Scientists develop faster COVID-19 test
Technique avoids RNA degradation and time-consuming extraction

Date:
August 16, 2021
Source:
NIH/National Eye Institute
Summary:
Scientists have developed a new sample preparation method to detect
SARS- CoV-2, the virus that causes COVID-19. The method bypasses
extraction of the virus' genetic RNA material, simplifying sample
purification and potentially reducing test time and cost.



FULL STORY ========================================================================== Scientists at the National Institutes of Health (NIH) have developed
a new sample preparation method to detect SARS-CoV-2, the virus that
causes COVID-19.

The method bypasses extraction of the virus' genetic RNA material,
simplifying sample purification and potentially reducing test time and
cost. The method is the result of a collaboration among researchers at
the National Eye Institute (NEI), the NIH Clinical Center (CC), and the National Institute of Dental and Craniofacial Research (NIDCR).


========================================================================== Diagnostic testing remains a crucial tool in the fight against the
COVID-19 pandemic. Standard tests for detection of SARS-CoV-2 involve amplifying viral RNA to detectable levels using a technique called
quantitative reverse transcription PCR (RT-qPCR). But first, the RNA
must be extracted from the sample. Manufacturers of RNA extraction kits
have had difficulty keeping up with demand during the COVID-19 pandemic, hindering testing capacity worldwide.

With new virus variants emerging, the need for better, faster tests is
greater than ever.

A team led by Robert B. Hufnagel, M.D., Ph.D., chief of the NEI Medical Genetics and Ophthalmic Genomic Unit, and Bin Guan, Ph.D., a fellow at
the Ophthalmic Genomics Laboratory at NEI, used a chelating agent made
by the lab supply company Bio-Rad called Chelex 100 resin to preserve SARS-CoV-2 RNA in samples for detection by RT-qPCR.

"We used nasopharyngeal and saliva samples with various virion
concentrations to evaluate whether they could be used for direct RNA detection," said Guan, the lead author of a report on the technique,
which published this week in iScience. "The answer was yes, with markedly
high sensitivity. Also, this preparation inactivated the virus, making
it safer for lab personnel to handle positive samples." Hufnagel's team
made their discovery by testing a variety of chemicals using synthetic and human samples to identify those that could preserve the RNA in samples
with minimal degradation while allowing direct detection of the virus
by RT-qPCR.

To validate the test, NIDCR's Blake M. Warner, D.D.S., Ph.D., M.P.H.,
and his team collected patient samples (on Research Protocol NIH IRB
20-D-0094) and stored them in either viral transport media, or the newly developed chelating- resin-buffer at the NIH Symptomatic Testing Facility.

The samples in viral transport media were tested by the COVID-19 testing
team at NIH's Clinical Center, led by Karen M. Frank, M.D., Ph.D.,
using conventional RNA extraction and RT-qPCR testing. The samples in
the chelating- resin-buffer were heated and the viral RNA was, then,
tested by RT-qPCR. The new preparation significantly increased the RNA
yield available for testing, compared to the standard method.

"We think this novel methodology has clear benefits of
increasing sensitivity, cost and time savings for testing,"
said Hufnagel, "The method stabilizes the RNA at room temperature
for easier transport, storage, and handling in clinical settings." ========================================================================== Story Source: Materials provided by NIH/National_Eye_Institute. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Bin Guan, Karen M. Frank, Jose' O. Maldonado, Margaret Beach, Eileen
Pelayo, Blake M. Warner, Robert B. Hufnagel. Sensitive
extraction-free SARS-CoV-2 RNA virus detection using a chelating
resin. iScience, 2021; 102960 DOI: 10.1016/j.isci.2021.102960 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210816112107.htm

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