CD4 and infection: 5–10 However, nonhuman primate models have demonstrated that the initial founder population of SIV-infected cells is primarily resting CD4+ memory T cells.11,12 Furthermore, HIV latency is maintained in the resting memory CD4+ T cell population,11–17 although there is debate about whether this reservoir arises from infection of resting cells or return of infected activated cells to a resting state.