Designing an ELISA method for measurement of human IgG and IgM antibodies against SARS-CoV-2

ABSTRACT

Background and purpose: Coronavirus disease 2019 (COVID-19) is a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, an indirect ELISA method was designed to measure the human IgM and IgG antibodies against SARS-CoV-2. Materials and methods: Protein sequence of nucleocapsid antigen from SARS-CoV-2 was expressed in E. coli BL21 and then was purified by chromatography. The purified protein was confirmed by SDS-PAGE and Western blotting. An indirect ELISA method was designed to measure the specific IgG and IgM antibodies against SARS-CoV-2 using recombinant N protein. The optimized ELISA method was then applied to measure the IgG and IgM antibodies in 61 infected or recovered COVID-19 patients and in 31 healthy controls. Finally, data obtained from the designed ELISA method were compared with those of a commercially approved ELISA kit.