Identification of a broad and potent V3 glycan site bNAb targeting an N332 _gp120 glycan-independent epitope

Broadly neutralizing antibodies (bNAbs) against HIV-1 can suppress viremia in vivo and inform vaccine development. Here, we characterized 007, a V3 glycan site bNAb exhibiting high levels of antiviral activity against multiclade pseudovirus panels ^1–3 (GeoMean IC ₅₀ = 0.012 µg/mL, breadth = 69%, 217 virus strains) by targeting a N332 _gp120 glycan-independent V3 epitope, a site of Env vulnerability to which only weakly neutralizing antibodies had previously been identified. Functional analyses demonstrated distinct binding and neutralization profiles compared to classical V3 glycan site bNAbs. A 007 Fab-Env cryo-EM structure revealed contacts with the V3 ³²⁴ GD/NIR ³²⁷ motif and interactions with N156 _gp120 and N301 _gp120 glycans. In contrast to classical V3 bNAbs, 007 binding to Env does not depend on the N332 _gp120 glycan, rendering it resistant to common escape mutations. Structures of 007 IgG-Env trimer complexes showed two Env trimers crosslinked by three bivalent IgGs, and bivalent 007 IgG was up to ∼300-fold more potent than monovalent 007 IgG heterodimer, suggesting a role for avidity in potent neutralization. Finally, in HIV-1 _ADA -infected humanized mice, 007 caused transient decline of viremia and overcame classical V3 escape mutations, highlighting 007’s potential for HIV-1 prevention, therapy, functional cure, and vaccine design.