Plasma vRNA loads and T-cell subsets in rhesus monkeys inoculated with SHIV-1157i or passaged virus. The five animals used for virus adaptation were grouped into progressors and non-progressors. (A, B) Plasma vRNA loads. (C, D) Absolute CD4+ T-cell counts. (E, F) Percentage CD4+CD29+ memory T cells. (G, H) CD4:CD8 ratios. The dashed lines in panels C and D designate 200 cells/μl, the case definition threshold for human AIDS. In panels E and F, the dashed line at 10% indicates the lower limit of normal for the percentage of CD4+CD29+ memory T cells. The threshold of detection of vRNA was 50 copies/ml. †, euthanasia due to AIDS-related disease (RPn-8) or unrelated reasons (RIl-8); monkey RKl-8 died during blood collection.