CD4 and infection: The negative correlation that we observed between the duration of untreated HIV infection and enrichment of viral DNA in HIV-specific CD4+ T cells, taken together with others’ findings (10, 12, 30), support the hypothesis that acute HIV infection leads to infection of HIV-specific CD4+ T cells and active viral replication for 6 or more months leads to HIV infection of both HIV-specific CD4+ T cells and CD4+ T cells with other antigen specificities.