DURHAM, N.C. — Biomedical engineers at Duke University have devised a test to quickly and easily assess how well someone's antibodies fight infection from multiple coronavirus variants.
The test, dubbed the COVID-19 Variant Spike-ACE2-Competitive Antibody Neutralization assay, or CoVariant-SCAN, could potentially tell doctors how protected a patient is from variants circulating in a community as well as new ones. It also could indicate which monoclonal antibody treatments would best help a patient.
"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," Dr. Cameron Wolfe, associate professor of medicine at the Duke University School of Medicine, said in a statement. "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’s technology hinges on a polymer brush coating that acts as a non-stick surface to stop anything but the desired biomarkers from attaching to a test slide when wet. The effectiveness of the non-stick shield makes the test sensitive to even low levels of its targets and allows researchers to print different molecular traps on various areas of the slide to catch multiple biomarkers at once, testing for protection from multiple variants with one test.
Researchers printed fluorescent human ACE2 proteins – the cellular targets of the coronavirus’ infamous spike protein – on a slide. They also printed spike proteins specific to each variant at different locations on the slide. When the test is run, the ACE2 proteins detach and are caught by the spike proteins on the slide, causing it to glow.
But in the presence of antibodies, the spike proteins aren't able to grab the ACE2 proteins, making the slide glow less and indicating the effectiveness of the antibodies. By printing different variants of the spike protein on different portions of the slide, researchers can see how effective the antibodies are at preventing each variant from latching onto their human cellular target.
To determine someone's resistance to virus variants, scientists currently have to isolate live virus and culture some cells, which can take 24 hours or more and requires a variety of safety precautions and specially trained technicians. Duke researchers said the CoVariant-SCAN test doesn't require any live virus, can be used in most settings and takes less than an hour – possibly as little as 15 minutes – to produce accurate results.
"We would love to have real-time visibility of the emerging variants and understand who still has functional immunity," Wolfe said. "To be able to pre-screen an individual's antibodies and predict whether they were sufficiently protected against a particular variant they are perhaps about to run into while traveling or that is emerging in their area. we have no way of doing that at the present time."
Researchers are now working to streamline the technique into a chip that could be mass produced and report results with only a few drops of blood, plasma or other liquid sample containing antibodies. But it would likely be a year before the test could get approval from the U.S. Food and Drug Administration and be in doctors' offices and clinics.
The research was conducted by a team led by Ashutosh Chilkoti, the Alan L. Kaganov Distinguished Professor and chairman of Duke's Department of Biomedical Engineering, and was funded by the National Institutes of Health, the National Science Foundation and the Department of Defense's Defense Advanced Research Projects Agency. It was published online Friday in the journal Science Advances.
