PT  - JOURNAL ARTICLE
AU  - Kui K. Chan
AU  - Timothy J.C. Tan
AU  - Krishna K. Narayanan
AU  - Erik Procko
TI  - An engineered decoy receptor for SARS-CoV-2 broadly binds protein S sequence variants
AID  - 10.1101/2020.10.18.344622
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.10.18.344622
4099  - http://biorxiv.org/content/early/2020/12/21/2020.10.18.344622.short
4100  - http://biorxiv.org/content/early/2020/12/21/2020.10.18.344622.full
AB  - The spike S of SARS-CoV-2 recognizes ACE2 on the host cell membrane to initiate entry. Soluble decoy receptors, in which the ACE2 ectodomain is engineered to block S with high affinity, potently neutralize infection and, due to close similarity with the natural receptor, hold out the promise of being broadly active against virus variants without opportunity for escape. Here, we directly test this hypothesis. We find an engineered decoy receptor, sACE22.v2.4, tightly binds S of SARS-associated viruses from humans and bats, despite the ACE2-binding surface being a region of high diversity. Saturation mutagenesis of the receptor-binding domain (RBD) followed by in vitro selection, with wild type ACE2 and the engineered decoy competing for binding sites, failed to find S mutants that discriminate in favor of the wild type receptor. Variant N501Y in the RBD, which has emerged in a rapidly spreading lineage (B.1.1.7) in England, enhances affinity for wild type ACE2 20-fold but remains tightly bound to engineered sACE22.v2.4. We conclude that resistance to engineered decoys will be rare and that decoys may be active against future outbreaks of SARS-associated betacoronaviruses.Competing Interest StatementThe University of Illinois has filed a provisional patent for engineered decoy receptors and E.P. and K.K.C. are co-founders of Orthogonal Biologics, Inc.