A new rapid test can identify the effectiveness of antibodies against Covid variants, including Omicron, in just 15 minutes.
Scientists say the quick and simple test could measure the patient’s immunity to several variants of Covid-19 – such as Omicron and Delta at once – and also indicate which treatments to use.
Biomedical engineers at Duke University in the United States designed the test to quickly and easily assess how well a person’s neutralizing antibodies fight infection with several variants of Covid.
They say the test could potentially tell doctors how protected a patient is against newer variants and those currently circulating in a community or, conversely, what antibodies to treat a Covid-19 patient.
Dr Cameron Wolfe, associate professor of medicine at Duke University School of Medicine, said: “We currently have no rapid way to assess variants, neither their presence in an individual, nor the capacity of the antibodies we have. to make a difference.
“It is one of the lingering fears that as we successfully vaccinate more and more people, a variant may emerge that more drastically escapes the vaccine-induced neutralization of antibodies.
“And if that fear came true – if Omicron turned out to be the worst-case scenario – how would we know soon enough?”
Professor Ashutosh Chilkoti, President of Biomedical Engineering at Duke, said: “While developing a point-of-care test for Covid-19 antibodies and biomarkers, we realized that there might be some benefit to being able to detect the ability of antibodies to neutralize variants, so we built a test around this idea.
“It only took us a week or two to incorporate the Delta variant into our test, and it could easily be extended to include the Omicron variant as well.
“All we need is this variant’s spike protein, which many groups around the world, including our group at Duke, are feverishly working to produce.”
The team called their test the Covid-19 Variant Spike-ACE2-Competitive Antibody Neutralization test, or CoVariant-SCAN for short.
The test technology relies on a polymer brush coating that acts as a kind of non-stick coating to prevent anything but the desired biomarkers from attaching to the test slide when wet.
Professor Chilkoti explained that the high efficiency of the non-stick shield makes the test “incredibly sensitive” even at low levels of its targets.
The approach allows researchers to print different molecular traps on different areas of the slide to capture multiple biomarkers at once.
Researchers print fluorescent human ACE2 proteins – the cellular targets of the virus’s infamous spike protein – onto a slide.
They also print spike proteins specific to each variant of Covid in different specific places.
When the test is run, the ACE2 proteins break away from the slide and are captured by the spike proteins still attached to the slide, causing the slide to glow.
But in the presence of neutralizing antibodies, the spike proteins are no longer able to cling to the ACE2 proteins, which makes the slide less shiny, indicating the effectiveness of the antibodies.
By printing different variants of the Covid-19 spike protein on different parts of the slide, scientists can see how effective the antibodies are at preventing each variant from simultaneously latching onto their human cellular target.
The Duke team tested the technology in several ways. They also tested plasma taken from healthy vaccinated people and those currently infected with the virus.
Jake Heggestad, a doctoral student working in Professor Chilkoti’s lab, said: “In all of our tests, the results largely mimicked what we’ve seen in the literature.
“And in this case, not finding anything new is a good sign, because it means that our test is working as well as the methods currently in use.”
Researchers say the critical difference between CoVariant-SCAN and current methods is the speed and ease with which it can produce results.
Typical current approaches require the isolation of live viruses and the cultivation of cells, which can take 24 hours or more and require a wide variety of safety precautions and specially trained technicians.
The CoVariant-SCAN, on the other hand, does not require a live virus, is easy to use in most settings, and takes less than an hour – potentially just 15 minutes – to produce accurate results.
Now, Duke’s team are working to streamline the technique into a microfluidic chip that could be mass-produced and report the results with just a few drops of blood, plasma, or other liquid samples containing antibodies.
The same approach has already been proven to work on a similar test that can distinguish Covid-19 from other coronaviruses.
Dr Wolfe said: “We would like to have real-time visibility of emerging variants and understand who still has functional immunity.
“Additionally, it suggests that there may be a technique to quickly assess which synthetic monoclonal antibody would be best to administer to a patient with a particular emerging variant.
“Right now we really have no way of knowing that in real time, so we’re relying on epidemiological data that can follow weeks behind.”
He added: “The reverse is also true. To be able to pre-screen an individual’s antibodies and predict whether they were sufficiently protected against a particular variant that they may be about to encounter while traveling, or that emerges in their region.
“We have no way of doing it right now. But a test like CoVariant-SCAN could make all of these scenarios possible.”
The results were published in the journal Science Advances.
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