FIG. 1.

SHIV-specific T-cell frequencies after vaccination. (A) SHIV-specific CD4⁺ and CD8⁺ T-cell frequencies in PBMC obtained at the indicated time points after the initial vaccination in group II, III, and IV macaques. In all macaques, SHIV-specific IFN-γ induction was undetectable before the initial vaccination. ND, not determined. (B) Dot plots showing SHIV-specific IFN-γ induction in group IV macaques after a SeV-Gag booster (2 weeks after the booster [wk 14] and just before challenge [wk 26]). CD4, SHIV-specific CD4⁺ T cells, gated on CD3⁺ CD4⁺; CD8, SHIV-specific CD8⁺ T cells, gated on CD3⁺ CD8⁺.