Our research focuses on the host-parasite relationship of both human immunodeficiency virus and hepatitis C, including transmission, pathogenesis, the effect of the virus-specific immune response, escape from this response, and the effects of treatment interventions, in children and their parents. As a consequence of these studies, we are determining the correlates of "good outcomes." In addition, we study the effects of secondary, i.e., opportunistic, infectious agents, their treatment, and prevention, specifically, cytomegalovirus, pneumococcus pneumoniae, mycobacteria, pneumocystis pneumoniae, and varicella zoster virus.