Structural and immunogenetic signatures guide CD4-mimetic HIV vaccine development

HIV vaccine strategies include aims to elicit broadly neutralizing antibodies (bnAbs) targeting the CD4-binding site, that are derived from immunoglobulin heavy-chain variable genes 1-2 (V_H1-2) and 1-46 (V_H1-46). Here, we present an integrated analysis of V_H1-46 bnAbs, including in vitro functional studies, cryo-electron microscopy structures of two V_H1-46 bnAbs (1-23 and 9-71) complexed with envelope trimers, and comprehensive structural and immunogenetic analyses, to help guide vaccine design. We show that V_H1-46-derived bnAbs use diverse light-chain variable (V_K/V_L) genes and LCDR3 lengths commonly found in human antibody repertoires, which generate unique LCDR3 signatures that influence both the antibody paratope and approach angle. We identify three V_H1-46 bnAb classes, 1B2530 (V_L1-47), CH235 (V_K3-15), and 561 (V_K3-20), with the 561 class further subdivided into types I and II. Our findings indicate that V_H1-46 priming immunogens should be tailored to each bnAb class, with 561-class bnAbs presenting optimal targets for germline-targeting vaccine design.