Immunoassay Detection of SARS-CoV-2 Using Monoclonal Antibody Binding to Viral Nucleocapsid Protein

Immunoassays represent sensitive, easy-to-use, and cost-effective tests useful for the detection of the SARS-CoV-2 virus. In this manuscript, we report on the binding specificity of a pair of novel monoclonal antibodies (MAbs) generated against the SARS-CoV-2 nucleocapsid protein (NP) and their development into sensitive sandwich enzyme-linked immunosorbent assays (sELISA) and a lateral flow immunoassay (LFIA). Binding of these MAbs to hCoVs is limited to variants of SARS-CoV-2 and SARS-CoV NP. Chemiluminescent and absorbance spectroscopy sELISAs report a limit of detection (LOD) for the SARS-CoV-2 B.1.1.529 NP variant at 15 pg/mL, and the LFIA using a red-dyed 200 nm particle at 10 ng/mL. The sELISA exhibits broad SARS-CoV-2 viral variant detection with assay LOD for SARS-CoV-2 B.1.1.529 virus at 1.4 × 10⁵ genome copies per mL (p ≤ 0.001). The availability of these MAbs should facilitate continued investment in the commercial development of immunoassays to increase global SARS-CoV-2 detection technologies.