SARS-CoV-2 specific antibody responses in COVID-19 patients

NISREEN M.A. OKBA; Marcel A Muller; Wentao Li; Chunyan Wang; Corine H. GeurtsvanKessel; Victor M. Corman; Mart M. Lamers; Reina S. Sikkema; Erwin de Bruin; Felicity D. Chandler; Yazdan Yazdanpanah; Quentin Le Hingrat; Diane Descamps; Nadhira Houhou-Fidouh; Chantal B. E. M. Reusken; Berend-Jan Bosch; Christian Drosten; Marion P.G. Koopmans; Bart L. Haagmans

Following infections, all three patients seroconverted between days 13 and 21 post onset of disease (Figure 1) , and antibodies were elicited against the SARS-CoV-2 S and S1 subunit including the N-terminal (S1 A ) domain and the receptor binding domain (RBD). Since the N protein of SARS-CoV-2 is 90% similar to that of SARS-CoV ( Table 2) , we used SARS-CoV N as an antigen to test for SARS-CoV-2 N-directed antibodies in an ELISA format. We found that, following infection, antibodies were elicited against the N protein and when tested in a PRNT assay these sera were able to neutralize SARS-CoV-2. We observed cross-reactivity with the SARS-CoV S and S1 proteins, and to a lower extent with MERS-CoV S protein, but not with the MERS-CoV S1 protein (Figure 1 G-H) . This was evident from analyzing the degree of similarity of the different CoV S protein domains to their corresponding SARS-CoV-2 proteins ( Table 2) , where SARS-CoV showed high similarities in all different S domains. The analysis showed that the spike S2 subunit is more conserved among CoVs and thus plays a role in the cross-reactivity seen when the whole S was used as an antigen. Thus, S1 is a more specific than S as an antigen for SARS-CoV-2 serological diagnosis. All rights reserved. No reuse allowed without permission.