Blood test detects COVID-19 in 20 min

Australian researchers have been able to detect positive COVID-19 cases using blood samples in about 20 minutes — a discovery that could advance worldwide efforts to limit the spread of the disease through robust contact tracing. Their work has been published in the journal ACS Sensors.

Led by BioPRIA and Monash University, including researchers from the ARC Centre of Excellence in Convergent Bio-Nano Science and Technology (CBNS), the research team developed a simple agglutination assay — an analysis to determine the presence and amount of a substance in blood — to detect the presence of antibodies raised in response to the SARS-CoV-2 infection. Their discovery could see medical practitioners across the world testing up to 200 blood samples an hour, or even up to 700 an hour in hospitals with high-grade diagnostic machines — about 16,800 each day.

The researchers collaborated with clinicians at Monash Health to collect blood samples from people recently infected with COVID-19, as well as samples from healthy individuals sourced before the pandemic emerged. Tests on 10 clinical blood samples involved incubating patient plasma or serum with red blood cells previously coated with short peptides representing pieces of the SARS-CoV-2 virus.

If the patient sample contained antibodies against SARS-CoV-2, these antibodies would bind to peptides and result in aggregation of the red blood cells. Researchers then used gel cards to separate aggregated cells from free cells, in order to see a line of aggregated cells indicating a positive response. In negative samples, no aggregates in the gel cards were observed.

“Detection of antibodies in patient plasma or serum involves pipetting a mixture of reagent red blood cells (RRBCs) and antibody-containing serum/plasma onto a gel card containing separation media, incubating the card for 5–15 minutes, and using a centrifuge to separate agglutinated cells from free cells,” said Dr Simon Corrie, a senior lecturer at Monash University and Chief Investigator at the CBNS.

“We found that by producing bioconjugates of anti-D-IgG and peptides from SARS-CoV-2 spike protein, and immobilising these to RRBCs, selective agglutination in gel cards was observed in the plasma collected from patients recently infected with SARS-CoV-2 in comparison to healthy plasma and negative controls,” added BioPRIA Director Professor Gil Garnier.

“Importantly, negative control reactions involving either SARS-CoV-2-negative samples, or RRBCs and SARS-CoV-2-positive samples without bioconjugates, all revealed no agglutination behaviour.”

While swab/PCR tests are currently used to identify people who are currently infected with COVID-19, the agglutination assay can determine whether someone had been recently infected once the infection is resolved — and could potentially be used to detect antibodies raised in response to vaccination. Study findings could thus help high-risk countries with population screening, case identification, contact tracing, confirming vaccine efficacy during clinical trials and vaccine distribution.

“This simple, rapid and easily scalable approach has immediate application in SARS-CoV-2 serological testing and is a useful platform for assay development beyond the COVID-19 pandemic,” said Professor Mark Banaszak Holl, Head of Chemical Engineering at Monash University.

A patent for the innovation has now been filed and researchers are seeking commercial and government support to upscale production.

“Funding is required in order to perform full clinical evaluation across many samples and sites,” Professor Banaszak Holl said. “With commercial support, we can begin to manufacture and roll out this assay to the communities that need it. This can take as little as six months depending on the support we receive.”

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