CD4 and infection: When also the CD4 T cell counts were considered, it became apparent that controllers exhibited during the chronic phase of the infection a significant reduction of viral loads (p<0.0001), high and durable anti-Tat IgG antibody titers (p<0.0001) and CD4+ T cell counts (p = 0.0004), as compared to viremics (Table 1), suggesting a role for anti Tat antibody responses in the observed control of viral replication in vaccinees.