TAT and infection: To investigate the kinetics of appearance and dissemination of escape mutants in SIVmac239 infection in different anatomic compartments, we next compared both the frequency and the character of Tat-SL8 CTL escape mutants in viral sequences derived from plasma virus and cell-associated viral DNA from peripheral blood mononuclear cells (PBMCs), lymph nodes (LNs) and intestinal mucosa that was sampled by rectal biopsies (RB).