CTLA-4PD-1 Memory CD4 T Cells Critically Contribute to Viral Persistence in Antiretroviral Therapy-Suppressed, SIV-Infected Rhesus Macaques.

Antiretroviral therapy (ART) suppresses viral replication in HIV-infected individuals but does not eliminate the reservoir of latently infected cells. Recent work identified PD-1 follicular helper T (Tfh) cells as an important cellular compartment for viral persistence. Here, using ART-treated, SIV-infected rhesus macaques, we show that CTLA-4PD-1 memory CD4 T cells, which share phenotypic markers with regulatory T cells, were enriched in SIV DNA in blood, lymph nodes (LN), spleen, and gut, and contained replication-competent and infectious virus. In contrast to PD-1 Tfh cells, SIV-enriched CTLA-4PD-1 CD4 T cells were found outside the B cell follicle of the LN, predicted the size of the persistent viral reservoir during ART, and significantly increased their contribution to the SIV reservoir with prolonged ART-mediated viral suppression. We have shown that CTLA-4PD-1 memory CD4 T cells are a previously unrecognized component of the SIV and HIV reservoir that should be therapeutically targeted for a functional HIV-1 cure.