To inform seroepidemiological studies, we characterized the IgG- responses in COVID-19 patients against the two major SARS-CoV-2 viral proteins, spike (S) and nucleocapsid (N). We tested 70 COVID-19 sera collected up to 85 days post-symptom onset and 230 non-COVID-19 sera, including 27 SARS sera from 2003. Although the average SARS-CoV-2 S and N-IgG titers were comparable, N-responses were more variable among individuals. S- and N-assay specificity tested with non-COVID-19 sera were comparable at 97.5% and 97.0%, respectively. Therefore, S will make a better target due to its lower cross-reactive potential and its' more consistent frequency of detection compared to N.
Xiao C, Ling S, Qiu M, Deng Z, Chen L, Zhu A, Chen Y, Liu Y, Lin X, Lin F, Wu Q, Shen L, Ye F, Liu X, Li Y, Zhao J, Yang Z, Cowling BJ, Webby R, Zanin M, Wong SS. (2020). Human post-infection serological response to the spike and nucleocapsid proteins of SARS-CoV-2. Influenza and other respiratory viruses