A team of scientists in India has developed an inexpensive paper test to detect infection with the Coronavirus, and the test can give quick results similar to a pregnancy test. BBC reporters, Sotik Biswas and Krotika Pathi shed light on how this test works.
The test, called “Veloda” and is the name of a famous investigator in a group of Indian stories, is based on a genetic gene-editing technique known as “CRISPR”. Scientists estimate that the test results will appear in less than an hour and cost 500 rupees (about 6.75 dollars). ).
The leading Indian company, Tata, is sponsoring the “Veloda” test, which may be the world’s first paper-based test to detect COVID-19 infection to be put on the market.
“This is a simple, accurate, reliable, scalable and affordable test,” Professor K Vijay Raghavan, a prominent scientific advisor to the Indian government, told the BBC.
Researchers at the Delhi-based CSIR Institute of Genomics and Integrative Biology, which developed the Veloda test, were able to test the test on samples that included about 2,000 patients, including people who had already tested positive for the Coronavirus.
The researchers concluded that the new test showed a sensitivity of 96 percent and an accuracy of 98 percent. The accuracy of the test depends on these two ratios, as the highly sensitive test can detect almost everyone infected with the disease, and the test, which is characterized by a high degree of accuracy, correctly excludes everyone who is not infected with the disease.
The first ratio ensures that there are not many false negative results, while the second ratio ensures that there are not many false positive results. The Medicines Regulatory Authority of India has approved the test for commercial use.
India is the second largest country in the world in terms of the number of cases of Covid-19, as the country has so far recorded more than six million cases of infection and 100,000 deaths.
Compared to its slow start, India is currently testing 1 million samples daily in more than 1,200 laboratories across the country.
The country uses two tests: The first is the BCR smear test, which uses chemicals to enlarge the gene carrying the virus in the laboratory. The second is the rapid antibody test, which works by detecting virus residues in the sample.
The BCR test is generally reliable, and costs 2,400 rupees, but it contains low false positives as well as low false negative rates.
The antibody tests are cheaper and more accurate in detecting positive cases, but they show false negative results more than the BCR test.
Anant Bhan, a researcher in global health and health policy, says that expanding testing in India does not mean that they are easily available yet.
“There are still long waiting lists when no tests are available. We run a lot of fast antibody tests that have problems with false negative results,” Bahan told the BBC.
It is believed that the Feloda test can replace antibody tests because it may be relatively cheaper and more accurate.
Anurag Agarwal, director of the Institute of Genomics and Integrative Biology, told the BBC: “The new test is as reliable as the PCR test. It is also faster and can be performed in smaller laboratories without advanced equipment.”
The collection of samples for the “Veloda” test will be similar to the “BCR” test, by means of a swab inserted a few inches into the nose to check for the presence of the Corona virus in the back of the nasal passage, and India does not yet allow Covid-19 tests from saliva samples. .
The traditional “BCR” test is based on sending the sample to an accredited laboratory, where the test must pass several “cycles” of work, before diagnosing a virus infection.
The new “Veloda” test uses “CRISPR”, which includes editing genes to detect the virus.
According to the researchers, gene editing works in a similar way to word processing, such as using the pointer to correct a typo by removing the incorrect letter and entering a correct letter, and this technique is very accurate and can remove and add a single genome. Gene editing is mainly used to prevent infections and treat diseases such as sickle cell disease.
And when using “CRISPR” as a diagnostic tool – like the “Veloda” test – that tool sticks to a set of letters of the gene that carries the fingerprint of the Corona virus, highlights it, and gives a reading on a piece of paper.
The two blue lines on that test indicate a positive result, and the single blue line indicates the test result is negative.
“The test remains a limited resource, and we must make every effort to improve its availability,” says Stephen Kessler, a researcher at Harvard Medical School. “So the Feloda test is an important step along that path.”
The tests, based on the CRISPR technology, are part of a “third wave of testing” after the time-consuming and labor-intensive PCR tests, according to Thomas Tsai of the Harvard Institute for Global Health.
And many companies and research laboratories, in the United States and the United Kingdom, are developing similar paper tape tests that can be inexpensive and mass-produced, and one of the most controversial of them was the paper tape developed by “Sherlock Bioscience”, which the US Food and Drug Administration approved Use it in an emergency.
The test is said to discover “unique genetic fingerprints of any DNA or RNA sequence” in any organism or pathogen.
DNA and RNA are sister molecules responsible for storing all the genetic information that supports life.
“The paper test would be the ideal and final test that you could do from home,” Tsai says. “But of course, there are some biological limitations to the technology, as we cannot expect people to extract and enlarge RNA from home.”
Debugioti Chakraborty, a molecular scientist and key member of the team of researchers who developed the “Veloda” test, told the BBC that they are working on a prototype test that “can extract and enlarge RNA using a PCR at home.”
“We try to provide a simple, affordable and caring test, so broad-based testing is not limited to the availability of machines or manpower,” he added.
Given its large population, India has a chance to demonstrate the value of this test, says Kessler.
The vaccine will be critical to a complete cure of the epidemic, and Kessler adds: “In the ideal world I imagine, the test would be as easy as brushing your teeth or preparing toast.”
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