Development of a serological assay to identify SARS-CoV-2 antibodies in COVID-19 patients

Huynh, A.; Arnold, D. M.; Kelton, J. G.; Smith, J. W.; Moore, J. C.; Chetty, V. T.; Stacey, H. D.; Ang, J. C.; Chagla, Z.; Harvey, B. J.; Bowdish, D. M.; Miller, M. S.; Nazy, I.

Coronavirus Disease 2019 (COVID-19) is a global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While molecular assays are used to detect viral genetic material for the diagnosis of acute infection, reliable serological assays are needed to measure immunity against SARS-CoV-2. In this report, we describe an enzyme-linked immunosorbent assay (ELISA) that detects antibodies against the following SARS-CoV-2 recombinant proteins: the full-length spike (S) protein and the receptor-binding domain (RBD). Our assay is sensitive and specific for immunoglobulin (Ig) G, IgA and IgM anti-S protein and anti-RBD antibodies. Samples were pre-treated with Triton X-100 to inactivate potential virus without affecting antibody detection. Our in-house ELISA performed as well as the commercial EUROIMMUN and Ortho assays for anti-SARS-CoV-2 antibodies. This method provides a high-throughput assay that does not require specialized instrumentation and can be widely used to determine immunity and the dynamic range of antibodies found within SARS-CoV-2.