Enhanced and sustained biodistribution of HIV-1 neutralizing antibody VRC01LS in human genital and rectal mucosa

To prevent sexually-acquired HIV-1 infection by immunoprophylaxis, effective concentrations of broadly neutralizing antibodies are likely needed at mucosal sites of exposure. Here, we examine the biodistribution of monoclonal antibody VRC01 and its extended half-life variant, VRC01LS, in colorectal and genitourinary tracts of healthy adults 1-52 weeks after intravenous infusion. At 1-2 weeks, VRC01LS levels are ~3-4 times higher than VRC01 in serum ( p = 0.048), rectal ( p = 0.067), vaginal ( p = 0.003) and cervical tissues ( p = 0.003); these differences increase over time. Both antibodies primarily localize within rectal lamina propria and cervicovaginal stroma, with limited and variable epithelial distribution. Although 8-28% of serum mAb levels reach mucosal tissues,