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Elise-Immun Neutralization Antibody Detection kit detects circulating neutralizing antibodies against SARS-CoV-2 that block the interaction between the receptor binding domain (RBD) of the viral spike glycoprotein with the ACE2 cell surface receptor. This kit would be instrumental in vaccine and therapeutic development as it is suitable for all antibody isotypes and can be used to determine neutralizing antibodies in animal models without modification. The kit will also help in current COVID-19 investigations of sero-prevalence, assessment of herd immunity, longevity of protective immunity, efficacy of different vaccine candidates as well as tracking infection in animals.

  • Most COVID-19 antibody test kits in the market evaluate the ability of a patient to generate antibodies bind virus, such as IgG, IgM, or total antibody, but they do not tell whether such antibodies can neutralize the virus and break virus life cycle, which is essential for a person’s acquired immunity against the pathogen. Our kit detects the antibodies that have blocking/neutralization function. Therefore, it is a better measure of potential resilience to re-infection.

  • Traditionally, the presence of neutralizing antibodies are detected by virus neutralization test(VNT). Conventional virus neutralization tests require live viruses and cells, biosafety containment facilities, highly skilled operators, are less sensitive, and take days to obtain results. Our  test does not involve live virus and cells and can be used in any lab, except the test sample itself is infectious and need biosafety level 2 or 3 (BSL2, BSL3) labs. The operation steps are much more straightforward and only take 1 hr to run.

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Results

Biochemical simulation of virus–receptor interaction and antibody-mediated neutralization

Immediately after SARS-CoV-2 was identified as the causative agent of the COVID-19 outbreak, it was shown that human ACE2 (hACE2) is the main functional receptor for viral entry3.

 

We hypothesized that the virus–receptor binding can be mimicked in vitro via a protein–protein interaction using purified recombinant hACE2 and the RBD of the SARS-CoV-2 S protein.

 

This interaction can be blocked by virus NAbs present in the test serum, using the same principle as cVNT conducted using live virus inside a BSL3 facility (Fig. 1a,b).