Broadly neutralizing antibodies (bNAbs) can confer protection against HIV-1 infection in humanized mice and in primate models, but whether immunotherapy with a monoclonal bNAb can control HIV-1 in humans remains unclear. In Nature, Nussenzweig and colleagues describe a phase I clinical trial designed to elicit passive anti-viral protection by the potent bNAb 3BNC117, which recognizes the CD4-binding site in HIV-1 Env and can neutralize 195 of 237 HIV-1 strains across six clades. A single infusion of a high dose of 3BNC117 elicits a transient drop in viral load (differing from baseline by 0.8–2.5 log10) in 10 of 11 HIV-1-infected volunteers, with the non-responder harboring a 3BNC117-resistent virus. The authors observed evidence of antibody-mediated viral selection in some patients, whereas others maintained their sensitivity to 3BNC117 for as long as it remained in circulation. These findings suggest that passive immunization, paired with other anti-HIV-1 treatment modalities, may protect infected people.

Nature (8 April 2015) doi:10.1038/nature14411