Rapid COVID-19 test developed to detect neutralizing antibodies with
high specificity and sensitivity

Date:
July 24, 2020
Source:
Duke-NUS Medical School
Summary:
A unique and rapid SARS-CoV-2 surrogate virus neutralisation
test (sVNT) may be the much needed boost to current COVID-19
investigations to determine infection rate, herd immunity, predicted
humoral protection, and vaccine efficacy during clinical trials.



FULL STORY ==========================================================================
As the current COVID-19 pandemic continues to adversely impact communities
and economies across the world, efficiency in testing for the infection
and antibodies is vital. A unique and rapid SARS-CoV-2 surrogate virus neutralisation test (sVNT), developed in Singapore, may be the much
needed boost to current COVID-19 investigations to determine infection
rate, herd immunity, predicted humoral protection, and vaccine efficacy
during clinical trials.


========================================================================== According to a study published in Nature Biotechnology, the sVNT is
capable of detecting the functional neutralising antibodies (NAbs)
that can block the binding of the coronavirus spike protein to the angiotensin-converting enzyme 2 (ACE2) host receptor, which mimics the virus-host interaction.

The sVNT was developed by scientists from Duke-NUS Medical School, in
close collaboration with National Centre for Infectious Diseases (NCID),
Agency for Science, Technology and Research (A*STAR)'s Institute of
Molecular and Cell Biology (IMCB) Singapore, and GenScript Biotech. The scientists in Singapore and China validated the test across two patient cohorts, with a sample size of 250 from China and 375 from Singapore,
achieving 99-100 per cent specificity and 95-100 per cent sensitivity.

"The sVNT kit can detect functional NAbs in an hour and differentiate
them with binding antibodies (BAbs), without the need for live virus or a biocontainment facility. It also has the ability to detect total receptor binding domain (RBD)-targeting neutralising antibodies in patient samples,
in contrast to most SARS-CoV-2 antibody tests published or marketed,
which are isotype-specific.

This makes the sVNT accessible to the broader community for both research
and clinical applications," said Professor Wang Linfa, Director of
Duke-NUS' Emerging Infectious Diseases programme. Prof Wang is considered
among the most recognised international experts on emerging zoonotic
viruses and is currently serving on multiple WHO committees on COVID-19.

Infection or immunity to the virus is diagnosed by the presence of
NAbs in a patient's blood sample, which would block the RBD-ACE2
interaction. At this critical moment of the international response to
the COVID-19 outbreak, there is an urgent need for a robust serological
test that detects NAbs, for accurate assessment of infection prevalence
and protective immunity at the individual and population level. Antibody
tests, such as the conventional virus neutralization test (cVNT) and
the pseudovirus-based virus neutralization test (pVNT), remain the only platforms for detecting NAbs. However, both require live viruses and
cells, highly skilled operators, and days to obtain results.

Other assays, such as the enzyme-linked immunosorbent assay (ELISA)
detect Babs but are unable to differentiate between BAbs and NAbs.

The sVNT can also measure NAbs from different animals in a
species-independent manner. It can therefore be a powerful tool to
investigate the role of animals in the transmission of COVID-19 from
natural reservoirs to intermediate hosts.

"It is an increasingly critical clinical question about what proportion of patients with COVID-19 develop antibodies to COVID-19, how long it lasts,
and whether antibodies protect patients from reinfection. Neutralising
antibody is the gold-standard serological platform to determine
this. Unfortunately, the conventional virus neutralisation assay is
laborious, time-consuming and requires Biosafety Level 3 for COVID-19. The
sVNT developed by Prof Wang, in collaboration with the national COVID-19 PROTECT study, makes it accessible to all hospital laboratories, and is a
great advance in COVID-19 serological assays," said Associate Professor
David Lye, Director, Infectious Disease Research and Training Office
(IDRTO), and Senior Consultant, NCID.

Dr Sidney Yee, CEO of A*STAR's Diagnostics Development Hub, said,
"Due to the SARS outbreak in 2003, researchers in Singapore have gained important insights into that virus, which shares some similarities with SARS-Cov-2. A*STAR supported the clinical tests in this collaboration with Duke-NUS by sharing data drawn from our research experience in SARS. We
are happy to have contributed to the validation of this innovative test,
which will be instrumental in our fight against the global pandemic."
"We are very pleased that Prof Wang's work has come to fruition," said
Mr David Martz, Vice President of New Product Management, Life Sciences
Group, at GenScript. "This is great news for scientists researching
herd immunity and vaccine efficacy as they will now have access to this innovative research tool to accurately determine the level of neutralising antibodies in a population.

We believe the test will shed new light on the current plaguing mysteries
of COVID-19." The sVNT kit is commercialised by GenScript and offered worldwide under the brand cPass[TM] for research use only. GenScript
has also filed for Emergency Use Authorisation with the US Food and Drug Administration and this filing is currently under review.


========================================================================== Story Source: Materials provided by Duke-NUS_Medical_School. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Chee Wah Tan, Wan Ni Chia, Xijian Qin, Pei Liu, Mark I.-C. Chen,
Charles
Tiu, Zhiliang Hu, Vivian Chih-Wei Chen, Barnaby E. Young, Wan
Rong Sia, Yee-Joo Tan, Randy Foo, Yongxiang Yi, David C. Lye,
Danielle E. Anderson, Lin-Fa Wang. A SARS-CoV-2 surrogate virus
neutralization test based on antibody-mediated blockage of
ACE2-spike protein-protein interaction.

Nature Biotechnology, 2020; DOI: 10.1038/s41587-020-0631-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200724104142.htm

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