The cytokine interleukin-7 (IL-7) may facilitate transmission of HIV-1 to the female reproductive tract, according to new research published in PLoS Pathogens (9, e1003148).

Credit: Montagnier / Institute Pasteur / CNRI / Science Source

Most HIV-1 infections in women occur after virus-containing semen contacts the vaginal mucosa. HIV-1–infected semen is rich in several molecules that may affect viral transmission, and IL-7 stands out as having one of the highest concentrations. Using human tissue, Andrea Introini et al. found that IL-7 can facilitate HIV-1 infection of the cervico-vaginal mucosa ex vivo.

Mechanistically, the authors found that IL-7 directly acted on CD4+ T cells, preventing their apoptosis and promoting their entry into the cell cycle. These results are consistent with a model in which IL-7 promotes the survival of the founder pool of infected CD4+ T cells in the female reproductive tract early during HIV-1 transmission.