The current COVID-19 pandemic is caused by SARS-CoV-2, a novel coronavirus genetically close to SARS-CoV, thus it is important to define the between antigenic cross-reactivity and neutralization. In this study, we first analyzed 20 convalescent serum samples collected from SARS-CoV infected individuals during the 2003 SARS outbreak. All patient sera reacted strongly with the S1 subunit and receptor-binding domain (RBD) of SARS-CoV, cross-reacted with the S ectodomain, S1, RBD, and S2 proteins of SARS-CoV-2, and neutralized both SARS-CoV and SARS-CoV-2 S protein-driven infections. Multiple...…The current COVID-19 pandemic is caused by SARS-CoV-2, a novel coronavirus genetically close to SARS-CoV, thus it is important to define the between antigenic cross-reactivity and neutralization. In this study, we first analyzed 20 convalescent serum samples collected from SARS-CoV infected individuals during the 2003 SARS outbreak. All patient sera reacted strongly with the S1 subunit and receptor-binding domain (RBD) of SARS-CoV, cross-reacted with the S ectodomain, S1, RBD, and S2 proteins of SARS-CoV-2, and neutralized both SARS-CoV and SARS-CoV-2 S protein-driven infections. Multiple...WW…