Highly specific monoclonal antibodies and epitope identification against SARS-CoV-2 nucleocapsid protein for antigen detection tests

The ongoing coronavirus disease 2019 (COVID-19) pandemic is a major global public health concern. Although rapid point-of-care testing for detecting viral antigen is important for management of the outbreak, the current antigen tests are less sensitive than nucleic acid testing. In our current study, we produce monoclonal antibodies (mAbs) that exclusively react with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and exhibit no cross-reactivity with other human coronaviruses, including SARS-CoV Molecular modeling suggests that the mAbs bind to epitopes present on the exterior surface of the nucleocapsid, making them suitable for detecting SARS-CoV-2 in clinical samples. We further select the optimal pair of antiSARS-CoV-2 nucleocapsid protein (NP) mAbs using ELISA and then use this mAb pair to develop immuno-chromatographic assay augmented with silver amplification technology. Our mAbs recognize the variants of concern (501Y.V1-V3) that are currently in circulation. Because of their high performance, the mAbs of this study can serve as good candidates for developing antigen detection kits for COVID-19.

Automated summary

This study produced monoclonal antibodies that exclusively react with SARS-CoV-2 with no cross-reactivity with other human coronaviruses, suitable for detecting the virus in clinical samples. The antibodies were selected and used to develop an immuno-chromatographic assay augmented with silver amplification technology, capable of detecting current circulating variants of concern. These antibodies can serve as good candidates for developing antigen detection kits for COVID-19 due to their high performance.