HIV-1 BaL, which is a widely used laboratory HIV-1 strain and common tool to study HIV infection in ex vivo mucosa models was used in this study (Merbah et al., 2012; King et al., 2013; Shen et al., 2012), and the findings show that there were little to no differences in HIV infection of CD4+ T cells between HIV-1 BaL and founder/transmitter HIV strains. Here, CD4 is linked to HIV infectious disease.