Wells of a 96-microtiter plate were coated with 4 µg/ml of SARS-CoV-2 Nucleocapsid protein (Cat#21-1003). The binding was detected by addition of different concentration of biotinylated anti-Nucleocapsid polyclonal antibody (Cat.# 11-2003-B) per well. The reactivity was detected by HRP-conjugated Streptavidin.