The ImmunoDiagnostics SARS-CoV2 S1RBD-ACE2 Binding Assay is designed to measure the interaction between the receptor binding domain of the viral spike glycoprotein (S1RBD) with the cell surface receptor ACE2. The assay can detect the presence of neutralizing antibodies in human plasma or serum after infection or vaccination.

This product is intended for research use only.

The ongoing global pandemic of coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 is an enveloped virus with a positive-sense RNA genome and a nucleocapsid of helical symmetry. The SARS-CoV-2 entry into host cells is mediated by the transmembrane spike (S) glycoprotein, which contains a receptor binding domain (RBD). S1RBD is responsible for binding with angiotensin converting enzyme-2 (ACE2), leading to endocytosis into the host cells and viral replication. S1RBD is the main target of neutralizing antibodies upon infection and the focus of the therapeutic drug and vaccine design. Molecules that inhibit formation of the S1RBD-ACE2 complex in vitro could be potential treatment for COVID-19 infection.

The SARS-COV2 S1RBD-ACE2 Binding Assay is a competitive ELISA assay, which can mimic the virus binding process. 96-well plates are coated with SARS-CoV-2 S1RBD protein that captures neutralization antibodies or compounds which bind to SARS-CoV-2 S1RBD protein in the sample. After washing away unbound materials, captured neutralization antibodies or compounds can block the binding between horseradish peroxidase (HRP) conjugated recombinant human ACE2 and SARS-CoV-2 S1RBD. After washing step, the chromogenic substrate 3,3’,5,5’-tetramethylbenzidine (TMB) is added. Color reaction is stopped by 2M H2SO4. The presence of neutralization antibodies or compounds against SARS-CoV-2 S1RBD captured inside the wells is inversely 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.
• 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, the recommended dilution factor is 10-fold.
• 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, the recommended dilution factor is 10-fold.
• Samples cannot be tested immediately should be aliquoted and must be stored frozen below -20°C. Avoid repeated freeze-thaw cycle.
• The dilution factor and concentrations of other testing samples (such as inhibitors and antibodies) should be determined by individual users.  

• 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.

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