In the present study, we developed and evaluated ELISA to detect antinucleocapsid antibodies (total Ab) using an rNP antigen expressed in plants and E. coli and compared their performance with three commercial ELISAs (SD Biosensor Standard E COVID-19 total Ab ELISA and EDI novel coronavirus COVID-19 IgG and IgM). This evidence concerns the gene CD40LG and COVID-19.