PDCD1 and infection: Though we did find significant evidence for a strong contribution of participant-specific variation to any enrichment of proviruses with intact tat/rev/RRE+ ORFs within specific cell subsets (Table 1), overall we observed that the estimated infection frequency of proviruses with intact tat/rev/RRE was highest in PD-1+ cells, followed by DN cells, DP cells and CTLA-4+ cells (Figure 4A).