CD4 and HIV infectious disease: Regarding HIV susceptibility, we found that compared to Ad5 vector-induced CD4 T cells in HVTN204 PBMC, which were highly susceptible to R5 HIV infection (mean p24+%: 26.9%), the ALVAC-induced CD4 T cells in RV144 PBMC were markedly less susceptible to R5 HIV (mean p24+%: 1.27%) (p<0.01) (day 3 post-infection) (Fig 1A).