Naive human B cells engage the receptor binding domain of SARS-CoV-2, variants of concern, and related sarbecoviruses

Jared Feldman, Julia Bals, Clara G. Altomare, Kerri St Denis, Evan C. Lam, Blake M. Hauser, Larance Ronsard, Maya Sangesland, Thalia Bracamonte Moreno, Vintus Okonkwo, Nathania Hartojo, Alejandro B. Balazs, Goran Bajic, Daniel Lingwood, Aaron G. Schmidt

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Initial exposure to a pathogen elicits an adaptive immune response to control and eradicate the threat. Interrogating the abundance and specificity of the naive B cell repertoire drives understanding of how to mount protective responses. Here, we isolated naive B cells from eight seronegative human donors targeting the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor binding domain (RBD). Single-cell B cell receptor (BCR) sequencing identified diverse gene usage and no restriction on complementarity determining region length. A subset of recombinant antibodies produced by naive B cell precursors bound to SARS-CoV-2 RBD and engaged circulating variants including B.1.1.7, B.1.351, and B.1.617.2, as well as preemergent bat-derived coronaviruses RaTG13, SHC104, and WIV1. By structural characterization of a naive antibody in complex with SARS-CoV-2 spike, we identified a conserved mode of recognition shared with infection-induced antibodies. We found that representative naive antibodies could signal in a B cell activation assay, and by using directed evolution, we could select for a higher-affinity RBD interaction, conferred by a single amino acid change. The minimally mutated, affinity-matured antibodies also potently neutralized SARS-CoV-2. Understanding the SARS-CoV-2 RBD–specific naive repertoire may inform potential responses capable of recognizing future SARS-CoV-2 variants or emerging coronaviruses, enabling the development of pan-coronavirus vaccines aimed at engaging protective germline responses.

Original languageEnglish
Article numbereabl5842
JournalScience immunology
Volume6
Issue number66
DOIs
StatePublished - Dec 2021

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