Screening of potent neutralizing antibodies against SARS-CoV-2 using convalescent patients-derived phage-display libraries

Pan, Yongbing; Du, Jianhui; Liu, Jia; Wu, Hai; Gui, Fang; Zhang, Nan; Deng, Xiaojie; Song, Gang; Li, Yufeng; Lu, Jia; Wu, Xiaoli; Zhan, ShanShan; Jing, Zhaofei; Wang, Jiong; Yang, Yimin; Liu, Jianbang; Chen, Ying; Chen, Qin; Zhang, Huanyu; Hu, Hengrui; Duan, Kai; Wang, Manli; Wang, Qisheng; Yang, Xiaoming

As the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to threaten public health worldwide, the development of effective interventions is urgently needed. Neutralizing antibodies (nAbs) have great potential for the prevention and treatment of SARS-CoV-2 infection. In this study, ten nAbs were isolated from two phage-display immune libraries constructed from the pooled PBMCs of eight COVID-19 convalescent patients. Eight of them, consisting of heavy chains encoded by the immunoglobulin heavy-chain gene-variable region (IGHV)3-66 or IGHV3-53 genes, recognized the same epitope on the receptor-binding domain (RBD), while the remaining two bound to different epitopes. Among the ten antibodies, 2B11 exhibited the highest affinity and neutralization potency against the original wild-type (WT) SARS-CoV-2 virus (K(D) = 4.76 nM for the S1 protein, IC(50) = 6 ng/mL for pseudoviruses, and IC(50) = 1 ng/mL for authentic viruses), and potent neutralizing ability against B.1.1.7 pseudoviruses. Furthermore, 1E10, targeting a distinct epitope on RBD, exhibited different neutralization efficiency against WT SARS-CoV-2 and its variants B.1.1.7, B.1.351, and P.1. The crystal structure of the 2B11–RBD complexes revealed that the epitope of 2B11 highly overlaps with the ACE2-binding site. The in vivo experiment of 2B11 using AdV5-hACE2-transduced mice showed encouraging therapeutic and prophylactic efficacy against SARS-CoV-2. Taken together, our results suggest that the highly potent SARS-CoV-2-neutralizing antibody, 2B11, could be used against the WT SARS-CoV-2 and B.1.1.7 variant, or in combination with a different epitope-targeted neutralizing antibody, such as 1E10, against SARS-CoV-2 variants.