Test Detects SARS-CoV-2 Neutralizing Antibodies In Hours

Not only is it much faster than conventional tests, it does not need to be performed in special biosafety laboratories.

AsianScientist (Jul. 24, 2020) – Researchers in Singapore have come up with a simple, rapid test­­ for studying SARS-CoV-2 neutralizing antibodies, which they describe in Nature Biotechnology.

The current gold standard test for detecting neutralizing antibodies requires the handling of the live SARS-CoV-2 virus in a biosafety level 3 laboratory containment facility. It is also time-consuming, taking two to four days to complete. The pseudovirus-based virus neutralization test can be conducted in a biosafety level 2 laboratory, but still requires the use of live viruses and cells.

Seeking to detect SARS-CoV-2 neutralizing antibodies quickly and safely, researchers led by Wang Lin-Fa and Danielle Anderson at Duke-NUS Medical School designed a surrogate virus neutralization test that does not require the use of live viruses or cells. Not only is it much faster than conventional tests—taking only one to two hours to complete—it does not need to be performed in special biosafety laboratories.

The test uses purified receptor binding domain from the SARS-CoV-2 spike protein and host cell receptor ACE2 to mimic the virus–host interaction in an enzyme-linked immunosorbent assay plate. This interaction can be blocked by specific neutralizing antibodies in patient or animal sera. The assay can also identify antibodies that bind to the receptor binding domain but do not neutralize the virus.

The authors validated their test with two groups of patients recovering from COVID-19—175 patients in Singapore and 50 patients in Nanjing, China. They found that their assay achieves 99.93 percent specificity and 95–100 percent sensitivity for antibody responses to SARS-CoV-2.

Although their surrogate virus neutralization assay may not be able to completely replace conventional virus neutralization assays, the authors note that it may be useful for the monitoring of infection rates, herd immunity and vaccine efficacy during clinical trials and after large-scale vaccination.

The article can be found at: Tan et al. (2020) A SARS-CoV-2 Surrogate Virus Neutralization Test Based on Antibody-mediated Blockage of ACE2–spike Protein–protein Interaction.


Source: Nature; Photo: ThisisEngineering RAEng/Unsplash.
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