CD4 and AIDS: We developed a model of experimental infection of Asian macaques with the late-stage SHIVSF162P3N isolate that exhibited many similarities to HIV-1 infection in humans including CCR5 coreceptor usage, mucosal transmissibility, acute depletion of mucosal memory CD4+ T cells, persistent infection, and progression to AIDS over a period of several months to years in a proportion of the infected animals [41,42].