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Covid breakthrough as test could measure levels of immunity in just 15 minutes

Finding out about the presence of Covid antibodies could take just 15 minutes using a new rapid test.

The quick and simple test could measure your immunity against a range of coronavirus variants – including the new worrying Omicron strain – all at once, say scientists.

The test will also be able to indicate which treatments should be used.

Biomedical engineers at Duke University in the United States have devised the test to quickly and easily assess how well a person’s neutralising antibodies fight infection from multiple strains of the virus.

Scientists also say that the test could provide information to doctors to allow them to protect patients from variants currently circulating as well as new strains that could develop over time.

The test returns results in just 15 minutes.

This information would let health professionals know which antibodies would be required to treat someone with the disease.

Doctor Cameron Wolfe, Associate Professor of medicine at Duke University School of Medicine, said: “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.

“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 neutralisation.

“And if that fear came true – if Omicron turned out to be a worst-case scenario – how would we know quickly enough?”

Professor Ashutosh Chilkoti, Chair of Biomedical Engineering at Duke, said: “While developing a point-of-care test for Covid-19 antibodies and biomarkers, we realised there could be some benefit to being able to detect the ability of antibodies to neutralise specific variants, so we built a test around that idea.

“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 team of scientists have named their test the Covid-19 Variant Spike-ACE2-Competitive Antibody Neutralization assay – or CoVariant-Scan for short.

The test work by using a polymer brush coating that acts as a sort of non-stick coating to stop anything but the desired biomarkers from clinging to the test when wet.

The details picked up will allow the test to identify the antibodies – if any- that are present.

Prof Chilkoti expalined that the high effectiveness of the non-stick shield makes the test “incredibly sensitive” to even low levels of its targets.

The approach will also allow researchers to print different molecular traps on different areas of the slide to catch multiple biomarkers at once.

Researchers print fluorescent human ACE2 proteins – the cellular targets of the virus’s infamous spike protein – on a slide.

They also print spike proteins specific to each variant of Covid at different specific locations.

When the test is run, the ACE2 proteins detach from the slide and are caught by the spike proteins still attached to the slide, causing the slide to glow.

But in the presence of neutralising antibodies, the spike proteins are no longer able to grab on to the ACE2 proteins, making the slide glow less, indicating the effectiveness of the antibodies.

By printing different variants of the Covid-19 spike protein on different portions of the slide, scientists can see how effective the antibodies are at preventing each variant from latching onto their human cellular target simultaneously.

The Duke team tested the technology several ways including using plasma taken from healthy vaccinated people and those currently infected with the virus.

Jake Heggestad, a PhD student working in Prof Chilkoti’s lab, said: “In all of our tests, the results largely mimicked what we’ve been seeing in the literature.

“And in this case, not finding anything new is a good sign, because it means our test is working just as well as the methods currently being used.”

The researchers say that the critical difference between the CoVariant-SCAN and current methods is the speed and ease with which it can produce results.

Typical current approaches require isolating live virus and culturing cells, which can take 24 hours or more and requires a wide variety of safety precautions and specially trained technicians.

The CoVariant-SCAN, in contrast, does not require live virus, is easy to use in most settings and takes less than an hour – potentially just 15 minutes – to produce accurate results.

Now the Duke team are working to streamline the technique into a microfluidic chip that could be mass-produced and report results with only a few drops of blood, plasma or other liquid sample 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 love to have real-time visibility of the emerging variants and understand who still has functional immunity.

“Additionally, this hints that there might be a technique whereby you could quickly assess which synthetic monoclonal antibody might be best to administer to a patient with a particular emergent variant.

“Currently we really have no real-time way of knowing that, so we rely on epidemiological data that can track 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 they are perhaps about to run into while travelling, or that is emerging in their area.

“We have no way of doing that at the present time. But a test like the CoVariant-SCAN could make all of these scenarios possible.”

The findings were published in the journal Science Advances.

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