Neutralizing antibody 5-7 defines a distinct site of vulnerability in SARS-CoV-2 spike N-terminal domain

Cell Rep. 2021 Nov 2;37(5):109928. doi: 10.1016/j.celrep.2021.109928. Epub 2021 Oct 16.

Abstract

Antibodies that potently neutralize SARS-CoV-2 target mainly the receptor-binding domain or the N-terminal domain (NTD). Over a dozen potently neutralizing NTD-directed antibodies have been studied structurally, and all target a single antigenic supersite in NTD (site 1). Here, we report the cryo-EM structure of a potent NTD-directed neutralizing antibody 5-7, which recognizes a site distinct from other potently neutralizing antibodies, inserting a binding loop into an exposed hydrophobic pocket between the two sheets of the NTD β sandwich. Interestingly, this pocket was previously identified as the binding site for hydrophobic molecules, including heme metabolites, but we observe that their presence does not substantially impede 5-7 recognition. Mirroring its distinctive binding, antibody 5-7 retains neutralization potency with many variants of concern (VOCs). Overall, we reveal that a hydrophobic pocket in NTD proposed for immune evasion can be used by the immune system for recognition.

Keywords: COVID-19; N-terminal domain; NTD; SARS-CoV-2; antigenic supersite; cryo-EM; neutralizing antibody; variants of concern.