In sexual transmission of simian immunodeficiency virus, and early and later stages of human immunodeficiency virus–type 1 (HIV-1) infection, both viruses were found to replicate predominantly in CD4 + T cells at the portal of entry and in lymphoid tissues. Infection was propagated not only in activated and proliferating T cells but also, surprisingly, in resting T cells. The infected proliferating cells correspond to the short-lived population that produces the bulk of HIV-1. Most of the HIV-1–infected resting T cells persisted after antiretroviral therapy. Latently and chronically infected cells that may be derived from this population pose challenges to eradicating infection and developing an effective vaccine.

Sexual Transmission and Propagation of SIV and HIV in Resting and Activated CD4+T Cells