As reported on September 27, 2020, the Drugs Controller General of India (DCGI) approved an accurate and low-cost paper-based test strip to detect Covid-19 in less than 30 minutes, for commercial launch. The test strip is developed by a research team led by Debojyoti Chakraborty and Souvik Maiti of the Council of Scientific and Industrial Research (CSIR) and Tata Group. The development comes at a time when India has been conducting an average of 10 lakh tests daily.
Salient Features of the Test Kit
The test kit has the following features:
- The Feluda test kit uses indigenously developed CRISPR gene-editing technology to identify and target the genetic material of the virus that causes Covid-19, namely, SARS-CoV2.
- The test matches accuracy levels of RT-PCR tests, considered the gold standard in the diagnosis of Covid-19, has a quicker turnaround time, and requires less expensive equipment.
- It has met high quality benchmarks, with 96 per cent sensitivity and 98 per cent specificity for detecting novel coronavirus.
- It is also the world’s first diagnostic test to deploy a specially adapted Cas9 protein to successfully detect the virus, as compared to other CRISPR tests, which use CAS12 and CAS13 proteins to detect SARS-CoV2.
- It is similar to a pregnancy test strip that will just change colour upon detection of the virus and can be used in a simple pathological lab. As per Dr Debojyoti Chakraborty, the Cas9 protein is barcoded to interact with the SARS-CoV2 sequence in the patient’s genetic material. The Cas9-SARS-CoV2 complex is then put on the paper strip, where using two lines (one control, one test) makes it possible to determine if the test sample was positive.
- It costs just about Rs 500 while the RT-PCR test costs anywhere between Rs 1,600 to Rs 2,000. Antibody tests can give results in 20-30 minutes, but costs somewhere between Rs 500 and Rs 600. Another rapid antigen test kit interprets a positive or negative test in 30 minutes and costs Rs 450. Similarly, TruNat test provides results within one hour, but the kit comes for about Rs 1,300.
The term ‘Feluda’ is a fictional private detective from West Bengal, created by renowned writer and filmmaker Satyajit Ray. Here, the term is an acronym for FNCAS9 Editor Linked Uniform Detection Assay. While working under the sickle cell mission for genome diagnostics and therapeutics, the CSIR research team realised that the technology could be harnessed to quickly develop a new diagnostic test for Covid-19.
CRISPR, discovered by Jennifer Anne Doudna, short form for Clustered Regularly Interspaced Short Palindromic Repeats, is a gene-editing technology, used in correcting genetic defects and treating and preventing the spread of diseases. This technology can detect specific sequences of DNA within a gene and uses an enzyme functioning as molecular scissors to snip it. The organisms use CRISPR-derived RNA and various Cas proteins, including Cas9. With this technology, researchers can easily alter DNA sequences and modify gene function. Furthermore, the technology can also be configured to detect many other pathogens in the future. Initially discovered in the E.coli genome in 1987, their functions were elucidated in 2007 as a safeguard against bacteriophages.
In May 2020, the United States had granted emergency-use approval of the world’s first CRISPR-based test for Covid-19, developed by Massachusetts Institute of Technology and Harvard University.
In March 2020 RT-PCR testing centres were available. Later, cartridge-based tests were approved by ICMR like TrueNat, CBNAAT, Abbott, and Roche. In the month of June 2020, rapid antigen kits were approved for testing.
Even though RT-PCR (reverse transcription-polymerase chain reaction) remains the gold standard of frontline testing for Covid-19, the Health Ministry has introduced a range of other tests from time to time as the country ramps up its testing to nearly 2.15 lakh per day.
Courtesy: Indian Express