Structural analysis of receptor engagement and antigenic drift within the BA.2 spike protein

Summary: The BA.2 sub-lineage of the Omicron (B.1.1.529) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant rapidly supplanted the original BA.1 sub-lineage in early 2022. Both lineages threatened the efficacy of vaccine-elicited antibodies and acquired increased binding to several...

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Bibliographic Details
Main Authors: James W. Saville, Dhiraj Mannar, Xing Zhu, Alison M. Berezuk, Spencer Cholak, Katherine S. Tuttle, Faezeh Vahdatihassani, Sriram Subramaniam
Format: Article
Language:English
Published: Elsevier 2023-01-01
Series:Cell Reports
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Online Access:http://www.sciencedirect.com/science/article/pii/S221112472201868X
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Summary:Summary: The BA.2 sub-lineage of the Omicron (B.1.1.529) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant rapidly supplanted the original BA.1 sub-lineage in early 2022. Both lineages threatened the efficacy of vaccine-elicited antibodies and acquired increased binding to several mammalian ACE2 receptors. Cryoelectron microscopy (cryo-EM) analysis of the BA.2 spike (S) glycoprotein in complex with mouse ACE2 (mACE2) identifies BA.1- and BA.2-mutated residues Q493R, N501Y, and Y505H as complementing non-conserved residues between human and mouse ACE2, rationalizing the enhanced S protein-mACE2 interaction for Omicron variants. Cryo-EM structures of the BA.2 S-human ACE2 complex and of the extensively mutated BA.2 amino-terminal domain (NTD) reveal a dramatic reorganization of the highly antigenic N1 loop into a β-strand, providing an explanation for decreased binding of the BA.2 S protein to antibodies isolated from BA.1-convalescent patients. Our analysis reveals structural mechanisms underlying the antigenic drift in the rapidly evolving Omicron variant landscape.
ISSN:2211-1247