids, and bacteriophages share TUDs within a species. TUDs varied between coding and noncoding DNA. Grouping prokaryotes based on TUD profiles resulted in relationships with important differences from those based on 16S rRNA phylogenies, which may reflect unequal rates of evolution of nucleotide usage patterns following divergence of particular organisms from a common ancestor. By both symmetrical tree distance and likelihood analysis, phylogenetic trees based on TUD profiles demonstrate a level of congruence with 16S rRNA trees similar to that of both RpoA and RecA trees. Congruence of these trees indicates that there exists phylogenetic signal in TUD patterns, most prominent in coding region DNA. Because relationships demonstrated in TUD-based analyses utilize whole genomes, they should be considered complementary to phylogenies based on single genetic elements, such as 16S rRNA
— id: 34571, year: 2003, vol: 13, page: 145, stat: Journal Article,

Long-term persistence of resistant Enterococcus species after antibiotics to eradicate Helicobacter pylori
Sjolund, Maria; Wreiber, Karin; Andersson, Dan I; Blaser, Martin J; Engstrand, Lars
2003 Sep 16;139(6):483-487, Annals of internal medicine
BACKGROUND: Antibiotic treatment selects for resistance not only in the pathogen to which it is directed but also in the indigenous microflora. OBJECTIVE: To determine whether a widely used regimen (clarithromycin, metronidazole, and omeprazole) for Helicobacter pylori eradication affects resistance development in enterococci. DESIGN: Cohort study. SETTING: Endoscopy units at 3 community hospitals in Sweden. PATIENTS: 5 consecutive dyspeptic patients who were colonized with H. pylori, had endoscopy-confirmed duodenal ulcer, and received antibiotic treatment, and 5 consecutive controls with dyspepsia but no ulcer who did not receive treatment. MEASUREMENTS: Fecal samples were obtained from patients and controls before, immediately after, 1 year after, and 3 years after treatment. From each patient and sample, enterococci were isolated and analyzed for DNA fingerprint, clarithromycin susceptibility, and presence of the erm(B) gene. RESULTS: In treated patients, all enterococci isolated immediately after treatment showed high-level clarithromycin resistance due to erm(B). In 3 patients, resistant enterococci persisted for 1 to 3 years after treatment. No resistance developed among controls. CONCLUSION: A common H. pylori treatment selects for highly resistant enterococci that can persist for at least 3 years without further selection
— id: 43537, year: 2003, vol: 139, page: 483, stat: Journal Article,

Tooth loss, pancreatic cancer, and Helicobacter pylori
Stolzenberg-Solomon, Rachael Z; Dodd, Kevin W; Blaser, Martin J; Virtamo, Jarmo; Taylor, Philip R; Albanes, Demetrius
2003 Jul;78(1):176-181, American journal of clinical nutrition
BACKGROUND: Poor dental health has been associated with increased risks of oral, esophageal, and gastric cancer and may also be associated with pancreatic cancer. In addition, Helicobacter pylori has been found in dental plaque and has been associated with periodontal disease and pancreatic cancer. OBJECTIVE: The objective was to investigate prospectively the relation between dentition history and pancreatic cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort in Finland and the association between dentition history and H. pylori seropositivity in a cross-sectional sample of subjects without cancer (n = 475) from the same cohort. DESIGN: Of the 29,104 male smokers aged 50-69 y in the cohort for whom there were complete data, 174 developed pancreatic cancer from 1985 to 1997. Cox proportional hazard models were used to estimate age-, smoking-, education-, urban living-, and height-adjusted hazard ratios and 95% CIs for pancreatic cancer, and logistic regression models were used to estimate age- and education-adjusted odds ratios for H. pylori carriage. RESULTS: Tooth loss was positively associated with pancreatic cancer (edentulous compared with missing 0-10 teeth: hazard ratio = 1.63; 95% CI: 1.09, 2.46; P for trend = 0.02) but was not significantly associated with H. pylori seropositivity (edentulous compared with missing 0-10 teeth: odds ratio = 1.30; 95% CI: 0.73, 2.32; P for trend = 0.37). CONCLUSION: Additional studies are needed to evaluate the association between tooth loss and pancreatic cancer, as well as cancers at other gastrointestinal sites, particularly with respect to possible biological mechanisms
— id: 43538, year: 2003, vol: 78, page: 176, stat: Journal Article,

An email alert system for internal medicine physicians
Triola, Marc M; Blaser, Martin J
2003 ;189(3):1035-1035, Proceedings (AMIA Annual Symposium)
This study evaluated the effectiveness of an email-based alerting system for internal medicine house staff and faculty in geographically dispersed locales. Responses to a test alert email message were used to quantify the rapidity by which physicians read the message, and to define subgroups in which this communication modality proved most successful. The results of this study are being used to improve our preparedness for emergencies
— id: 43535, year: 2003, vol: 189, page: 1035, stat: Journal Article,

Structure and genotypic plasticity of the Campylobacter fetus sap locus
Tu, Zheng-Chao; Wassenaar, Trudy M; Thompson, Stuart A; Blaser, Martin J
2003 May;48(3):685-698, Molecular microbiology
The Campylobacter fetus surface layer proteins (SLPs), encoded by five to nine sapA homologues, are major virulence factors. To characterize the sapA homologues further, a 65.9 kb C. fetus genomic region encompassing the sap locus from wild-type strain 23D was completely sequenced and analysed; 44 predicted open reading frames (ORFs) were recognized. The 53.8 kb sap locus contained eight complete and one partial sapA homologues, varying from 2769 to 3879 bp, sharing conserved 553-2622 bp 5' regions, with partial sharing of 5' and 3' non-coding regions. All eight sapA homologues were expressed in Escherichia coli as antigenic proteins and reattached to the surface of SLP- strain 23B, indicating their conserved function. Analysis of the sap homologues indicated three phylogenetic groups. Promoter-specific polymerase chain reactions (PCRs) and sapA homologue-specific reverse transcription (RT)-PCRs showed that the unique sapA promoter can potentially express all eight sapA homologues. Reciprocal DNA recombination based on the 5' conserved regions can involve each of the eight sapA homologues, with frequencies from 10(-1) to 10(-3). Intragenic recombination between sapA7 and sapAp8, mediated by their conserved regions with a 10(-1)-10(-2) frequency, allows the formation of new sap homologues. As divergent SLP C-termini possess multiple antigenic sites, their reciprocal recombination behind the unique sap promoter leads to continuing antigenic variation
— id: 34569, year: 2003, vol: 48, page: 685, stat: Journal Article,

Polymorphisms of Helicobacter pylori HP0638 reflect geographic origin and correlate with cagA status
Ando, T; Peek, R M; Pride, D; Levine, S M; Takata, T; Lee, Y-C; Kusugami, K; van der Ende, A; Kuipers, E J; Kusters, J G; Blaser, M J
2002 Jan;40(1):239-246, Journal of clinical microbiology
Since the associations between Helicobacter pylori genotype and disease differ in Asia and the West, we investigated the correlation between HP0638, encoding an outer membrane protein, and potential markers of virulence (cagA, vacA, and iceA). For 109 strains from nine countries, the status of cagA, vacA, and iceA was determined by PCR and/or a line probe assay. We also studied 18 strains from 8 patients (parents and 6 daughters) from a Dutch family and paired strains collected on average 8 years apart from 11 patients. When the HP0638 signal sequences were amplified by PCR and DNA sequence determinations were performed, 89 (96%) of 93 cagA-positive strains had HP0638 in frame, versus none (0%) of 16 cagA-negative strains (P < 0.001). Among strains in which HP0638 was in frame, a six-CT dinucleotide repeat pattern was dominant in Western countries (23 of 33 strains [70%]), while a pattern of three CT repeats with another CT after four T's (3 + 1-CT-repeat pattern) was dominant in East Asia (31 of 46 strains [67%]); however, specific CT repeat patterns did not correlate with clinical outcome. HP0638 phylogenetic trees also showed geographic characters. The HP0638 frame status and CT dinucleotide repeat patterns were identical for 9 of 11 pairs of strains obtained on average 8 years apart from individuals and the 15 strains obtained from the mother and all six daughters. Thus, HP0638 frame status and cagA status are strongly correlated. The CT dinucleotide repeat pattern in the putative HP0638 signal sequence has geographic characters and appears stable in particular patients and families over a period of years. Analysis of HP0638 CT polymorphisms may serve as a new typing system to discriminate H. pylori isolates for epidemiological purposes
— id: 39735, year: 2002, vol: 40, page: 239, stat: Journal Article,

Host cell responses to genotypically similar Helicobacter pylori isolates from United States and Japan
Ando, Takafumi; Peek, Richard M Jr; Lee, Yong-Chan; Krishna, Uma; Kusugami, Kazuo; Blaser, Martin J
2002 Jan;9(1):167-175, Clinical & diagnostic laboratory immunology
Associations of Helicobacter pylori genotypes with disease differ between Western countries and Asia. Therefore, we directly compared histopathological and in vitro responses to clinical isolates with similar genotypes. Sixty-three cagA(+) vacAs1/m1 H. pylori isolates (United States, n = 24; Japan, n = 39) and eight cagA-negative vacAs2/m2 strains were incubated with AGS cells, and supernatants were assayed for interleukin-8 (IL-8) and for DNA fragmentation. CagA tyrosine phosphorylation in AGS cells and the sequence of the putative HP0638 (oipA) signal sequence region were determined for 22 representative strains. HP0638 and/or cag island mutant strains were created and examined in IL-8 and CagA tyrosine phosphorylation assays. Levels of IL-8 induction and DNA fragmentation were similar in the U.S. and Japanese cagA(+) vacAs1/m1 isolates. All 10 of the isolates with the highest IL-8 induction and 8 of the 10 isolates with the lowest IL-8 induction had an in-frame oipA open reading frame, and all 10 of the isolates with the highest IL-8 induction and 7 of the 10 isolates with the lowest IL-8 induction induced CagA tyrosine phosphorylation in AGS cells. Eight isolates from gastric ulcer patients induced significantly more apoptosis in vitro, and more severe gastritis and atrophy in vivo, than other Japanese isolates. Disruption of HP0638 did not affect IL-8 induction or CagA tyrosine phosphorylation. Thus, H. pylori cagA(+) vacAs1/m1 isolates from the United States and Japan induce similar IL-8 and apoptosis levels. Inactivation of HP0638 does not alter epithelial responses mediated by the cag island in vitro. Assessment of apoptosis in vitro identified a group of H. pylori isolates that induce more severe gastric inflammation and atrophy
— id: 39731, year: 2002, vol: 9, page: 167, stat: Journal Article,

A Helicobacter pylori restriction endonuclease-replacing gene, hrgA, is associated with gastric cancer in Asian strains
Ando, Takafumi; Wassenaar, Trudy M; Peek, Richard M Jr; Aras, Rahul A; Tschumi, Ariane I; van Doorn, Leen-Jan; Kusugami, Kazuo; Blaser, Martin J
2002 Apr 15;62(8):2385-2389, Cancer research
The sensitivity of Helicobacter pylori chromosomal DNA to MboI digestion was investigated in 208 strains from several continents. Only 11 (5%) of strains were sensitive to MboI, and it was hypothesized that HpyIII, a type II restriction/modification enzyme with sequence homology to MboI, mediated the protection. This was confirmed by PCR analysis of the gene locus of hpyIII, normally composed of hpyIIIR and hpyIIIM. In all but one strain sensitive to MboI, no PCR product of hpyIIIR was obtained. In contrast, all strains yielded a product for hpyIIIM, independent of MboI phenotype. Further examination of the hpyIII locus in strains lacking a hpyIIIR PCR product identified a novel gene, hrgA, upstream of hpyIIIM. All 208 strains examined had either hpyIIIR or hrgA, but not both, upstream of hpyIIIM. Although hrgA has homology with a Campylobacter jejuni gene (Cj1602), its function is not known. In Western countries, hrgA was more prevalent (53%) than in Asia (25%; P < 0.0001, chi(2)). In Asia, hrgA was more prevalent among gastric cancer patients (18 of 43; 42%) than among noncancer patients (16 of 95; 17%; P = 0.001, chi(2)). All 143 Asian strains tested were cagA(+), but among Western strains, hrgA was more prevalent in cagA(+) strains (26 of 42; 62%) than in cagA(-) strains (9 of 23; 39%; P = 0.04, chi(2)). In coculture with epithelial cells, hpyIIIR and hrgA strains did not show any significant differences in interleukin-8 induction and apoptosis. Although a direct function for hrgA in virulence could not be demonstrated, our data indicate that hrgA is a strain-specific gene that might be associated with gastric cancer among H. pylori isolates from Asian patients
— id: 39674, year: 2002, vol: 62, page: 2385, stat: Journal Article,

Helicobacter pylori interstrain restriction-modification diversity prevents genome subversion by chromosomal DNA from competing strains
Aras, Rahul A; Small, Aaron J; Ando, Takafumi; Blaser, Martin J
2002 Dec 15;30(24):5391-5397, Nucleic acids research
Helicobacter pylori, bacteria that colonize the human gastric mucosa, possess a large number of genes for restriction-modification (R-M) systems, and essentially, every strain possesses a unique complement of functional and partial R-M systems. Nearly half of the H.pylori strains studied possess an active type IIs R-M system, HpyII, with the recognition sequence GAAGA. Recombination between direct repeats that flank the R-M cassette allows for its deletion whereas strains lacking hpyIIRM can acquire this cassette through natural transformation. We asked whether strains lacking HpyII R-M activity can acquire an active hpyIIRM cassette [containing a 1.4 kb kanamycin resistance (aphA) marker], whether such acquisition is DNase sensitive or resistant and whether restriction barriers limit acquisition of chromosomal DNA. Our results indicate that natural transformation and conjugation-like mechanisms may contribute to the transfer of large (4.8 kb) insertions of chromosomal DNA between H.pylori strains, that inactive or partial R-M systems can be reactivated upon recombination with a functional allele, consistent with their being contingency genes, and that H.pylori R-M diversity limits acquisition of chromosomal DNA fragments of >/=1 kb
— id: 34573, year: 2002, vol: 30, page: 5391, stat: Journal Article,

The ecology of height: the effect of microbial transmission on human height
Beard, Albertine S; Blaser, Martin J
2002 Fall;45(4):475-498, Perspectives in biology & medicine
The height that adult humans achieve results from a complex interplay between genetic endowment and environmental exposures during development. We hypothesize that exposure to microbes--both exogenous pathogens and endogenous biota--are critical environmental determinants of the expression of human height in a community. Both experimental studies and historical changes in height in relation to presumed microbial transmission support this hypothesis
— id: 34580, year: 2002, vol: 45, page: 475, stat: Journal Article,

Infections of the gastrointestinal tract
Blaser, Martin J
Philadelphia PA : Lippincott Williams & Wilkins, 2002,
— id: 2002, year: 2002, vol: , page: , stat: ,

Polymorphic bacteria persisting in polymorphic hosts: assessing Helicobacter pylori-related risks for gastric cancer
Blaser, Martin J
2002 Nov 20;94(22):1662-1663, Journal of the National Cancer Institute
— id: 34576, year: 2002, vol: 94, page: 1662, stat: Journal Article,

The genetic gymnastics of our indigenous microbes
Blaser, Martin J
2002 Jun 27;346(26):2083-2085, New England journal of medicine
— id: 34585, year: 2002, vol: 346, page: 2083, stat: Journal Article,

Trends in reported adenocarcinomas of the oesophagus and gastric cardia in Japan
Blaser, Martin J; Saito, Daizo
2002 Feb;14(2):107-113, European journal of gastroenterology & hepatology
Adenocarcinomas involving the oesophagus and gastric cardia are becoming more common in Western countries, but data from Japan are limited. We sought to determine whether the frequency of these cancers in Japan has increased in recent decades. Review of national cancer mortality data, national registries of oesophageal and gastric cancer cases, and records from two large cancer centres for various time periods between 1950 and 1998 did not show increased reporting of oesophageal adenocarcinomas. In contrast, both national and cancer centre data indicate an absolute increase in the number of gastric cancers involving the C-area (proximal third of the stomach). From a national registry of resected primary gastric cancer cases, those arising in the C-area as a proportion of all tumours rose by 41.8% between 1963 (12.2% of all registered cases) and 1990 (17.3%). Analysis of true cardia (<2 cm distal to oesophagus-cardia junction) early cancers from the two cancer centres showed significant increases in both absolute number and in proportion to other gastric cancers over a 36-year period. These data suggest that the frequency of cardia cancers is increasing in Japan. Lack of a parallel increase in oesophageal adenocarcinomas could be due to misclassification artefacts and/or coding preferences for gastro-oesophageal junction tumours
— id: 43544, year: 2002, vol: 14, page: 107, stat: Journal Article,

Molecular analysis of sarcoidosis tissues for mycobacterium species DNA
Drake, Wonder Puryear; Pei, Zhiheng; Pride, David T; Collins, Robert D; Cover, Timothy L; Blaser, Martin J
2002 Nov;8(11):1334-1341, Emerging infectious diseases
We performed polymerase chain reaction analysis, for Mycobacterium species 16S rRNA, rpoB, and IS6110 sequences, on 25 tissue specimens from patients with sarcoidosis and on 25 control tissue specimens consisting of mediastinal or cervical lymph nodes and lung biopsies. Mycobacterium species 16S rRNA sequences were amplified from 12 (48%) rpoB sequences and from 6 (24%) of the sarcoidosis specimens. In total, 16S rRNA or rpoB sequences were amplified from 15 sarcoidosis specimens (60%) but were not detected in any of the control tissues (p=0.00002, chi square). In three specimens, the sequences resembled Mycobacterium species other than M. tuberculosis. All specimens with sequences consistent with M. tuberculosis were negative for IS6110. We provide evidence that one of a variety of Mycobacterium species, especially organisms resembling M. tuberculosis, is found in most patients with sarcoidosis
— id: 34575, year: 2002, vol: 8, page: 1334, stat: Journal Article,

Cutaneous anthrax associated with microangiopathic hemolytic anemia and coagulopathy in a 7-month-old infant
Freedman, Abigail; Afonja, Olubunmi; Chang, Mary Wu; Mostashari, Farzad; Blaser, Martin; Perez-Perez, Guillermo; Lazarus, Herb; Schacht, Robert; Guttenberg, Jane; Traister, Michael; Borkowsky, William
2002 Feb 20;287(7):869-874, JAMA
A 7-month-old infant with cutaneous anthrax developed severe systemic illness despite early treatment with antibiotics. The infant displayed severe microangiopathic hemolytic anemia with renal involvement, coagulopathy, and hyponatremia. These findings are unusual with cutaneous anthrax, but have been described in illness resulting from spider toxin and may delay correct diagnosis. The systemic manifestations of the disease persisted for nearly a month despite corticosteroid therapy, but resolved
— id: 26017, year: 2002, vol: 287, page: 869, stat: Journal Article,

East Asian genotypes of Helicobacter pylori strains in Amerindians provide evidence for its ancient human carriage
Ghose, Chandrabali; Perez-Perez, Guillermo I; Dominguez-Bello, Maria-Gloria; Pride, David T; Bravi, Claudio M; Blaser, Martin J
2002 Nov 12;99(23):15107-15111, Proceedings of the National Academy of Sciences of the United States of America
Phylogenies of indigenous microbes have been used as surrogates for the origins of the hosts that carry them. Conversely, polymorphisms may be used to date the spread of a microbial species when information about their host populations is available. Therefore, we examined polymorphisms in Helicobacter pylori, which persistently colonize the human stomach, to test the hypothesis that they have been ancient inhabitants of humans. Three H. pylori loci that previously have been shown to have phylogeographic affinity have been analyzed for two populations with different ethnic origins from Venezuela. In a group of Amerindian subjects from Amazonia, East Asian H. pylori genotypes were present for each of the loci examined but were absent in a mestizo population from Caracas. These findings provide evidence that H. pylori has been present in humans at least since ancestors of Amerindians migrated from Asia more than 11,000 years ago
— id: 34577, year: 2002, vol: 99, page: 15107, stat: Journal Article,

Serum antibodies to Helicobacter pylori and the CagA antigen do not explain differences in the prevalence of precancerous gastric lesions in two Chinese populations with contrasting gastric cancer rates
Groves, Frank D; Perez-Perez, Guillermo; Zhang, Lian; You, Wei-cheng; Lipsitz, Stuart R; Gail, Mitchell H; Fraumeni, Joseph F Jr; Blaser, Martin J
2002 Oct;11(10 Pt 1):1091-1094, Cancer epidemiology biomarkers & prevention
Incidence and mortality rates for gastric cancer in rural People's Republic of China differ greatly over short distances. In Shandong Province, we studied asymptomatic adult subjects from Bei Duan village (n = 196) in Linqu County (a high-risk area for gastric cancer) and from Shi Huang village (n = 192) in Cangshan County (a low-risk area for gastric cancer). The prevalence of advanced precancerous gastric lesions (APGL) was assessed by microscopic examination of endoscopic stomach biopsies. ELISAs were used to detect serum IgG to Helicobacter pylori whole-cell antigen and to the CagA protein. A logistic regression model was used to quantify the role of the two H. pylori seromarkers in explaining the differences in prevalence of APGL between the two villages after adjusting for age and sex. The prevalence of APGL was much greater in Bei Duan than in Shi Huang. Although H. pylori seroprevalence by the whole-cell ELISA was similar in the two populations, seroprevalence of CagA was significantly greater in Bei Duan. Although age, sex, and both H. pylori seromarkers were associated with APGL in the logistic regression model, the effect of village of residence remained strong after adjustment for all four covariates. Only a relatively small proportion of the difference in prevalence of APGL between these two rural Chinese populations can be explained by differences in H. pylori or CagA seroprevalence
— id: 34582, year: 2002, vol: 11, page: 1091, stat: Journal Article,

PCR-based detection of Bacillus anthracis in formalin-fixed tissue from a patient receiving ciprofloxacin
Levine, Steven M; Perez-Perez, Guillermo; Olivares, Asalia; Yee, Herman; Hanna, Bruce A; Blaser, Martin J
2002 Nov;40(11):4360-4362, Journal of clinical microbiology
We demonstrate that Bacillus anthracis may be detected from a formalin-fixed, paraffin-embedded biopsy specimen, even after the patient has received antibiotic treatment. Although traditional PCR methods may not be sufficiently sensitive for anthrax detection in such patients, cycle numbers can be increased or PCR can be repeated by using an aliquot from a previous PCR as the template
— id: 34579, year: 2002, vol: 40, page: 4360, stat: Journal Article,

Helicobacter pylori seropositivity and colorectal cancer risk: a prospective study of male smokers
Limburg, Paul J; Stolzenberg-Solomon, Rachael Z; Colbert, Lisa H; Perez-Perez, Guillermo I; Blaser, Martin J; Taylor, Philip R; Virtamo, Jarmo; Albanes, Demetrius
2002 Oct;11(10 Pt 1):1095-1099, Cancer epidemiology biomarkers & prevention
Because Helicobacter pylori colonization can produce systemic as well as local effects, it may be associated with carcinogenesis in extra gastric target organs. The currently available data regarding a possible link between H. pylori seropositivity and colorectal cancer risk are limited and inconclusive. In this prospective case-control study nested within the Alpha-Tocopherol, Beta-Carotene Study cohort of Finnish male smokers aged 50-69 years, we examined the association between H. pylori seropositivity and incident colorectal adenocarcinoma. Separate risk estimates were derived by colorectal cancer anatomical subsite and by H. pylori CagA seropositivity status. Demographic, dietary, and lifestyle variables were accounted for in the data analyses using information obtained from a prerandomization questionnaire and physical examination. Baseline serum samples from 118 cases and 236 matched controls were assayed for both H. pylori whole cell and H. pylori CagA antibodies. In total, 258 (73%) and 212 (60%) subjects expressed whole cell and CagA antibodies, respectively. H. pylori seropositivity, defined as one or both antibody assays positive, was present in 273 (77%) subjects. None of the seropositivity results were statistically different between cases and controls. Multivariate odds ratio (95% confidence interval) estimates for whole cell, cagA, and H. pylori seropositivity were 1.05 (0.63-1.74), 1.17 (0.74-1.84), and 0.91 (0.53-1.55), respectively. Stratification by colorectal cancer subsite yielded similarly unremarkable results. On the basis of these data, H. pylori carriage does not appear to be an important risk factor for colorectal adenocarcinoma
— id: 34581, year: 2002, vol: 11, page: 1095, stat: Journal Article,

Helicobacter pylori CagA seropositivity and gastric carcinoma risk in a Japanese American population
Nomura, Abraham M Y; Lee, James; Stemmermann, Grant N; Nomura, Ryan Y; Perez-Perez, Guillermo I; Blaser, Martin J
2002 Oct 15;186(8):1138-1144, Journal of infectious diseases
Helicobacter pylori colonization is associated with gastric cancer, but whether and to what extent the risk is greater for strains with the cagA gene than for those without needs to be determined. Between 1967 and 1977, 9963 Japanese American men were recruited and examined. By 1996, incident cases of gastric carcinoma of the distal stomach had been diagnosed in 261 men. Stored serum samples from these case patients and 261 age-matched control subjects were tested for immunoglobulin G antibodies to H. pylori and to the CagA product of H. pylori, using antibody-specific enzyme-linked immunosorbent assays. Compared with H. pylori-negative, CagA-negative men, H. pylori-positive, CagA-negative men had an odds ratio (OR) of 2.7 (95% confidence interval [CI], 1.3-5.6) for intestinal gastric carcinoma. Men seropositive for both H. pylori and CagA had an OR of 4.1 (95% CI, 2.2-7.7). This suggests that colonization by an H. pylori strain with the cagA gene is associated with a greater risk of intestinal gastric carcinoma
— id: 34583, year: 2002, vol: 186, page: 1138, stat: Journal Article,

Relation between Helicobacter pylori cagA status and risk of peptic ulcer disease
Nomura, Abraham M Y; Perez-Perez, Guillermo I; Lee, James; Stemmermann, Grant; Blaser, Martin J
2002 Jun 1;155(11):1054-1059, American journal of epidemiology
Although colonization with any Helicobacter pylori strain is associated with peptic ulcer, it is uncertain whether the risk is greater with cagA(+) or cagA(-) strains, which differ in their biology. A nested case-control study was done, based on a cohort of 5,443 Japanese-American men examined on the Hawaiian island of Oahu from 1967 to 1970. A total of 150 men with gastric ulcer, 65 with duodenal ulcer, and 14 with both diseases were identified. The authors matched the 229 cases with 229 population controls and tested their serum for immunoglobulin G antibodies to H. pylori and immunoglobulin G antibodies to the cagA product of H. pylori using enzyme-linked immunosorbent assays. Persons with H. pylori positivity had an odds ratio of 4.0 (95% confidence interval (CI): 1.9, 8.5) for gastric ulcer and 2.5 (95% CI: 0.8, 7.4) for duodenal ulcer. For CagA positivity, the odds ratios were 1.4 (95% CI: 0.9, 2.4) for gastric ulcer and 2.6 (95% CI: 1.1, 5.8) for duodenal ulcer. Subjects who were seropositive for both H. pylori and CagA had an odds ratio of 4.4 (95% CI: 1.8, 10.5) for gastric ulcer and 5.8 (95% CI: 1.1, 30.0) for duodenal ulcer. The results suggest that colonization with a cag(+) H. pylori strain elevates the risk beyond that of a cag(-) H. pylori strain for both gastric and duodenal ulcers
— id: 34587, year: 2002, vol: 155, page: 1054, stat: Journal Article,

Helicobacter pylori and gastrointestinal tract adenocarcinomas
Peek, Richard M Jr; Blaser, Martin J
2002 Jan;2(1):28-37, Nature reviews. Cancer
Although gastric adenocarcinoma is associated with the presence of Helicobacter pylori in the stomach, only a small fraction of colonized individuals develop this common malignancy. H. pylori strain and host genotypes probably influence the risk of carcinogenesis by differentially affecting host inflammatory responses and epithelial-cell physiology. Understanding the host-microbial interactions that lead to neoplasia will improve cancer-targeted therapeutics and diagnostics, and provide mechanistic insights into other malignancies that arise within the context of microbially initiated inflammatory states
— id: 43546, year: 2002, vol: 2, page: 28, stat: Journal Article,

Evidence that cagA(+) Helicobacter pylori strains are disappearing more rapidly than cagA(-) strains
Perez-Perez, G I; Salomaa, A; Kosunen, T U; Daverman, B; Rautelin, H; Aromaa, A; Knekt, P; Blaser, M J
2002 Mar;50(3):295-298, Gut: journal of the British Society of Gastroenterology
Background and aims: The prevalence of Helicobacter pylori colonisation in populations in developed country has been declining, as shown by community based serological surveys of adults in Vammala, Finland in 1973 and 1994. In this study, we determined whether the proportion of subjects colonised by cagA(+) or cagA(-) H pylori strains has changed as the overall prevalence of H pylori(+) has declined. Methods: We examined 911 sera from Vammala's study for antibodies to the CagA antigen of H pylori using a truncated CagA protein as the antigen in an ELISA and we examined the trend in acquisition and carriage of cagA(+) strains. Results: As expected, the prevalence of carriage of both cagA(+) and cagA(-) strains fell between 1973 and 1994 (p<0.001). However, the prevalence of cagA(+) strains among those <45 years declined (34% to 8%) significantly (p<0.001) more than for cagA(-) strains (12% to 6%). Of 221 subjects with paired serum samples, 12 (5.4%) changed H pylori status; the estimated seroconversion and reversion rates were 0.4% and 0.13% per year, respectively. Except for the few individuals who changed serostatus, absolute antibody levels to H pylori antigens, including CagA, changed little over the 21 year period. Conclusions: The decline in CagA seroprevalence predominantly reflects declining acquisition of cag(+) strains in younger subjects. In addition, these data confirm that H pylori acquisition chiefly occurs during childhood but continues to occur during adulthood, albeit at low rates, in developed countries
— id: 25600, year: 2002, vol: 50, page: 295, stat: Journal Article,

Concerted evolution between duplicated genetic elements in Helicobacter pylori
Pride, David T; Blaser, Martin J
2002 Feb 22;316(3):629-642, Journal of molecular biology
The Helicobacter pylori genome includes a family of outer membrane proteins (OMPs) with substantial N and C-terminal identity. To better understand their evolution, the nucleotide sequences for two members, babA and babB, were determined from a worldwide group of 23 strains. The geographic origin of each strain was found to be the major determinant of phylogenetic structure, with strains of Eastern and Western origin showing greatest divergence. For strains 96-10 (Japan) and 96-74 (USA), the 5' regions of babB are replaced with babA sequences, demonstrating that recombination occurs between the two loci. babA and babB have nearly equivalent variation in nucleotide and amino acid identity, and frequencies of synonymous and non-synonymous substitutions. Both genes have segmental conservation but within the 3' segment, substitution patterns are nearly identical. Although babA and babB 5' and midregion segment phylogenies show strong interstrain similarity, the 3' segments show strong intrastrain similarity, indicative of concerted evolution. Within these 3' segments, the lower intrastrain than interstrain frequencies of nucleotide substitutions, which are below mean background H. pylori substitution frequencies, indicate selection against intrastrain diversification. Since babA/babB gene conversions likely underlie the concerted evolution of the 3' segments, in an experimental system, we demonstrate that gene conversions can frequently (10(-3)) occur in H. pylori. That these events are recA-dependent and DNase-resistant indicates their likely cause is intragenomic recombination
— id: 43548, year: 2002, vol: 316, page: 629, stat: Journal Article,

Responses of endoscopy patients in Ladakh, India, to Helicobacter pylori whole-cell and Cag A antigens
Romero-Gallo, Judith; Perez-Perez, Guillermo I; Novick, Richard P; Kamath, Patrick; Norbu, Tsering; Blaser, Martin J
2002 Nov;9(6):1313-1317, Clinical & diagnostic laboratory immunology
Although Helicobacter pylori is a cosmopolitan colonizer of the human stomach, the responses among persons in remote populations from whom H. pylori was cultured have not been studied. We report on studies of 189 persons in the Ladakh region of India in whom serum immunoglobulin G responses to H. pylori whole-cell and Cag A antigens were measured. H. pylori was isolated from 68 of these patients. An H. pylori whole-cell antigen derived from Ladakhi strains outperformed a similar antigen from U.S. strains, as determined by antigen-specific enzyme-linked immunosorbent assays. In total, 95% of the population was seropositive, including individuals responding only to the Cag A antigen. Correlation with culture results showed that these were true positives and, therefore, that the H. pylori whole-cell serology was falsely negative in some cases. In addition to establishing a collection of H. pylori isolates from a remote area in the world, we show that use of H. pylori whole-cell and Cag A serology together increases the sensitivity for the detection of colonization
— id: 34578, year: 2002, vol: 9, page: 1313, stat: Journal Article,

Phenotypic and genotypic variation in methylases involved in type II restriction-modification systems in Helicobacter pylori
Takata, Tohru; Aras, Rahul; Tavakoli, Donald; Ando, Takafumi; Olivares, Asalia Z; Blaser, Martin J
2002 Jun 1;30(11):2444-2452, Nucleic acids research
To determine relationships between Helicobacter pylori geographical origin and type II methylase activity, we examined 122 strains from various locations around the world for methylase expression. Most geographic regions possessed at least one strain resistant to digestion by each of 14 restriction endonucleases studied. Across all of the strains studied, the average number of active methylases was 8.2 +/- 1.9 with no significant variation between the major geographic regions. Although seven pairs of isolates showed the same susceptibility patterns, their cagA/vacA status differed, and the remaining 108 strains each possessed unique patterns of susceptibility. From a single clonal group, 15 of 18 strains showed identical patterns of resistance, but diverged with respect to M.MboII activity. All of the methylases studied were present in all major human population groupings, suggesting that their horizontal acquisition pre-dated the separation of these populations. For the hpyV and hpyAIV restriction-modification systems, an in-depth analysis of genotype, indicating extensive diversity of cassette size and chromosomal locations regardless of the susceptibility phenotype, points toward substantial strain-specific selection involving these loci
— id: 34586, year: 2002, vol: 30, page: 2444, stat: Journal Article,

Helicobacter pylori does not require Lewis X or Lewis Y expression to colonize C3H/HeJ mice
Takata, Tohru; El-Omar, Emad; Camorlinga, Margarita; Thompson, Stuart A; Minohara, Yutaka; Ernst, Peter B; Blaser, Martin J
2002 Jun;70(6):3073-3079, Infection & immunity
Helicobacter pylori strains frequently express Lewis X (Le(x)) and/or Le(y) on their cell surfaces as constituents of the O antigens of their lipopolysaccharide molecules. To assess the effect of Le(x) and Le(y) expression on the ability of H. pylori to colonize the mouse stomach and to adhere to epithelial cells, isogenic mutants were created in which fucT1 alone or fucT1 and fucT2, which encode the fucosyl transferases necessary for Le(x) and Le(y) expression, were deleted. C3H/HeJ mice were experimentally challenged with either wild-type 26695 H. pylori or its isogenic mutants. All strains, whether passaged in the laboratory or recovered after mouse passage, colonized the mice well and without consistent differences. During colonization by the mutants, there was no reversion to wild type. Similarly, adherence to AGS and KatoIII cells was unaffected by the mutations. Together, these findings indicate that Le expression is not necessary for mouse gastric colonization or for H. pylori adherence to epithelial cells
— id: 43543, year: 2002, vol: 70, page: 3073, stat: Journal Article,

Contagion on the Internet
Wassenaar, Trudy M; Blaser, Martin J
2002 Mar;8(3):335-336, Emerging infectious diseases
— id: 43545, year: 2002, vol: 8, page: 335, stat: Journal Article,

Dynamics of bacterial phenotype selection in a colonized host
Webb, G F; Blaser, M J
2002 Mar 5;99(5):3135-3140, Proceedings of the National Academy of Sciences of the United States of America
The population dynamics of Helicobacter pylori during colonization in an infected animal host provide a quantifiable experimental model of in vivo microbial phenotype evolution. Phenotype variability in H. pylori populations can be typed as polymorphic expression of Lewis antigens on their cell surfaces. The high mutational frequency of H. pylori for Lewis expression provides substrate for differential selection by the host. Experimental challenge and successful colonization of mice and gerbils allows tracking of H. pylori phenotype variability from the initial inoculation to the ultimate establishment of a quasispecies. Colonization data provide a quantitative experimental model of phenotype evolution in a relatively large population (>10(4) individuals) over a relatively long evolutionary time scale (>10(3) generations). A mathematical model is developed to interpret the data in terms of the dynamic processes occurring during colonization. The mathematical model distinguishes the roles of selection and mutation; quantifies the effects of initial phenotype diversity, mutational frequency, and selective advantage; and applies generally to phenotype evolution in biological populations
— id: 43547, year: 2002, vol: 99, page: 3135, stat: Journal Article,

Mailborne transmission of anthrax: Modeling and implications
Webb, Glenn F; Blaser, Martin J
2002 May 14;99(10):7027-7032, Proceedings of the National Academy of Sciences of the United States of America
A mathematical model is developed to analyze the transmission of inhalational anthrax through the postal system by cross-contamination of mail. The model consists of state vectors describing the numbers of cross-contaminated letters generated, the numbers of anthrax spores on these letters, the numbers of resulting infections in recipients, and matrices of transition probabilities acting on these vectors. The model simulates the recent outbreak in the United States, and provides a general framework to investigate the potential impact of possible future outbreaks
— id: 43542, year: 2002, vol: 99, page: 7027, stat: Journal Article,

Functional analysis of iceA1, a CATG-recognizing restriction endonuclease gene in Helicobacter pylori
Xu, Qing; Morgan, R D; Roberts, R J; Xu, S Y; van Doorn, L J; Donahue, J P; Miller, G G; Blaser, Martin J
2002 Sep 1;30(17):3839-3847, Nucleic acids research
iceA1 in Helicobacter pylori is a homolog of nlaIIIR, which encodes the CATG-specific restriction endonuclease NlaIII in Neisseria lactamica. Analysis of iceA1 sequences from 49 H.pylori strains shows that a full-length NlaIII-like ORF is present in 10 strains, including CH4, but in other strains, including strain 60190, the ORFs are truncated due to a variety of mutations. Our goal was to determine whether iceA1 can encode a NlaIII-like endonuclease. Overexpression in Escherichia coli of iceA1 from CH4, but not from 60190, yielded NlaIII-like activity, indicating that the full-length iceA1 is a functional endonuclease gene. Repair of the iceA1 frameshift mutation in strain 60190 and its expression in E.coli yielded functional NlaIII-like activity. We conclude that iceA1 in CH4 is a functional restriction endonuclease gene, while iceA1 in 60190 is not, due to a frameshift mutation, but that its repair restores its restriction endonuclease activity
— id: 34584, year: 2002, vol: 30, page: 3839, stat: Journal Article,

Regulation of the HpyII restriction-modification system of Helicobacter pylori by gene deletion and horizontal reconstitution
Aras RA; Takata T; Ando T; van der Ende A; Blaser MJ
2001 Oct;42(2):369-382, Molecular microbiology
Helicobacter pylori, Gram-negative, curved bacteria colonizing the human stomach, possess strain-specific complements of functional restriction-modification (R-M) systems. Restriction-modification systems have been identified in most bacterial species studied and are believed to have evolved to protect the host genome from invasion by foreign DNA. The large number of R-Ms homologous to those in other bacterial species and their strain-specificity suggest that H. pylori may have horizontally acquired these genes. A type IIs restriction-modification system, hpyIIRM, was active in two out of the six H. pylori strains studied. We demonstrate now that in most strains lacking M.HpyII function, there is complete absence of the R-M system. Direct DNA repeats of 80 bp flanking the hpyIIRM system allow its deletion, resulting in an 'empty-site' genotype. We show that strains possessing this empty-site genotype and strains with a full but inactive hpyIIRM can reacquire the hpyIIRM cassette and functional activity through natural transformation by DNA from the parental R-M+ strain. Identical isolates divergent for the presence of an active HpyII R-M pose different restriction barriers to transformation by foreign DNA. That H. pylori can lose HpyII R-M function through deletion or mutation, and can horizontally reacquire the hpyIIRM cassette, is, in composite, a novel mechanism for R-M regulation, supporting the general hypothesis that H. pylori populations use mutation and transformation to regulate gene function
— id: 32230, year: 2001, vol: 42, page: 369, stat: Journal Article,

Helicobacter pylori genetic diversity and risk of human disease
Blaser MJ; Berg DE
2001 Apr;107(7):767-773, Journal of clinical investigation
— id: 19026, year: 2001, vol: 107, page: 767, stat: Journal Article,

Bacterial polymorphisms and disease in humans
Blaser MJ; Musser JM
2001 Feb;107(4):391-392, Journal of clinical investigation
— id: 19032, year: 2001, vol: 107, page: 391, stat: Journal Article,

Assessment of Helicobacter pylori vacA and cagA Genotypes and Host Serological Response
Figueiredo C; Quint W; Nouhan N; van Den Munckhof H; Herbrink P; Scherpenisse J; de Boer W; Schneeberger P; Perez-Perez G; Blaser MJ; van Doorn LJ
2001 Apr;39(4):1339-1344, Journal of clinical microbiology
Helicobacter pylori strains can be distinguished by genotyping of virulence-associated genes, such as vacA and cagA. Because serological discrimination between strain types would reduce the need for endoscopy, 61 patients carrying H. pylori were studied by vacA and cagA genotyping of H. pylori in gastric biopsy specimens and by detection of specific serum antibodies. Serological responses to H. pylori were determined by Helicoblot (versions 2.0 and 2.1). Antibodies to CagA also were determined by a rapid anti-CagA assay (Pyloriset screen CagA) as well as by two noncommercially developed enzyme immunoassays, each using a recombinant CagA protein. Assessment of performance of the Helicoblot assays indicated substantial interobserver variation, with kappa values between 0.20 and 0.93. There was no relationship between the serological profiles on the Helicoblot and the genotypes from the same patients, except for strong associations between the presence of anti-CagA and the cagA-positive and vacA s1 H. pylori genotypes. Detection of anti-CagA by the five different assays varied considerably, with kappa values ranging from 0.21 to 0.78. Using the cagA genotype as the 'gold standard,' the sensitivity and specificity of the anti-CagA assays varied from 71.4 to 85.7% and from 54.2 to 100%, respectively. Thus, serological profiles of antibodies to H. pylori are heterogeneous and, with the exception of anti-CagA antibodies, show no relation to the H. pylori vacA and cagA genotypes. Detection of anti-CagA antibodies is strongly dependent on the test used
— id: 19027, year: 2001, vol: 39, page: 1339, stat: Journal Article,

Helicobacter pylori strain-specific differences in genetic content, identified by microarray, influence host inflammatory responses
Israel DA; Salama N; Arnold CN; Moss SF; Ando T; Wirth HP; Tham KT; Camorlinga M; Blaser MJ; Falkow S; Peek RM
2001 Mar;107(5):611-620, Journal of clinical investigation
Helicobacter pylori enhances the risk for ulcer disease and gastric cancer, yet only a minority of H. pylori-colonized individuals develop disease. We examined the ability of two H. pylori isolates to induce differential host responses in vivo or in vitro, and then used an H. pylori whole genome microarray to identify bacterial determinants related to pathogenesis. Gastric ulcer strain B128 induced more severe gastritis, proliferation, and apoptosis in gerbil mucosa than did duodenal ulcer strain G1.1, and gastric ulceration and atrophy occurred only in B128+ gerbils. In vitro, gerbil-passaged B128 derivatives significantly increased IL-8 secretion and apoptosis compared with G1.1 strains. DNA hybridization to the microarray identified several strain-specific differences in gene composition including a large deletion of the cag pathogenicity island in strain G1.1. Partial and complete disruption of the cag island in strain B128 attenuated induction of IL-8 in vitro and significantly decreased gastric inflammation in vivo. These results indicate that the ability of H. pylori to regulate epithelial cell responses related to inflammation depends on the presence of an intact cag pathogenicity island. Use of an H pylori whole genome microarray is an effective method to identify differences in gene content between H. pylori strains that induce distinct pathological outcomes in a rodent model of H. pylori infection
— id: 19031, year: 2001, vol: 107, page: 611, stat: Journal Article,

Helicobacter pylori seropositivity and subsite-specific gastric cancer risks in Linxian, China
Limburg P; Qiao Y; Mark S; Wang G; Perez-Perez G; Blaser M; Wu Y; Zou X; Dong Z; Taylor P; Dawsey S
2001 Feb 7;93(3):226-233, Journal of the National Cancer Institute
BACKGROUND: Helicobacter pylori carriage (i.e., persistent exposure to the organism without gastric epithelial cell invasion) is an established risk factor for noncardia gastric cancer. However, its association with the risk of cancer of the gastric cardia is controversial. Consequently, we designed this prospective, nested case-control study to further explore the subsite-specific gastric cancer risks associated with H. pylori seropositivity (a surrogate marker for persistent exposure). METHODS: A total of 99 patients with gastric cardia cancer, 82 patients with noncardia gastric cancer, and 192 cancer-free subjects were selected from among the participants (n = 29 584) of a nutrition intervention trial previously conducted in Linxian, China. H. pylori seropositivity was determined by assaying for the presence of H. pylori whole cell and CagA antibodies in baseline serum samples from all subjects. Seropositivity was defined as one or both serum assays being positive. Odds ratios (ORs) for subsite-specific gastric cancer were estimated by multivariate logistic regression analyses. All statistical comparisons were two-sided (alpha =.05). RESULTS: H. pylori seropositivity rates for subjects with gastric cardia cancer, noncardia gastric cancer, and gastric cardia and noncardia cancers combined were 70% (P =.02), 72% (P: =.01), and 71% (P =.003) compared with 56% for cancer-free control subjects. OR estimates for H. pylori seropositivity were 1.87 (95% confidence interval [CI] = 1.10 to 3.17) for gastric cardia cancer, 2.29 (95% CI = 1.26 to 4.14) for noncardia gastric cancer, and 2.04 (95% CI = 1.31 to 3.18) for gastric cardia and noncardia cancers combined. CONCLUSIONS: H. pylori seropositivity was associated with increased risks for both gastric cardia cancer and noncardia gastric cancer in this well-characterized cohort. Thus, H. pylori carriage may increase the risk of cancer throughout the stomach
— id: 34627, year: 2001, vol: 93, page: 226, stat: Journal Article,

DNA diversity of the wla gene cluster among serotype HS:19 and non-HS:19 Campylobacter jejuni strains
Misawa N; Kawashima K; Kondo F; Allos BM; Blaser MJ
2001 ;7(5):349-358, Journal of endotoxin research
Campylobacter jejuni infection is an important trigger of Guillain-Barre syndrome (GBS), and serotype HS:19 strains are over-represented among GBS-associated isolates. Structures in C. jejuni lipooligosaccharide (LOS) resemble human gangliosides, suggesting that molecular mimicry could be important in triggering the neural injury. We assessed the genetic diversity among 36 C. jejuni serotype HS:19 and non-HS:19 strains by analysis of PCR-based restriction fragment length polymorphism (RFLP) patterns of 12 LOS biosynthesis-related genes (wla cluster). PCR amplification revealed that the size, order, and direction of each wla gene was identical among all strains tested. However, an additional ORF, located between wlaI and wlaK, was detected in 28 of the 36 isolates examined, and nucleotide sequence analysis revealed that the gene was identical to orfE in C. jejuni strain NCTC 11168. An inverted repeat motif was found downstream of the wlaI stop codon and upstream of the orfE stop codon, an organization allowing pairing of repeated sequences that could lead to deletion of the internal segment. Digestion of the PCR products with restriction endonuclease DdeI or AluI and cluster analysis of RFLP banding patterns showed that all HS:19 strains were closely related and distinct from non-HS:19 strains, consistent with earlier analyses, suggesting that HS:19 strains represent a highly clonal population. RFLP analysis of wla genes also may be useful for epidemiological studies
— id: 43549, year: 2001, vol: 7, page: 349, stat: Journal Article,

Increased gastric epithelial cell apoptosis associated with colonization with cagA + Helicobacter pylori strains
Moss SF; Sordillo EM; Abdalla AM; Makarov V; Hanzely Z; Perez-Perez GI; Blaser MJ; Holt PR
2001 Feb 15;61(4):1406-1411, Cancer research
Gastric colonization by Helicobacter pylori is a risk factor for noncardia gastric cancer. The association between H. pylori and cancer may be attributable to increased epithelial cell turnover, possibly related to antigastric antibodies. Two previous studies reported a disproportionate increase in proliferation relative to apoptosis in patients with H. pylori strains expressing the virulence-related cagA gene. This has led to the hypothesis that an abrogation of apoptosis by cagA-positive strains may promote neoplasia. We, therefore, examined the effect of H. pylori on gastric epithelial proliferation, apoptosis, and the presence of serum antiparietal cell antibodies in a large prospective study. Proliferation and apoptosis were evaluated 'blindly' using validated immunohistochemical methods in two antral and two gastric corpus biopsies from 60 patients with nonulcer dyspepsia, and results were correlated with the presence of serum antiparietal cell antibodies. H. pylori colonization was assessed by histology, biopsy urease test, and serology. Proliferation was increased 2-fold in both antrum and corpus in H. pylori-positive patients, was not related to H. pylori cagA status, and was positively correlated with histological gastritis. Apoptosis was increased in the antrum and body only in patients with cagA-positive H. pylori strains. Antiparietal cell antibodies were not more prevalent in H. pylori colonization, and their presence was inversely related to epithelial apoptosis scores we therefore conclude that in patients with nonulcer dyspepsia, H. pylori carriage is associated with increased proliferation. Futhermore the cag pathogenicity island is associated with increased apoptosis. Our results do not support the hypothesis that there is a relative deficiency of gastric epithelial cell apoptosis associated with the carriage of cagA-positive strains. Host factors may be more important than bacterial products in determining the long-term outcome of H. pylori colonization
— id: 19030, year: 2001, vol: 61, page: 1406, stat: Journal Article,

Allelic Variation within Helicobacter pylori babA and babB
Pride DT; Meinersmann RJ; Blaser MJ
2001 Feb;69(2):1160-1171, Infection & immunity
Helicobacter pylori strains show both geographic and disease-associated allelic variation. We investigated the diversity present in two genes, babA and babB, which are members of a paralogous family of outer membrane proteins. Eleven family members within a single H. pylori strain, predicted to encode proteins with substantial N- and C-terminal similarity to each other, were classified as babA paralogues. In their central regions, most are less than 54% related to one another. Examining the babA and babB central regions in 42 H. pylori strains from different geographic locales, we identified five different allele groups of babA (AD1 to AD5) and three different allele groups of babB (BD1 to BD3). Phylogenetic analysis revealed that the allelic groupings of babA and babB are independent of one another and that, for both, geographic variation is present. Analysis of synonymous and nonsynonymous substitutions in these regions showed that babA is more diverse, implying an earlier origin than that of the same region of babB, but that the babA diversity region may have more functional constraints. Although recombination has been central to the evolution of both genes, with babA and babB showing low mean compatibility scores and homoplasy ratios of 0.71 and 0.67, respectively, recombination is not sufficient to obscure evidence of clonal descent. Despite the involvement of babA in binding to the host blood group antigen Lewis B, neither the presence of different babA allele groups nor that of different babB allele groups is a determining factor in Lewis B binding of H. pylori strains
— id: 19033, year: 2001, vol: 69, page: 1160, stat: Journal Article,

Heterogeneity of Helicobacter pylori cag genotypes in experimentally infected mice
Sozzi M; Crosatti M; Kim SK; Romero J; Blaser MJ
2001 Sep 11;203(1):109-114, FEMS microbiology letters
Our aim was to assess whether the Helicobacter pylori population recovered from experimentally infected mice show heterogeneity in cag genotypes. Wild-type FVB/N mice were challenged with strain Hp1 and sacrificed 8 weeks later. Direct PCR on gastric tissue was performed using primers for glmM and cagA, and for these two genes and for cagE and virB11 using DNA from the infecting and the emerging strains. The gastric tissues of two of five mice were PCR+ for glmM but not cagA. For the infecting strain, the PCRs for all four genes studied were strongly positive, but the sweeps from the emerging strains from both mice gave weaker signals for cagA and cagE. Examination of single colonies showed reduced or absent signals for cagA and cagE in relation to glmM and virB11. Serial dilution PCR of sweep isolates from the mice showed a 10- to 100-fold decrease in cagA signal compared to the infecting strain. The decrease of cagA and cagE, but not virB11, amplification and lack of cagA hybridization in Southern blots indicates a selective loss of the right half of the cag island during murine infection. This phenomenon is consistent with host-induced adaptive changes of cag genotype in the population of colonizing H. pylori cells
— id: 43550, year: 2001, vol: 203, page: 109, stat: Journal Article,

Helicobacter pylori seropositivity as a risk factor for pancreatic cancer
Stolzenberg-Solomon RZ; Blaser MJ; Limburg PJ; Perez-Perez G; Taylor PR; Virtamo J; Albanes D
2001 Jun 20;93(12):937-941, Journal of the National Cancer Institute
BACKGROUND: Pancreatic cancer is among the most fatal cancers worldwide and one for which few preventable risk factors have been established. Gastric carriage of Helicobacter pylori, particularly cytotoxin-associated gene-A-positive (CagA+) strains, is known to be a risk factor for peptic ulcer disease and gastric cancer and may have a similar etiologic relationship with pancreatic cancer. METHODS: We investigated the association of H. pylori carriage and exocrine pancreatic cancer in a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort of 29 133 male Finnish smokers aged 50-69 years at baseline. Case subjects (n = 121) were matched on date of baseline serum collection, study center, age, trial intervention, and completion of the dietary questionnaire to 226 control subjects who were alive at the time the matching case subject was diagnosed and who remained free of cancer, during up to 10 years of follow-up. Levels of immunoglobulin G antibodies to H. pylori whole-cell and CagA+ antigens from stored baseline serum were measured by enzyme-linked immunosorbent assay. Smoking-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by use of conditional logistic regression. Statistical tests were two-sided. RESULTS: Seroprevalence of H. pylori was 82% and 73% among case and control subjects, respectively. Compared with seronegative subjects, those with H. pylori or CagA+ strains were at statistically significantly elevated risk of pancreatic cancer (OR = 1.87 [95% CI = 1.05 to 3.34]; OR = 2.01 [95% CI = 1.09 to 3.70], respectively). CONCLUSIONS: Our findings support a possible role for H. pylori carriage in the development of exocrine pancreatic cancer
— id: 34624, year: 2001, vol: 93, page: 937, stat: Journal Article,

Helicobacter pylori genotypes, host factors, and gastric mucosal histopathology in peptic ulcer disease
Tham KT; Peek RM; Atherton JC; Cover TL; Perez-Perez GI; Shyr Y; Blaser MJ
2001 Mar;32(3):264-273, Human pathology
From 183 patients undergoing upper gastrointestinal endoscopy, we used antral and corpus gastric biopsies for bacterial culture and histopathologic examination, blood samples to detect immunoglobulin G antibodies against Helicobacter pylori, and H pylori genomic DNA to analyze cytotoxin-associated gene A (cagA) and vacuolating cytotoxin (vacA) genotypes. As expected, among H pylori biopsy-positive patients, those with duodenal ulcer (DU) (n = 34) had significantly more severe chronic and acute inflammation (P <.001) and epithelial degeneration (P =.004) in the gastric antrum than in the gastric corpus. Each of those 3 parameters and H pylori density were significantly higher in the antrum of patients with DU than in patients with gastric ulcer (GU) or no ulcer. Colonization with vacA s1/cagA-positive strains of H pylori was associated with inflammation and epithelial degeneration in gastric mucosa and increased risk for peptic ulcer disease (PUD), whereas colonization with vacA s2m2/cagA-negative strains was associated with mild gastric histopathology and was not associated with any significant risk for PUD. The predominant H pylori strains in African Americans were vacA s1bm1/cagA-positive, whereas all genotypes were well represented in non-Hispanic-Caucasians. By multivariate analysis, H pylori colonization was significantly associated with DU (Adjusted odds ratio [AdjOR] = 3.2 [1.4-7.2]) and nonsteroidal anti-inflammatory drugs (NSAID) use was inversely associated (AdjOR = 0.3 [0.2-0.7]). NSAID use (AdjOR = 4.3 [1.02-18.5]) and African-American ethnicity (AdjOR = 10.9 [2.6-50]) were significantly associated with GU. Smoking and age were not significantly associated with either DU or GU. These data indicate that DU is associated with an antral-dominant gastritis, and H pylori genotype and NSAID use independently contribute to the pathogenesis of PUD. HUM PATHOL 32:264-273. This is a US Government work. There are no restrictions on its use
— id: 19028, year: 2001, vol: 32, page: 264, stat: Journal Article,

Evidence that the Campylobacter fetus sap locus is an ancient genomic constituent with origins before mammals and reptiles diverged
Tu ZC; Dewhirst FE; Blaser MJ
2001 Apr;69(4):2237-2244, Infection & immunity
Campylobacter fetus bacteria, isolated from both mammals and reptiles, may be either subsp. fetus or subsp. venerealis and either serotype A or serotype B. Surface layer proteins, expressed and secreted by genes in the sap locus, play an important role in C. fetus virulence. To assess whether the sap locus represents a pathogenicity island and to gain further insights into C. fetus evolution, we examined several C. fetus genes in 18 isolates. All of the isolates had 5 to 9 sapA or sapB homologs. One strain (85-387) possessed both sapA and sapB homologs, suggesting a recombinational event in the sap locus between sapA and sapB strains. When we amplified and analyzed nucleotide sequences from portions of housekeeping gene recA (501 bp) and sapD (450 bp), a part of the 6-kb sap invertible element, the phylogenies of the genes were highly parallel. Among the 15 isolates from mammals, serotype A and serotype B strains generally had consistent positions. The fact that the serotype A C. fetus subsp. fetus and subsp. venerealis strains were on the same branch suggests that their differentiation occurred after the type A-type B split. Isolates from mammals and reptiles formed two distinct tight phylogenetic clusters that were well separated. Sequence analysis of 16S rRNA showed that the reptile strains form a distinct phylotype between mammalian C. fetus and Campylobacter hyointestinalis. The phylogenies and sequence results showing that sapD and recA have similar G + C contents and substitution rates suggest that the sap locus is not a pathogenicity island but rather is an ancient constituent of the C. fetus genome, integral to its biology
— id: 19029, year: 2001, vol: 69, page: 2237, stat: Journal Article,

Campylobacter fetus uses multiple loci for DNA inversion within the 5' conserved regions of sap homologs
Tu ZC; Ray KC; Thompson SA; Blaser MJ
2001 Nov;183(22):6654-6661, Journal of bacteriology
Campylobacter fetus cells possess multiple promoterless sap homologs, each capable of expressing a surface layer protein (SLP) by utilizing a unique promoter present on a 6.2-kb invertible element. Each sap homolog includes a 626-bp 5' conserved region (FCR) with 74 bp upstream and 552 bp within the open reading frame. After DNA inversion, the splice is seamless because the FCRs are identical. In mutant strain 23D:ACA2K101, in which sapA and sapA2 flanking the invertible element in opposite orientations were disrupted by promoterless chloramphenicol resistance (Cm(r)) and kanamycin resistance (Km(r)) cassettes, respectively, the frequency of DNA inversion is 100-fold lower than that of wild-type strain 23D. To define the roles of a 15-bp inverted repeat (IR) and a Chi-like site (CLS) in the FCR, we mutagenized each upstream of sapA2 in 23D:ACA2K101 by introducing NotI and KpnI sites to create strains 23D:ACA2K101N and 23D:ACA2K101K, respectively. Alternatively selecting colonies for Cm(r) or Km(r) showed that mutagenizing the IR or CLS had no apparent effect on the frequency of the DNA inversion. However, mapping the unique NotI or KpnI site in relation to the Cm(r) or Km(r) cassette in the cells that changed phenotype showed that splices occurred both upstream and downstream of the mutated sites. PCR and sequence analyses also showed that the splice could occur in the 425-bp portion of the FCR downstream of the cassettes. In total, these data indicate that C. fetus can use multiple sites within the FCR for its sap-related DNA inversion
— id: 26593, year: 2001, vol: 183, page: 6654, stat: Journal Article,

Promoters of the CATG-specific methyltransferase gene hpyIM differ between iceA1 and iceA2 Helicobacter pylori strains
Xu Q; Blaser MJ
2001 Jul;183(13):3875-3884, Journal of bacteriology
Helicobacter pylori strains can be divided into two groups, based on the presence of two unrelated genes, iceA1 and iceA2, that occupy the same genomic locus. hpyIM, located immediately downstream of either gene, encodes a functional CATG-specific methyltransferase. Despite the strong conservation of the hpyIM open reading frame (ORF) among all H. pylori strains, the sequences upstream of the ORF in iceA1 and iceA2 strains are substantially different. To explore the roles of these upstream sequences in hpyIM regulation, promoter analysis of hpyIM was performed. Both deletion mutation and primer extension analyses demonstrate that the hpyIM promoters differ between H. pylori strains 60190 (iceA1) and J188 (iceA2). In strain 60190, hpyIM has two promoters, P(a) or P(I), which may function independently, whereas only one hpyIM promoter, P(c), was found in strain J188. The XylE assay showed that the hpyIM transcription level was much higher in strain 60190 than in strain J188, indicating that regulation of hpyIM transcription differs between the H. pylori iceA1 strain (60190) and iceA2 strains (J188). Since the iceA1 and iceA2 sequences are highly conserved within iceA1 or iceA2 strains, we conclude that promoters of the CATG-specific methylase gene hpyIM differ between iceA1 and iceA2 strains, which leads to differences in regulation of hpyIM transcription
— id: 43551, year: 2001, vol: 183, page: 3875, stat: Journal Article,

Helicobacter pylori prevalence and CagA status among children in two counties of China with high and low risks of gastric cancer
You WC; Zhang L; Pan KF; Jiang J; Chang YS; Perez-Perez GI; Liu WD; MA JL; Gail MH; Blaser MJ; Fraumeni JF; Xu GW
2001 Nov;11(8):543-546, Annals of epidemiology
BACKGROUND: Studies in adult populations in selected countries with widely varying rates of gastric cancer have shown a weak correlation between gastric cancer mortality rates and the prevalence of CagA+ strains of H. pylori. However, only limited data are available in ethnically homogenous populations with varying rates in the same region. METHODS; We compared the prevalence of H. pylori in general and of CagA+ strains in particular among children in Shandong Province, China in areas at high (Linqu County) and low risk (Cangshan County) of gastric cancer. H. pylori status among children aged 3 to 12 years was determined by 13C-UBT, and CagA status was determined by enzyme-linked immunosorbent assay (ELISA). Because of the difficulty in obtaining blood from young children aged 3 to 4 years and from some children aged 5 years, CagA status was determined among part of children 5 years old and children 6 to 12 years old. RESULTS; Among 98 children aged 3 to 12 years in Linqu, 68 (69.4%) was H. pylori-positive, as compared with 29 (28.7%) among 101 children in Cangshan. Among children positive for 13C-UBT, the proportion of the CagA+ strains were identified was 46 (88.5%) of 52 in Linqu and 13 (81.3%) of 16 in Cangshan, respectively. CONCLUSIONS: The prevalence of H. pylori was nearly three times higher among children in Linqu than in Cangshan, which may contribute to the large differential in gastric cancer rates for two neighboring populations in Shandong Province
— id: 25601, year: 2001, vol: 11, page: 543, stat: Journal Article,

Anti-CagA immunoglobulin G responses correlate with interleukin-8 induction in human gastric mucosal biopsy culture
Ando T; Perez-Perez GI; Kusugami K; Ohsuga M; Bloch KC; Blaser MJ
2000 Sep;7(5):803-809, Clinical & diagnostic laboratory immunology
Helicobacter pylori persists in the human stomach despite eliciting both cellular and humoral immune responses and inducing proinflammatory cytokines. To determine whether local humoral and cytokine responses are related to each other and to histologic responses, we studied 66 Japanese patients who underwent gastroscopy. Using specific enzyme-linked immunosorbent assays, we examined gastric antral mucosal-organ biopsy culture supernatants to assess interleukin-6 (IL-6) and interleukin-8 (IL-8) levels and antibody responses to H. pylori whole-cell antigens CagA, HspA, and HspB. Of the patients studied, 11 were H. pylori negative and 55 were H. pylori positive; by PCR, all strains were cagA(+). As expected, compared to H. pylori-negative patients, H. pylori-positive patients had significantly higher humoral responses to all H. pylori antigens and had higher IL-8 (47.8+/-3.5 versus 10.1+/-4.3 ng/mg of biopsy protein; P<0.001) and IL-6 levels (2.8+/-0.3 versus 0.26+/-0.2 ng/mg of protein; P<0.001). Among the H. pylori-positive patients, supernatant anti-CagA immunoglobulin G (IgG) levels were significantly associated with H. pylori density (P<0.005) and neutrophil infiltration (P<0.005) scores. Anti-CagA immunoglobulin A levels were correlated with intestinal metaplasia (P<0.05). Mononuclear cell infiltration scores were significantly associated with supernatant IL-6 levels (P<0.005) and with IgG responses to whole-cell antigens (P<0.05). Supernatant IL-8 levels were significantly associated with anti-CagA IgG (r = 0.75, P<0.001). Anti-CagA responses correlated with neutrophil infiltration, intestinal metaplasia, H. pylori density, and IL-8 levels, suggesting that the absolute levels of these antibodies may be markers for gastric inflammation and premalignant changes in individual hosts
— id: 19041, year: 2000, vol: 7, page: 803, stat: Journal Article,

Restriction-modification system differences in Helicobacter pylori are a barrier to interstrain plasmid transfer
Ando T; Xu Q; Torres M; Kusugami K; Israel DA; Blaser MJ
2000 Sep;37(5):1052-1065, Molecular microbiology
Helicobacter pylori cells are naturally competent for the uptake of both plasmid and chromosomal DNA. However, we demonstrate that there are strong barriers to transformation of H. pylori strains by plasmids derived from unrelated strains. We sought to determine the molecular mechanisms underlying these barriers. Transformation efficiency was assessed using pHP1, an Escherichia coli-H. pylori shuttle vector conferring kanamycin resistance. Transformation of 33 H. pylori strains was attempted with pHP1 purified from either E. coli or H. pylori, and was successfully introduced into only 11 strains. Digestion of H. pylori chromosomes with different restriction endonucleases (REs) showed that DNA methylation patterns vary substantially among strains. The strain most easily transformed, JP26, was found to have extremely low endogenous RE activity and to lack a restriction-modification (R-M) system, homologous to MboI, which is highly conserved among H. pylori strains. When we introduced this system to JP26, pHP1 from MboI.M+ JP26, but not from wild-type JP26, transformed MboI R-M+ JP26 and heterologous MboI R-M+ wild-type H. pylori strains. Parallel studies with pHP1 from dam+ and dam- E. coli strains confirmed these findings. These data indicate that the endogenous REs of H. pylori strains represent a critical barrier to interstrain plasmid transfer among H. pylori
— id: 19043, year: 2000, vol: 37, page: 1052, stat: Journal Article,

Linking Helicobacter pylori to gastric cancer
Blaser MJ
2000 Apr;6(4):376-377, Nature medicine
— id: 19050, year: 2000, vol: 6, page: 376, stat: Journal Article,

Reply
Blaser MJ
2000 Feb;181(2):806-806, Journal of infectious diseases
— id: 19054, year: 2000, vol: 181, page: 806, stat: Journal Article,

Overcoming the restriction barrier to plasmid transformation of Helicobacter pylori
Donahue JP; Israel DA; Peek RM; Blaser MJ; Miller GG
2000 Sep;37(5):1066-1074, Molecular microbiology
Helicobacter pylori strains demonstrate substantial variability in the efficiency of transformation by plasmids from Escherichia coli, and many strains are completely resistant to transformation. Among the barriers to transformation are numerous strain-specific restriction-modification systems in H. pylori. We have developed a method to protect plasmid DNA from restriction by in vitro site-specific methylation using cell-free extracts of H. pylori before transformation. In two cases, plasmid DNA treated with cell-free extracts in vitro acquired the restriction pattern characteristic of genomic DNA from the source strain. Among three strains examined in detail, the transformation frequency by treated plasmid shuttle and suicide vectors was significantly increased compared with mock-treated plasmid DNA. The results indicate that the restriction barrier in H. pylori can be largely overcome by specific DNA methylation in vitro. The approach described should significantly enhance the ability to manipulate gene function in H. pylori and other organisms that have substantial restriction barriers to transformation
— id: 19042, year: 2000, vol: 37, page: 1066, stat: Journal Article,

Analysis of iceA1 transcription in Helicobacter pylori
Donahue JP; Peek RM; Van Doorn LJ; Thompson SA; Xu Q; Blaser MJ; Miller GG
2000 Mar;5(1):1-12, Helicobacter
BACKGROUND: Transcription of the Helicobacter pylori iceA1 gene is induced following adherence of the bacterium to gastric epithelial cells in vitro, suggesting that this gene might be involved in H. pylori pathogenesis. Consequently, the current studies were undertaken to characterize iceA1 transcription and to define the structure of iceA1-containing transcripts to evaluate the potential of this gene to encode functional proteins. MATERIALS AND METHODS: Northern blots and primer extension of RNA isolated from broth-grown cultures of various H. pylori strains was done to analyze iceA1-specific gene transcription. Reverse transcriptase (RT)-PCR was used to determine the levels of iceA1 transcripts derived from readthrough transcription that was initiated upstream of iceA1 within the 5'-flanking cysE gene. RESULTS: Three major transcripts were detected and each was initiated from a common promoter, designated PI. Two of these transcripts were comprised of iceA1 sequence, while a third transcript was dicistronic and included the downstream gene, hpyIM. In addition, 10-fold lower levels of iceA1 transcripts were initiated upstream of PI, either within or immediately downstream of cysE. CONCLUSIONS: The present analysis suggests that iceA1 does not encode a functional protein in the majority of H. pylori strains. However, transcription of hpyIM, which encodes a highly conserved DNA adenine methyltransferase, is linked to iceA1 transcription. Therefore, iceA1 may affect H. pylori virulence in vivo through transcriptional regulation of hpyIM expression levels, which may result in specific variations in DNA methylation patterns leading to alteration in the expression of genes involved in virulence or pathogenesis
— id: 19053, year: 2000, vol: 5, page: 1, stat: Journal Article,

Theoretical and experimental approaches for studying factors defining the Helicobacter pylori-host relationship
Falk PG; Syder AJ; Guruge JL; Kirschner D; Blaser MJ; Gordon JI
2000 Jul;8(7):321-329, Trends in microbiology
Mathematical modeling has helped develop hypotheses about the role of microbial and host parameters in the initial and subsequent phases of Helicobacter pylori colonization. Transgenic mice have been used to test the hypothesis that the outcome of colonization is influenced by whether bacteria can adhere to available epithelial cell receptors. Complementary use of modeling and experimental approaches should facilitate studies of H. pylori pathogenesis
— id: 19045, year: 2000, vol: 8, page: 321, stat: Journal Article,

Genetic organization and heterogeneity of the iceA locus of Helicobacter pylori
Figueiredo C; Quint WG; Sanna R; Sablon E; Donahue JP; Xu Q; Miller GG; Peek RM; Blaser MJ; van Doorn LJ
2000 Apr 4;246(1-2):59-68, Gene
The genetic organization and sequence heterogeneity of the iceA locus of Helicobacter pylori was studied, and the existence of two distinct gene families, iceA1 and iceA2, at this locus was confirmed. iceA1 has significant sequence homology to nlaIIIR, encoding an endonuclease in Neisseria lactamica, but the similarity at the protein level is limited, due to frameshift mutations of iceA1 in most H. pylori strains. In only five of the 19 iceA1 strains studied, a full-length open reading frame (ORF), capable of encoding a 228aa protein, with 52% homology to NlaIII was observed. The region upstream of iceA2 is highly variable in length, containing up to 15 copies of 8bp tandem repeats. iceA2 can encode proteins of 24, 59, 94, or 129 amino acids, consisting of 14 and 10aa domains, conserved in all iceA2 strains, flanking 0, 1, 2, or 3 copies of a 35aa cassette. This 35aa cassette consists of domains of 13, 16 and 6aa, respectively. The 13aa and 6aa domains are highly conserved, but the 16aa domain exists in two variants. In total, five distinct iceA2 subtypes were defined. Database searches did not reveal any homologous sequences. Recombinant IceA1 and IceA2 proteins were expressed in Escherichia coli, confirming the predicted ORFs. Genotype-specific PCR primers permitted iceA genotyping in 318 (99. 1%) of a worldwide collection of 321 H. pylori strains. The conserved sizes of the amplification products confirmed the worldwide distribution of discrete variants of iceA1 and iceA2
— id: 19047, year: 2000, vol: 246, page: 59, stat: Journal Article,

Restriction fragment length polymorphism analysis using random chromosomal gene probes for epidemiological analysis of Campylobacter jejuni infections
Fujimoto S; Umene K; Saito M; Horikawa K; Blaser MJ
2000 Apr;38(4):1664-1667, Journal of clinical microbiology
We have evaluated the ability of a new genotyping method for Campylobacter jejuni based on restriction fragment length polymorphisms using random chromosomal gene probes. DNAs from C. jejuni strains digested with each of three restriction enzymes, HhaI, HaeIII, and HpaII, were analyzed by Southern hybridization using each of two unrelated cosmid clones, P14 and P15 (respectively containing 30- and 35-kb genomic DNA fragments of C. jejuni strain OH4384). The method reported provides a stable and discriminating means for identifying C. jejuni strains and should be useful for epidemiological analyses
— id: 19049, year: 2000, vol: 38, page: 1664, stat: Journal Article,

Roles of the surface layer proteins of Campylobacter fetus subsp. fetus in ovine abortion
Grogono-Thomas R; Dworkin J; Blaser MJ; Newell DG
2000 Mar;68(3):1687-1691, Infection & immunity
The role of the surface (S)-layer proteins of Campylobacter fetus subsp. fetus has been investigated using an ovine model of abortion. Wild-type strain 23D induced abortion in up to 90% of pregnant ewes challenged subcutaneously. Isolates recovered from both dams and fetuses expressed S-layer proteins with variable molecular masses. The spontaneous S-layer-negative variant, strain 23B, neither colonized nor caused abortions in pregnant ewes. A series of isogenic sapA and recA mutants, derived from 23D, also were investigated in this model. A mutant (501 [sapA recA(+)]) caused abortion in one of five challenged animals and was recovered from the placenta of a second animal. Another mutant (502 [sapA recA]) with no S-layer protein expression caused no colonization or abortions in challenged animals but caused abortion when administered intraplacentally. Mutants 600(2) and 600(4), both recA, had fixed expression of 97- and 127-kDa S-layer proteins, respectively. Two of the six animals challenged with mutant 600(4) were colonized, but there were no abortions. As expected, all five strains recovered expressed a 127-kDa S-layer protein. In contrast, mutant 600(2) was recovered from the placentas of all five challenged animals and caused abortion in two. Unexpectedly, one of the 16 isolates expressed a 127-kDa rather than a 97-kDa S-layer protein. Thus, these studies indicate that S-layer proteins appear essential for colonization and/or translocation to the placenta but are not required to mediate fetal injury and that S-layer variation may occur in a recA strain
— id: 19052, year: 2000, vol: 68, page: 1687, stat: Journal Article,

Acute gastritis with hypochlorhydria: report of 35 cases with long term follow up
Harford WV; Barnett C; Lee E; Perez-Perez G; Blaser MJ; Peterson WL
2000 Oct;47(4):467-472, Gut: journal of the British Society of Gastroenterology
BACKGROUND: Between 1976 and 1987, 35 cases of acute gastritis with hypochlorhydria (AGH) were seen in our research laboratory. The aims of this study were to determine the natural history of AGH and the role of Helicobacter pylori in its pathogenesis. METHODS: Archived serum and gastric biopsy samples obtained from AGH subjects were examined for evidence of H pylori colonisation. Twenty eight of 33 (85%) surviving AGH subjects returned a mean of 12 years after AGH for follow up studies, including determination of H pylori antibodies, basal and peak acid output, endoscopy, and gastric biopsies. A matched control group underwent the same studies. RESULTS: Archived material provided strong evidence of new H pylori acquisition in a total of 14 subjects within two months, in 18 within four months, and in 22 within 12 months of recognition of AGH. Prevalence of H pylori colonisation at follow up was 82% (23 of 28) in AGH subjects, significantly (p<0.05) higher than in matched controls (29%). Basal and peak acid output returned to pre-AGH levels in all but two subjects. CONCLUSIONS: One of several possible initial manifestations of H pylori acquisition in adults may be AGH. While H pylori colonisation usually persists, hypochlorhydria resolves in most subjects
— id: 19040, year: 2000, vol: 47, page: 467, stat: Journal Article,

Characteristics of Helicobacter pylori natural transformation
Israel DA; Lou AS; Blaser MJ
2000 May 15;186(2):275-280, FEMS microbiology letters
For Helicobacter pylori, which exhibits substantial genetic diversity, many strains are naturally competent for transformation by exogenous DNA. To better understand the mechanism of natural transformation and its role in the generation of diversity, we sought to systematically identify factors important for natural transformation in H. pylori. We now show that the highest frequency of H. pylori transformation occurs when DNA is introduced prior to exponential phase growth, and that it is a saturable phenomenon. That transformation can be inhibited by DNA from Helicobacter (H. pylori and Helicobacter bilis) but not Escherichia coli suggests specificity based on DNA source. Finally, the cag island was determined to be unnecessary for high-frequency transformation
— id: 19046, year: 2000, vol: 186, page: 275, stat: Journal Article,

CagA antibodies in Japanese children with nodular gastritis or peptic ulcer disease
Kato S; Sugiyama T; Kudo M; Ohnuma K; Ozawa K; Iinuma K; Asaka M; Blaser MJ
2000 Jan;38(1):68-70, Journal of clinical microbiology
cagA(+) Helicobacter pylori strains have been linked to more severe gastric inflammation, peptic ulcer disease, and gastric cancer in adults, but there have been few studies of cagA in children. We examined the relationship between H. pylori cagA status and clinical status in Japanese children. Forty H. pylori-positive children were studied: 15 with nodular gastritis, 5 with gastric ulcers, and 20 with duodenal ulcers. H. pylori status was confirmed by biopsy-based tests and serum anti-H. pylori immunoglobulin G (IgG) antibody. As controls, 77 asymptomatic children with sera positive for anti-H. pylori IgG were enrolled. Levels of IgG antibodies to CagA in serum were measured by an antigen-specific enzyme-linked immunosorbent assay. In 16 patients with successful H. pylori eradication, posttreatment levels of CagA and H. pylori IgG antibodies also were studied. The CagA antibody seropositivities of asymptomatic controls (81.8%) and patients with nodular gastritis, gastric ulcers, and duodenal ulcers (80.0 to 95.0%) were not significantly different. Compared with pretreatment levels of CagA antibodies, posttreatment levels decreased progressively and significantly. We conclude that, as in Japanese adults, a high prevalence of cagA(+) H. pylori strains was found in Japanese children, and that there was no association with nodular gastritis or peptic ulcer disease. In the assessment of eradicative therapies, monitoring of serum anti-CagA antibodies does not appear to offer any direct benefit over monitoring of anti-H. pylori antibodies
— id: 19056, year: 2000, vol: 38, page: 68, stat: Journal Article,

Quasispecies development of Helicobacter pylori observed in paired isolates obtained years apart from the same host
Kuipers EJ; Israel DA; Kusters JG; Gerrits MM; Weel J; van Der Ende A; van Der Hulst RW; Wirth HP; Hook-Nikanne J; Thompson SA; Blaser MJ
2000 Jan;181(1):273-282, Journal of infectious diseases
Helicobacter pylori isolates show greater genetic diversity than other bacterial species studied, but the basis for this phenomenon is unknown. Whether detectable genomic mutation appears within an H. pylori population during persistent colonization was investigated. Paired H. pylori populations obtained across 7- to 10-year intervals from 13 patients were characterized by use of methods including polymerase chain reaction (PCR) genotyping for cagA, vacA, iceA, recA, and IS605; random arbitrarily primed DNA (RAPD)-PCR and amplified fragment length polymorphism (AFLP) analysis; and ELISA, to determine Lewis phenotypes. Genotyping, including recA sequence analysis, revealed that initial and follow-up populations represented the same population in 11 patients (85%). Nevertheless, distinct dissimilarities were shown within each of these 11 pairs by both RAPD-PCR and AFLP analyses. During follow-up, Lewis-y levels, but not Lewis-x levels, decreased significantly. The changes detected by RAPD-PCR and AFLP indicate that genetic drift occurs within H. pylori populations over the course of years of colonization of a single host
— id: 19059, year: 2000, vol: 181, page: 273, stat: Journal Article,

Colonization with cagA-positive Helicobacter pylori strains inversely associated with reflux esophagitis and Barrett's esophagus
Loffeld RJ; Werdmuller BF; Kuster JG; Perez-Perez GI; Blaser MJ; Kuipers EJ
2000 ;62(2-3):95-99, Digestion
AIM: The hypothesis that colonization with cagA(+) Helicobacter pylori strains protects against the development of gastroesophageal reflux disease (GERD) and its complications is tested. METHODS: Patients with reflux esophagitis and Barrett's esophagus were studied. Antral biopsy specimens were obtained for detection of H. pylori. A serum sample was obtained for determination of IgG antibodies to H. pylori and to the CagA protein. RESULTS: 736 patients were studied. 118 patients had reflux esophagitis, 36 had Barrett's esophagus, 108 had hiatal hernia without signs of inflammation (the reflux group), and 20 patients had esophageal or stomach cancer. The remaining 454 patients had no signs of GERD. The 262 patients with reflux disease had a significantly lower prevalence of H. pylori (34.9%) than the 454 controls (54.6%; p<0. 001). Among 310 H. pylori-positive patients from whom serum was available, colonization with cagA(+) strains was detected in 59% in the control group versus 35% in the reflux group (p<0.001). Conclusion: Patients with reflux esophagitis and Barrett's esophagus have a significantly lower prevalence of H. pylori colonization than controls, in particular of the cagA(+) type. These data suggest that colonization with cagA(+) H. pylori strains may be protective against the development of GERD
— id: 19035, year: 2000, vol: 62, page: 95, stat: Journal Article,

Detection and characterization of autoagglutination activity by Campylobacter jejuni
Misawa N; Blaser MJ
2000 Nov;68(11):6168-6175, Infection & immunity
In several gram-negative bacterial pathogens, autoagglutination (AAG) activity is a marker for interaction with host cells and virulence. Campylobacter jejuni strains also show AAG, but this property varies considerably among strains. To examine the characteristics of C. jejuni AAG, we developed a quantitative in vitro assay. For strain 81-176, which shows high AAG, activity was optimal for cells grown for < or = 24 h, was independent of growth temperature, and was best measured for cells suspended in phosphate-buffered saline at 25 degrees C for 24 h. AAG activity was heat labile and was abolished by pronase or acid-glycine (pH 2.2) treatment but not by lipase, DNase, or sodium metaperiodate. Strain 4182 has low AAG activity, but extraction with water increased AAG, suggesting the loss of an inhibitor. Strain 6960 has weak AAG with no effect due to water extraction. Our study with clinical isolates suggests that C. jejuni strains may be grouped into three AAG phenotypes. A variant derived from strain 81116 that is flagellate but immotile showed the strong AAG exhibited by the parent strain, suggesting that motility per se is not necessary for the AAG activity. AAG correlated with both bacterial hydrophobicity and adherence to INT407 cells. Mutants which lack flagella (flaA, flaB, and flbA) or common cell surface antigen (peb1A) were constructed in strain 81-176 by natural transformation-mediated allelic exchange. Both AAG activity and bacterial hydrophobicity were abolished in the aflagellate mutants but not the peb1A mutant. In total, these findings indicate that C. jejuni AAG is highly associated with flagellar expression
— id: 19034, year: 2000, vol: 68, page: 6168, stat: Journal Article,

Campylobacter
Nachamkin, Irving; Blaser, Martin J
Washington DC : ASM Press, 2000,
— id: 2001, year: 2000, vol: , page: , stat: ,

Persistent bacterial infections
Nataro, James P; Blaser, Martin J; Cunningham-Rundles, Susanna
Washington DC : ACM Press, 2000,
— id: 1999, year: 2000, vol: , page: , stat: ,

Quantitative detection of Helicobacter pylori gene expression in vivo and relationship to gastric pathology
Peek RM Jr; van Doorn LJ; Donahue JP; Tham KT; Figueiredo C; Blaser MJ; Miller GG
2000 Oct;68(10):5488-5495, Infection & immunity
The iceA locus of Helicobacter pylori includes one of two mutually exclusive gene families, iceA1 and iceA2. Colonization with iceA1 strains is associated with enhanced acute mucosal inflammation, and adherence to gastric epithelial cells in vitro induces expression of iceA1 but not iceA2 mRNA; however, both transcripts can be detected in vivo. The aim of this study was to determine whether differing levels of iceA transcription in vivo may contribute to disease pathogenesis. RNA from 41 H. pylori-positive gastric biopsy specimens was reverse transcribed to cDNA. Quantitative PCR was performed using biotinylated iceA1, iceA2, and 16S rRNA primers, and binding of biotinylated products to streptavidin-coated plates was detected by hybridization with a fluorescein-labeled probe. iceA genotypes were determined by PCR and sequence analysis. All 41 samples contained detectable H. pylori 16S rRNA, with similar levels in iceA1- (n = 10) and iceA2 (n = 31)-colonized patients (P = 0.34). Biopsy specimens from four (40%) and 19 (61%) persons colonized with iceA1 or iceA2 strains, respectively, had detectable iceA RNA. Acute inflammatory scores were significantly higher in iceA1 RNA-positive patients than in iceA1 RNA-negative, iceA2 RNA-positive, or iceA2 RNA-negative subjects (P </= 0.05 for each). Within the iceA2 RNA-positive group, H. pylori strains with a single 35-amino-acid cassette were associated with significantly higher mucosal iceA2 transcript levels (P = 0.014 versus strains with two cassettes). These results indicate that the levels of transcription of H. pylori iceA1 and iceA2 and of 16S rRNA are independent and that particular iceA2 gene structures are associated with enhanced transcription. The finding that iceA1 transcription levels are significantly associated with the intensity of neutrophilic infiltration suggests that heterogeneity in inflammatory scores among persons colonized with H. pylori iceA1 strains reflects levels of iceA1 transcription in vivo
— id: 32245, year: 2000, vol: 68, page: 5488, stat: Journal Article,

Helicobacter pylori alters gastric epithelial cell cycle events and gastrin secretion in Mongolian gerbils
Peek RM; Wirth HP; Moss SF; Yang M; Abdalla AM; Tham KT; Zhang T; Tang LH; Modlin IM; Blaser MJ
2000 Jan;118(1):48-59, Gastroenterology
BACKGROUND & AIMS: Human colonization with Helicobacter pylori increases the risk for distal gastric adenocarcinoma, possibly by altering gastric epithelial cell cycle events and/or gastrin secretion. This study aimed to determine whether H. pylori virulence-related characteristics affect apoptosis, proliferation, and gastrin levels in a rodent model of gastric adenocarcinoma. METHODS: Mongolian gerbils were challenged with H. pylori wild-type or isogenic cagA(-) and vacA(-) mutants, and apoptotic and proliferating cells were identified by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling and proliferating cell nuclear antigen immunohistochemistry, respectively. Serum gastrin levels were determined by radioimmunoassay. RESULTS: Gastric epithelial cell turnover was no different after infection with the wild-type, cagA(-), or vacA(-) strains. H. pylori infection significantly increased antral apoptosis 2-4 weeks after challenge, before apoptotic indices decreased to baseline. In contrast, antral proliferation rates were significantly higher 16-20 weeks after inoculation, but then decreased by 40 weeks. Antral proliferation was significantly related to serum gastrin levels, whereas antral apoptosis was inversely related to acute inflammation and lymphoid follicles. CONCLUSIONS: In H. pylori-infected gerbils, enhanced antral apoptosis is an early and transient cell cycle event. Epithelial cell proliferation peaks later and is significantly related to increased gastrin levels, suggesting that epithelial cell growth in H. pylori-colonized mucosa may be mediated by gastrin-dependent mechanisms
— id: 19058, year: 2000, vol: 118, page: 48, stat: Journal Article,

Campylobacter fetus sap inversion occurs in the absence of RecA function
Ray KC; Tu ZC; Grogono-Thomas R; Newell DG; Thompson SA; Blaser MJ
2000 Oct;68(10):5663-5667, Infection & immunity
Phase variation of Campylobacter fetus surface layer proteins (SLPs) occurs by inversion of a 6.2-kb DNA segment containing the unique sap promoter, permitting expression of a single SLP-encoding gene. Previous work has shown that the C. fetus sap inversion system is RecA dependent. When we challenged a pregnant ewe with a recA mutant of wild-type C. fetus (strain 97-211) that expressed the 97-kDa SLP, 15 of the 16 ovine-passaged isolates expressed the 97-kDa protein. However, one strain (97-209) expressed a 127-kDa SLP, suggesting that chromosomal rearrangement may have occurred to enable SLP switching. Lack of RecA function in strains 97-211 and 97-209 was confirmed by their sensitivity to the DNA-damaging agent methyl methanesulfonate. Southern hybridization and PCR of these strains indicated that the aphA insertion into recA was stably present. However, Southern hybridizations demonstrated that in strain 97-209 inversion had occurred in the sap locus. PCR data confirmed inversion of the 6.2-kb DNA element and indicated that in these recA mutants the sap inversion frequency is reduced by 2 to 3 log(10) units compared to that in the wild type. Thus, although the major sap inversion pathway in C. fetus is RecA dependent, alternative lower-frequency, RecA-independent inversion mechanisms exist
— id: 19039, year: 2000, vol: 68, page: 5663, stat: Journal Article,

Inverse relationship between gastric colonization of Helicobacter pylori and diarrheal illnesses in children: results of a population-based cross-sectional study
Rothenbacher D; Blaser MJ; Bode G; Brenner H
2000 Nov;182(5):1446-1449, Journal of infectious diseases
It has been suggested that carriage of Helicobacter pylori may protect against infections by exogenous intestinal pathogens. An analysis was done of all children who were screened for school fitness during 1996-1998 in Ulm, Germany, to compare rates of diarrheal illnesses in H. pylori-positive and H. pylori-negative children. Of 2477 5-8-year-old children studied, 304 (12.3%) were H. pylori-positive by carbon 13-labeled urea breath test. For H. pylori-positive children, diarrhea within the prior 3 months was less often reported than for H. pylori-negative children (54.3% vs. 76.1%; P<.001, adjusted for nationality). Compared with H. pylori-negative children, the odds ratio (OR) for the occurrence of diarrhea within the prior 3 months was 0.37 (95% confidence interval [CI], 0.28-0.49) for H. pylori-positive children; after adjustment for covariates, the OR was 0.56 (95% CI, 0.42-0.76). These data support the hypothesis that H. pylori colonization may protect against diarrheagenic gastrointestinal infections
— id: 19037, year: 2000, vol: 182, page: 1446, stat: Journal Article,

Primary isolation of Ehrlichia chaffeensis from patients with febrile illnesses: clinical and molecular characteristics
Standaert SM; Yu T; Scott MA; Childs JE; Paddock CD; Nicholson WL; Singleton J; Blaser MJ
2000 Mar;181(3):1082-1088, Journal of infectious diseases
Ehrlichia chaffeensis was sought among patients with a history of tick exposure and fever, and the accuracy of other diagnostic tests was compared with that of primary isolation. Among the 38 patients enrolled, E. chaffeensis was isolated from the blood of 7 (18%) and from cerebrospinal fluid specimens of 2 of these 7. All 7 patients also were positive by polymerase chain reaction (PCR) of blood, and 6 patients developed diagnostic titers of antibody to E. chaffeensis. The isolates were characterized by molecular analysis of the 16S rRNA gene, the 120-kDa protein gene, and the variable-length PCR target (VLPT) of E. chaffeensis. On the basis of the 120-kDa and VLPT genotypes, the cerebrospinal fluid and blood isolates from the same patients were identical. This study demonstrates that both PCR and culture of blood for E. chaffeensis have high diagnostic yields. More frequent isolation of E. chaffeensis from patients with infection should further our understanding of the pathogenesis of this infection
— id: 19051, year: 2000, vol: 181, page: 1082, stat: Journal Article,

CagA-positive strains of Helicobacter pylori may protect against Barrett's esophagus
Vaezi MF; Falk GW; Peek RM; Vicari JJ; Goldblum JR; Perez-Perez GI; Rice TW; Blaser MJ; Richter JE
2000 Sep;95(9):2206-2211, American journal of gastroenterology
OBJECTIVE: Helicobacter pylori (H. pylori) colonization is associated with chronic gastritis, peptic ulcer disease, and adenocarcinoma of the distal stomach. However, the role of H. pylori strain variation in complicated gastroesophageal reflux disease, especially Barrett's esophagus, is unknown. Therefore, the aim of this study was to evaluate the prevalence of colonization by cagA+ and cagA- H. pylori strains in the spectrum of gastroesophageal reflux disease, including Barrett's esophagus. METHODS: A total of 251 patients undergoing endoscopy were categorized into four groups: controls, patients with gastroesophageal reflux disease alone, and patients with short- and long-segment Barrett's esophagus. All patients underwent upper endoscopies with biopsies and serum collections. H. pylori and degree of mucosal inflammation in gastric biopsies were assessed and serological assessment made for H. pylori and cagA status. RESULTS: The overall prevalence of H. pylori colonization in the study population was 35% (95% confidence interval = 29.5-41.4%) which did not differ significantly among the groups. However, colonization by cagA+ H. pylori strains was significantly more prevalent among controls (11/25; 44%) and patients with gastroesophageal reflux disease (13/36; 36%) than in patients with short-segment (2/10; 20%) or long-segment Barrett's esophagus (0/18; 0%). Patients with Barrett's esophagus were less likely to be colonized by cagA+ H. pylori strains than reflux patients without Barrett's esophagus (odds ratio = 0.27, 95% confidence interval = 0.11-0.67, p = 0.004). CONCLUSIONS: Colonization by cagA+ H. pylori strains may be protective against the formation of short- and long-segment Barrett's esophagus and its malignant complications
— id: 19038, year: 2000, vol: 95, page: 2206, stat: Journal Article,

Identification of type II restriction and modification systems in Helicobacter pylori reveals their substantial diversity among strains
Xu Q; Morgan RD; Roberts RJ; Blaser MJ
2000 Aug 15;97(17):9671-9676, Proceedings of the National Academy of Sciences of the United States of America
A total of 22 type II restriction endonucleases with 18 distinct specificities have been identified in six Helicobacter pylori strains. Among these 18 specificities are three completely new endonucleases, Hpy178III, Hpy99I, and Hpy188I, that specifically cleave DNA at TCNNGA, CGWCG, and TCNGA sites, respectively. The set of endonucleases identified in each strain varies, but all have four- or five-base recognition sequences. Among 16 H. pylori strains, examination of the DNA modification status at the recognition sites of 15 restriction endonucleases reveals that each strain has a substantially different complement of type II modification systems. We conclude that the type II restriction-modification systems in H. pylori are highly diverse between strains, a unique characteristic of H. pylori. The diverse methylation status of H. pylori chromosomal DNA may serve as a new typing system to discriminate H. pylori isolates for epidemiological and clinical purposes. This study also demonstrates that H. pylori is a rich source of type II restriction endonucleases
— id: 19044, year: 2000, vol: 97, page: 9671, stat: Journal Article,

Purification of the novel endonuclease, Hpy188I, and cloning of its restriction-modification genes reveal evidence of its horizontal transfer to the Helicobacter pylori genome
Xu Q; Stickel S; Roberts RJ; Blaser MJ; Morgan RD
2000 Jun 2;275(22):17086-17093, Journal of biological chemistry
We have isolated a novel restriction endonuclease, Hpy188I, from Helicobacter pylori strain J188. Hpy188I recognizes the unique sequence, TCNGA, and cleaves the DNA between nucleotides N and G in its recognition sequence to generate a one-base 3' overhang. Cloning and sequence analysis of the Hpy188I modification gene in strain J188 reveal that hpy188IM has a 1299-base pair (bp) open reading frame (ORF) encoding a 432-amino acid product. The predicted protein sequence of M.Hpy188I contains conserved motifs typical of aminomethyltransferases, and Western blotting indicates that it is an N-6 adenine methyltransferase. Downstream of hpy188IM is a 513-bp ORF encoding a 170-amino acid product, that has a 41-bp overlap with hpy188IM. The predicted protein sequence from this ORF matches the amino acid sequence obtained from purified Hpy188I, indicating that it encodes the endonuclease. The Hpy188I R-M genes are not present in either strain of H. pylori that has been completely sequenced but are found in two of 11 H. pylori strains tested. The significantly lower G + C content of the Hpy188I R-M genes implies that they have been introduced relatively recently during the evolution of the H. pylori genome
— id: 19048, year: 2000, vol: 275, page: 17086, stat: Journal Article,

Gastric dysplasia and gastric cancer: Helicobacter pylori, serum vitamin C, and other risk factors
You WC; Zhang L; Gail MH; Chang YS; Liu WD; Ma JL; Li JY; Jin ML; Hu YR; Yang CS; Blaser MJ; Correa P; Blot WJ; Fraumeni JF; Xu GW
2000 Oct 4;92(19):1607-1612, Journal of the National Cancer Institute
BACKGROUND: Gastric cancer is generally thought to arise through a series of gastric mucosal changes, but the determinants of the precancerous lesions are not well understood. To identify such determinants, we launched a follow-up study in 1989-1990 among 3433 adults in Linqu County, China, a region with very high rates of gastric cancer. METHODS: Data on cigarette smoking, alcohol consumption, and other characteristics of the participants were obtained by interview in 1989-1990, when an initial endoscopy was taken. At study entry, antibodies to Helicobacter pylori were assayed in 2646 adults (77% of people screened), and levels of serum micronutrients were measured in approximately 450 adults. Follow-up endoscopic and histopathologic examinations were conducted in 1994. Antibodies to H. pylori, levels of serum micronutrients, and other baseline characteristics were compared between subjects whose condition showed progression to dysplasia or gastric cancer from study entry to 1994 and subjects with no change or with regression of their lesions over the same time frame. All P: values are two-sided. RESULTS: The presence of H. pylori at baseline was associated with an increased risk of progression to dysplasia or gastric cancer (odds ratio [OR] = 1.8; 95% confidence interval [CI] = 1.2-2.6). The risk of progression to dysplasia or gastric cancer also was moderately increased with the number of years of cigarette smoking. In contrast, the risk of progression was decreased by 80% (OR = 0.2; 95% CI = 0.1-0.7) among subjects with baseline ascorbic acid levels in the highest tertile compared with those in the lowest tertile, and there was a slightly elevated risk in those individuals with higher levels of alpha-tocopherol. Conclusions: H. pylori infection, cigarette smoking, and low levels of dietary vitamin C may contribute to the progression of precancerous lesions to gastric cancer in this high-risk population
— id: 19036, year: 2000, vol: 92, page: 1607, stat: Journal Article,

HP0333, a member of the dprA family, is involved in natural transformation in Helicobacter pylori
Ando T; Israel DA; Kusugami K; Blaser MJ
1999 Sep;181(18):5572-5580, Journal of bacteriology
Helicobacter pylori is naturally competent for DNA transformation, but the mechanism by which transformation occurs is not known. For Haemophilus influenzae, dprA is required for transformation by chromosomal but not plasmid DNA, and the complete genomic sequence of H. pylori 26695 revealed a dprA homolog (HP0333). Examination of genetic databases indicates that DprA homologs are present in a wide variety of bacterial species. To examine whether HP0333 has a function similar to dprA of H. influenzae, HP0333, present in each of 11 strains studied, was disrupted in two H. pylori isolates. For both mutants, the frequency of transformation by H. pylori chromosomal DNA was markedly reduced, but not eliminated, compared to their wild-type parental strains. Mutation of HP0333 also resulted in a marked decrease in transformation frequency by a shuttle plasmid (pHP1), which differs from the phenotype described in H. influenzae. Complementation of the mutant with HP0333 inserted in trans in the chromosomal ureAB locus completely restored the frequency of transformation to that of the wild-type strain. Thus, while dprA is required for high-frequency transformation, transformation also may occur independently of DprA. The presence of DprA homologs in bacteria known not to be naturally competent suggests a broad function in DNA processing
— id: 19064, year: 1999, vol: 181, page: 5572, stat: Journal Article,

Simple and accurate PCR-based system for typing vacuolating cytotoxin alleles of Helicobacter pylori
Atherton JC; Cover TL; Twells RJ; Morales MR; Hawkey CJ; Blaser MJ
1999 Sep;37(9):2979-2982, Journal of clinical microbiology
Alleles of the vacuolating cytotoxin gene (vacA) of Helicobacter pylori vary between strains, particularly in the region encoding the signal sequence (which may be type s1 or s2) and the midregion (which may be type m1 or m2). Using a PCR-based typing system developed in the United States, we showed that 36 strains from Asia and South America were all vacA signal sequence type s1; 3 were midregion type m1 and 11 were m2, but 22 could not be typed for the vacA midregion. All strains possessed cagA (cytotoxin-associated gene A), another virulence marker. vacA nucleotide sequence analysis showed that midregion typing failure was due to base substitutions at the primer annealing sites. Using the new sequence data, we developed two new PCR-based vacA midregion typing systems, both of which correctly typed 41 U.S. strains previously typed by the old system and successfully typed all 36 of the non-U.S. strains. All previously untypeable strains were vacA m1, other than one m1/m2 hybrid. In summary, we describe and validate a simple PCR-based system for typing vacuolating cytotoxin (vacA) alleles of H. pylori and show that this system correctly identifies the signal and midregion types of vacA in 77 strains from Asia and North and South America
— id: 19065, year: 1999, vol: 37, page: 2979, stat: Journal Article,

Vacuolating cytotoxin (vacA) alleles of Helicobacter pylori comprise two geographically widespread types, m1 and m2, and have evolved through limited recombination
Atherton JC; Sharp PM; Cover TL; Gonzalez-Valencia G; Peek RM; Thompson SA; Hawkey CJ; Blaser MJ
1999 Oct;39(4):211-218, Current microbiology
Vacuolating cytotoxin (vacA) alleles of Helicobacter pylori vary, particularly in their mid region (which may be type m1 or m2) and their signal peptide coding region (type s1 or s2). We investigated nucleotide diversity among vacA alleles in strains from several locales in Asia, South America, and the USA. Phylogenetic analysis of vacA mid region sequences from 18 strains validated the division into two main groups (m1 and m2) and showed further significant divisions within these groups. Informative site analysis demonstrated one example of recombination between m1 and m2 alleles, and several examples of recombination among alleles within these groups. Recombination was not sufficiently extensive to destroy phylogenetic structure entirely. Synonymous nucleotide substitution rates were markedly different between regions of vacA, suggesting different evolutionary divergence times and implying horizontal transfer of genetic elements within vacA. Non-synonymous/synonymous rate ratios were greater between m1 and m2 sequences than among m1 sequences, consistent with m1 and m2 alleles encoding functions fitting strains for slightly different ecological niches
— id: 19063, year: 1999, vol: 39, page: 211, stat: Journal Article,

Allelic variation in Helicobacter pylori: progress but no panacea
Blaser MJ
1999 Oct;45(4):477-478, Gut: journal of the British Society of Gastroenterology
— id: 19062, year: 1999, vol: 45, page: 477, stat: Journal Article,

Hypothesis: the changing relationships of Helicobacter pylori and humans: implications for health and disease
Blaser MJ
1999 Jun;179(6):1523-1530, Journal of infectious diseases
Helicobacter pylori has apparently colonized the human stomach since time immemorial and is superbly adapted for persistence. Several genotypes, including cag+, are associated with increased risk of gastric and duodenal diseases. With modern life, for probably the first time in human history, there are large numbers of noncolonized persons. Duodenal ulceration has been present essentially for only 200 years; that its incidence rose just as H. pylori was waning is best explained by changes in gastric microecology. As H. pylori is disappearing, duodenal ulceration and gastric cancer rates are falling. However, more proximal diseases, gastroesophageal reflux (GERD), Barrett's esophagus, and adenocarcinomas of the gastric cardia and lower esophagus, are increasing; colonization with cag+ H. pylori strains appears protective against these diseases. Thus, in the 21st century, the continuing decline in H. pylori may lead to the disappearance of duodenal ulcers and distal gastric cancers and toward a marked increase in GERD, Barrett's esophagus, and esophageal adenocarcinoma
— id: 19072, year: 1999, vol: 179, page: 1523, stat: Journal Article,

In a world of black and white, Helicobacter pylori is gray
Blaser MJ
1999 Apr 20;130(8):695-697, Annals of internal medicine
— id: 19074, year: 1999, vol: 130, page: 695, stat: Journal Article,

Prepare for, not create, the future
Blaser MJ
1999 Summer;62(3):51-52, Pharos of Alpha Omega Alpha Honor Medical Society
— id: 19061, year: 1999, vol: 62, page: 51, stat: Journal Article,

Where does Helicobacter pylori come from and why is it going away?
Blaser MJ
1999 Dec 15;282(23):2260-2262, JAMA
— id: 19060, year: 1999, vol: 282, page: 2260, stat: Journal Article,

Dynamics of Helicobacter pylori colonization in relation to the host response
Blaser MJ; Kirschner D
1999 Jul 20;96(15):8359-8364, Proceedings of the National Academy of Sciences of the United States of America
The dynamics of Helicobacter pylori colonization from its acquisition through the development of steady-state are examined through a mathematical model that includes the host response. The model encompasses both host and microbiological variation. The individual capacity of the host response is shown to be a key model parameter, leading to either transient or persistent colonization, whereas the growth rate of that response has little effect. Analyses of competing strains indicate that each must occupy a specific niche, otherwise exclusion occurs. The model implies that there exists a lower bound on the host response to the indigenous microflora that is consistent with current biological views of H. pylori. Parallel models may be useful in understanding other persistent host-microbial interactions
— id: 19066, year: 1999, vol: 96, page: 8359, stat: Journal Article,

Panel discussion: breaking the link--clinical options to minimize risk
Blaser MJ; Kuipers EJ; Ernst P; Axon A; Megraud F
1999 Mar;13 Suppl 1(8):19-23, Alimentary pharmacology & therapeutics
— id: 19075, year: 1999, vol: 13 Suppl 1, page: 19, stat: Journal Article,

Helicobacter pylori and gastic cancer
Blaser, Martin J
Oxford : Blackwell Science, 1999,
— id: 2024, year: 1999, vol: , page: , stat: ,

Helicobacter pylori factors associated with disease
Cover TL; Blaser MJ
1999 Jul;117(1):257-261, Gastroenterology
— id: 19068, year: 1999, vol: 117, page: 257, stat: Journal Article,

Host specificity of Helicobacter pylori strains and host responses in experimentally challenged nonhuman primates
Dubois A; Berg DE; Incecik ET; Fiala N; Heman-Ackah LM; Del Valle J; Yang M; Wirth HP; Perez-Perez GI; Blaser MJ
1999 Jan;116(1):90-96, Gastroenterology
BACKGROUND & AIMS: The specificity of colonization by Helicobacter pylori and complex host-bacterium interactions cannot be readily examined in humans. The aim of this study was to perform such analyses in rhesus monkeys. METHODS: Four animals that had been cured of natural H. pylori colonization were challenged with a mixture of 7 strains of human origin, and bacteria recovered during periodic videogastroscopy were DNA fingerprinted. RESULTS: Three animals carried mixtures of several strains for 4 months, after which strain J166 predominated. In the fourth animal, only strain J238 was isolated from the earliest phase of colonization through 7 months, but strain J166 again became predominant by 10 months after the challenge. Gastritis scores and plasma gastrin and anti-H. pylori immunoglobulin G titers reached levels observed in naturally colonized animals by 4 months after the challenge; however, no plasma immunoglobulin A response was observed up to 10 months. CONCLUSIONS: These results show that (1) natural colonization does not elicit protective immunity against subsequent H. pylori challenge; (2) individuals differ in susceptibility to different H. pylori strains during initial stages of colonization; and (3) certain strains are better suited than others for long-term survival in different hosts. These observations show the complexity of H. pylori-host interactions
— id: 19077, year: 1999, vol: 116, page: 90, stat: Journal Article,

Helicobacter pylori heat shock protein A: serologic responses and genetic diversity
Ng EK; Thompson SA; Perez-Perez GI; Kansau I; van der Ende A; Labigne A; Sung JJ; Chung SC; Blaser MJ
1999 May;6(3):377-382, Clinical & diagnostic laboratory immunology
Helicobacter pylori synthesizes an unusual GroES homolog, heat shock protein A (HspA). The present study was aimed at an assessment of the serological response to HspA in a group of Chinese patients with defined gastroduodenal pathologies and determination of whether diversity is present in the nucleotide sequences encoding HspA in isolates from these patients. Serum samples collected from 154 patients who had an upper gastrointestinal pathology and the presence of H. pylori defined by biopsy were tested for an immunoglobulin G (IgG) serologic response to H. pylori HspA by an enzyme linked immunosorbant assay. HspA-encoding nucleotide sequences in H. pylori isolates from 14 patients (7 seropositive and 7 seronegative for HspA) were analyzed by PCR and direct sequencing of the PCR products. The sequencing results were compared to those of 48 isolates from other parts of the world. Of the 154 known H. pylori-positive patients, 54 (35.1%) were seropositive for HspA. The A domain (GroES homology) of HspA was highly conserved in the 14 isolates tested. Although the B domain (metal-binding site unique to H. pylori) resembled that in the known major variant, particular amino acid substitutions allowed definition of an HspA variant associated with isolates from East Asia. There were no associations between patient characteristics and HspA seropositivity or amino acid sequences. We confirmed in this study that the clinical outcomes of H. pylori infection are not related to HspA antigenicity or to sequence variation. However, B-domain sequence variation may be a marker for the study of the genetic diversity of H. pylori strains of different geographic origins
— id: 19073, year: 1999, vol: 6, page: 377, stat: Journal Article,

Role of Helicobacter pylori cagA(+) strains and specific host immune responses on the development of premalignant and malignant lesions in the gastric cardia
Peek RM Jr; Vaezi MF; Falk GW; Goldblum JR; Perez-Perez GI; Richter JE; Blaser MJ
1999 Aug 12;82(4):520-524, International journal of cancer
The incidence rates of gastric cardia and esophageal adenocarcinomas are increasing, but data suggest that carriage of cagA(+) Helicobacter pylori strains may protect against development of Barrett's esophagus and esophageal adenocarcinoma. Our aims were to examine the relationship between pre-malignant and malignant lesions in the gastric cardia and serum antibodies to H. pylori antigens in patients with and without complications of Barrett's esophagus. The prevalence of carditis was 40% in controls compared with 13% in patients with complicated or uncomplicated Barrett's esophagus and cardia adenocarcinoma (p < 0.001). Cardia intestinal metaplasia (IM) and atrophy were present and concordant in 28% of controls but less frequent in patients with Barrett's alone or with dysplasia/adenocarcinoma (0% for each, p < 0.001). Carriage of cagA(+) strains was present in 34% of patients with carditis and significantly associated with increased frequency and severity of cardia inflammation, IM, and atrophy but not with adenocarcinoma. IgA and HspA seropositivity were significantly increased in H. pylori-colonized patients with carditis compared to persons with normal cardia histology (p </= 0.005) but not in persons with esophageal disease or cardia adenocarcinoma. We conclude that carriage of cagA(+) H. pylori strains and induction of particular serological responses are significantly associated with marked histological findings in the gastric cardia but not with adenocarcinoma of either the gastric cardia or esophagus
— id: 32251, year: 1999, vol: 82, page: 520, stat: Journal Article,

Helicobacter pylori strain-specific genotypes and modulation of the gastric epithelial cell cycle
Peek RM; Blaser MJ; Mays DJ; Forsyth MH; Cover TL; Song SY; Krishna U; Pietenpol JA
1999 Dec 15;59(24):6124-6131, Cancer research
Helicobacter pylori cag+ strains enhance gastric epithelial cell proliferation and attenuate apoptosis in vivo, which may partially explain the increased risk of gastric cancer associated with these strains. The goals of this study were to identify specific H. pylori genes that regulate epithelial cell cycle events and determine whether these effects were dependent upon p53-mediated pathways. AGS gastric epithelial cells were cultured alone or in the presence of 21 clinical H. pylori isolates, H. pylori reference strain 60190, or its isogenic cagA-, picB-, vacA-, or picB-/vacA- derivatives. Coculture of H. pylori with AGS cells significantly decreased cell viability, an effect most prominent with cag+ strains (P < 0.001 versus cag-strains). cag+ strains significantly increased progression of AGS cells from G1 into G2-M at 6 h and enhanced apoptosis by 72 h. Compared with the parental 60190 strain, the picB- mutant attenuated cell cycle progression at 6 h (P < or = 0.05), and decreased apoptosis with enhanced AGS cell viability at 24 h (P < or = 0.04). The vacA- mutant decreased apoptosis and enhanced viability at later (48-72 h) time points (P < or = 0.05). Compared with the wild-type strain, the picB-/vacA- double mutant markedly attenuated apoptosis and increased cell viability at all time points (P < or = 0.05). Furthermore, cocolonization with H. pylori had no significant effect on expression of p53, p21, and MDM2. The diminished AGS cell viability, progression to G2-M, and apoptosis associated with cag+ H. pylori strains were dependent upon expression of vacA and genes within the cag pathogenicity island. These results may explain heterogeneity in levels of gastric epithelial cell proliferation and apoptosis found within H. pyloricolonized mucosa
— id: 19055, year: 1999, vol: 59, page: 6124, stat: Journal Article,

Detection of anti-VacA antibody responses in serum and gastric juice samples using type s1/m1 and s2/m2 Helicobacter pylori VacA antigens
Perez-Perez GI; Peek RM; Atherton JC; Blaser MJ; Cover TL
1999 Jul;6(4):489-493, Clinical & diagnostic laboratory immunology
Several different families of vacuolating toxin (vacA) alleles are present in Helicobacter pylori, and they encode products with differing functional activities. H. pylori strains containing certain types of vacA alleles have been associated with an increased risk for peptic ulcer disease. In this study, we tested serum samples and gastric juice from 19 H. pylori-negative and 39 H. pylori-positive patients for enzyme-linked immunosorbent assay reactivity with two different types of VacA antigens (types s1/m1 and s2/m2), which were purified from H. pylori 60190 and 86-338, respectively. Both antigens were recognized better by serum immunoglobulin G (IgG) from H. pylori-positive persons than by serum IgG from H. pylori-negative persons (P < 0.01). The s1/m1 VacA antigen was better recognized by sera from patients carrying vacA type s1/m1 strains than by sera from patients carrying vacA type s2/m2 or s1/m2 strains (P < 0.01). Conversely, the s2/m2 VacA antigen was better recognized by sera from patients carrying type s2/m2 or s1/m2 strains (P = 0.03). Serum IgG anti-VacA antibodies were present more frequently in patients carrying type s1/m1 strains than in other H. pylori-positive patients (P = 0.0002). In addition, the highest levels of IgA anti-VacA antibodies were detected in the gastric juice of patients carrying type s1/m1 strains. These data indicate that different VacA isoforms have distinct antigenic properties and that multiple forms of VacA elicit antibody responses in H. pylori-positive humans
— id: 19067, year: 1999, vol: 6, page: 489, stat: Journal Article,

Geographic distribution of vacA allelic types of Helicobacter pylori
Van Doorn LJ; Figueiredo C; Megraud F; Pena S; Midolo P; Queiroz DM; Carneiro F; Vanderborght B; Pegado MD; Sanna R; De Boer W; Schneeberger PM; Correa P; Ng EK; Atherton J; Blaser MJ; Quint WG
1999 Apr;116(4):823-830, Gastroenterology
BACKGROUND & AIMS: Distinct allelic types of Helicobacter pylori vacA have been defined. The geographic distribution of vacA alleles and cagA was assessed in this study. METHODS: A total of 735 cultures from patients in 24 countries were analyzed by polymerase chain reaction and reverse hybridization on a line probe assay (LiPA). RESULTS: In 124 (16.9%) of the 735 cultures, multiple vacA genotypes were detected, permitting analysis of 611 strains. In Europe, a distribution gradient of s1 subtypes was observed. In northern and eastern Europe, 89% were subtype s1a. s1a and s1b were equally present in France and Italy, whereas in Spain and Portugal 89% of strains were subtype s1b. s1a and s1b were approximately equally prevalent in North America. In Central and South America, virtually all s1 strains were subtype s1b. Subtype s1c was observed in 77% of the s1 isolates from East Asia. m1 and m2a have equal presence, except on the Iberian peninsula and in Central and South America, where m1 (86.2%) is more prevalent than m2 (13.8%). Subtype m2b was found exclusively among East Asian s1c strains. In all parts of the world, vacA s1/cagA-positive genotypes were associated with peptic ulcer disease (P < 0.001). CONCLUSIONS: These data indicate a geographic distribution of H. pylori genotypes and aid in understanding the relationship of H. pylori with disease
— id: 19076, year: 1999, vol: 116, page: 823, stat: Journal Article,

Distinct variants of Helicobacter pylori cagA are associated with vacA subtypes
van Doorn LJ; Figueiredo C; Sanna R; Blaser MJ; Quint WG
1999 Jul;37(7):2306-2311, Journal of clinical microbiology
The diversity of the cytotoxin-associated gene (cagA) of Helicobacter pylori was analyzed in 45 isolates obtained from nine countries. We examined variation in the 5' end of the cagA open reading frame as determined by PCR and sequencing. Phylogenetic analysis revealed the existence of at least two distinct types of cagA. One variant (cagA1) was found exclusively in strains from Europe, the United States, and Australia, whereas a novel variant (cagA2) was found in strains from East Asia. The greatest diversity between cagA1 and cagA2 was found in the first 20 amino acids of the cagA open reading frame, where several consistent insertions or deletions were observed. Additional cagA sequence variants that could be classified as separate subtypes were found in two of three Peruvian and in five of seven U.S. strains tested. The calculated isoelectric point of the first 154 amino acids of the cagA1 variants (7.52 +/- 1.54) was significantly higher than that of the first 154 amino acids of the cagA2 variants (5.61 +/- 0.94; P < 0.001). Most cagA2 strains contained vacA subtype s1c (P < 0.001), and in vacA m1 strains cagA1 was more frequently observed than cagA2. These results show the epidemiological relationship between cagA and vacA at the subtype level and indicate the existence of distinct H. pylori lineages that are not uniformly distributed over the globe
— id: 19069, year: 1999, vol: 37, page: 2306, stat: Journal Article,

Rapid identification of thermotolerant Campylobacter jejuni, Campylobacter coli, Campylobacter lari, and Campylobacter upsaliensis from various geographic locations by a GTPase-based PCR-reverse hybridization assay
van Doorn LJ; Verschuuren-van Haperen A; Burnens A; Huysmans M; Vandamme P; Giesendorf BA; Blaser MJ; Quint WG
1999 Jun;37(6):1790-1796, Journal of clinical microbiology
Recently, a gene from Campylobacter jejuni encoding a putative GTPase was identified. Based on two semiconserved GTP-binding sites encoded within this gene, PCR primers were selected that allow amplification of a 153-bp fragment from C. jejuni, C. coli, C. lari, and C. upsaliensis. Sequence analysis of these PCR products revealed consistent interspecies variation, which allowed the definition of species-specific probes for each of the four thermotolerant Campylobacter species. Multiple probes were used to develop a line probe assay (LiPA) that permits analysis of PCR products by a single reverse hybridization step. A total of 320 reference strains and clinical isolates from various geographic origins were tested by the GTP-based PCR-LiPA. The PCR-LiPA is highly specific in comparison with conventional identification methods, including biochemical and whole-cell protein analyses. In conclusion, a simple method has been developed for rapid and highly specific identification of thermotolerant Campylobacter species
— id: 19070, year: 1999, vol: 37, page: 1790, stat: Journal Article,

Pathophysiology of Campylobacter jejuni infections of humans
Wassenaar TM; Blaser MJ
1999 Oct;1(12):1023-1033, Microbes & infection
Campylobacter jejuni and closely related organisms are major causes of human bacterial enteritis. These infections can lead to extraintestinal disease and severe long-term complications. Of these, neurological damage, apparently due to the immune response of the host, is the most striking. This review examines current knowledge of the pathophysiology of the organism. Diversity of C. jejuni isolates in genotypic and phenotypic characteristics now is recognized and clinically relevant examples are presented. Expected future directions are outlined
— id: 19057, year: 1999, vol: 1, page: 1023, stat: Journal Article,

Phenotypic diversity in Lewis expression of Helicobacter pylori isolates from the same host
Wirth HP; Yang M; Peek RM; Hook-Nikanne J; Fried M; Blaser MJ
1999 May;133(5):488-500, Journal of laboratory & clinical medicine
Populations of Helicobacter pylori cells show a stable expression of Lewis surface antigens, although phase variation may occur among individual organisms grown in vitro. We searched for variation in Lewis phenotypes among H. pylori cells of minimally in vitro-passaged isolates. Lewis expression in 180 clonal H. pylori populations from the primary culture of 20 gastric biopsy samples from 12 patients, and that in 160 isolates from primary cultures from 16 experimentally infected rodents, were examined by enzyme immunoassays. Substantial differences in Lewis expression were found among the isolates from 9 (75%) of 12 patients. These differences were unrelated to overall genetic diversity as determined by polymerase chain reactions for random amplified polymorphic DNA or cagA status, and they persisted during subsequent in vitro passage. In contrast, Lewis expression was highly uniform in H. pylori isolates from different rodents infected for up to 20 weeks. Variation in H. pylori Lewis expression in genetically closely related organisms in human subjects may provide a pool of bacterial phenotypes for the continuous selection of optimally host-adapted populations suitable for persistence
— id: 19071, year: 1999, vol: 133, page: 488, stat: Journal Article,

Insensitivity of the CLOtest for H. pylori, Especially in the Elderly
Abdalla AM; Sordillo EM; Hanzely Z; Perez-Perez GI; Blaser MJ; Holt PR; Moss SF
1998 Jul;115(1):243b-244, Gastroenterology
— id: 19089, year: 1998, vol: 115, page: 243b, stat: Journal Article,

Campylobacter jejuni strains from patients with Guillain-Barre syndrome
Allos BM; Lippy FT; Carlsen A; Washburn RG; Blaser MJ
1998 Apr-Jun;4(2):263-268, Emerging infectious diseases
Guillain-Barre syndrome (GBS), an acute demyelinating peripheral neuropathy, may be triggered by an acute infectious illness; infection with Campylobacter jejuni is the most frequently reported antecedent event. In Japan, O:19 is the most common serotype among GBS-associated C. jejuni strains. To determine whether serotype O:19 occurs among GBS-associated strains in the United States and Europe, we serotyped seven such strains and found that two (29%) of seven GBS-associated strains from patients in the United States and Germany were serotype O:19. To determine whether GBS-associated strains may be resistant to killing by normal human serum (NHS), we studied the serum susceptibility of 17 GBS- and 27 enteritis-associated strains (including many O:19 and non-O:19 strains) using C. jejuni antibody positive (pool 1) or negative (pool 2) human serum. Using pool 1 serum we found that one (6%) of 18 serotype O:19 strains compared with 11 (42%) of 26 non-O:19 strains were killed; results using pool 2 serum were nearly identical. Finally, 8 O:19 and 8 non-O:19 strains were not significantly different in their ability to bind complement component C3. Serotype O:19 C. jejuni strains were overrepresented among GBS-associated strains in the United States and Germany and were significantly more serum-resistant than non-O:19 strains. The mechanism of this resistance appears unrelated to C3 binding
— id: 19094, year: 1998, vol: 4, page: 263, stat: Journal Article,

Differential normalization of mucosal interleukin-8 and interleukin-6 activity after Helicobacter pylori eradication
Ando T; Kusugami K; Ohsuga M; Ina K; Shinoda M; Konagaya T; Sakai T; Imada A; Kasuga N; Nada T; Ichiyama S; Blaser MJ
1998 Oct;66(10):4742-4747, Infection & immunity
There is differential resolution of mucosal infiltration with neutrophils and mononuclear cells following successful Helicobacter pylori eradication. We investigated the effects of H. pylori eradication on mucosal interleukin-8 (IL-8) and IL-6 activity in relation to the resolution of H. pylori-associated gastritis. Eighty-one duodenal ulcer patients with H. pylori infection received dual- or triple-treatment eradication therapy, and mucosal biopsy specimens obtained at the initial and follow-up endoscopic examinations were cultured in vitro for 24 h. The levels of IL-8 and IL-6 were measured by enzyme-linked immunosorbent assays. In the 42 patients in whom H. pylori eradication failed, there was little change in the numbers of neutrophils and mononuclear cells infiltrating the mucosa and in IL-8 and IL-6 activity. In the 39 patients in whom H. pylori was eradicated, there was normalization both in the numbers of infiltrating neutrophils and in mucosal IL-8 activity, which was evident within 1 month following therapy. In contrast, there was a gradual resolution of mononuclear cell infiltration over a 6-month period, accompanied by a gradual normalization in IL-6 levels. Addition of H. pylori to cultures of mucosal tissues induced a significant increase in IL-8 activity in both uninfected control subjects and patients from whom H. pylori was eradicated. However, this introduction yielded a significant increase in IL-6 activity only in the latter group. This study indicates a dichotomy in the changes of mucosal IL-8 and IL-6 activity after H. pylori eradication. The rapid normalization of IL-8 after H. pylori eradication and the ability of H. pylori cells to stimulate IL-8 in control tissues indicate that IL-8 induction is a part of the innate (nonimmune) responses to this organism. In contrast, the results of experiments analyzing IL-6 activity in cultured mucosal tissues suggest that the gradual resolution of mucosal IL-6 activity and mononuclear infiltration after successful eradication observed in vivo may reflect gradually diminishing residual immune responses against H. pylori
— id: 19084, year: 1998, vol: 66, page: 4742, stat: Journal Article,

Campylobacter fetus--emerging infection and model system for bacterial pathogenesis at mucosal surfaces
Blaser MJ
1998 Aug;27(2):256-258, Clinical infectious diseases
— id: 19085, year: 1998, vol: 27, page: 256, stat: Journal Article,

Helicobacter pylori and gastric diseases
Blaser MJ
1998 May 16;316(7143):1507-1510, British medical journal. BMJ (International ed.)
— id: 19096, year: 1998, vol: 316, page: 1507, stat: Journal Article,

Helicobacters and biliary tract disease
Blaser MJ
1998 Apr;114(4):840-842, Gastroenterology
— id: 19100, year: 1998, vol: 114, page: 840, stat: Journal Article,

Helicobacters are indigenous to the human stomach: duodenal ulceration is due to changes in gastric microecology in the modern era
Blaser MJ
1998 Nov;43(5):721-727, Gut: journal of the British Society of Gastroenterology
— id: 19080, year: 1998, vol: 43, page: 721, stat: Journal Article,

Passover and plague
Blaser MJ
1998 Winter;41(2):243-256, Perspectives in biology & medicine
— id: 19103, year: 1998, vol: 41, page: 243, stat: Journal Article,

Helicobacter : approaches to a complex organism
Blaser, Martin J
Challenges for tomorrow's vaccines Rochester NY : University of Rochester Medical Center, 1998,
— id: 5272, year: 1998, vol: , page: 1 video tape, stat: Chapter,

An inverse relation between cagA+ strains of Helicobacter pylori infection and risk of esophageal and gastric cardia adenocarcinoma
Chow WH; Blaser MJ; Blot WJ; Gammon MD; Vaughan TL; Risch HA; Perez-Perez GI; Schoenberg JB; Stanford JL; Rotterdam H; West AB; Fraumeni JF
1998 Feb 15;58(4):588-590, Cancer research
Gastric colonization with Helicobacter pylori, especially cagA+ strains, is a risk factor for noncardia gastric adenocarcinoma, but its relationship with gastric cardia adenocarcinoma is unclear. Although incidence rates for noncardia gastric adenocarcinoma have declined steadily, paralleling a decline in H. pylori prevalence, rates for adenocarcinomas of esophagus and gastric cardia have sharply increased in industrialized countries in recent decades. To clarify the role of H. pylori infection in these tumors with divergent incidence trends, we analyzed serum IgG antibodies to H. pylori and to a recombinant fragment of CagA by antigen-specific ELISA among 129 patients newly diagnosed with esophageal/gastric cardia adenocarcinoma, 67 patients with noncardia gastric adenocarcinoma, and 224 population controls. Cancer risks were estimated by odds ratios (OR) and 95% confidence intervals (CI) using logistic regression models. Infection with cagA+ strains was not significantly related to risk for noncardia gastric cancers (OR, 1.4; CI, 0.7-2.8) but was significantly associated with a reduced risk for esophageal/cardia cancers (OR, 0.4; CI, 0.2-0.8). However, there was little association with cagA- strains of H. pylori for either cancer site (OR, 1.0 and 1.1, respectively). These findings suggest that the effects of H. pylori strains on tumor development vary by anatomical site. Further studies are needed to confirm these results and to assess whether the decreasing prevalence of H. pylori, especially cagA+ strains, may be associated with the rising incidence of esophageal/gastric cardia adenocarcinomas in industrialized countries
— id: 19105, year: 1998, vol: 58, page: 588, stat: Journal Article,

Cure of Helicobacter pylori infection by omeprazole-clarithromycin-based therapy in non-human primates
Dubois A; Berg DE; Fiala N; Heman-Ackah LM; Perez-Perez GI; Blaser MJ
1998 Feb;33(1):18-22, Journal of gastroenterology
Rhesus monkeys raised in colonies tend to become naturally infected by Helicobacter pylori early in life. Earlier attempts to cure H. pylori infection with a 10-day triple therapy (metronidazole, amoxicillin, and peptobismol) were only partially (60%) successful, probably because of preexisting metronidazole resistance. This study was carried out to determine the efficacy of an alternative clarithromycin-omeprazole-based therapy for curing H. pylori infection in Rhesus monkeys (Macaca mulatta), and to examine histologic and serologic correlates of curing. Five monkeys were endoscoped under ketamine anesthesia. Histology and culture of gastric biopsies and serologic tests demonstrated that they were H. pylori-positive. Two animals had not received prior anti-H. pylori treatment, while three other animals had failed triple therapy and carried metronidazole-resistant H. pylori strains. Quadruple therapy with omeprazole, clarithromycin, amoxicillin, and bismuth subsalicylate was given for 10 days to these five animals. All five animals were cured of the infection, and remained H. pylori-free, based on histology and culture at regular intervals for the 5 months posttherapy during which they were followed. Gastritis scores and anti-H. pylori IgG levels decreased in each animal during this period to levels characteristic of uninfected animals. These results indicate that an omeprazole-clarithromycin-based regimen can cure H. pylori infection in Rhesus monkeys, with resolution of abnormal histology and serologic responses. They suggest that this preclinical animal model is useful for testing new anti-H. pylori therapies
— id: 19102, year: 1998, vol: 33, page: 18, stat: Journal Article,

Heterogeneity in levels of vacuolating cytotoxin gene (vacA) transcription among Helicobacter pylori strains
Forsyth MH; Atherton JC; Blaser MJ; Cover TL
1998 Jul;66(7):3088-3094, Infection & immunity
Broth culture supernatants from Tox+ Helicobacter pylori strains induce vacuolation of HeLa cells in vitro and contain VacA in concentrations that are higher than those found in supernatants from Tox- H. pylori strains. To investigate the basis for this phenomenon, we analyzed the transcription of the vacuolating cytotoxin gene (vacA) in eight Tox+ strains (each with a type s1/m1 vacA genotype) and nine Tox- strains (each with a type s2/m2 vacA genotype). Most of the Tox+ and Tox- strains tested used the same vacA transcriptional start point, but Tox+ strains yielded significantly stronger primer extension signal intensities than did Tox- strains (mean densitometry values of 15.8 +/- 1.9 versus 8.9 +/- 1.7, P = 0. 0016). Correspondingly, when we introduced vacA::xylE transcriptional fusions into the chromosomes of a Tox+ strain (60190) and a Tox- strain (86-313), the level of XylE activity in 60190 vacA::xylE was about 30-fold higher than that in 86-313 vacA::xylE. Sequence analysis and promoter exchange experiments indicated that the different levels of vacA transcription in these two strains cannot be explained solely by a difference in promoter strength. These data indicate that Tox+ and Tox- H. pylori strains typically differ not only in the VacA amino acid sequence but also in the level of vacA transcription
— id: 19091, year: 1998, vol: 66, page: 3088, stat: Journal Article,

Epithelial attachment alters the outcome of Helicobacter pylori infection
Guruge JL; Falk PG; Lorenz RG; Dans M; Wirth HP; Blaser MJ; Berg DE; Gordon JI
1998 Mar 31;95(7):3925-3930, Proceedings of the National Academy of Sciences of the United States of America
Genetically defined in vivo models are needed to assess the importance of target cell attachment in bacterial pathogenesis. Gastric colonization by Helicobacter pylori in human populations is common and persistent, and has various outcomes including peptic ulcers and cancer. The impact of attachment on the course of infection was examined in transgenic mice expressing a human receptor for H. pylori in their gastric epithelium. Persistent infection by a clinical isolate occurred at comparable microbial densities in transgenic and nontransgenic littermates. However, microbial attachment in transgenic mice resulted in production of autoantibodies to Lewisx carbohydrate epitopes shared by bacteria and acid-secreting parietal cells, chronic gastritis, and parietal cell loss. This model should help identify bacterial and host genes that produce attachment-related pathology
— id: 19099, year: 1998, vol: 95, page: 3925, stat: Journal Article,

DNA sequence conservation and diversity in transposable element IS605 of Helicobacter pylori
Hook-Nikanne J; Berg DE; Peek RM; Kersulyte D; Tummuru MK; Blaser MJ
1998 Jun;3(2):79-85, Helicobacter
BACKGROUND: IS605, a transposable element-like sequence identified in the virulence-associated cag region of Helicobacter pylori reference strain NCTC11638, is unusual in containing two oppositely-oriented open reading frames whose products are homologues of the single transposases of the unrelated elements, IS200 and IS1341. METHODS: One hundred independent H. pylori isolates from different parts of the world were screened by PCR and dot blot hybridization to determine the presence of IS605. For some positive isolates, southern hybridizations and sequence analyses were done. RESULTS: Of the 100 isolates, 31 were found to contain sequences related to each ORF with orientation and spacing matching those in canonical IS605-hybridizing sequences. No isolate containing just one ORF and not the other was found. The frequencies of IS605 carriage were independent of geographical origin (U.S. vs. non-U.S.), and of the probable virulence of the isolate (cag status, toxin production or vacA alleles, patient symptoms). Southern blot hybridization of six IS605-containing strains revealed one to nine IS605 copies per genome. Two types of DNA sequence diversity were found: first, a specific 100 bp deletion in two isolates; second, base substitution divergence of 0.4% to 7.5% in pairwise comparisons among the eight isolates characterized, a level of divergence similar to that seen in other H. pylori chromosomal genes. CONCLUSIONS: Based on these findings, we speculate that IS605 is a relatively ancient component of the H. pylori gene pool that has proliferated in this species by horizontal gene transfer, homologous recombination, and transposition
— id: 19092, year: 1998, vol: 3, page: 79, stat: Journal Article,

Fellowship training in infectious diseases: a report from the regional and national meetings of infectious diseases division chiefs and program directors
Joiner KA; Powderly WG; Blaser MJ; Klempner MS; Locksley RM; Mandell GL; Preheim LC; Remington JS; Slama TG; Steigbigel NH; Bartlett JG
1998 May;26(5):1060-1065, Clinical infectious diseases
During the 2-year period April 1995 to April 1997, six regional meetings and one national meeting of division chiefs and program directors of adult infectious diseases programs in the United States were held to review fellowship training. Herein, we report data on job availability and job selection for recently graduated fellows. We summarize discussions on decreasing the number of fellows in training, and we outline suggested components of a core clinical curriculum and of three training tracks--clinician track, clinical investigator track, and basic investigator track
— id: 19097, year: 1998, vol: 26, page: 1060, stat: Journal Article,

Acid-tolerance response in Helicobacter pylori and differences between cagA+ and cagA- strains
Karita M; Blaser MJ
1998 Jul;178(1):213-219, Journal of infectious diseases
Helicobacter pylori cagA transcription and translation are maximal at pH 6 in stationary phase. The aim of this study was to determine whether H. pylori has an acid-tolerance response and whether that response is related to CagA expression, by investigating whether preexposure to pH 5 or 6 improved survival of cells subsequently exposed to pH 3. Cell number was determined after broth growth, after exposure to pH 5, 6, or 7, and then after a 30-min exposure to pH 3 without urea. H. pylori cells preexposed to pH 6 or 5 survived pH 3 exposure 100-fold better than did cells preexposed to pH 7. Cells of cagA+ strains grown at pH 6 for 48 h, which induced maximal CagA expression, were significantly more susceptible to pH 3 than were wild type cagA- strains or isogenic cagA- knockouts. Thus, H. pylori strains possess a urea-independent acid-tolerance response. Differential acid susceptibility may contribute to preferential colonization of particular H. pylori strains in specific mucus layer niches
— id: 19088, year: 1998, vol: 178, page: 213, stat: Journal Article,

Evidence for a conjugation-like mechanism of DNA transfer in Helicobacter pylori
Kuipers EJ; Israel DA; Kusters JG; Blaser MJ
1998 Jun;180(11):2901-2905, Journal of bacteriology
Many strains of Helicobacter pylori are naturally competent for transformation in vitro. Since there is a high degree of genetic variation among H. pylori strains, we sought to determine whether mechanisms of DNA exchange other than transformation exist in these organisms. Studies were done with H. pylori cells that each were resistant to two different antibiotics; the procedure used involved mating of cells on plates or in broth, in the absence or presence of DNase. In each experiment, such matings produced progeny with the markers of both parents. Examination of the full resistance profile and random arbitrarily primed DNA PCR (RAPD-PCR) profiles of the progeny indicated that DNA transfer was bidirectional. DNase treatment reduced but did not eliminate transfer; only the presence of both DNase and a membrane separating the cells did so. For progeny derived from matings in the presence of DNase, antibiotic resistance and RAPD profiles indicated that transfer was unidirectional. DNase-treated cell-free supernatants also did not transform, ruling out transduction. These experiments indicate that both a DNase-sensitive mechanism (transformation) and a DNase-resistant conjugation-like mechanism involving cell-to-cell contact may contribute to DNA transfer between H. pylori cells
— id: 19095, year: 1998, vol: 180, page: 2901, stat: Journal Article,

Acid-induced expression of an LPS-associated gene in Helicobacter pylori
McGowan CC; Necheva A; Thompson SA; Cover TL; Blaser MJ
1998 Oct;30(1):19-31, Molecular microbiology
To investigate urease-independent mechanisms by which Helicobacter pylori resists acid stress, subtractive RNA hybridization was used to identify H. pylori genes whose expression is induced after exposure to acid pH. This approach led to the isolation of a gene that encoded a predicted 34.8kDa protein (WbcJ), which was homologous to known bacterial O-antigen biosynthesis proteins involved in the conversion of GDP-mannose to GDP-fucose. An isogenic wbcJ null mutant strain failed to express O-antigen and Lewis X or Lewis Y determinants and was more sensitive to acid stress than was the wild-type strain. Qualitative differences in LPS profiles were observed in H. pylori cells grown at pH 5 compared with pH 7, which suggests that H. pylori may alter its LPS structure in response to acidic pH. This may be an important adaptation facilitating H. pylori colonization of the acidic gastric environment
— id: 19082, year: 1998, vol: 30, page: 19, stat: Journal Article,

Differentiation of Campylobacter jejuni serotype O19 strains from non-O19 strains by PCR
Misawa N; Allos BM; Blaser MJ
1998 Dec;36(12):3567-3573, Journal of clinical microbiology
Guillain-Barre syndrome (GBS), a neurologic disease characterized by acute paralysis, is frequently preceded by Campylobacter jejuni infection. Serotype O19 strains are overrepresented among GBS-associated C. jejuni isolates. We previously showed that all O19 strains tested were closely related to one another by randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism analyses. RAPD analysis demonstrated a 1.4-kb band in all O19 strains tested but in no non-O19 strains. We cloned this O19-specific band; nucleotide sequence analysis revealed a truncated open reading frame with significant homology to DNA gyrase subunit B (gyrB) of Helicobacter pylori. PCR using the random primer and a primer specific for gyrB showed that in non-O19 strains, the random primer did not recognize the downstream gyrB binding site. The regions flanking each of the random primer binding sites were amplified by degenerate PCR for further sequencing. Although the random primer had several mismatches with the downstream gyrB binding site, a single nucleotide polymorphism 6 bp upstream from the 3' terminus was found to distinguish O19 and non-O19 strains. PCR using 3'-mismatched primers based on this polymorphism was designed to differentiate O19 strains from non-O19 strains. When a total of 42 (18 O19 and 24 non-O19) strains from five different countries were examined, O19 strains were distinguishable from non-O19 strains in each case. This PCR method should permit identification of O19 C. jejuni strains
— id: 19081, year: 1998, vol: 36, page: 3567, stat: Journal Article,

Simultaneous expression of type 1 and type 2 Lewis blood group antigens by Helicobacter pylori lipopolysaccharides. Molecular mimicry between h. pylori lipopolysaccharides and human gastric epithelial cell surface glycoforms
Monteiro MA; Chan KH; Rasko DA; Taylor DE; Zheng PY; Appelmelk BJ; Wirth HP; Yang M; Blaser MJ; Hynes SO; Moran AP; Perry MB
1998 May 8;273(19):11533-11543, Journal of biological chemistry
Previous structural investigations performed on the lipopolysaccharides (LPSs) from the human gastric pathogen Helicobacter pylori have revealed that these cell surface glycan molecules express type 2 partially fucosylated, glucosylated, or galactosylated N-acetyllactosamine O antigen chains (O-chains) of various lengths, which may or may not be terminated at the nonreducing end by Lewis X (Lex) and/or Ley blood group epitopes in mimicry of human cell surface glycoconjugates and glycolipids. Subsequently, serological experiments with commercially available Lewis-specific monoclonal antibodies also have recognized the presence of Lex and Ley blood group antigens in H. pylori but, in addition, have indicated the presence of type 1 chain Lea, Leb, and Led (H-type 1) blood group epitopes in some H. pylori strains. To confirm their presence, structural studies and additional serological experiments were undertaken on H. pylori strains suspected of carrying type 1 chain epitopes. These investigations revealed that the O-chain region of H. pylori strain UA948 carried both Lea (type 1) and Lex (type 2) blood group determinants. The O-chain from H. pylori UA955 LPS expressed the terminal Lewis disaccharide (type 1 chain) and Lex and Ley antigens (type 2). The O-chain of H. pylori J223 LPS carried the type 1 chain precursor Lec, the H-1 epitope (Led, type 1 chain) and an elongated nonfucosylated type 2 N-acetyllactosamine chain (i antigen). Thus, O-chains from H. pylori LPSs can also express fucosylated type 1 sequences, and the LPS from a single H. pylori strain may carry O-chains with type 1 and 2 Lewis blood groups simultaneously. That monoclonal antibodies putatively specific for the Leb determinant can detect glycan substructures (Le disaccharide, Lec, and Led) of Leb indicates their nonspecificity. The expression of both type 1 and 2 Lewis antigens by H. pylori LPSs mimics the cell surface glycomolecules present in both the gastric superficial (which expresses mainly type 1 determinants) and the superficial and glandular epithelium regions (both of which express predominantly type 2 determinants). Therefore, each H. pylori strain may have a different niche within the gastric mucosa, and each individual LPS blood group antigen may have a dissimilar role in H. pylori adaptation
— id: 19093, year: 1998, vol: 273, page: 11533, stat: Journal Article,

Adherence to gastric epithelial cells induces expression of a Helicobacter pylori gene, iceA, that is associated with clinical outcome
Peek RM; Thompson SA; Donahue JP; Tham KT; Atherton JC; Blaser MJ; Miller GG
1998 Nov-Dec;110(6):531-544, Proceedings of the Association of American Physicians
Most persons infected with Helicobacter pylori strains that produce vacuolating cytotoxin and possess cytotoxin-associated gene A (cagA) genotype nonetheless remain asymptomatic, suggesting that additional genes are important in virulence. We hypothesized that adherence to gastric epithelium provides stimuli that induce expression of some virulence genes. Our aims were to identify expression of H. pylori genes induced by adherence and to determine if such genes were correlated with peptic ulceration, mucosal interleukin-8 (IL-8) levels, and gastric inflammation. RNA was isolated from an ulcer-derived strain and a gastritis-derived strain that were exposed or not exposed to gastric epithelial cells. These RNAs were used for random arbitrarily primed reverse transcription polymerase chain reaction to identify newly expressed transcripts unique to the ulcer-derived strain following adherence. Clinical isolates of H. pylori were characterized for presence of the newly identified gene, and mucosal IL-8 and inflammation were examined in gastric biopsies from the source patients. A novel H. pylori gene, iceA (induced by contact with epithelium), was identified. DNA sequences revealed two families, iceA1 and iceA2. iceA1 strains were significantly associated with peptic ulceration and increased mucosal concentrations of IL-8. Both iceA1 and iceA2 were expressed in vivo by respective H. pylori strains in gastric biopsies. Adherence to gastric epithelial cells in vitro stimulates the transcription of iceA1, an H. pylori gene that is highly correlated with pathological outcome
— id: 19079, year: 1998, vol: 110, page: 531, stat: Journal Article,

Mutation in the peb1A locus of Campylobacter jejuni reduces interactions with epithelial cells and intestinal colonization of mice
Pei Z; Burucoa C; Grignon B; Baqar S; Huang XZ; Kopecko DJ; Bourgeois AL; Fauchere JL; Blaser MJ
1998 Mar;66(3):938-943, Infection & immunity
Campylobacter jejuni is one of the leading causes of bacterial diarrhea throughout the world. We previously found that PEB1 is a homolog of cluster 3 binding proteins of bacterial ABC transporters and that a C. jejuni adhesin, cell-binding factor 1 (CBF1), if not identical to, contains PEB1. A single protein migrating at approximately 27 to 28 kDa was recognized by anti-CBF1 and anti-PEB1. To determine the role that the operon encoding PEB1 plays in C. jejuni adherence, peb1A, the gene encoding PEB1, was disrupted in strain 81-176 by insertion of a kanamycin resistance gene through homologous recombination. Inactivation of this operon completely abolished expression of CBF1, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. In comparison to the wild-type strain, the mutant strain showed 50- to 100-fold less adherence to and 15-fold less invasion of epithelial cells in culture. Mouse challenge studies showed that the rate and duration of intestinal colonization by the mutant were significantly lower and shorter than with the wild-type strain. In summary, PEB1 is identical to a previously identified cell-binding factor, CBF1, in C. jejuni, and the peb1A locus plays an important role in epithelial cell interactions and in intestinal colonization in a mouse model
— id: 19104, year: 1998, vol: 66, page: 938, stat: Journal Article,

Helicobacter pylori upregulates expression of epidermal growth factor-related peptides, but inhibits their proliferative effect in MKN 28 gastric mucosal cells
Romano M; Ricci V; Di Popolo A; Sommi P; Del Vecchio Blanco C; Bruni CB; Ventura U; Cover TL; Blaser MJ; Coffey RJ; Zarrilli R
1998 Apr 15;101(8):1604-1613, Journal of clinical investigation
Acute exposure to Helicobacter pylori causes cell damage and impairs the processes of cell migration and proliferation in cultured gastric mucosal cells in vitro. EGF-related growth factors play a major role in protecting gastric mucosa against injury, and are involved in the process of gastric mucosal healing. We therefore studied the acute effect of H. pylori on expression of EGF-related growth factors and the proliferative response to these factors in gastric mucosal cells (MKN 28) derived from gastric adenocarcinoma. Exposure of MKN 28 cells to H. pylori suspensions or broth culture filtrates upregulated mRNA expression of amphiregulin (AR) and heparin-binding EGF-like growth factor (HB-EGF), but not TGFalpha. This effect was specifically related to H. pylori since it was not observed with E. coli, and was independent of VacA, CagA, PicA, PicB, or ammonia. Moreover, H. pylori broth culture filtrates stimulated extracellular release of AR and HB-EGF protein by MKN 28 cells. AR and HB-EGF dose-dependently and significantly stimulated proliferation of MKN 28 cells in the absence of H. pylori filtrate, but had no effect in the presence of H. pylori broth culture filtrates. Inhibition of AR- or HB-EGF- induced stimulation of cell growth was not mediated by downregulation of the EGF receptor since EGF receptor protein levels, EGF binding affinity, number of specific binding sites for EGF, or HB-EGF- or AR-dependent tyrosine phosphorylation of the EGF receptor were not significantly altered by incubation with H. pylori broth culture filtrates. Increased expression of AR and HB-EGF were mediated by an H. pylori factor > 12 kD in size, whereas antiproliferative effects were mediated by both VacA and a factor < 12 kD in size. We conclude that H. pylori increases mucosal generation of EGF-related peptides, but in this acute experimental model, this event is not able to counteract the inhibitory effect of H. pylori on cell growth. The inhibitory effect of H. pylori on the reparative events mediated by EGF-related growth factors might play a role in the pathogenesis of H. pylori-induced gastroduodenal injury
— id: 19098, year: 1998, vol: 101, page: 1604, stat: Journal Article,

Activation of IL-8 gene expression by Helicobacter pylori is regulated by transcription factor nuclear factor-kappa B in gastric epithelial cells
Sharma SA; Tummuru MK; Blaser MJ; Kerr LD
1998 Mar 1;160(5):2401-2407, Journal of immunology
In vivo, gastric infection with Helicobacter pylori leads to substantial production of the inflammatory cytokines IL-1, IL-6, TNF-alpha, and IL-8. H. pylori strains that contain the cag pathogenicity island (cag+) and are associated with ulceration and gastric carcinoma induce greater cytokine production than cag- strains. Expression of these cytokines is often regulated by the transcription factor complex, nuclear factor-kappa B (NF-kappa B) through kappa B-binding elements in the enhancer/promoter regions of their genes. We report that more virulent cag+ H. pylori strains induce increased NF-kappa B-DNA binding activity, which elevates IL-8 expression in AGS gastric epithelial cells. The cag+ H. pylori strains induce significant stimulation of IL-8 promoter-driven reporter activity, while cag- strains do not. Furthermore, mutation of specific genes within the cag island (picA1 and picB) ablates enhanced NF-kappa B activation and IL-8 transcription. Increased IL-8 expression is inhibited by mutation in either the NF-kappa B or NF-IL-6 binding element. The cag+ strains, compared with the cag- strains, induce enhanced nuclear localization of a RelA-containing NF-kappa B binding complex, but no increase in NF-IL-6 binding activity. These studies demonstrate that the ability of different types of H. pylori strains to activate NF-kappa B correlates with their ability to induce IL-8 transcription and indicate a mechanism for the heightened inflammatory response seen in subjects infected with cag+ H. pylori strains
— id: 19101, year: 1998, vol: 160, page: 2401, stat: Journal Article,

Review article: Pathogenesis of the transformation from gastritis to malignancy
Sipponen P; Hyvarinen H; Seppala K; Blaser MJ
1998 Feb;12 Suppl 1(9):61-71, Alimentary pharmacology & therapeutics
Helicobacter pylori acquisition is the main cause of chronic gastritis in humans. In up to half of the infected subjects, chronic gastritis progresses to atrophic gastritis and intestinal metaplasia. During this course, various mechanisms are triggered that may contribute to the pathogenesis of gastric cancer. Such mechanisms include the inflammation-related cascades of cytokine and free radical reactions, up- and downregulation of growth factors and their receptors, and the atrophy-related impairment of acid output and intraluminal acidity. An array of other factors may also have become significant including overgrowth of bacteria other than H. pylori in the hypochlorhydric or achlorhydric stomach, a high dietary consumption of salt, nitrate, or nitrite, smoking, deficiency of vitamins or micronutrients, influence of sex hormones, or an inherited liability of the dividing epithelial cells to gene errors. These factors may vary in effect between populations and individuals but, if active, may affect the cell genome which may further influence the course and progression of chronic gastritis, and can finally result in overt gastric neoplasia. The molecular biology of gastric cancer has revealed a spectrum of gene errors which vary in type and extent between different histological types of cancer, and between individual cases. There now is evidence that the intestinal metaplasia or the gastric epithelium in atrophic gastritis reveal signs of abnormal expression of various regulatory genes well before the appearance of gastric neoplasia. It is possible that the mechanisms leading to mutation of the genes in epithelial cells are triggered very early in the H. pylori gastritis cascade, and that atrophic gastritis and intestinal metaplasia result from these processes
— id: 19087, year: 1998, vol: 12 Suppl 1, page: 61, stat: Journal Article,

Campylobacter fetus surface layer proteins are transported by a type I secretion system
Thompson SA; Shedd OL; Ray KC; Beins MH; Jorgensen JP; Blaser MJ
1998 Dec;180(24):6450-6458, Journal of bacteriology
The virulence of Campylobacter fetus, a bacterial pathogen of ungulates and humans, is mediated in part by the presence of a paracrystalline surface layer (S-layer) that confers serum resistance. The subunits of the S-layer are S-layer proteins (SLPs) that are secreted in the absence of an N-terminal signal sequence and attach to either type A or B C. fetus lipopolysaccharide in a serospecific manner. Antigenic variation of multiple SLPs (encoded by sapA homologs) of type A strain 23D occurs by inversion of a promoter-containing DNA element flanked by two sapA homologs. Cloning and sequencing of the entire 6.2-kb invertible region from C. fetus 23D revealed a probable 5.6-kb operon of four overlapping genes (sapCDEF, with sizes of 1,035, 1,752, 1,284, and 1,302 bp, respectively) transcribed in the opposite direction from sapA. The four genes also were present in the invertible region of type B strain 84-107 and were virtually identical to their counterparts in the type A strain. Although SapC had no database homologies, SapD, SapE, and SapF had predicted amino acid homologies with type I protein secretion systems (typified by Escherichia coli HlyBD/TolC or Erwinia chrysanthemi PrtDEF) that utilize C-terminal secretion signals to mediate the secretion of hemolysins, leukotoxins, or proteases from other bacterial species. Analysis of the C termini of four C. fetus SLPs revealed conserved structures that are potential secretion signals. A C. fetus sapD mutant neither produced nor secreted SLPs. E. coli expressing C. fetus sapA and sapCDEF secreted SapA, indicating that the sapCDEF genes are sufficient for SLP secretion. C. fetus SLPs therefore are transported to the cell surface by a type I secretion system
— id: 19078, year: 1998, vol: 180, page: 6450, stat: Journal Article,

Expanding allelic diversity of Helicobacter pylori vacA
van Doorn LJ; Figueiredo C; Sanna R; Pena S; Midolo P; Ng EK; Atherton JC; Blaser MJ; Quint WG
1998 Sep;36(9):2597-2603, Journal of clinical microbiology
The diversity of the gene encoding the vacuolating cytotoxin (vacA) of Helicobacter pylori was analyzed in 98 isolates obtained from different geographic locations. The studies focused on variation in the previously defined s and m regions of vacA, as determined by PCR and direct sequencing. Phylogenetic analysis revealed the existence of four distinct types of s-region alleles: aside from the previously described s1a, s1b, and s2 allelic types, a novel subtype, designated s1c, was found. Subtype s1c was observed exclusively in isolates from East Asia and appears to be the major s1 allele in that part of the world. Three different allelic forms (m1, m2a, and m2b) were detected in the m region. On the basis of sequence alignments, universal PCR primers that allow effective amplification of the s and m regions from H. pylori isolates from all over the world were defined. Amplimers were subsequently analyzed by reverse hybridization onto a line probe assay (LiPA) that allows the simultaneous and highly specific hybridization of the different vacA s- and m-region alleles and tests for the presence of the cytotoxin-associated gene (cagA). This PCR-LiPA method permits rapid analysis of the vacA and cagA status of H. pylori strains for clinical and epidemiological studies and will facilitate identification of any further variations
— id: 19086, year: 1998, vol: 36, page: 2597, stat: Journal Article,

The seroprevalence of cagA-positive Helicobacter pylori strains in the spectrum of gastroesophageal reflux disease
Vicari JJ; Peek RM; Falk GW; Goldblum JR; Easley KA; Schnell J; Perez-Perez GI; Halter SA; Rice TW; Blaser MJ; Richter JE
1998 Jul;115(1):50-57, Gastroenterology
BACKGROUND & AIMS: The role of Helicobacter pylori in the pathogenesis of gastroesophageal reflux disease (GERD) is unknown. We determined the prevalence of cagA-positive (cagA+) H. pylori strains in patients with GERD or its complications compared with controls of similar age. METHODS: A total of 153 consecutive patients with GERD, Barrett's esophagus, and Barrett's esophagus complicated by dysplasia or adenocarcinoma were compared with 57 controls who underwent upper endoscopy for reasons other than GERD. H. pylori infection and CagA antibody status were determined by histology and enzyme-linked immunosorbent assay. RESULTS: H. pylori prevalence was lower (34%) in patients with GERD and its sequelae than in the control group (45.6%)(P = 0.15). Regardless of the group, increasing age was associated with higher prevalence of H. pylori (P = 0.003). When compared with controls (42.3%), the prevalence of cagA+ H. pylori strains decreased (P = 0.008) in patients with more severe complications of GERD (GERD, 36.7% [nonerosive GERD, 41.2%; erosive GERD, 30.8%]; Barrett's esophagus, 13.3%; and Barrett's with adenocarcinoma/dysplasia, 0%). CONCLUSIONS: Prevalence of H. pylori in patients with GERD and its sequelae was lower but not significantly different than that of a control group. However, patients carrying cagA+ strains of H. pylori may be protected against the complications of GERD, especially Barrett's esophagus and its associated dysplasia and adenocarcinoma
— id: 19090, year: 1998, vol: 115, page: 50, stat: Journal Article,

Experimental infection of Mongolian gerbils with wild-type and mutant Helicobacter pylori strains
Wirth HP; Beins MH; Yang M; Tham KT; Blaser MJ
1998 Oct;66(10):4856-4866, Infection & immunity
Experimental Helicobacter pylori infection was studied in Mongolian gerbils with fresh human isolates that carry or do not carry cagA (cagA-positive or cagA-negative, respectively), multiply passaged laboratory strains, wild-type strain G1.1, or isogenic ureA, cagA, or vacA mutants of G1.1. Animals were sacrificed 1 to 32 weeks after challenge, the stomach was removed from each animal for quantitative culture, urease test, and histologic testing, and blood was collected for antibody determinations. No colonization occurred after >/=20 in vitro passages of wild-type strain G1.1 or with the ureA mutant of G1.1. In contrast, infection occurred in animals challenged with wild-type G1.1 (99 of 101 animals) or the cagA (25 of 25) or vacA (25 of 29) mutant of G1.1. Infection with G1.1 persisted for at least 8 months. All 15 animals challenged with any of three fresh human cagA-positive isolates became infected, in contrast to only 6 (23%) of 26 animals challenged with one of four fresh human cagA-negative isolates (P < 0.001). Similar to infection in humans, H. pylori colonization of gerbils induced gastric inflammation and a systemic antibody response to H. pylori antigens. These data confirm the utility of gerbils as an animal model of H. pylori infection and indicate the importance of bacterial strain characteristics for successful infection
— id: 19083, year: 1998, vol: 66, page: 4856, stat: Journal Article,

Clinical and pathological importance of heterogeneity in vacA, the vacuolating cytotoxin gene of Helicobacter pylori
Atherton JC; Peek RM; Tham KT; Cover TL; Blaser MJ
1997 Jan;112(1):92-99, Gastroenterology
BACKGROUND & AIMS: vacA encodes the vacuolating cytotoxin of Helicobacter pylori and exhibits marked variation in signal sequence and midgene coding regions. The implications for gastroduodenal pathology are unknown. The aim of this study was to define the association of vacA genotype with gastric inflammation and injury, in vitro cytotoxin activity, and peptic ulceration. METHODS: Sixty-one consecutive dyspeptic patients underwent endoscopy and gastric biopsy. The biopsy specimens were processed for H. pylori culture, and 52 specimens were also processed for histology. H. pylori vacA was typed by polymerase chain reaction and colony hybridization. Cytotoxin activity was assessed by a HeLa cell vacuolation assay. RESULTS: vacA signal sequence type s1a strains were associated with greater antral mucosal neutrophil and lymphocyte infiltration than s1b or s2 strains (P < 0.05). vacA midregion type m1 strains were associated with greater gastric epithelial damage than m2 strains (P < 0.05). Both midregion and signal sequence were associated with cytotoxin activity in vitro. Duodenal ulcer disease occurred in 89% of 18 patients with s1a strains vs. 29% of 14 with s1b strains (P < 0.01), 20% of 10 with s2 strains (P < 0.001), and 16% of 19 uninfected patients (P < 0.001). CONCLUSIONS: H. pylori strains of vacA signal sequence type s1a are associated with enhanced gastric inflammation and duodenal ulceration. vacA s2 strains are associated with less inflammation and lower ulcer prevalence
— id: 19138, year: 1997, vol: 112, page: 92, stat: Journal Article,

Molecular biology of S-layers
Bahl H; Scholz H; Bayan N; Chami M; Leblon G; Gulik-Krzywicki T; Shechter E; Fouet A; Mesnage S; Tosi-Couture E; Gounon P; Mock M; Conway de Macario E; Macario AJ; Fernandez-Herrero LA; Olabarria G; Berenguer J; Blaser MJ; Kuen B; Lubitz W; Sara M; Pouwels PH; Kolen CP; Boot HJ; Resch S
1997 Jun;20(1-2):47-98, FEMS microbiology reviews
In this chapter we report on the molecular biology of crystalline surface layers of different bacterial groups. The limited information indicates that there are many variations on a common theme. Sequence variety, antigenic diversity, gene expression, rearrangements, influence of environmental factors and applied aspects are addressed. There is considerable variety in the S-layer composition, which was elucidated by sequence analysis of the corresponding genes. In Corynebacterium glutamicum one major cell wall protein is responsible for the formation of a highly ordered, hexagonal array. In contrast, two abundant surface proteins from the S-layer of Bacillus anthracis. Each protein possesses three S-layer homology motifs and one protein could be a virulence factor. The antigenic diversity and ABC transporters are important features, which have been studied in methanogenic archaea. The expression of the S-layer components is controlled by three genes in the case of Thermus thermophilus. One has repressor activity on the S-layer gene promoter, the second codes for the S-layer protein. The rearrangement by reciprocal recombination was investigated in Campylobacter fetus. 7-8 S-layer proteins with a high degree of homology at the 5' and 3' ends were found. Environmental changes influence the surface properties of Bacillus stearothermophilus. Depending on oxygen supply, this species produces different S-layer proteins. Finally, the molecular bases for some applications are discussed. Recombinant S-layer fusion proteins have been designed for biotechnology
— id: 19129, year: 1997, vol: 20, page: 47, stat: Journal Article,

Effect of Helicobacter pylori products and recombinant cytokines on gastrin release from cultured canine G cells
Beales I; Blaser MJ; Srinivasan S; Calam J; Perez-Perez GI; Yamada T; Scheiman J; Post L; Del Valle J
1997 Aug;113(2):465-471, Gastroenterology
BACKGROUND & AIMS: The pathophysiology of hypergastrinemia in Helicobacter pylori infection is undefined, but the infected antrum shows a marked inflammatory response with local production of cytokines. Hypergastrinemia and inflammatory infiltrate clear with successful eradication. The aim of this study was to examine whether the cytokines tumor necrosis factor alpha or interleukin 8 (IL-8), which are produced in the gastric mucosa of patients with H. pylori-induced peptic disease or H. pylori products, can stimulate gastrin release from isolated cultured canine G cells. METHODS: Canine G cells were isolated by collagenase digestion, enriched by centrifugal elutriation, incubated with cytokines, bacterial components, or both, and gastrin release was measured by radioimmunoassay. RESULTS: IL-8 (1 and 10 nmol/L) stimulated gastrin release by 34% +/- 13% and 43% +/- 23% (P < 0.05) above basal, respectively. H. pylori sonicates, water extract preparations, and lipopolysaccharide had no stimulatory actions, but the sonicates from two of four strains potentiated the effects of IL-8, leading to maximal gastrin release of 230% +/- 130% and 232% +/- 33% above basal, respectively (P < 0.05). CONCLUSIONS: IL-8 stimulated gastrin release from isolated G cells, and the effect was potentiated by H. pylori products. The interaction of cytokines and H. pylori may contribute to the hypergastrinemia seen in vivo
— id: 19122, year: 1997, vol: 113, page: 465, stat: Journal Article,

Ecology of Helicobacter pylori in the human stomach
Blaser MJ
1997 Aug 15;100(4):759-762, Journal of clinical investigation
— id: 19121, year: 1997, vol: 100, page: 759, stat: Journal Article,

Epidemiologic and clinical features of Campylobacter jejuni infections
Blaser MJ
1997 Dec;176 Suppl 2(1):S103-S105, Journal of infectious diseases
Gram-negative bacteria of the genus Campylobacter and of related genera frequently colonize the gastrointestinal tracts of humans, other mammals, and birds. One organism, Campylobacter jejuni, has been recognized as an important human pathogen, usually causing a diarrheal illness. Infection is common throughout the world, but clinical and epidemiologic features differ in developed and developing countries. The high incidence of C. jejuni infections and their propensity to invade tissue and to induce inflammation are compatible with a role in the causation of Guillain-Barre syndrome
— id: 19110, year: 1997, vol: 176 Suppl 2, page: S103, stat: Journal Article,

Helicobacter pylori eradication and its implications for the future
Blaser MJ
1997 Apr;11 Suppl 1(9057):103-107, Alimentary pharmacology & therapeutics
It has become evident that at least some strains of Helicobacter pylori are pathogenic for humans. However, H. pylori are highly diverse and at least part of this variation involves characteristics related to pathogenicity. A large amount of evidence suggests that H. pylori infection of humans is ancient, and in general, the interaction is not terribly destructive. However, we should try to understand better the risks associated with infection with particular H. pylori strains, and limit treatment to those situations in which the indications for eradicating H. pylori are clear-cut. It is entirely possible that some H. pylori strains are commensals, and that others are symbionts. Eradicating those infections could ultimately cause more harm than good. It is too early to reach firm conclusions about whether all H. pylori infections need to be eradicated
— id: 19134, year: 1997, vol: 11 Suppl 1, page: 103, stat: Journal Article,

Heterogeneity of Helicobacter pylori
Blaser MJ
1997 Apr;9 Suppl 1(9057):S3-S6, European journal of gastroenterology & hepatology
Although many physicians view Helicobacter pylori strains as a homogenous group of organisms, it has become increasingly clear that populations in humans are highly diverse. This heterogeneity can be analyzed at two different levels: genotypic variation among strains and variations in H. pylori populations within an individual host. Genotypic variation includes point mutations in conserved genes (e.g. ureC), variation in the gene order on physical maps, mosaicism in conserved genes (e.g. vacAs1a), non-conserved genes (e.g. cagA) and extragenetic elements (e.g. IS605). Population differences include the observations that humans can be simultaneously infected with two or more H. pylori strains and that a single strain may represent a cluster of closely related organisms (a 'quasispecies'). The presence of multiple organisms within a host may occur as a result of recombination events leading to genetic shift, whereas ongoing mutation within a strain can lead to the formation of quasispecies by genetic drift. Over recent years it has become increasingly clear that observations on the fundamental biology of H. pylori have considerable clinical relevance. Several genotypic markers (e.g. cagA, vacA, sIa and iceA1) are associated with an increased risk of disease. Also, the multiplicity of infection and quasispecies indicates that analysis of a single H. pylori isolate is inaccurate for defining the genotype of H. pylori strains present in a patient. Global assays, such as serology, are more suitable. The aim of this paper is to review the general phenomenon of diversity in H. pylori and to describe particular heterogeneities that are related to clinical outcome
— id: 19133, year: 1997, vol: 9 Suppl 1, page: S3, stat: Journal Article,

Not all Helicobacter pylori strains are created equal: should all be eliminated?
Blaser MJ
1997 Apr 5;349(9057):1020-1022, Lancet
— id: 19132, year: 1997, vol: 349, page: 1020, stat: Journal Article,

The versatility of Helicobacter pylori in the adaptation to the human stomach
Blaser MJ
1997 Sep;48(3):307-314, Journal of physiology & pharmacology
A growing body of data indicates that H. pylori colonization of human is ancient, which is consistent with its high prevalence, chronicity of carriage, and generally low level of disease, which, when it occurs has only marginal or no effects on host reproductive capacity. All of these phenomena are markers for a relatively benign co-existence, which may include all of the entire spectrum of interactions from parasitism, through commensalism, to symbiosis. Recent studies suggest the emergence of 'quasispecies' during prolonged colonization, and the presence of multiple strains colonizing individual hosts. Such observations suggest that concepts of competition between strains and mutualism will be important in understanding the ecology of colonization and its effects on hosts. The presence of particular pathologies in the host may in part be a function of the characteristics of the bacterial population present. At a genomic level, H. pylori appears to adapt to changing conditions by point mutation, genomic rearrangement, and horizontal gene transfer, the latter is favored by its natural competence. The ability of H. pylori to alter phenotypic properties including superficial Lewis antigen expression and secretion of proinflammatory molecules is evidence of its sensitivity to environmental signals from the host. In such a universe, disease outcomes such as ulceration or neoplasia may be considered as accidents secondary to microbial persistence
— id: 19114, year: 1997, vol: 48, page: 307, stat: Journal Article,

Helicobacter pylori and peptic ulcer disease
Blaser, Martin J; Misiewicz, Jerzy Jacek
London : Rapid Science Publishers, 1997,
— id: 2023, year: 1997, vol: , page: , stat: ,

Apoptosis in gastric epithelial cells is induced by Helicobacter pylori and accompanied by increased expression of BAK
Chen G; Sordillo EM; Ramey WG; Reidy J; Holt PR; Krajewski S; Reed JC; Blaser MJ; Moss SF
1997 Oct 20;239(2):626-632, Biochemical & biophysical research communications
Carriage of the bacterium H. pylori in the human stomach is associated with evidence of increased epithelial cell apoptosis. This may be of significance in the etiology of gastritis, peptic ulcers, and neoplasia. The ability of H. pylori to directly induce epithelial apoptosis was examined in vitro by fluorescence and electron microscopy, flow cytometry, and DNA fragmentation ELISA. The induction of apoptosis by H. pylori was time and concentration-dependent and inhibited by preventing direct bacterial-epithelial cell contact. Apoptosis was accompanied by increased expression of Bak, with little change in expression of other Bcl-2 family proteins. The expression of Bak was also increased in gastric biopsies from patients colonized by H. pylori. Thus, H. pylori induces gastric epithelial cell apoptosis, by a Bak-dependent pathway
— id: 19113, year: 1997, vol: 239, page: 626, stat: Journal Article,

Helicobacter pylori
Dunn BE; Cohen H; Blaser MJ
1997 Oct;10(4):720-741, Clinical microbiology reviews
Helicobacter pylori is a gram-negative bacterium which causes chronic gastritis and plays important roles in peptic ulcer disease, gastric carcinoma, and gastric lymphoma. H. pylori has been found in the stomachs of humans in all parts of the world. In developing countries, 70 to 90% of the population carries H. pylori. In developed countries, the prevalence of infection is lower. There appears to be no substantial reservoir of H. pylori aside from the human stomach. Transmission can occur by iatrogenic, fecal-oral, and oral-oral routes. H. pylori is able to colonize and persist in a unique biological niche within the gastric lumen. All fresh isolates of H. pylori express significant urease activity, which appears essential to the survival and pathogenesis of the bacterium. A variety of tests to diagnose H. pylori infection are now available. Histological examination of gastric tissue, culture, rapid urease testing, DNA probes, and PCR analysis, when used to test gastric tissue, all require endoscopy. In contrast, breath tests, serology, gastric juice PCR, and urinary excretion of [15N]ammonia are noninvasive tests that do not require endoscopy. In this review, we highlight advances in the detection of the presence of the organism and methods of differentiating among types of H. pylori, and we provide a background for appropriate chemotherapy of the infection
— id: 19115, year: 1997, vol: 10, page: 720, stat: Journal Article,

Molecular mechanisms of Campylobacter fetus surface layer protein expression
Dworkin J; Blaser MJ
1997 Nov;26(3):433-440, Molecular microbiology
Cells of the Gram-negative bacteria Campylobacter fetus are covered by monomolecular arrays of surface layer proteins (SLPs) critical for both persistence in their natural hosts and for virulence. For C. fetus cells, expression of SLPs essentially eliminates C3b binding and their antigenic variation thwarts host immunological defences. Each cell possesses multiple partially homologous and highly conserved SLP gene cassettes, tightly clustered in the genome, that encode SLPs of 97-149 kDa. These attach non-covalently via a conserved N-terminus to the cell wall lipopolysaccharide. Recent studies indicate that C. fetus reassorts a single promoter, controlling SLP expression, and one, or more, complete open reading frame strictly by DNA inversion, and that rearrangement is independent of the distance between sites of inversion. In contrast to previously reported programmed DNA inversion systems, inversion in C. fetus is recA-dependent. These rearrangements permit variation in protein expression from the family of SLP genes and suggest an expanding paradigm of programmed DNA rearrangements among microorganisms
— id: 19107, year: 1997, vol: 26, page: 433, stat: Journal Article,

Nested DNA inversion as a paradigm of programmed gene rearrangement
Dworkin J; Blaser MJ
1997 Feb 4;94(3):985-990, Proceedings of the National Academy of Sciences of the United States of America
Programmed gene rearrangements are employed by a variety of microorganisms, including viruses, prokaryotes, and simple eukaryotes, to control gene expression. In most instances in which organisms mediate host evasion by large families of homologous gene cassettes, the mechanism of variation is not thought to involve DNA inversion. Here we report that Campylobacter fetus, a pathogenic Gram-negative bacterium, reassorts a single promoter, controlling surface-layer protein expression, and one or more complete ORFs strictly by DNA inversion. Rearrangements were independent of the distance between sites of inversion. These rearrangements permit variation in protein expression from the large surface-layer protein gene family and suggest an expanding paradigm of programmed DNA rearrangements among microorganisms
— id: 19136, year: 1997, vol: 94, page: 985, stat: Journal Article,

Nested DNA inversion of Campylobacter fetus S-layer genes is recA dependent
Dworkin J; Shedd OL; Blaser MJ
1997 Dec;179(23):7523-7529, Journal of bacteriology
Wild-type strains of Campylobacter fetus are covered by a monomolecular array of surface layer proteins (SLPs) critical for virulence. Each cell possesses eight SLP gene cassettes, tightly clustered in the genome, that encode SLPs of 97 to 149 kDa. Variation of SLP expression occurs by a mechanism of nested DNA rearrangement that involves the inversion of a 6.2-kb sapA promoter-containing element alone or together with one or more flanking SLP gene cassettes. The presence of extensive regions of identity flanking the 5' and 3' ends of each SLP gene cassette and of a Chi-like recognition sequence within the 5' region of identity suggests that rearrangement of SLP gene cassettes may occur by a generalized (RecA-dependent) homologous recombination pathway. To explore this possibility, we cloned C. fetus recA and created mutant strains by marker rescue, in which recA is disrupted in either S+ or S- strains. These mutants then were assessed for their abilities to alter SLP expression either in the presence or absence of a complementary shuttle plasmid harboring native recA. In contrast to all previously reported programmed DNA inversion systems, inversion in C. fetus is recA dependent
— id: 19111, year: 1997, vol: 179, page: 7523, stat: Journal Article,

Role of vacuolating cytotoxin in gastritis due to Helicobacter pylori in gnotobiotic piglets
Eaton KA; Cover TL; Tummuru MK; Blaser MJ; Krakowka S
1997 Aug;65(8):3462-3464, Infection & immunity
To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gnotobiotic piglets were colonized with either toxigenic H. pylori or a nontoxigenic isogenic mutant. Only piglets given the toxigenic strain developed toxin-neutralizing antibodies (indicating that toxin is expressed in vivo), but there was no difference in bacterial colonization, epithelial vacuolation, or gastritis between the two groups of piglets
— id: 19123, year: 1997, vol: 65, page: 3462, stat: Journal Article,

Restriction fragment length polymorphism analysis and random amplified polymorphic DNA analysis of Campylobacter jejuni strains isolated from patients with Guillain-Barre syndrome
Fujimoto S; Allos BM; Misawa N; Patton CM; Blaser MJ
1997 Oct;176(4):1105-1108, Journal of infectious diseases
Campylobacter jejuni serotype O19 strains associated with the Guillain-Barre syndrome (GBS) and other strains were examined by restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction products of the flaA genes and by random amplified polymorphic DNA (RAPD) analysis. RFLP analysis showed that regardless of LIO serotype, geographic origins, or association with GBS, the O19 isolates shared an identical digestion pattern by each of four restriction endonucleases, DdeI, MboI, MseI, and AluI. In contrast, among C. jejuni O1 or O2 strains, RFLP patterns were different even among strains of the same LIO serotype. The results of the RAPD analysis were consistent with the flaA RFLP data. These data indicate that all of the O19 strains that were tested were closely related to one another whether they were or were not associated with GBS
— id: 19116, year: 1997, vol: 176, page: 1105, stat: Journal Article,

Lack of serologic evidence for Helicobacter pylori infection in head and neck cancer
Grandis JR; Perez-Perez GI; Yu VL; Johnson JT; Blaser MJ
1997 May;19(3):216-218, Head & neck
BACKGROUND: Several epidemiologic investigations have established a link between Helicobacter pylori infection and gastric malignancies. Because the stomach is in continuity with the oral cavity and the bacterium has been isolated from dental plaque and saliva, we hypothesized that H. pylori infection of the upper aerodigestive tract might result in mucosal disruption, allowing for subsequent transformation by known carcinogens such as tobacco and alcohol. METHODS: To test this hypothesis, we assayed for the presence of IgG antibodies to H. pylori in the serum of 21 patients with squamous cell carcinoma of the head and neck (SCCHN) and 21 matched controls without a history of head and neck cancer. RESULTS: The incidence of seropositivity in the SCCHN patients was 57% and in the controls, 62% (p > 0.05). CONCLUSIONS: These data do not support an etiologic role for H. pylori infection in head and neck cancer
— id: 19131, year: 1997, vol: 19, page: 216, stat: Journal Article,

Comparison of two enzyme-linked immunosorbent assay tests for diagnosis of Helicobacter pylori infection in China
Groves FD; Zhang L; Li JY; You WC; Chang YS; Zhao L; Liu WD; Rabkin CS; Perez-Perez GI; Blaser MJ; Gail MH
1997 Jul;6(7):551-552, Cancer epidemiology biomarkers & prevention
An ELISA based on a pool of United States strains of Helicobacter pylori was compared with a newly developed ELISA based on a pool of Chinese strains. Both assays were tested using sera from 132 Chinese study subjects with biopsy-proven H. pylori infection. Using cutpoints designed to yield equal specificities of 94.9% in an uninfected control population, the sensitivity of the Chinese assay was 100.0%, compared to 97.7% for the United States assay (P = 0.25 by McNemar test). These results suggest that a H. pylori assay based on pooled antigens from United States strains will perform as well in the rural Chinese population as one based on antigens from Chinese strains
— id: 19126, year: 1997, vol: 6, page: 551, stat: Journal Article,

Antigenic characterization of Helicobacter pylori strains from different parts of the world
Hook-Nikanne J; Perez-Perez GI; Blaser MJ
1997 Sep;4(5):592-597, Clinical & diagnostic laboratory immunology
Although Helicobacter pylori is considered to be relatively homogeneous at the phenotypic level, our aim was to describe its antigenic heterogeneity and to examine differences in host response. Whole-cell lysates of H. pylori strains originally isolated from persons from Africa, the People's Republic of China, Japan, Peru, Thailand, or the United States or from monkeys were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoblots were performed by using sera from H. pylori-infected persons from different areas of the world and rabbit immune sera against H. pylori antigens. Specific H. pylori antibody responses in persons from the United States and the People's Republic of China were analyzed by enzyme-linked immunosorbent assay with antigens prepared from U.S. or Chinese strains. Despite diverse origins, the strains showed conserved major bands of 84, 60, 56, 31, and 25 kDa. Although there were clear differences in minor bands, there was no obvious geographic pattern. The anti-CagA serum recognized 120- to 140-kDa bands in cagA+ strains from around the world. Although antigenic preparations from individual U.S. or Chinese strains were not optimally sensitive for serologic detection of infection in the heterologous country, use of pools of strains largely overcame this phenomenon. We conclude that conserved H. pylori antigens exist and are recognized by sera from persons from many parts of the world. The heterogeneity of H. pylori antigens and the serological responses of infected hosts is not fully explained by geographic differences. Use of pools may allow development of antigens for serologic testing in any country
— id: 19120, year: 1997, vol: 4, page: 592, stat: Journal Article,

Characterization of Helicobacter pylori dapE and construction of a conditionally lethal dapE mutant
Karita M; Etterbeek ML; Forsyth MH; Tummuru MK; Blaser MJ
1997 Oct;65(10):4158-4164, Infection & immunity
Helicobacter pylori colonizes the human gastric mucosa and causes gastritis, ulceration, or gastric cancer. A previously uncharacterized region of the H. pylori genome was identified and sequenced. This region includes a putative operon containing three open reading frames termed gidA (1,866 bp), dapE (1,167 bp), and orf2 (753 bp); the gidA and dapE products are highly homologous to other bacterial proteins. In E. coli, dapE encodes N-succinyl-L-diaminopimelic acid desuccinylase, which catalyzes the hydrolysis of N-succinyl-L-diaminopimelic acid to L-diaminopimelic acid (L-DAP) and succinate. When wild-type H. pylori strains were transformed to select for dapE mutagenesis, mutants were present when plates were supplemented with DAP but not with lysine; orf2 mutants were selected without DAP supplementation. Consistent with the finding that GidA is essential in Escherichia coli, we were unable to obtain a gidA mutant in H. pylori despite evidence that insertional mutagenesis had occurred. The positions of gidA, dapE, and orf2 suggest that they form an operon, which was supported by slot blot RNA hybridization and reverse transcriptase PCR studies. The data imply that the H. pylori dapE mutant may be useful as a conditionally lethal vaccine
— id: 19119, year: 1997, vol: 65, page: 4158, stat: Journal Article,

Helicobacter pylori lipopolysaccharide stimulates histamine release and DNA synthesis in rat enterochromaffin-like cells
Kidd M; Miu K; Tang LH; Perez-Perez GI; Blaser MJ; Sandor A; Modlin IM
1997 Oct;113(4):1110-1117, Gastroenterology
BACKGROUND & AIMS: Helicobacter pylori alterations in gastric acid output and mucosal proliferation may involve the enterochromaffin-like (ECL) cell. To test whether H. pylori affects ECL cell histamine secretion and proliferation, the effect of lipopolysaccharide (LPS) on ECL cell function in vitro was investigated. METHODS: Using a rat ECL cell preparation of high purity (+/-95%), basal and stimulated histamine secretion and DNA synthesis were measured by enzyme immunoassay and bromodeoxyuridine (BrdU) uptake, respectively. RESULTS: Escherichia coli LPS (10(-12) to 10(-6) mol/L) had no effect on basal and stimulated histamine secretion at concentrations of > 10(-6) mol/L. H. pylori LPS stimulated basal and gastrin-stimulated histamine secretion. These effects were completely inhibited by somatostatin (10(-10) mol/L) but not by the gastrin receptor antagonist L365,260 at 10(-6) mol/L. E. coli LPS had a weak stimulatory effect on ECL cell BrdU uptake at 10(-6) mol/L but had no effect on gastrin-stimulated BrdU uptake. H. pylori LPS did not stimulate basal synthesis but significantly increased (1.5-fold) gastrin-stimulated BrdU uptake. CONCLUSIONS: H. pylori influences both ECL cell proliferation and secretion in vitro. An interaction between H. pylori LPS and ECL cells may contribute to the reported abnormalities in acid secretion and gastric pathobiology noted in H. pylori infections
— id: 19118, year: 1997, vol: 113, page: 1110, stat: Journal Article,

Helicobacter pylori lipopolysaccharide can activate 70Z/3 cells via CD14
Kirkland T; Viriyakosol S; Perez-Perez GI; Blaser MJ
1997 Feb;65(2):604-608, Infection & immunity
Helicobacter pylori persistently colonizes the human gastrointestinal tract and is associated with chronic gastritis and, in some cases, peptic ulcer disease or gastric neoplasms. One factor in the persistence of this organism may be its inability to elicit a strong inflammatory response. Lipopolysaccharide (LPS) is a proinflammatory substance found in the cell walls of all gram-negative bacteria. H. pylori LPS has been found by several different measures to be less active than LPS from Enterobacteriaceae. This study addresses the role of CD14 and LPS-binding protein in the cellular response to H. pylori LPS. We report that H. pylori LPS activates mammalian cells expressing CD14 at much lower LPS concentrations than those for control cells not expressing CD14. The maximal activation of CD14-70Z/3 cells by H. pylori LPS also requires LPS-binding protein. H. pylori LPS at concentrations as high as 30 microg/ml does not elicit an interleukin-8 (IL-8) response from the epithelial cell line SW620 in the presence of CD14; 10 ng of Escherichia coli LPS per ml elicits a maximal IL-8 response. Furthermore, in contrast to some other types of LPS with little activity, H. pylori LPS does not inhibit the CD14-70Z/3 cell response to E. coli LPS. From these studies, we conclude that H. pylori LPS, though much less active than E. coli LPS, stimulates cells via CD14
— id: 19137, year: 1997, vol: 65, page: 604, stat: Journal Article,

Workshop summary and recommendations regarding the development of Guillain-Barre syndrome following Campylobacter infection
Lang DR; Allos BM; Blaser MJ
1997 Dec;176 Suppl 2(1):S198-S200, Journal of infectious diseases
— id: 19109, year: 1997, vol: 176 Suppl 2, page: S198, stat: Journal Article,

Development of Guillain-Barre syndrome following Campylobacter infection
Lang, Dennis R; Blaser, Martin J
Chicago : University of Chicago Press, 1997,
— id: 2021, year: 1997, vol: , page: , stat: ,

Analysis of F1F0-ATPase from Helicobacter pylori
McGowan CC; Cover TL; Blaser MJ
1997 Jul;65(7):2640-2647, Infection & immunity
The adaptive mechanisms that permit Helicobacter species to survive within the gastric mucosa are not well understood. The proton-translocating F1F0-ATPase is an important enzyme for regulating intracellular pH or synthesizing ATP in many other enteric bacteria; therefore, we used degenerate primers derived from conserved bacterial F1F0-ATPase sequences to PCR amplify and clone the gene (atpD) encoding the H. pylori F1F0-ATPase beta subunit. The deduced amino acid sequences of the F1F0-ATPase beta subunits from H. pylori and Wolinella succinogenes were 85% identical (91% similar). To characterize a potential functional role of F1F0-ATPase in H. pylori, H. pylori or Escherichia coli cells were incubated for 60 min in buffered solutions at pH 7, 6, 5, or 4, with or without 100 microM N,N'-dicyclohexylcarbodiimide (DCCD), a specific inhibitor of F1F0-ATPase. At pH 5 and 4, there was no significant decrease in survival of H. pylori in the presence of DCCD compared to its absence, whereas incubation with DCCD at pH 7 and 6 significantly decreased H. pylori survival. E. coli survival was unaffected by DCCD at any pH value tested. We next disrupted the cloned beta-subunit sequence in E. coli by insertion of a kanamycin resistance cassette and sought to construct an isogenic F1F0-ATPase H. pylori mutant by natural transformation and allelic exchange. In multiple transformations of H. pylori cells grown at pH 6 or 7, no kanamycin-resistant F1F0 mutants were isolated, despite consistently successful mutagenesis of other H. pylori genes by using a similar approach and PCR experiments providing evidence for integration of the kanamycin resistance cassette into atpD. The sensitivity of H. pylori to DCCD at pH 7 and 6, and failure to recover F1F0 H. pylori mutants under similar conditions, suggests that the function of this enzyme is required for survival of H. pylori at these pHs
— id: 19127, year: 1997, vol: 65, page: 2640, stat: Journal Article,

Pathophysiology of Helicobacter pylori-induced gastritis and peptic ulcer disease
Peek RM; Blaser MJ
1997 Feb;102(2):200-207, American journal of medicine
Helicobacter pylori causes persistent infection and inflammation in the human stomach, yet only a small fraction of persons harboring this organism develop peptic ulcer disease. An important question is why this variation in infection outcome exists. Recent studies have demonstrated that H pylori isolates possess substantial phenotypic and genotypic diversity that may engender differential host inflammatory responses that influence clinical outcome. Further investigation in this field may help to define which H pylori-infected persons bear the highest risk for subsequent development of peptic ulcer disease, and thus enable physicians to focus eradication therapy
— id: 19135, year: 1997, vol: 102, page: 200, stat: Journal Article,

Helicobacter pylori cagA+ strains and dissociation of gastric epithelial cell proliferation from apoptosis
Peek RM; Moss SF; Tham KT; Perez-Perez GI; Wang S; Miller GG; Atherton JC; Holt PR; Blaser MJ
1997 Jun 18;89(12):863-868, Journal of the National Cancer Institute
BACKGROUND: Infection with Helicobacter pylori induces chronic gastritis in virtually all infected persons, and such gastritis has been associated with an increased risk of developing gastric cancer. This risk is further enhanced with cagA+ (positive for cytotoxin-associated gene A) H. pylori strains and may be a consequence of induced gastric cell proliferation and/or alteration in apoptosis (programmed cell death) in the gastric epithelium. PURPOSE: To determine whether the H. pylori cagA genotype and another virulence-related characteristic, the vacA (vacuolating cytotoxin A) s1a genotype, differentially affect epithelial cell proliferation, apoptosis, and the histologic parameters of inflammation and injury, we quantitated these characteristics in infected and uninfected persons. METHODS: Fifty patients underwent upper gastrointestinal endoscopy, and biopsy specimens were taken. Apoptotic cells in the specimens were quantitated after terminal deoxynucleotidyl transferase labeling of DNA fragments with digoxigenin-deoxyuridine triphosphate; epithelial cell proliferation was scored by immunohistochemical analysis of the proliferation-associated antigen Ki-67. Antibodies directed against H. pylori and CagA protein were measured in the serum of patients by means of enzyme-linked immunosorbent assays. Analysis of H. pylori genomic DNA, by use of the polymerase chain reaction, was performed to determine the cagA and vacA genotypes. Acute and chronic inflammation, epithelial cell degeneration, mucin depletion, intestinal metaplasia, glandular atrophy, and vacuolation were each scored in a blinded manner. Reported P values are two-sided. RESULTS: Persons harboring cagA+ strains (n = 20) had significantly higher gastric epithelial proliferation scores than persons infected with cagA-strains (n = 9) or uninfected persons (n = 21) (P = .025 and P<.001, respectively), but the difference in cell proliferation between the latter two groups was not statistically significant. The number of apoptotic cells per 100 epithelial cells (apoptotic index) in persons infected with cagA+ strains was lower than in persons infected with cagA-strains (P = .05). Apoptotic indices in the cagA+ group were similar to those in the uninfected group (P = .2). Epithelial cell proliferation was significantly correlated with acute gastric inflammation, but only in the cagA+ group (r = .44; P = .006). The cagA+ and vacA s1a genotypes were found to be concordant, confirming the close relationship between these virulence-related genotypes. CONCLUSIONS: Gastric mucosal proliferation was significantly correlated with the severity of acute gastritis in persons infected with cagA+ vacA s1a strains of H. pylori. This increased proliferation was not accompanied by a parallel increase in apoptosis. IMPLICATIONS: Increased cell proliferation in the absence of a corresponding increase in apoptosis may explain the heightened risk for gastric carcinoma that is associated with infection by cagA+ vacA s1a strains of H. pylori
— id: 19128, year: 1997, vol: 89, page: 863, stat: Journal Article,

Country-specific constancy by age in cagA+ proportion of Helicobacter pylori infections
Perez-Perez GI; Bhat N; Gaensbauer J; Fraser A; Taylor DN; Kuipers EJ; Zhang L; You WC; Blaser MJ
1997 Jul 29;72(3):453-456, International journal of cancer
Helicobacter pylori strains may be either cagA+ or cagA-, and in logitudinal studies, infection with a cagA+ strain has been associated with increased risk for the development of atrophic gastritis and cancer of the distal stomach. We sought to determine the relative proportion of strains producing CagA in different geographic locales, and the extent to which CagA seroprevalence varied in countries with different gastric and esophageal cancer rates. Using an enzyme-linked immunosorbent assay (ELISA) to detect serum IgG to CagA, we examined sera from 468 asymptomatic H. pylori-infected adults from Canada, Peru, China, Thailand, The Netherlands and 3 different ethnic groups in New Zealand. The CagA seroprevalence in Peru and Thailand (82.2% and 78.8%, respectively) were each substantially higher than for the Chinese (37.9%), Canadian (41.9%), Dutch (39.0%) and New Zealand (28.2%) subjects, but within each population, rates were relatively constant across gender and age groups. Reported gastric but not esophageal cancer rates for the 8 studied populations were significantly associated with H. pylori seroprevalence. Variation in CagA positivity rates was not significantly associated with variation in either gastric or esophageal cancer rates. Our data suggest that CagA seroprevalence is not the major factor influencing gastric cancer rates
— id: 19124, year: 1997, vol: 72, page: 453, stat: Journal Article,

Value of serology as a noninvasive method for evaluating the efficacy of treatment of Helicobacter pylori infection
Perez-Perez GI; Cutler AF; Blaser MJ
1997 Nov;25(5):1038-1043, Clinical infectious diseases
The systemic humoral response to Helicobacter pylori was studied in 86 infected adult patients before antimicrobial therapy and at intervals following therapy. Endoscopy with collection of biopsy specimens was performed immediately before treatment; a 13C-labeled urea breath test was performed, and blood specimens were collected before treatment and at 1, 3, 6, 9, and 12 months after treatment. Serum samples from three patient groups (eradication success [n = 50], eradication failure [n = 16], and no treatment [n = 20]) were assayed for IgA and IgG antibodies to H. pylori by enzyme-linked immunosorbent assay. Levels of antibody to H. pylori before treatment were similar in all three groups. As expected, the no treatment and eradication failure groups had no significant changes in antibody levels during the study period. In contrast, for the eradication success group, the specific IgA and IgG antibody levels decreased progressively and significantly. We conclude that serology is a potentially useful way to monitor the success of treatment of H. pylori infection without using invasive or more expensive methods
— id: 19106, year: 1997, vol: 25, page: 1038, stat: Journal Article,

Serendipitous detection of persistent Campylobacter jejuni subspecies jejuni bacteremia in a patient undergoing bone marrow transplantation
Schuster M; Blaser MJ; Nachamkin I
1997 Jun;24(6):1270-1270, Clinical infectious diseases
— id: 19130, year: 1997, vol: 24, page: 1270, stat: Journal Article,

T-cell, antibody, and cytokine responses to homologs of the 60-kilodalton heat shock protein in Helicobacter pylori infection
Sharma SA; Miller GG; Peek RA; Perez-Perez G; Blaser MJ
1997 Jul;4(4):440-446, Clinical & diagnostic laboratory immunology
For Helicobacter pylori, the hsp60 heat shock protein encoded by hspB is being considered as a potential candidate for subunit vaccines. We investigated the humoral and cellular responses to H. pylori hsp60 and its cross-reactivity with the homologous Mycobacterium bovis p65 protein and autologous human hsp60 protein. H. pylori-infected persons had significantly higher levels than uninfected persons of serum immunoglobulin G antibodies recognizing H. pylori hsp60, but not M. bovis p65 or human hsp60, as determined by enzyme-linked immunosorbent assay. In contrast, immunoblotting demonstrated cross-reactivity of H. pylori hsp60 with human hsp60. T-cell recognition of H. pylori hsp60 was found in both infected and uninfected subjects, and there was no recognition of human hsp60. T cells from infected and uninfected subjects that had been activated in response to H. pylori hsp60 or M. bovis p65 were phenotypically similar but appeared to secrete different levels of gamma interferon and interleukin-10. These results demonstrate an apparent difference in the epitopes recognized by the T and B cells responding to H. pylori hsp60 in H. pylori-infected persons. In contrast to the T-cell responses, which were highly variable in all subjects and showed no recognition of autologous proteins, a specific B-cell response that may have cross-reactivity to human hsp60 is evident in some infected subjects
— id: 19125, year: 1997, vol: 4, page: 440, stat: Journal Article,

Helicobacter pylori Lewis expression is related to the host Lewis phenotype
Wirth HP; Yang M; Peek RM; Tham KT; Blaser MJ
1997 Oct;113(4):1091-1098, Gastroenterology
BACKGROUND & AIMS: Lewis antigens occur in human gastric epithelium and in Helicobacter pylori lipopolysaccharide; their expression is polymorphic in both. Autoimmune mechanisms induced by bacterial Lewis expression have been proposed to cause gastritis. The aim of this study was to examine the relationship between bacterial and host gastric Lewis expression, as determined by the erythrocyte Lewis(a/b) phenotype, and between gastric histopathology and bacterial Lewis expression. METHODS: H. pylori Lewis expression was determined by enzyme immunoassays, erythrocyte Lewis phenotype was assessed by agglutination tests, and gastric histopathology was scored blindly. RESULTS: The host Lewis phenotype was (a+b-) in 15, (a-b+) in 34, and (a-b-) in 17 patients, therefore expressing Lewis x, y, or neither as their major gastric epithelial Lewis type 2 antigen. H. pylori from patients with Lewis(a+b-) expressed Lewis x more than y (1147 +/- 143 vs. 467 +/- 128 optical density units [ODU]; P = 0.006), isolates from patients with Lewis(a-b+) expressed Lewis x less than y (359 +/- 81 vs. 838 +/- 96 ODU; P = 0.0001), and isolates from Lewis(a-b-) patients expressed Lewis x and y approximately equally. Gastritis was unrelated to H. pylori Lewis expression. CONCLUSIONS: In mimicking host gastric epithelium, H. pylori cells not only express Lewis x and y, but the relative proportion of expression corresponds to the host Lewis phenotype, suggesting selection for host-adapted organisms
— id: 19117, year: 1997, vol: 113, page: 1091, stat: Journal Article,

The Helicobacter pylori genome is modified at CATG by the product of hpyIM
Xu Q; Peek RM; Miller GG; Blaser MJ
1997 Nov;179(21):6807-6815, Journal of bacteriology
To understand mechanisms of DNA methylation in Helicobacter pylori, a human pathogen associated with peptic ulcer disease and gastric adenocarcinoma, we cloned a putative DNA methyltransferase gene, hpyIM. This gene contains a 990-bp open reading frame encoding a 329-amino-acid protein, M.HpyI. Sequence analysis revealed that M.HpyI was closely related to CATG-recognizing adenine DNA methyltransferases, including M.NlaIII in N. lactamica. hpyIM was present in all H. pylori strains tested. DNA from wild-type H. pylori strains was resistant to digestion by SphI and NlaIII, which recognize DNA at sites containing CATG, whereas their isogenic hpyIM mutants were susceptible, indicating lack of modification. Overexpression of hpyIM in Escherichia coli rendered DNA from these cells resistant to NlaIII digestion, confirming the role of hpyIM in modifying CATG sites. We conclude that hpyIM encodes a DNA methyltransferase, M.HpyI, that is well conserved among diverse H. pylori strains and that modifies H. pylori genomes at CATG sites
— id: 19112, year: 1997, vol: 179, page: 6807, stat: Journal Article,

Density of Helicobacter pylori infection in vivo as assessed by quantitative culture and histology
Atherton JC; Tham KT; Peek RM; Cover TL; Blaser MJ
1996 Sep;174(3):552-556, Journal of infectious diseases
Helicobacter pylori density was assessed by quantitative culture and histologic examination of gastric biopsy specimens from 29 H. pylori-infected dyspeptic patients. Density was correlated with cagA and vacA genotypes (assessed by polymerase chain reaction and colony hybridization), gastric inflammation and epithelial injury (assessed histologically), and peptic ulceration. Quantitative culture was more reproducible than histology, and antral density was more reproducible than corpus density. Mean antral density of cagA+/vacA sl strains was 4-fold higher than that of cagA-/vacA s2 strains (1.9 X 10(6) vs. 4.5 x 10(5) cfu/g, P = .02). Antral density was associated with mucosal neutrophilic and lymphocytic infiltration (P < .01) and with epithelial injury (P < .05). Mean antral bacteria] density was 5-fold higher in duodenal ulcer patients than in others (P = .005). In conclusion, H. pylori density in vivo is easily quantified and is associated with bacterial virulence determinants, gastric inflammation, and duodenal ulceration, suggesting a central role in pathogenesis
— id: 19145, year: 1996, vol: 174, page: 552, stat: Journal Article,

How safe is our food? Lessons from an outbreak of salmonellosis
Blaser MJ
1996 May 16;334(20):1324-1325, New England journal of medicine
— id: 19150, year: 1996, vol: 334, page: 1324, stat: Journal Article,

Role of vacA and the cagA locus of Helicobacter pylori in human disease
Blaser MJ
1996 Apr;10 Suppl 1(20):73-77, Alimentary pharmacology & therapeutics
Helicobacter pylori are 'slow' bacteria that may cause disease decades after acquisition. Bacterial pathogenesis often involves features, including conserved genes, shared by many different species. As such, despite its unique niche in the human body, the pathogenesis of H. pylori infection most likely shares mechanisms with other bacteria. In this paper, two genes, vacA and cagA, which appear unique to H. pylori and which may reflect the particular requirements of H. pylori for long-term residence in the human stomach will be discussed. At present the function of these genes for H. pylori is not known yet other characteristics have been defined
— id: 19151, year: 1996, vol: 10 Suppl 1, page: 73, stat: Journal Article,

The bacteria behind ulcers
Blaser MJ
1996 Feb;274(2):104-107, Scientific american
— id: 19154, year: 1996, vol: 274, page: 104, stat: Journal Article,

CagA and the outcome of Helicobacter pylori infection
Blaser MJ; Crabtree JE
1996 Nov;106(5):565-567, American journal of clinical pathology
— id: 19140, year: 1996, vol: 106, page: 565, stat: Journal Article,

Helicobacter pylori infection, a paradigm for chronic mucosal inflammation: pathogenesis and implications for eradication and prevention
Cover TL; Blaser MJ
1996 ;41(2):85-117, Advances in internal medicine
— id: 19155, year: 1996, vol: 41, page: 85, stat: Journal Article,

Transient and persistent experimental infection of nonhuman primates with Helicobacter pylori: implications for human disease
Dubois A; Berg DE; Incecik ET; Fiala N; Heman-Ackah LM; Perez-Perez GI; Blaser MJ
1996 Aug;64(8):2885-2891, Infection & immunity
Helicobacter pylori can establish chronic infection in the human gastric mucosa, and it is a major cause of peptic ulcer disease and a principal risk factor for gastric cancer. This creates a need for H. pylori infection models that mimic the human condition. To test the suitability of rhesus monkeys as infection models, H. pylori-free animals were inoculated intragastrically with mixtures of H. pylori strains, bacteria recovered from colonized animals were typed by arbitrarily primed PCR, and host inflammatory and immunologic responses were monitored. Among five H. pylori-free animals inoculated with a mixture of two human strains plus one monkey strain, one became persistently infected and one became only transiently infected. The recovered bacteria matched the monkey input strain in DNA fingerprint. A subsequent trial using two new human isolates and three animals that had resisted colonization by the monkey strain resulted in persistent infection in one animal and transient infection in two others. Antral gastritis, anti-H. pylori serum immunoglobulin G, and atrophy all increased, but with patterns that differed among animals. We conclude that (i) rhesus monkeys can be infected experimentally with H. pylori, (ii) individuals differ in susceptibility to particular bacterial strains, (iii) infections may be transient, and (iv) the fitness of a particular strain for a given host helps determine the consequences of exposure to that strain
— id: 19147, year: 1996, vol: 64, page: 2885, stat: Journal Article,

Generation of Campylobacter fetus S-layer protein diversity utilizes a single promoter on an invertible DNA segment
Dworkin J; Blaser MJ
1996 Mar;19(6):1241-1253, Molecular microbiology
Wild-type strains of Campylobacter fetus contain a monomolecular array of surface layer proteins (SLPs) and vary the antigenicity of the predominant SLP expressed. Reciprocal recombination events among the eight genomic SLP gene cassettes, which encode 97- to 149 kDa SLPs, permit this variation. To explore whether SLP expression utilizes a single promoter, we created mutant bacterial strains using insertional mutagenesis by rescue of a marker from plasmids. Experimental analysis of the mutants created clearly indicates that SLP expression solely utilizes the single sapA promoter, and that for variation C. fetus uses a mechanism of DNA rearrangement involving inversion of a 6.2 kb segment of DNA containing this promoter. This DNA inversion positions the sapA promoter immediately upstream of one of two oppositely oriented SLP gene cassettes, leading to its expression. Additionally, a second mechanism of DNA rearrangement occurs to replace at least one of the two SLP gene cassettes bracketing the invertible element. As previously reported promoter inversions in prokaryotes, yeasts and viruses involve alternate expression of at most two structural genes, the ability of C. fetus to use this phenomenon to express one of multiple cassettes is novel
— id: 19152, year: 1996, vol: 19, page: 1241, stat: Journal Article,

Risk factors for upper gastrointestinal bleeding in intensive care unit patients: role of helicobacter pylori. Federal Hyperimmune Immunoglobulin Therapy Study Group
Ellison RT; Perez-Perez G; Welsh CH; Blaser MJ; Riester KA; Cross AS; Donta ST; Peduzzi P
1996 Dec;24(12):1974-1981, Critical care medicine
OBJECTIVE: To determine the role of preexisting Helicobacter pylori infection in the development of acute upper gastrointestinal (GI) hemorrhage in intensive care unit (ICU) patients in relation to other potential predisposing risk factors. DESIGN: Prospective, multicenter, cohort study. SETTING: Medical and surgical ICUs in six tertiary care Department of Veterans Affairs Medical Centers. PATIENTS: Eight-hundred seventy-four patients without previous GI bleeding or peptic ulcer disease who were enrolled in a multicenter, randomized, controlled trial of prophylactic intravenous immunoglobulin to prevent ICU-associated infections. INTERVENTIONS: This substudy of the larger intravenous immunoglobulin study only involved data analysis and had no intervention. All patients were enrolled in the larger study where they received intravenous immunoglobulin or placebo as intervention. MEASUREMENTS AND MAIN RESULTS: Patients were prospectively evaluated for the development of acute upper GI hemorrhage while in an ICU. Anti-H. pylori immunoglobulin G and immnoglobulin A concentrations were determined by enzyme immunoassay on preintervention serum samples. Seventy-six (9%) patients had over upper GI bleeding and a mortality rate of 49%, as compared with a 15% mortality rate in patients who did not bleed (p < .001). By logistic regression analysis, the following factors were associated with an increased risk of bleeding: acute hepatic failure, prolonged duration of nasogastric tube placement, alcoholism, and an increased serum concentration of anti-H. pylori immunoglobulin A. CONCLUSIONS: Increased anti-H. pylori immunoglobulin A concentrations, prolonged nasogastric intubation, alcoholism, and acute hepatic failure were found to be independently correlated with the development of acute GI bleeding in an ICU setting. These observations should be prospectively confirmed in an independent population before being used for treatment guidelines
— id: 19139, year: 1996, vol: 24, page: 1974, stat: Journal Article,

Susceptibility of Helicobacter pylori to the bactericidal activity of human serum
Gonzalez-Valencia G; Perez-Perez GI; Washburn RG; Blaser MJ
1996 Mar;1(1):28-33, Helicobacter
BACKGROUND: Human serum represents an important barrier to the entry of most mucosal organisms into tissues and to the systemic circulation. If at all present, Helicobacter pylori within gastric tissue is rare, and bacteremia for this organism has been described only once. METHODS: To assess the susceptibility of H. pylori to the bactericidal activity present in normal human serum (NHS), we examined 13 H. pylori isolates. To assess the contributions of the classical and alternative complement pathways to killing, we added either C2-deficient or factor B-deficient serum, respectively, to heat-inactivated NHS. Also we assessed the ability of the strains to bind 125I-C3. RESULTS: After incubation for 60 minutes at 37 degrees C, all 13 H. pylori strains were killed by NHS; heating to 56 degrees C for 30 minutes ablated killing, indicating complement dependence for this phenomenon. In the absence of an antibody source, there was no killing when either an alternative or classical complement pathway source was used. Adding B-deficient serum to heat-inactivated normal human serum did not restore killing, but adding C2-deficient serum permitted partial killing. All of the 13 strains bound 125I-C3. Although the kinetics varied from strain to strain, C3 bound was significantly correlated (r = 0.61, p = 0.03) with serum susceptibility. CONCLUSIONS: H. pylori are susceptible to complement, alternative pathway activation appears critical, and C3 binding is a major locus of variability
— id: 19108, year: 1996, vol: 1, page: 28, stat: Journal Article,

Helicobacter pylori cytotoxin induces vacuolation of primary human mucosal epithelial cells
Harris PR; Cover TL; Crowe DR; Orenstein JM; Graham MF; Blaser MJ; Smith PD
1996 Nov;64(11):4867-4871, Infection & immunity
We investigated whether Helicobacter pylori cytotoxin induces vacuolation in primary epithelial cells from normal human mucosa. Epithelial cells purified by enzyme digestion and elutriation were evaluated for vacuolation in a blinded protocol by light and electron microscopy before and after incubation with culture supernatant (CS) from H. pylori 60190, which has vacuolating activity for HeLa cells (Tox+), and isogenic H. pylori mutant 60190-v1, which lacks this activity (Tox-). Primary epithelial cells (>98% pure) exposed to CS from Tox+ H. pylori exhibited marked vacuolation (52% +/- 5% of cells) compared with epithelial cells exposed to either CS from Tox- H. pylori (23% +/- 3.2%) or uninoculated control broth (23% +/- 3.7%) (P < 0.05) by light microscopy, which was confirmed by electron microscopy and antibody inhibition studies. These are the first data to show that H. pylori cytotoxin causes vacuolation of primary human mucosal epithelial cells
— id: 19142, year: 1996, vol: 64, page: 4867, stat: Journal Article,

Helicobacter pylori urease is a potent stimulus of mononuclear phagocyte activation and inflammatory cytokine production
Harris PR; Mobley HL; Perez-Perez GI; Blaser MJ; Smith PD
1996 Aug;111(2):419-425, Gastroenterology
BACKGROUND & AIMS: Helicobacter pylori surface proteins induce the production of proinflammatory mediators by mononuclear phagocytes, but the protein responsible for this stimulation has not been identified. This study determined whether urease, the major component of the soluble proteins extracted from H. pylori grown in culture, activates mononuclear phagocytes and stimulates them to produce proinflammatory cytokines. METHODS: Primary human blood monocytes were incubated with column-purified H. pylori urease and assayed by flow cytometry, Immunoassay, and reverse-transcription polymerase chain reaction for phenotypic, functional, and molecular evidence of activation. RESULTS: H. pylori urease induced monocyte expression of surface interleukin 2 receptors and increased expression of HLA-DR, phenotypic changes consistent with activation. Urease also stimulated dose-dependent production of interleukin 1 beta, interleukin 6, interleukin 8, and tumor necrosis factor alpha peptides and messenger RNA. These urease-induced phenotypic and functional changes were inhibited by preincubation of the urease with antisera to H. pylori whole bacteria, purified urease, or the 31-kilodalton subunit of urease. CONCLUSIONS: Among the soluble proteins released by H. pylori, urease is capable of activating monocytes for proinflammatory cytokines production. The local production of cytokines by urease-stimulated mononuclear phagocytes may play a central role in the development of H. pylori gastroduodenal inflammation
— id: 19148, year: 1996, vol: 111, page: 419, stat: Journal Article,

Effect of growth phase and acid shock on Helicobacter pylori cagA expression
Karita M; Tummuru MK; Wirth HP; Blaser MJ
1996 Nov;64(11):4501-4507, Infection & immunity
Helicobacter pylori strains possessing cagA are associated with peptic ulceration. To understand the regulation of expression of cagA, picB, associated with interleukin-8 induction, and ureA, encoding the small urease subunit, we created gene fusions of cagA, ureA, and picB of strain 3401, using a promoterless reporter (xylE). Expression of XylE after growth in broth culture revealed that basal levels of expression of cagA and urea in H. pylori were substantially greater than for picB. For cagA expression in stationary-phase cells, brief exposure to acid pH caused a significant increase in xylE expression compared with neutral pH. In contrast, expression of xylE in urea or picB decreased after parallel exposure to acid pH (pH 7 > 6 > 5 > 4), regardless of the growth phase. Expression of the CagA protein varied with growth phase and pH exposure in parallel with the observed transcriptional variation. The concentration of CagA in a cell membrane-enriched fraction after growth at pH 6 was significantly higher than after growth at pH 5 or 7. We conclude that the promoterless reporter xylE is useful for studying the regulation of gene expression in H. pylori and that regulation of CagA production occurs mainly at the transcriptional level
— id: 19144, year: 1996, vol: 64, page: 4501, stat: Journal Article,

Helicobacter pylori and gastric acid: biological and therapeutic implications
McGowan CC; Cover TL; Blaser MJ
1996 Mar;110(3):926-938, Gastroenterology
Helicobacter pylori is highly adapted to its unusual ecological niche in the human stomach. Urease activity permits H. pylori survival at a pH of <4 in vitro and is required for the organism to colonize in animal models. However, urease does not play an important role in the survival of the organism in a pH range between 4 and 7. Other mechanisms of pH homeostasis remain poorly understood, but preliminary studies indicate that novel proteins are produced when H.pylori cells are shifted from pH 7 to 3, and the gene encoding a P-type adenosine triphosphatase that may catalyze NH4+/H+ exchange across the cytoplasmic membrane has been cloned. Mechanisms of pH homeostasis in other enteric bacteria are reviewed and provide insight into additional pathways that may be used by H. pylori. An important adaptation of H. pylori to the gastric environment may be its ability to alter gastric acid secretion. Acute infection is associated with transient hypochlorhydria, whereas chronic infection is associated with hypergastrinemia and decreased somatostatin levels. Thus, the survival of H. pylori in the gastric environment may be attributed to both the development of specialized intrinsic defenses and the organism's ability to induce physiological alterations in the host environment
— id: 19153, year: 1996, vol: 110, page: 926, stat: Journal Article,

Relationship of immune response to heat-shock protein A and characteristics of Helicobacter pylori-infected patients
Perez-Perez GI; Thiberge JM; Labigne A; Blaser MJ
1996 Nov;174(5):1046-1050, Journal of infectious diseases
Heat-shock protein A (HspA) is a GroES homolog in Helicobacter pylori. Using a recombinant HspA-maltose-binding protein fusion, the serologic response to HspA were determined. For 139 H. pylori-uninfected persons, responses to HspA were low-level or absent. In a survey of 273 infected persons, 105 (38.5%) were seropositive; there was no relationship between clinical outcome of infection and HspA seropositivity. Using paired sera obtained from 39 subjects (mean, 7.1 years apart), the stability of seroresponsiveness to HspA was examined. For 34 persons there was no change in status between the paired sera, but 5 (20%) of 25 initially seronegative persons seroconverted. The hypothesis that HspA seropositivity was related to patient age was examined using sera from 121 asymptomatic H. pylori-infected persons. Both the HspA seropositivity rate and the intensity of the response rose with age. In total, these findings indicate that HspA seropositivity is not universal but may be a consequence of prolonged H. pylori infection
— id: 19141, year: 1996, vol: 174, page: 1046, stat: Journal Article,

Campylobacter and helicobacter
Perez-Perez, Guillermo I; Blaser, Martin J
Medical microbiology [Galveston, Tex.] : University of Texas Medical Branch at Galveston, c1996,
— id: 5808, year: 1996, vol: , page: ?, stat: Chapter,

Effect of Helicobacter pylori on gastric epithelial cell migration and proliferation in vitro: role of VacA and CagA
Ricci V; Ciacci C; Zarrilli R; Sommi P; Tummuru MK; Del Vecchio Blanco C; Bruni CB; Cover TL; Blaser MJ; Romano M
1996 Jul;64(7):2829-2833, Infection & immunity
Helicobacter pylori infection is associated with inflammation of the gastric mucosa and with gastric mucosal damage. In this study, we sought to test the hypothesis that two H. pylori virulence factors (VacA and CagA) impair gastric epithelial cell migration and proliferation, the main processes involved in gastric mucosal healing in vivo. Human gastric epithelial cells (MKN 28) were incubated with undialyzed or dialyzed broth culture filtrates from wild-type H. pylori strains or isogenic mutants defective in production of VacA, CagA, or both products. We found that (i) VacA specifically inhibited cell proliferation without affecting cell migration, (ii) CagA exerted no effect on either cell migration or proliferation, and (iii) undialyzed H. pylori broth culture filtrates inhibited both cell migration and proliferation through a VacA- and CagA-independent mechanism. These findings demonstrate that, in addition to damaging the gastric mucosa, H. pylori products may also impair physiological processes required for mucosal repair
— id: 19149, year: 1996, vol: 64, page: 2829, stat: Journal Article,

Expression of the human cell surface glycoconjugates Lewis x and Lewis y by Helicobacter pylori isolates is related to cagA status
Wirth HP; Yang M; Karita M; Blaser MJ
1996 Nov;64(11):4598-4605, Infection & immunity
Monoclonal antibodies were used in an enzyme-linked immunosorbent assay for the detection of human Lewis immunodeterminants in the lipopolysaccharide of Helicobacter pylori. In 94 H. pylori isolates, expression of Lewis(x) (Le(x)) and Le(y) was a stable phenotypic marker independent of the growth medium and cell age; 46 (49%) of the isolates expressed both and 34 (36%) of the isolates expressed either Le(x) or Le(y); 14 (15%) were negative for both determinants. Twelve (13%) isolates expressed Le(b), 3 (3%) expressed Le(a), and 2 (2%) expressed sialyl-Le(x). H. pylori isolates positive for both Le(x) and Le(y) were predominantly cagA+ (P < 0.001) and possessed the s1 signal sequence (P < 0.05) and the m1 midregion type (P = 0.033) of vacA. Isogenic mutants of H. pylori CPY3401 were created by interruption of the cagA, picB, or ureA gene. The cagA-ablated strain (but not the picB- and ureA-ablated mutant strains) had significantly (P < 0.01) diminished expression of Le(y) compared with that of the wild-type strain; for all four strains, expression of Le(x) was similar. In conclusion, 89% of H. pylori isolates express Le determinants in their lipopolysaccharide, mimicking human cell surface glycoconjugates. Strong expression of Le(x) and Le(y) by cagA+ isolates could counterbalance their enhanced proinflammatory activities and thereby facilitate persistence
— id: 19143, year: 1996, vol: 64, page: 4598, stat: Journal Article,

Helicobacter pylori antibodies in relation to precancerous gastric lesions in a high-risk Chinese population
Zhang L; Blot WJ; You WC; Chang YS; Kneller RW; Jin ML; Li JY; Zhao L; Liu WD; Zhang JS; Ma JL; Samloff IM; Correa P; Blaser MJ; Xu GW; Fraumeni JF
1996 Aug;5(8):627-630, Cancer epidemiology biomarkers & prevention
Helicobacter pylori infection is a major cause of gastritis and may be a key risk factor for stomach cancer, but its role in the process of gastric carcinogenesis is not well understood. Herein, we examine H. pylori prevalence in relation to demographic and lifestyle factors and to severity of precancerous lesions in an area of China with one of the highest rates of stomach cancer in the world. H. pylori serum IgG antibody positivity was assayed among 2646 adults, ages 35-64, participating in a population-based gastroscopic screening survey in the high-risk area. The prevalence of positivity was evaluated according to gastric histology, environmental and lifestyle variables determined by interviews during the screening, and level of serum pepsinogens. The odds of advanced precancerous lesions (intestinal metaplasia and dysplasia) of the stomach among those with antibody positivity were estimated by logistic regression. Seventy-two % of the population was H. pylori antibody-positive, with nonsignificant variation by sex, age, income, education, family size, and cigarette smoking habits. H. pylori positivity was higher among those who ate sour pancakes, a fermented indigenous staple that is a risk factor for gastric dysplasia and stomach cancer in this population. The prevalence of H. pylori varied most notably, however, with gastric pathology. The percent of H. pylori positivity increased from 55 to 60 to 87% among those with superficial (nonatrophic) gastritis, mild chronic atrophic gastritis, and severe chronic atrophic gastritis, respectively, before falling to 78% among those with intestinal metaplasia or dysplasia. H. pylori antibody positivity also was strongly correlated with serum pepsinogen concentrations, particularly pepsinogen II, but knowledge of H. pylori status did not markedly improve serological identification of advanced precancerous lesions above that provided by pepsinogen ratios alone. The findings suggest that H. pylori infection contributes to the process of gastric carcinogenesis, particularly during the early stages, in this high-risk area
— id: 19146, year: 1996, vol: 5, page: 627, stat: Journal Article,

Campylobacter jejuni and the expanding spectrum of related infections
Allos BM; Blaser MJ
1995 May;20(5):1092-1099, Clinical infectious diseases
— id: 19173, year: 1995, vol: 20, page: 1092, stat: Journal Article,

Mosaicism in vacuolating cytotoxin alleles of Helicobacter pylori. Association of specific vacA types with cytotoxin production and peptic ulceration
Atherton JC; Cao P; Peek RM; Tummuru MK; Blaser MJ; Cover TL
1995 Jul 28;270(30):17771-17777, Journal of biological chemistry
Approximately 50% of Helicobacter pylori strains produce a cytotoxin, encoded by vacA, that induces vacuolation of eukaryotic cells. Analysis of a clinically isolated tox- strain (Tx30a) indicated secretion of a 93-kDa product from a 3933-base pair vacA open reading frame. Characterization of 59 different H. pylori isolates indicated the existence of three different families of vacA signal sequences (s1a, s1b, and s2) and two different families of middle-region alleles (m1 and m2). All possible combinations of these vacA regions were identified, with the exception of s2/m1 (p < 0.001); this mosaic organization implies that recombination has occurred in vivo between vacA alleles. Type s1/m1 strains produced a higher level of cytotoxin activity in vitro than type s1/m2 strains; none of 19 type s2/m2 strains produced detectable c