Going beyond clinical routine in SARS-CoV-2 antibody testing - A multiplex corona virus antibody test for the evaluation of cross-reactivity to endemic coronavirus antigens
Given the importance of the humoral immune response to SARS-CoV-2 as a global benchmark for immunity, a detailed analysis is needed to (i) monitor seroconversion in the general population, (ii) understand manifestation and progression of the disease, and (iii) predict the outcome of vaccine development. Currently available serological assays utilize single analyte technologies such as ELISA to measure antibodies against SARS-CoV-2 antigens including spike (S) or nucleocapsid (N) protein. To measure individual antibody (IgG and IgA) responses against SARS-CoV-2 and the endemic human coronaviruses (hCoVs) NL63, 229E, OC43, and HKU1, we developed a multiplexed immunoassay (CoVi-plex), for which we included S and N proteins of these coronaviruses in an expanded antigen panel. Compared to commercial in vitro diagnostic (IVD) tests our CoVi-plex achieved the highest sensitivity and specificity when analyzing 310 SARS-CoV-2 infected and 866 uninfected individuals. Simultaneously we see high IgG responses against hCoVs throughout all samples, whereas no consistent cross reactive IgG response patterns can be defined. In summary, our CoVi-plex is highly suited to monitor vaccination studies and will facilitate epidemiologic screenings for the humoral immunity toward pandemic as well as endemic coronaviruses.