The coronavirus pandemic has created a great demand for rapidly diagnosing SARS-CoV-2 infections. (Credit: Mostphotos)

An antigen-based detection technique could be used to analyze as many as 500 samples per hour. In a recently completed study, the rapid test was able to diagnose a viral infection almost as accurately as PCR tests, which are known for their sensitivity. The new rapid test format can also be used to rapidly diagnose other respiratory infections.

The researchers developed the new rapid assay principle for viral antigen detection, applying it to diagnosing SARS-CoV-2 infections. The test is based on a phenomenon known as time-resolved Förster resonance energy transfer (TR-FRET), where energy travels between two light-sensitive molecules when they are close enough to each other. TR-FRET makes it possible to measure viral particles or the body’s own proteins by using what are known as mix-and-read-type tests on complex biological samples, such as serum or even whole blood.

They investigated the functioning of the rapid test using 48 specimens which had been selected on the basis of a positive SARS-CoV2 PCR test, with varying concentrations of viral RNA. The technique was able to detect almost all positive specimens (37/38), from which they were able to isolate SARS-CoV-2 in cell culture. In other words, the carriers were likely to continue to spread the virus at the time of sample collection.

Rapid antigen-based tests could be particularly useful for testing not only travellers, but also people at educational institutions. A TR-FRET reader roughly the size of a desktop computer is needed for the test, making it possible, at least in theory, to carry out testing almost anywhere.