RESUMO
BO_SCPLOWACKGROUNDC_SCPLOWSeroreactivity against human endemic coronaviruses has been linked to disease severity after SARS-CoV-2 infection. Assays that are capable of concomitantly detecting antibodies against endemic coronaviridae such as OC43, 229E, NL63, and SARS-CoV-2 may help to elucidate this question. We set up a platform for serum-screening and developed a bead-based Western blot system, namely DigiWest, capable of running hundreds of assays using microgram amounts of protein prepared directly from different viruses. MO_SCPLOWETHODSC_SCPLOWThe parallelized and miniaturised DigiWest assay was adapted for detecting antibodies using whole protein extract prepared from isolated SARS-CoV-2 virus particles. After characterisation and optimization of the newly established test, whole virus lysates of OC43, 229E, and NL63 were integrated into the system. RO_SCPLOWESULTSC_SCPLOWThe DigiWest-based immunoassay system for detection of SARS-CoV-2 specific antibodies shows a sensitivity of 87.2 % and diagnostic specificity of 100 %. Concordance analysis with the SARS-CoV-2 immunoassays available by Roche, Siemens, and Euroimmun indicates a comparable assay performance (Cohens Kappa ranging from 0.8799-0.9429). In the multiplexed assay, antibodies against the endemic coronaviruses OC43, 229E, and NL63 were detected, displaying a high incidence of seroreactivity against these coronaviruses. CO_SCPLOWONCLUSIONC_SCPLOWThe DigiWest-based immunoassay, which uses authentic antigens from isolated virus particles, is capable of detecting individual serum responses against SARS-CoV-2 with high specificity and sensitivity in one multiplexed assay. It shows high concordance with other commercially available serologic assays. The DigiWest approach enables a concomitant detection of antibodies against different endemic coronaviruses and will help to elucidate the role of these possibly cross-reactive antibodies.
RESUMO
Given the importance of the humoral immune response to SARS-CoV-2 as a global benchmark for immunity, a detailed analysis is needed to monitor seroconversion in the general population, understand manifestation and progression of COVID-19 disease, and ultimately predict the outcome of vaccine development. In contrast to currently available serological assays, which are only able to resolve the SARS-CoV-2 antibody response on an individual antigen level, we developed a multiplex immunoassay, for which we included spike and nucleocapsid proteins of SARS-CoV-2 and the endemic human coronaviruses (NL63, OC43, 229E, HKU1) in an expanded antigen panel. Compared to three commercial in vitro diagnostic tests, our MULTICOV-AB assay achieved the highest sensitivity and specificity when analyzing a well-characterized sample set of SARS-CoV-2 infected and uninfected individuals. Simultaneously, high IgG responses against endemic coronaviruses became apparent throughout all samples, but no consistent cross-reactive IgG response patterns could be defined. In summary, we have established and validated, a robust, high-content-enabled, and antigen-saving multiplex assay MULTICOV-AB, which is highly suited to monitor vaccination studies and will facilitate epidemiologic screenings for the humoral immunity toward pandemic as well as endemic coronaviruses.
