Although CD8+ T-cells and B cells had little divergence in the two groups (Figures 2C,D), the CD4+/CD8+ T-cell ratio declined more rapidly in the stHIV-1sv infected NPMs compared to the HIV-1NL4−R3A infected NPMs during the primary infection (Figure 2E), consistent with the respective viral loads in the two groups. Here, CD4 is linked to infection.