Diagnostics have played a significant role in the effective management of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nucleocapsid protein (N protein) is the primary antigen of the virus for the development of sensitive diagnostic assays. Thus far, limited knowledge exists about the antigenic properties of the N protein. In this paper, we demonstrate the significant impact of dimerization of SARS-CoV-2 nucleocapsid protein on the sensitivity of enzyme-linked immunosorbent assay (ELISA) based diagnostics of COVID-19. The expressed purified protein from E.coli consists of dimeric and monomeric forms, which have been further characterized by biophysical and immunological means. Indirect ELISA indicated elevated susceptibility of the dimeric form of the nucleocapsid protein for identification of protein-specific monoclonal antibody as compared to the monomeric form of the protein. These findings have also been confirmed with the modeled structure of monomeric and dimeric nucleocapsid protein via HHPred software and its solvent accessible surface area, which indicates higher stability and antigenicity of the dimeric type as compared to the monomeric form. It is evident that the use of the dimeric form will increase the sensitivity of the current nucleocapsid-dependent ELISA for rapid COVID-19 diagnostic. The sensitivity and specificity at 95% CI are 99.0% (94.5-99.9) and 95.0% (83.0-99.4) respectively for the highest purified dimeric form of the nucleocapsid protein. Further, the results indicate that monitoring and maintaining the monomer-dimer composition are critical for accurate and robust diagnostics.

Dimerization of SARS-CoV-2 nucleocapsid protein affects the sensitivity of ELISA based diagnostics of COVID-19

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.