At Duke University a team of scientists developed a test that rapidly provides data on how effective antibodies are at neutralizing different COVID-19 variants. The test could be very handy in determining the immunity of a specific patient against various variants, or in deciding on the best monoclonal antibody therapy to use. The researchers have called their technology the COVID-19 Variant Spike-ACE2-Competitive Antibody Neutralization assay (CoVariant-SCAN).
As the Omicron variant spreads around the world, many vaccinated people are worried that they may not have sufficient immunity against such a heavily mutated variant of the virus. Technology like the test presented here could allow individuals to find out relatively quickly.
“We currently really have no rapid way of assessing variants, neither their presence in an individual, nor the ability of antibodies we possess to make a difference,” said Cameron Wolfe, of the study leads, in a press release. “It’s one of the lingering fears that, as we successfully vaccinate more and more people, a variant may emerge that more radically evades vaccine-induced antibody neutralization. And if that fear came true – if Omicron turned out to be a worst-case scenario – how would we know quickly enough?”
The test consists of a slide containing fluorescent ACE2 proteins, which is the binding target of the viral spike protein. The slide also contains versions of spike proteins from specific viral variants. During a performance of the test, the ACE2 proteins detach and can bind to the spike proteins, resulting in a measurable fluorescent glow. However, neutralizing antibodies can prevent spike protein/ACE2 binding, causing a change in the fluorescent signal and a proxy measurement of antibody efficacy.
“While developing a point-of-care test for COVID-19 antibodies and biomarkers, we realized there could be some benefit to being able to detect the ability of antibodies to neutralize specific variants, so we built a test around that idea,” said Ashutosh Chilkoti, another researcher involved in the study. “It only took us a week or two to incorporate the Delta variant in our test, and it could easily be expanded to also include the Omicron variant. All we need is the spike protein of this variant, which many groups across the world – including our group at Duke – are feverishly working to produce.”
The test can be completed in as little as 15 minutes, which compares very favorably with current techniques to achieve the same things. These involve culturing cells and a live virus, posing a variety of safety and technical hurdles.
Study in Science Advances: Rapid test to assess the escape of SARS-CoV-2 variants of concern