SARS-CoV-2 and SARS-CoV Spike-RBD Structure and Receptor Binding Comparison and Potential Implications on Neutralizing Antibody and Vaccine Development

Chunyun Sun; Long Chen; Ji Yang; Chunxia Luo; Yanjing Zhang; Jing Li; Jiahui Yang; Jie Zhang; Liangzhi Xie

SARS-CoV nAbs were generated by immunizing mouse or rabbit with SARS-CoV S1 or RBD protein. Two SARS-CoV S-protein rabbit polyclonal antibodies (Table 1 ) and four monoclonal antibodies ( Table 2 ) were analyzed for cross-reactivity to SARS-CoV-2 S1 protein and cross-neutralizing activities to SARS-CoV-2 PSV. As expected, the polyclonal antibodies showed weaker binding to SARS-CoV-2 S1 protein (EC 50 >100ng/mL) as compared to SARS-CoV S1 protein (EC 50 <25ng/mL). Neutralizing activities against SARS-CoV-2 PSV were lower by more than two-orders of magnitudes than SARS-CoV PSV (Table 1) , presenting a pessimistic forecast for the probability to identify highly potent and cross-reactive nAbs to SARS-CoV-2 from SARS-CoV antibodies or antibody libraries.