The Human SARS-CoV-2 Nucleoprotein IgG Antibody ELISA Kit is designed for the qualitative detection of human SARS-CoV-2 nucleoprotein (NP) IgG antibody in biological fluids such as serum and plasma.

Coronaviruses (CoV), including SARS-CoV-2, are enveloped and contain single-stranded (positive-sense) RNA associated with a nucleoprotein. These nucleoproteins are abundantly produced within CoV-infected cells, where their primary function is to package the viral genome into flexible, helical ribonucleoprotein complexes called nucleocapsids. The nucleocapsid binds to genomic RNA and is understood to interact with viral membrane proteins during virion assembly, therefore playing a critical role in ensuring the efficiency of viral transcription, translation, and assembly. In host cells, the nucleocapsid can directly impact normal cell functions and cause cell-cycle deregulation, increased COX-2 production, and inhibition of interferon production.

The assay is based on the indirect ELISA method, in which samples are added to ELISA strip plates pre-coated with human novel coronavirus nucleoprotein. Antibodies present in the sample specific for the coronavirus nucleoprotein will bind to the pre-coated antigen. The captured antibodies are detected by addition of an anti-human IgG-conjugated horseradish peroxidase (HRP). Addition of the chromogenic enzyme substrate 3,3’,5,5’ tetramethylbenzidine (TMB) results in a colored product with an intensity directly proportional to the concentration of human novel coronavirus nucleoprotein IgG antibody in the sample.