Kinetics of virus-specific CD8+ T cells and the control of human immunodeficiency virus infection

Several primate models indicate that cytotoxic T lymphocyte-inducing vaccines may be unable to prevent human immunodeficiency virus infection but may have a long-term benefit in controlling viral replication and delaying disease progression. Here we show that analysis of the kinetics of antigen-specific CD8(+) T-cell expansion suggests a delay in activation following infection that allows unimpeded early viral replication. Viral kinetics do not differ between controls and vaccinees during this delay phase. An increase in virus-specific CD8(+) T-cell numbers around day 10 postinfection coincides with a slowing in viral replication in vaccinees and reduces peak viral loads by around I log. However, this response is too little too late to prevent establishment of persistent infection.