Rapid test for the determination of antibodies against Sars-Cov-2

Date:
July 30, 2020
Source:
Ruhr-University Bochum
Summary:
Researchers present a test that determines the amount of
neutralizing antibodies within a short period of time.



FULL STORY ==========================================================================
To determine immunity to Sars-Cov-2 and the effectiveness of potential vaccines, the amount of neutralising antibodies in the blood of recovered
or vaccinated individuals must be determined. A traditional neutralisation
test usually takes two to three days and must be carried out with
infectious coronaviruses in a laboratory complying to biosafety level 3. A Swiss-German research team from Bern and Bochum has launched a test that
takes only 18 hours and doesn't have high biosafety requirements. The researchers have published their report in the journal Vaccines on 15
July 2020.


==========================================================================
The test was developed at the Institute of Virology and Immunology (IVI)
of the University of Bern and the Swiss Federal Office for Food Safety
and Animal Health, and evaluated in cooperation with colleagues from the Ruhr-Universita"t Bochum (RUB) using serum samples from Covid-19 patients.

Disguising a harmless virus as Sars-Cov-2 In order to detect antibodies
against Sars-Cov-2, the researchers used another virus that doesn't
propagate. They exchanged the envelope protein of this virus for the
spike protein of the novel coronavirus, which mediates virus entry and infection. "As a result, the viruses can be identified by antibodies
against Sars-Cov-2," explains lead author Toni-Luise Meister from
the Department of Molecular and Medical Virology at Ruhr-Universita"t
Bochum. "The antibodies bind to the viruses that have been altered in this
way and neutralise them so that no longer can penetrate the host cells." Luminescence helps determine immunity Since the virus pseudotyped
in this way can't propagate in host cells, no elaborate biosafety
precautions are necessary for the test. In order to determine the amount
of antibodies, the researchers genetically modified the virus so that
green fluorescent protein and a luciferase, an enzyme from fireflies,
will be produced by infected cells. "After a single round of infection,
we can then determine how many cells show green fluorescence," says lead
author Ferdinand Zettl from the Institute of Virology and Immunology
in Bern. The green fluorescence is an indicator of infection with the pseudotyped virus. The less green cells the researchers are finding,
the more neutralizing antibodies are present which blocked the virus. In addition, a luminometer may be used to read the luminescence signal
produced by the luciferase enzyme - - another way of evaluating the test.

Quick and reliable In order to check the reliability and comparability
with the conventional neutralisation test, the researchers applied it to
blood samples from Covid-19 patients. "The direct comparison showed a good correlation between the two test systems," explains corresponding author Professor Stephanie Pfa"nder from the Department of Molecular and Medical Virology at RUB. Compared to 56 hours for the conventional test, the
new test is much faster, with only 18 hours to the test result. "Another
great advantage is that it can be carried out in almost all medical labs, because no sophisticated safety precautions are necessary," points out
Dr. Gert Zimmer from the Institute of Virology and Immunology in Bern, corresponding author of the study.


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


========================================================================== Journal Reference:
1. Ferdinand Zettl, Toni Luise Meister, Tanja Vollmer, Bastian Fischer,
Jo"rg Steinmann, Adalbert Krawczyk, Philip V'kovski,
Daniel Todt, Eike Steinmann, Stephanie Pfaender, Gert
Zimmer. Rapid Quantification of SARS- CoV-2-Neutralizing
Antibodies Using Propagation-Defective Vesicular Stomatitis
Virus Pseudotypes. Vaccines, 2020; 8 (3): 386 DOI: 10.3390/
vaccines8030386 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200730110119.htm

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