Have you ever wondered how a COVID-19 test can be done using a paper strip and can give results in less than an hour?
We all know that the results of the COVID-19 test are time-consuming. To overcome this problem, a team led by two scientists, Dr. Souvik Maiti and Dr. Debjyoti Chakraborty, Institute of Genomics and Integrative Biology [CSIR-IGIB] in New Delhi have come up with a simple strip-test to tell if you have COVID-19. This kit has received regulatory approvals from the Drug Controller General of India (DCGI) for commercial launch.
Feluda
Feluda is a paper-based test strip that detects COVID-19 in an hour. The name comes from Satyajit Ray’s popular fictional detective, ‘Feluda‘. FNCAS9 Editor-Limited Uniform Detection Assay (FELUDA), uses an indigenously developed, cutting-edge CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technology for detection of the genomic sequence of SARS-CoV-2 virus, the scientists said. This Indian kit was shared with Tata Sons for production and manufacturing.
Testing
There are four steps in the testing process. Viral RNA is extracted from the nasal and throat swab samples collected from a suspected patient. The viral RNA is converted into DNA using the reverse transcriptase method with the help of a PCR (polymerase chain reaction) machine, which also amplifies the DNA multiple times, making several copies. The Feluda mix is prepared, containing the Cas9 protein, which can bind to the DNA of the virus. Chemicals are added to the CRISPR complex and to the DNA during the amplification process to generate a colorimetric reaction on the paper strip. The paper strip is immersed in the Feluda mix. It generates two lines for positive and one line for negative, which is similar to a pregnancy test kit.
The price of the test kit is cheaper than the RT-PCR test kit. A sensitive test is one which detects almost everyone who has the disease. A specific test, on the other hand, rules out almost everyone who doesn’t have the disease. The accuracy of any test is based on these two aspects.
A test’s sensitivity indicates the likelihood of false-negative results; its specificity indicates the likelihood of false-positive results. Feluda had 96% sensitivity and 98% specificity for detecting the novel coronavirus, meeting ICMR’s quality benchmark, which is based on a gene-editing technology called CRISPR.
CRISPR is a gene-editing technology and is used in correcting genetic defects that can also help in the treatment and prevention of diseases. This technology can detect specific sequences of DNA within a gene, and uses an enzyme functioning as molecular scissors to snip it.
Feluda, CSIR scientists said, was tested on samples of 2,000 people, including those who had already tested positive for coronavirus. Feluda test kit can help stem the pathogen’s spread in poor and remote areas. This could be a boon to the medical team fighting against COVID-19.
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