Identification of Common Features in Prototype Broadly Neutralizing Antibodies to HIV Envelope V2 Apex to Facilitate Vaccine Design.

Broadly neutralizing antibodies (bnAbs) directed to the V2 apex of the HIV envelope (Env) trimer isolated from individual HIV-infected donors potently neutralize diverse HIV strains, but strategies for designing immunogens to elicit bnAbs have not been identified. Here, we compared four prototypes (PG9, CH01, PGT145, and CAP256.VRC26.09) of V2 apex bnAbs and showed that all recognized a core epitope of basic V2 residues and the glycan-N160. Two prototype bnAbs were derived from VH-germlines that were 99% identical and used a common germline D-gene encoded YYD-motif to interact with the V2-epitope. We identified isolates that were neutralized by inferred germline (iGL) versions of three of the prototype bnAbs. Soluble Env derived from one of these isolates was shown to form a well-ordered Env trimer that could serve as an immunogen to initiate a V2-apex bnAb response. These studies illustrate a strategy to transition from panels of bnAbs to vaccine candidates.