Scientists have developed a low-cost swab test that candiagnose COVID-19 infection in about 45 minutes, an advance that may helppublic health officials scrambling to cope with testing backlogs as the numberof cases continues to climb.
The test named the “SARS-CoV-2 DETECTR” is easy toimplement and to interpret, and requires no specialised equipment, saidresearchers from the University of California, San Francisco (UCSF) in the US.
This quality is likely to make the test, described in apaper published in the journal Nature Biotechnology, more widely available thanthe current crop of COVID-19 test kits, they said.
Though the new test has yet to receive formal approval forclinical use from the US Food and Drug Administration, the researchers areclinically validating the test in an effort to fast-track the approval process.
“The introduction and availability of CRISPR technologywill accelerate deployment of the next generation of tests to diagnose COVID-19infection,” said Charles Chiu, a professor at UCSF, and co-lead developerof the new test.
The new SARS-CoV-2 DETECTR assay is among the first to useCRISPR gene-targeting technology to test for the presence of the novelcoronavirus, the researchers said.
Since CRISPR can be modified to target any genetic sequence,the developers “programmed” the test to home in on two target regionsin the genome of the novel coronavirus.
One of these sequences is common to all”SARS-like” coronaviruses, while the other is unique to SARS-CoV-2,which causes COVID-19, according to the researchers.
Testing for the presence of both sequences ensures that thenew DETECTR tool can distinguish between SARS-CoV-2 and closely relatedviruses, they said.
Much like the diagnostic kits currently in use, the new testcan detect the novel coronavirus in samples obtained from respiratory swabs,the researchers said.
While the widely used tests based on polymerase chainreaction (PCR) techniques take about four hours to produce a result from arespiratory sample, the new DETECTR test takes only 45 minutes, rapidlyaccelerating the pace of diagnosis, they said.
Researchers noted that another key advantage of the newDETECTR test is that it can be performed in virtually any lab, usingoff-the-shelf reagents and common equipment.
This stands in stark contrast to PCR-based tests, whichrequire expensive, specialized equipment, limiting those tests to well-equippeddiagnostic labs, they said.
The new DETECTR test, researchers said, is easy tointerpret: much like a store-bought pregnancy test, dark lines that appear ontest strips indicate the presence of viral genes.
They said it is very sensitive and can detect the presenceof as few as 10 coronaviruses in a microlitre of fluid taken from a patient —a volume many hundreds of times smaller than an average drop of water.
Though slightly less sensitive than existing PCR-basedtests, which can detect as few as 3.2 copies of the virus per microlitre, thedifference is unlikely to have a noticeable impact in diagnosis, as infectedpatients typically have much higher viral loads, the researchers said.