Second, the frequency of wildtype Tat-SL8 epitope in RBs and PBMCs at day 28 post infection was strongly correlated with levels of Tat-SL8 CD8+ T cells in RBs at day 14 post infection (Figure 4D–E; Spearman's correlation, RB: r = 0.7992, p = 0.001; PBMC: r = 0.6485, p = 0.0121), perhaps suggesting a local effect of mucosal SIV-specific CTL responses in determining the emergence of escape mutants. The gene discussed is TAT; the disease is infection.