Singapore scientists find out rapid COVID-19 test method
Singapore (VNA) - Scientists at the Nanyang
Technological University (NTU) of Singapore on July 27 discovered a way to
deliver coronavirus testing results within 36 minutes, about a quarter of the
time required by existing gold-standard tests.
Currently, the most sensitive method of testing for the coronavirus is through
a laboratory technique called polymerase chain reaction (PCR), where a machine
amplifies genetic material by copying it over and over again so any trace of
the coronavirus can be detected.
A big problem is purifying the ribonucleic
acid (RNA) from other components in the patient sample – a process that
requires chemicals that are now "in short supply worldwide”, NTU said.
“The method developed by NTU LKCMedicine combines many of these steps and
allows direct testing on the crude patient sample, cutting down the turnaround
time from sample-to-result, and removing the need for RNA purification
chemicals,” the university added.
In PCR tests, the genetic material on the swab sample has to be extracted to
remove substances in the sample that prevent the test from working. One example
of an inhibitor is mucin, a main component of mucus.
The test designed by the NTU team uses the
“direct PCR method”, but removes the need for RNA purification – a
time-consuming and costly step.
“Instead, they added
inhibitor-resistant enzymes and reagents targeting compounds that obstruct RNA
amplification, such as mucin … these enzymes and reagents, which are
commercially available, have high resistance to such compounds that otherwise
inhibit PCR, rendering the test inaccurate," said NTU.
The biochemical mix of crude sample and inhibitor-resistant enzymes and
reagents is placed into a single tube, which is inserted into a laboratory
thermocycler, a machine used to amplify genetic material in PCR. After 36
minutes, results reveal whether there is any trace of COVID-19 “with
confidence”.
The team also tested this method on a portable
thermocycler, which can be deployed in low-resource settings and endemic areas,
pointing to the possibility of having this test done in community healthcare
settings by frontline healthcare workers.
Senior research fellow Dr Sivalingam
Paramalingam Suppiah said: “By skipping the RNA extraction step with our
direct-PCR method, we see cost savings on nucleic acid extraction kits, and
avoid the problem of reagents in short supply when lab testing is ramped up and
the demand increases globally.”/.