CD4 and infection: On the other hand, the functional nature of these CD4+ or CD8+ T-cell subsets upon infection with HIV could be predicted from the expression of several negative immune checkpoint molecules, for instance PD-1, TIM3, LAG3, and CD160 (Hoffmann et al., 2016; Trautmann et al., 2006), which all correlate with HIV viral load in the host (Day et al., 2006).