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From hours to minutes: Taking road less travelled to speed up COVID-19 test results

It is crucial to move beyond RT-PCR tests because they would have “very little value” in the event people with positive antibodies to the virus (meaning they have COVID-19 but their immune system has tackled the virus) are tested, according to her.

Written by Prabha Raghavan | New Delhi | Updated: March 28, 2020 10:05:46 am
novel coronavirus, SARS-COV-2, COVID-19 testing, coronavirus outbreak, economy news, indian express news At THSTI, diagnostic tools are being developed that could be a significant addition to India’s resources to test for the spread of the virus.

In a quiet biosafety lab at the Translational Health Science and Technology Institute’s (THSTI) leafy Faridabad campus on the outskirts of the national capital, glass flasks of varying sizes, stuck on green mats and filled with pink liquid have been rotating anti-clockwise, “shaking” non-stop in an incubator for days.

These flasks are growing cells containing synthetically-made copies of the novel coronavirus (SARS-COV-2), and the protein produced here will help THSTI make two diagnostic tools it hopes will speed up testing for COVID-19 disease going forward.

The first one is a rapid diagnostic tool called ‘alisa’, which will measure antibodies to the SARS-COV-2 virus using a test that uses chemically-produced DNA or RNA molecules, known as aptamers. The second test is a point-of-care tool similar to a glucometer that THSTI hopes doctors can use to check for COVID-19 in their patients within a span of 20-30 minutes.

The tools might be a significant addition to the country’s resources to test for the spread of the virus. They deviate from the real-time polymerase chain reaction (RT-PCR) tests recognised as the gold standard for COVID-19 testing, but the institute hopes to make them up to 95 per cent accurate, so the government sees merit in their use. Under THSTI executive director Dr Gagandeep Kang’s guidance, work on these tools have been on since January through collaboration of protein biochemist Dr Tripti Shrivastava and biotechnology researcher Dr Tarun Kumar Sharma.

“We have people with a fair amount of expertise looking at developing a point of care diagnostic,” says Dr Kang, adding it will “certainly” have to go through “a lot” of testing and validation before it can be approved for use here. At THSTI’s HIV Vaccine Translational Research Lab, Dr Shrivastava’s job has been to create, for these diagnostic tools, what she calls, a “valid target” — a representation of the protein that exists on the surface of the virus. “In case of actual infection, these are the surface proteins, which inside the body basically generate the antibodies,” Dr Shrivastava explains.

Once the protein is ready, expectedly this week, Dr Sharma and his team will get cracking on it with the alisa technology. This consists of experiments using a “huge” aptamer library to find the one molecule that would bind with the protein samples to detect the virus most accurately.

“It is like you have a bunch of keys (the aptamers) and, from those keys, you have to fish out the one that can open the lock (the one that helps detect the viral protein the best),” he explains.

The institute hopes samples can be tested within five hours using a colorimetric assay technique — the aptamer and other reagents would be added into several tubes containing the samples using a pipette. A few hours later, if the samples are yellow, this means the patient has COVID-19.

Unlike the government’s PCR procedure followed so far, a second test would not be required to confirm this, according to Dr Sharma. Once perfected, this would be used to create the point-of-care diagnostic, making it possible for doctors treating fever patients to screen for COVID-19 in half an hour.

If done right and on time, THSTI’s aptamer based tests may be the first of their kind in rapidly detecting COVID-19.
The World Health Organization has recommended RT-PCR and serological tests (analysing blood serums) for detecting the contagious virus.

“I’m guessing there would be several others working on aptamers (for testing COVID-19) now and it depends on who will get off the ground fastest. It’s not about who’s first,” says Dr Kang.
It is crucial to move beyond RT-PCR tests because they would have “very little value” in the event people with positive antibodies to the virus (meaning they have COVID-19 but their immune system has tackled the virus) are tested, according to her.

“Right now, PCR is a great test because it easily detects very tiny amounts of virus. While RT-PCR will continue to be useful for detection, what we will move to is also antibody based tests, where you will be looking for evidence of a fresh infection, which means you will find IgM antibodies,” she says.

THSTI’s aptamer based technology hopes to address this need for antibody-based tests. “We are already working on them. We will get to talking to the government about it when we need regulatory permission,” Dr Kang adds.

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