Figure 6

Lymphocyte subsets in naïve and PEP-macaques inoculated intravenously with 10 AID₅₀ chimeric SIV/HIV-1 called SHIV_89.6P. Figure 1 shows absolute numbers of CD4 T cells. Figure 1B shows CD4:CD8 ratio. PEP, post exposure prophylaxis. Macaques 95020 and M94312 were persistently virus-negative and weakly SIV-antibody positive (V^-Ab^±) after the first SIV_mne infection/PMPA PEP regimen (1^st PEP) [15]. Four years later, macaque M94312 received a second PEP regimen (2^nd PEP) involving one treatment interruption plus SIV_mne challenge at week 1 of a 5-week PMPA treatment. Thereafter, this macaque became persistently virus-negative and strongly-SIV antibody positive (V^-Ab⁺). Macaque 95020 was not given a second PEP and remained persistently virus-negative and weakly-antibody positive (V^-Ab^±). Both macaques were then challenged with SHIV_89.6P at the same time at 2.5 years after the 2^nd PEP (i.e. 6.5 years after the 1^st PEP). Two naïve macaques (99111 and 99107) served as infection controls. Lymphocyte subsets are analyzed in peripheral blood by FACScan for absolute number of CD4+CD3+ T lymphocytes and CD8+CD3+ T lymphocytes and used to calculate the ratio of CD4:CD8 T lymphocytes in peripheral blood.