Increased expression of SAMHD1 in a subset of HIV-1 elite controllers.

SAMHD1 and the CDKN1A (p21) cyclin-dependent kinase inhibitor have been postulated to mediate HIV-1 restriction in CD4+ cells. We have shown that p21 affects HIV replication through its effect on SAMHD1. Thus, we aimed at evaluating the expression of SAMHD1 and p21 in different HIV+ phenotypic groups. We evaluated SAMHD1 and CDKN1A mRNA expression in CD4+ T cells from HIV+ individuals including elite controllers (naEuroS=aEuroS12), individuals who control HIV without the need for antiretroviral treatment, viraemic progressors (naEuroS=aEuroS10) and HIV-1 seronegative healthy donors (naEuroS=aEuroS14). Immunological variables were measured by flow cytometry. We show that a subset of HIV+ elite controllers with lower T cell proliferation levels (Ki67+ cells) expressed higher SAMHD1 compared with healthy donors or viraemic progressors. Conversely, there was no difference in p21 expression before or after T cell activation with a bispecific CD3/CD8 antibody. Our results suggest that SAMHD1 may play a role in controlling virus replication in HIV+ individuals and slow the rate of disease progression.