January 23, 2022

New rapid test can measure antibody efficacy against Covid variants, scientists say

A new rapid test is able to identify how effective a person’s immune system is against Covid variants, a study has found.

Scientists have created a test that they say is very effective in measuring power of antibodies to fight against variants such as omnicron and delta.

The test could also help doctors identify which monoclonal anti-viral antibodies to treat a Covid patient with, the researchers said.

The test, called the Covid-19 Variant Spike-ACE2-Competitive Antibody Neutralisation (CoVariant-SCAN) assay, uses a polymer brush coating that only allows desired biomarkers to attach to the slide when it is wet.

Researchers say the non-stick surface makes the test very sensitive to low levels of the biomarkers being targeted.

Scientists are able to print different “molecular traps” on different areas of the slide to be able to catch multiple biomarkers at once.

Fluorescent human ACE2 proteins – the cellular targets of the virus’s spike protein – are printed on a slide.

Spike proteins specific to each variant of Covid are also printed at different specific locations.

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

In the presence of neutralising antibodies, the spike proteins cannot grab onto the ACE2 proteins, making the slide glow less, and indicating the effectiveness of the antibodies.

The omicron variant has been found to have 32 mutations on its spike protein. Some scientists have said the high number is worrying as it may show that the variant is more transmissible and able to evade natural and vaccine immunity.

Cameron Wolfe, associate professor of medicine at the US-based 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?”

While developing a test for coronavirus antibodies and biomarkers, the researchers realised there could be some benefit to being able to detect the ability of antibodies to neutralise specific variants.

The technology was tested in a number of different ways, with researchers trying monoclonal antibodies either derived from real-life patients or from Regeneron’s commercial prophylactic treatment.

Scientists also tested plasma taken from healthy vaccinated people and those currently infected with the virus.

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

The findings have been published in the journal Science Advances.

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