Although SIVmac239 infection changed the composition of T cells, with decreased CD4+ T cells and increased CD8+ T cells, the activation (defined by HLA-DR expression, data not plotted) and exhaustion (defined by PD-1 expression) of CD4+ T cells and CD8+ T cells were very similar between the SIV− and SIV+ NPMs (Figure 2G). The gene discussed is CD8A; the disease is infection.