top of page


SKU: 41A248R

★ Download Datasheet PDF ★





Each kit is sufficient for 96 tests and contains the following components:


  • One aluminum pouch with a Microwell plate (12 strips of 8 wells each) coated with SARS-CoV-2 NP protein, sealed. The microwell strips can be used separately.
  • 10×Wash buffer-40 ml.
  • 5×Assay buffer-20 ml.
  • 100×Detection antibody solution: HRP-conjugated anti-human IgA monoclonal antibody, 0.12 ml.
  • 10×Human anti-NP IgA antibody (positive control), 22 ul
  • Substrate solution, 12 ml, ready for use.
  • Stop solution, 12 ml, ready for use.
  • Blank control, 0.5 ml, ready to use

    SARS-CoV-2 NP IgA ELISA Kit is a highly sensitive and specific immunoassay developed by ImmunoDiagnostics for qualitative detection of IgA class antibodies against the NP of SARS-CoV-2 in human blood.

    This product is intended for research use only.


    SARS-CoV-2 is an enveloped virus with a positive-sense RNA genome and a nucleocapsid of helical symmetry. Nucleocapsid protein (NP) is the most abundant protein on the helical nucleocapsid of coronaviruses, which plays an important role during host cell entry and virus particle assembly. Anti-NP antibodies have been shown to be the earliest and the most predominant antibodies detectable in patient’s blood samples after infection. Immunoglobulin A (IgA) plays a crucial role in the immune function of mucous membranes. In the blood, IgA interacts with Fc receptor to initiate inflammatory responses.


    96-well plates are coated with SARS-CoV-2 NP protein that captures antibodies against SARS-CoV-2 NP protein in the sample. After washing away unbound materials, captured IgA against SARS-CoV-2 NP is detected by anti-human IgA monoclonal antibodies conjugated with horse radish peroxidase (HRP), which is specific to human IgA, with no cross-reaction with human IgG or IgM. After washing step, the chromogenic substrate 3,3’,5,5’-tetramethylbenzidine (TMB) is added. Color reaction is stopped by 2M H2SO4. The amount of IgA class antibodies against SARS-CoV-2 NP captured inside the wells is proportional to the color density generated in the coupled oxidation-reduction reaction.


    Handle serum or plasma sample in accordance with National Committee for Clinical Laboratory Standards guidelines for preventing transmission of blood-borne infection.

    • Do not use grossly hemolyzed or lipemic samples.
    • Human Serum: Use a blood separator tube and allow sample to clot for 30 minutes, then centrifuge for 10 minutes at 1000g. When the human serum is tested, it should be diluted 100-fold at least.
    • Human plasma: Treat blood with anticoagulant such as citrate, EDTA or heparin. Centrifuge for 10 minutes at 1000g within 30 minutes for plasma collection. When the human plasma is tested, it should be diluted 100-fold at least.
    • Samples cannot be tested immediately should be aliquoted and must be stored frozen below  -20°C. Avoid repeated freeze-thaw cycle.
    • Perform preliminary experiment to determine the optimum detection sample dilution.

    • The kit should be stored at 2-8°C, and all reagents should be equilibrated to room temperature before use. Immediately after use remaining reagents should be returned to cold storage (2-8°C).
    • Expiry of the kit and reagents is stand on labels. 
    • Once opened, the strips may be stored at 2-8°C for up to one month.

    1. Bachtiar EW, Soeroso Y, Haerani N, Ismah N, Adiati EC, Bachtiar BM. Immunoglobulin A response to SARS-CoV-2-N-protein potentially persists in oral fluids of patients with periodontitis six months after mRNA vaccine administration. Journal of Dental Sciences. 2023 Aug 29.

The currency used on this website is United States Dollars (USD). All prices are displayed and transactions are processed in USD. For orders outside Hong Kong or if you would like to have other currencies available, please contact us for a quote.

bottom of page