To characterize the emergence of CTL escape mutants in our cohort of SIVmac239-infected RMs, we amplified a 435 nucleotide region surrounding the Gag-CM9 epitope and a 390 nucleotide region surrounding the Tat-SL8 epitope from reverse transcribed plasma viral RNA and genomic DNA derived from PBMCs, RB, and LNs collected at multiple time points post infection. This evidence concerns the gene TAT and infection.