HIV-1 CD4-binding site germline antibody-Env structures inform vaccine design.

Dam, Kim-Marie A; Barnes, Christopher O; Gristick, Harry B; Schoofs, Till; Gnanapragasam, Priyanthi N P; Nussenzweig, Michel C; Bjorkman, Pamela J · Nat Commun · 2022

basic_science · Level V

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Abstract

BG24, a VRC01-class broadly neutralizing antibody (bNAb) against HIV-1 Env with relatively few somatic hypermutations (SHMs), represents a promising target for vaccine strategies to elicit CD4-binding site (CD4bs) bNAbs. To understand how SHMs correlate with BG24 neutralization of HIV-1, we report 4.1 Å and 3.4 Å single-particle cryo-EM structures of two inferred germline (iGL) BG24 precursors complexed with engineered Env-based immunogens lacking CD4bs N-glycans. Structures reveal critical Env contacts by BG24<sub>iGL</sub> and identify antibody light chain structural features that impede Env recognition. In addition, biochemical data and cryo-EM structures of BG24<sub>iGL</sub> variants bound to Envs with CD4bs glycans present provide insights into N-glycan accommodation, including structural modes of light chain adaptations in the presence of the N276<sub>gp120</sub> glycan. Together, these findings reveal Env regions critical for germline antibody recognition and potential sites to alter in immunogen design.

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