Antibody-mediated protection against SHIV challenge includes systemic clearance of distal virus

HIV-1–specific broadly neutralizing antibodies (bNAbs) can protect rhesus monkeys against simian-human immunodeficiency virus (SHIV) challenge. However, the site of antibody interception of virus and the mechanism of antibody-mediated protection remain unclear. We administered a fully protective dose of the bNAb PGT121 to rhesus monkeys and challenged them intravaginally with SHIV-SF162P3. In PGT121-treated animals, we detected low levels of viral RNA and viral DNA in distal tissues for seven days following challenge. Viral RNA–positive tissues showed transcriptomic changes indicative of innate immune activation, and cells from these tissues initiated infection after adoptive transfer into naive hosts. These data demonstrate that bNAb-mediated protection against a mucosal virus challenge can involve clearance of infectious virus in distal tissues.