Production of SARS-CoV-2 nucleocapsid protein in Escherichia coli and its characterization

Abstract

SARS-CoV-2 encodes a nucleocapsid protein that binds to the single-stranded RNA genome present inside the viral particles. It is one of the predominant proteins expressed during infection and tends to be highly immunogenic in infected individuals. Consequently, it has been recognized as an important diagnostic marker for the development of antigen or antibody detection-based diagnostic platforms for COVID-19. In this work, we have described cloning, autoinduction-based expression, and purification of full-length SARS-CoV-2 nucleocapsid protein using Escherichia coli as the heterologous host. We have characterized the purified protein using commercial rapid antigen test kits and indirect ELISA to demonstrate its suitability as bait for diagnostic assays. The purified recombinant protein reported in this study can be useful for numerous applications including the development of monoclonal or polyclonal antibodies, studying protein structure and function, and mapping B- and T-cell epitopes for designing suitable vaccines and therapeutics.