Fab-dimerized glycan-reactive antibodies are a structural category of natural antibodies.

Williams, Wilton B; Meyerhoff, R Ryan; Edwards, R J; Li, Hui; Manne, Kartik; Nicely, Nathan I; Henderson, Rory; Zhou, Ye et al. · Cell · 2021

basic_science · Level V

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Abstract

Natural antibodies (Abs) can target host glycans on the surface of pathogens. We studied the evolution of glycan-reactive B cells of rhesus macaques and humans using glycosylated HIV-1 envelope (Env) as a model antigen. 2G12 is a broadly neutralizing Ab (bnAb) that targets a conserved glycan patch on Env of geographically diverse HIV-1 strains using a unique heavy-chain (V<sub>H</sub>) domain-swapped architecture that results in fragment antigen-binding (Fab) dimerization. Here, we describe HIV-1 Env Fab-dimerized glycan (FDG)-reactive bnAbs without V<sub>H</sub>-swapped domains from simian-human immunodeficiency virus (SHIV)-infected macaques. FDG Abs also recognized cell-surface glycans on diverse pathogens, including yeast and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike. FDG precursors were expanded by glycan-bearing immunogens in macaques and were abundant in HIV-1-naive humans. Moreover, FDG precursors were predominately mutated IgM<sup>+</sup>IgD<sup>+</sup>CD27<sup>+</sup>, thus suggesting that they originated from a pool of antigen-experienced IgM<sup>+</sup> or marginal zone B cells.

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