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11th December 2020  Author: Paul Carton

SARS-CoV-2 Lateral-Flow Antigen Test Uses ACE-2 Receptor & Stool Specimen


There is a good indication from surveillance testing of wastewater that faecal specimens can be a reliable source for the diagnosis of a SARS-CoV-2 infection and therefore a rapid self-test of an individual's stool sample could be seen as a viable alternative to the primary invasive nasopharyngeal and oropharyngeal method. 

With most of the infections occurring primarily in private households, shared bathroom facilities have been suspected as a route for the virus to spread. This information has been taken onboard by proprietors of public venues where they have restricted bathroom use.

For example, the norovirus, also known as the winter vomiting bug, although an intestinal virus, that comes from ingestion or handling of contaminated food can be spread person-to-person by inhalation of faecal aerosols or by the faecal-to-oral route. Guidelines from health authorities strongly recommend a thorough cleaning of the bathroom and toilet bowl when there is a suspected case in the house, 

A recent study into how SARS-CoV-2 circulated within a high-rise building into households living above each other concluded that the drainage system carrying faecal aerosols between the apartments had most likely been the cause of the coronavirus spreading between the households.

Apollo Biomedical USA, based in Salt Lake City, Utah, are in the process of filing for FDA-EUA for its novel patent-pending SARS-CoV-2 rapid antigen test that can take either a stool or sputum specimen and are able to manufacture between 300,000-500,000 a day. 

The test is already CE-marked and is currently under evaluation in EU-member countries. According to Michael Berger, President at Apollo Biomedical, the test showed 95% sensitivity and 100% specificity in an early clinical trial when it was validated using a Chinese Food and Drug Administration (CFDA) approved RT-PCR test from Shanghai ZJ Bio-Tech Co., Ltd.

But unlike other rapid lateral-flow antigen tests on the market that use an immobilized anti-SARS-CoV-2 protein antibody on the test strip this ‘Novel Spike Glycoprotein Detection Kit’ utilizes in vitro expressed human angiotensin I converting enzyme 2 (ACE2) protein to capture and visualize viral particles in test samples.

Developed in partnership with Professor Chun Lei Fan back in February 2020, this approach was selected for a variety of reasons: “The advantage of our test strips is that the receptor method is not affected by virus mutation and the specificity of the S-protein detection is much better than that of N-protein detection” said Prof. Fan.

“Sputum and stool testing is non-invasive and more acceptable than nasopharyngeal swab sampling, as well as the fact that sputum and faeces have a higher viral load than saliva or nasopharyngeal swabs, making the detection more accurate” explained Fan.

The test requires the user to collect specimens from 6 points of a stool sample, using just one swab or alternatively it can be collected with a swab after a bowel movement prior to using toilet paper. The swab must then be inserted into a buffering agent and allowed to stand for a few minutes. A dropper pipette (supplied) is then used to aspirate the fluid and then applied to the lateral-flow inlet. 

The test strip is intended for home testing use, with an easy to test protocol delivering a visual result in just 15-minutes.


    

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Date Published: 11th December 2020

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