Kavli Affiliate: Robert Edwards
| Authors: Sai Luo, Jun Zhang, Alex J.B. Kreutzberger, Amanda Eaton, Robert J. Edwards, Changbin Jing, Hai-Qiang Dai, Gregory D. Sempowski, Kenneth Cronin, Robert Parks, Adam Yongxin Ye, Katayoun Mansouri, Maggie Barr, Novalia Pishesha, Aimee Chapdelaine Williams, Lucas Vieira Francisco, Anand Saminathan, Hanqin Peng, Himanshu Batra, Lorenza Bellusci, Surender Khurana, S. Munir Alam, David C. Montefiori, Kevin O. Saunders, Ming Tian, Hidde Ploegh, Tom Kirchhausen, Bing Chen, Barton F. Haynes and Frederick W. Alt
SARS-CoV-2 Omicron variants have generated a world-wide health crisis due to resistance to most approved SARS-CoV-2 neutralizing antibodies and evasion of antibodies induced by vaccination. Here, we describe the SARS-CoV-2 neutralizing SP1-77 antibody that was generated from a humanized mouse model with a single human VH1-2 and Vκ1-33-associated with immensely diverse complementarity-determining-region-3 (CDR3) sequences. SP1-77 potently and broadly neutralizes SARS-CoV-2 variants of concern and binds the SARS-CoV-2 spike protein receptor-binding-domain (RBD) via a novel-CDR3-based mode. SP1-77 does not block RBD-binding to the ACE2-receptor or endocytosis step of viral entry, but rather blocks membrane fusion. Our findings provide the first mechanistic insight into how a non-ACE2 blocking antibody potently neutralizes SARS-CoV-2, which may inform strategies for designing vaccines that robustly neutralize current and future SARS-CoV-2 variants.