©2019 by ImmunoDiagnostics Limited.


SKU: 41A222

Supplied Reagents and Materials



SARS-CoV-2 nucleoprotein (NP) coated ELISA plate         

12 strips of 8 wells (96 wells in total) in a frame and sealed in a foil bag.


5x Assay Buffer

20 ml


10x Wash Buffer

40 ml


100x Detection Antibody Solution

150 µl


Substrate solution                 

12 ml


Stop solution

15 ml


Negative control

1 ml


    Since December 2019, outbreak of SARS-CoV-2 infection has become a major epidemic threat in China and brought back the attention of pathogenic coronavirus to the spotlight. 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 viron structural proteins to play important roles during host cell entry and virus particle assembly and release. Human anti-COVID-19 nucleocapsid protein (NP) IgG ELISA kit is a highly sensitive and specific ELISA kit developed by ImmunoDiagnostics for the precision detection and quantitative measurement of titres of anti-NP IgG class antibodies in human serum.

    This product is intended for use by professional persons only.

    This product is intended for research use only.



    Recombinant nucleocapsid protein (NP) of SARS-CoV-2(Cat No. 41A220) coated onto the plate wells can specifically recognize anti-NP antibodies in human sera. After a 1 hour incubation, anti-NP antibodies are captured by immobilized NP protein while the unbound components were discarded and washed away. Afterwards, HRP-conjugated anti-human IgG is added for another 1 hour incubation, wherein the anti-human IgG detects IgG class antibodies previously bound to NP protein on the plate. After removal of nonspecific bindings, bound anti-human IgG is revealed by the addition of substrate solution containing 3,3′,5,5′-Tetramethylbenzidine (TMB), resulting in the formation of a blue color. Color reaction will be further stopped by 2M H2SO4, transforming the blue color to yellow signals. The absorbance of yellow reaction mixture is measured by plate reader at 450nm. The higher the reading is, the higher concentration of anti-NP IgGs.

  • Storage and Preparation of Test Serum Samples

    • Test samples are suggested to be assayed immediately after separation of serum, or preferably stored at -20°C or below in aliquots. Duplicate test is recommended.
    • When required, vortex test serum samples at room to ensure homogeneity. Then centrifuge samples at 10,000 to 15,000 rpm for 5 minutes prior to assay to remove particulates. Please do not omit this centrifugation step if samples are cloudy and containing particles.

    The kit should be stored at 2-8°C upon receipt, and all reagents should be equilibrated to room temperature before use. Remove any unused antigen-coated strips from the microplate, return them to the foil pouch and re-seal.  Once opened, the strips may be stored at 2-8°C for up to one month.