Sex-specific innate immune selection of HIV-1 in utero is associated with increased female susceptibility to infection

Female children and adults typically generate more efficacious immune responses to vaccines and infections than age-matched males, but also suffer greater immunopathology and autoimmune disease. We here describe, in a cohort of>170 in utero HIV-infected infants from KwaZulu-Natal, South Africa, fetal immune sex differences resulting in a 1.5-2-fold increased female susceptibility to intrauterine HIV infection. Viruses transmitted to females have lower replicative capacity (p=0.0005) and are more type I interferon-resistant (p=0.007) than those transmitted to males. Cord blood cells from females of HIV-uninfected sex-discordant twins are more activated (p=0.01) and more susceptible to HIV infection in vitro (p=0.03). Sex differences in outcome include superior maintenance of aviraemia among males (p=0.007) that is not explained by differential antiretroviral therapy adherence. These data demonstrate sex-specific innate immune selection of HIV associated with increased female susceptibility to in utero infection and enhanced functional cure potential among infected males. Sex differences in the immune response to vaccines and infections have been well described in children and adults. Here the authors describe, in a cohort of 177 HIV-infected infants, innate immune sex differences in fetal life that increase female susceptibility to intrauterine HIV infection and increase the chances of subsequent HIV remission in infected males.