In a set of experiments performed using a simple immersion model of SHIVSF162P3 infection of vaginal explants, we found that, in the absence of HSV-2, the expression of α4β7 and CCR5 on CD4+ T cells and the frequency of α4β7+ HLA-DR+ Lin− DCs at base line (prior to infection) correlated with SHIVSF162P3 replication 3 days post-infection (Fig. 10A). This evidence concerns the gene CD4 and infection.