New COVID-19 Test Pinpoints Human Antibodies Specific to Particular Part of SARS-CoV-2 Spike Protein

Scientists at the University of North Carolina at Chapel Hill School of Medicine (Chapel Hill, NC, USA) developed the new kind of antibody test, a simplified experimental assay that could be ramped up to test thousands of blood samples at labs that do not have the resources of commercial labs and large academic medical centers. The test can be ramped up to document past and recent COVID-19 infections and possibly used to identify asymptomatic virus infection and the level of immunity in individuals.

The researchers created a blood test to pinpoint SARS-CoV-2 antibodies that target one unique piece of the SARS-CoV-2 spike protein. That piece is called a receptor binding domain, or RBD. Their RBD-based antibody test can measure the levels of that domain, which they found correlate to the levels of the all-important neutralizing antibodies that provide immunity. The RBD of the spike protein in SARS-CoV-2 is not shared among other known human or animal coronaviruses. Therefore, antibodies against this domain are likely to be highly specific to SARS-CoV-2, and so these antibodies reveal if an individual has been exposed to the virus that can cause COVID-19. Indeed, when the researchers tested blood collected from people exposed to other coronaviruses, none had antibodies to the RBD of SARS-CoV-2.

“Our assay is extremely specific for antibodies to the virus that causes COVID-19, which is not the case for some currently available antibody tests,” said co-senior author Aravinda de Silva, professor of microbiology and immunology and member of the UNC Institute for Global Health and Infectious Diseases. “Our results strongly support the use of RBD-based antibody assays for population-level surveillance and as a correlate of the neutralizing antibody levels in people who have recovered from SARS-CoV-2 infections.”

“We are now further streamlining our test into an inexpensive assay, so that instead of the test taking four to five hours to complete, our assay could be completed in about 70 minutes without compromising quality,” said first and co-senior author Prem Lakshmanane, PhD, assistant professor of microbiology and immunology at UNC.

Related Links:
Scripps Research
University of North Carolina at Chapel Hill School of Medicine