Examining the impact of the MRKAd5 HIV-1 vaccine on CD8+ T-cell IFN-γ responses after infection in Phambili subjects with available PBMCs, we observed that vaccinees had significantly higher Gag-specific breadth and magnitude than placebo recipients (P = .03 and P = .02, respectively, 2 months after diagnosis; and P = .05 and P = .02, respectively, 12 months after diagnosis; Figure 1D). This evidence concerns the gene IFNG and infection.