SARS-CoV-2 NP IgG ELISA kit is a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) for the detection and qualitative measurement of IgG class antibodies against the nucleocapsid protein (NP) of SARS-CoV-2 virus in human blood.

In december 2019, a novel coronavirus, now officially named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been identified in Wuhan China, which caused the outbreak of a coronavirusassociated acute respiratory disease called coronavirus disease 19 (COVID-19), Signs and symptoms of COVID-19 may occur 2 to 14 days after infection, which include fever, cough, shortness of breath or difficulties in breathing, pain in the muscle and tiredness. In severe cases, the infection can further lead to pneumonia, severe acute respiratory syndrome (SARS), kidney failure and death. Nucleocapsid protein (NP) is the most abundant protein on the helical nucleocapsid of coronaviruses, which envelopes the entire genomic RNA. NP also interacts with other viral structural proteins to play important roles during host cell entry and virus particle assembly and release. Anti-NP antibodies have been shown to be the earliest and the most predominant antibodies detectable in patient’s blood samples after coronavirus infection.

ImmunoDiagnostics SARS-CoV-2 NP IgG ELISA kit is a two-step incubation immunoassay kit. Recombinant nucleocapsid protein (NP) of SARS-CoV-2 pre-coated onto the polystyrene microwell strips can specifically recognize anti-NP antibodies in human serum or plasma specimens. After a 1-hour incubation, anti-NP antibodies are captured by immobilized NP protein while the unbound components are washed away. Afterwards, a detection solution containing HRP-conjugated anti-human IgG is added for another 1-hour incubation, wherein HRPconjugated anti-human IgG binds to the IgG class antibodies previously bound to NP protein on the plate. After removal of nonspecific bindings, a HRP substrate solution containing 3,3′,5,5′-Tetramethylbenzidine (TMB) is added, resulting in the formation of a blue color. Color reaction is stopped by 2M H2SO4, transforming the blue color to yellow signals, which is quantified by an absorbance microplate reader at 450 nm. The color intensity is proportional to the amount of anti-NP antibodies captured inside the wells.