Highly sensitive saliva test for SARS-CoV-2 virus antigens can deliver result in under 15 minutes

Mass testing that is fast, non-invasive and able to identify cases before people show symptoms holds the key to boosting COVID-19 detection, improving contact tracing and managing disease outbreaks.

In an Australian first, scientists at the University of Technology Sydney (UTS) have used novel optical technology to design a highly sensitive saliva test for the SARS-CoV-2 virus antigens, or viral protein fragments. The test can deliver a positive result in under 15 minutes.

The rapid antigen test collects saliva in a cartridge placed in an existing hand-held device, first developed by West Australian company Alcolizer for illicit drug testing. Customized iStrip technology measures the viral load in the saliva sample, even at very low levels, and displays the result on the instrument's small screen. This device has GPS location technology and integration to cloud reporting tools to assist with contact tracing.

The test bypasses the time-consuming molecular amplification currently in use. With the quick turnaround of results and a cost of less than $A25 per test, it would allow testing rates to increase.

The iStrip technology is based on the pioneering work of UTS Professor Dayong Jin in using nanophotonic probes for disease diagnostics. The technology is sensitive enough to detect the presence of as little as a trillionth of a gram of SARS-CoV-2 viral protein.

In collaboration with long-standing industry partner Alcolizer, Professor Jin and his team have developed a prototype, with laboratory trials on live virus expected to begin within two months. Manufacture of iStrips and testing instruments would take place in Australia, at Alcolizer's fully automated robotic facility in Balcatta, Western Australia.

Professor Jin said his team's goal is detection of the presence of SARS-CoV-2 viral protein when a person has yet to show symptoms but is highly infectious.

"A person with COVID-19 may be contagious 72 hours before starting to show symptoms. With the sensitivity of our optical technology, we aim to identify the viral protein in saliva from asymptomatic but already infectious patients. This would allow for much more effective contact tracing and rapid discovery of pockets of disease before it is transmitted to others.

"Currently, a PCR swab from the nose or throat is being processed in the lab over a day or more, meaning valuable time is lost in finding, testing and isolating those known contacts of people who are infected with the virus."

Professor Jin said that currently available antigen tests are not sensitive enough to screen people when they are showing no signs of illness. They also produce a number of false-negative results, he said.

"Short of a vaccine, our best hope for containing community transmission and returning to some sort of normal life lies in a fast, highly sensitive and accurate testing regime. We believe our technology will help to realize that ambition."

Alcolizer general manager Roger Hunt said: "This will be a quantum step in the community's ability to identify COVID-19 on the front line. Once commercialized, this test will fight the disease, generate significant employment, and greatly enhance export opportunities.

A vaccine for COVID-19 is not guaranteed, and therefore a test like this is vital for reopening our borders and the economy. The test could be used in airports, hospitals, nursing homes and workplaces. The health, economic and social benefits are clear."

Roger Hunt, General Manager, Alcolizer


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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