Effect of Vaccination on Turnover of Lamivudine (3TC) Sensitive and Resistant Virus Populations in HIV-1-Infected Individuals

To ascertain whether the origin of plasma HIV-1-RNA following T cell activation represents the activation of latently infected cells or an increase in cells permissive for replacing viral mutants. The mechanism by which immune stimulation increases circulating levels of HIV-1 is not known. In particular, it is uncertain whether the transient increase in plasma HIV-1 RNA is due to enhanced replication of an actively replicating pool of HIV-1, or is due instead to activation of proviral sequences in previously resting CD4+ cells. One approach to discriminate these alternatives is a "molecular pulse-chase" experiment. In this approach, drug resistant mutants would be selected by administration of Lamivudine (3TC). The mechanism by which immune stimulation increases circulating levels of HIV-1 is not known. In particular, it is uncertain whether the transient increase in plasma HIV-1 RNA is due to enhanced replication of an actively replicating pool of HIV-1, or is due instead to activation of proviral sequences in previously resting CD4+ cells. One approach to discriminate these alternatives is a "molecular pulse-chase" experiment. In this approach, drug resistant mutants would be selected by administration of Lamivudine (3TC). Twenty subjects without prior 3TC experience will be treated with 3TC for 2 weeks. On day 14, half of the subjects will receive immunization with both the influenza and pneumococcal vaccine. 3TC will be discontinued at this time. Patients will be followed for 4 weeks after the immunization.