Cheaper, quicker kit can help in scaling up testing: Researcher
India’s first diagnostic kit for Covid-19 based on the gene editing technology CRISPR Cas9 has been approved for commercial use by the Drug Controller General of India. The kit was found to have high sensitivity of 96% and specificity of 98%, meaning it can accurately detect both positive and negative casesUpdated: Sep 22, 2020, 08:54 IST
India’s first diagnostic kit for coronavirus disease (Covid-19) based on the gene editing technology CRISPR Cas9 has been approved for commercial use by the Drug Controller General of India. The testing kit, developed by researchers from the Council for Scientific and Industrial Research-Institute of Genomics and Integrative Biology (CSIR-IGIB), was found to have high sensitivity of 96% and specificity of 98%, meaning it can accurately detect both positive and negative cases.
The cost-effective and quicker test has been named after the fictional Bengali detective Feluda who stars in series of novels by filmmaker Satyajit Ray. It is also an acronym for FNCAS9 Editor Linked Uniform Detection Assay.
The test barcodes the Cas9 protein – a component of the CRISPR gene editing system – to interact specifically with the genetic material of SARS-CoV-2 virus that causes Covid-19. This complex of Cas9 and CoV2 is then applied on a paper-strip test, which gives the result in the form of two lines for a positive and a single line for a negative just like the home pregnancy test. The test kits will be manufactured and marketed by Tata group.
Dr Debjyoti Chakraborty, who developed the kit along with Dr Souvik Maiti, spoke to HT about how the new kit can help the government in scaling up testing for Covid-19 further:
How does Feluda compare to the current gold-standard RT PCR test?
The method of sample collection and extraction of RNA from the swab will remain much the same, but the processing of the sample will be quicker and done on a machine that is cheaper and more readily available than the ones currently used for RT-PCR test. And, it is almost as accurate as RT-PCR test.
Within the lab, it took us about an hour to process the sample but the time will vary a little depending on how the final kit is packaged by the company. (An RT PCR test takes about five to six hours to be completed). It will reduce the sample to report time.
How will the kits help the government in scaling up testing?
The machine used for these kits are cheaper and readily available at all diagnostic labs and even colleges, which will help in increasing the number of tests that can be done. It also does not use the expensive probes needed for the RT-PCR test.
And, it uses a lateral flow paper strip for giving a negative or positive result that can be interpreted visually by anyone. In comparison, the results given by the RT-PCR machine requires a trained person to interpret the result.
The government has been using rapid antigen tests for ramping up India’s testing capacity? Will this be a better alternative?
This test cannot be done in the field and still requires a lab to process the sample, but it is more sensitive, thereby reducing chances of throwing up false positives. The rapid antigen test detects the presence of the antigen or the viral protein. The problem with is that unless there is enough protein in the sample, the test may not detect it.
In comparison, Feluda and other nucleic acid tests can detect very low copy numbers of the virus (through amplification) so the sensitivity is very high. This means the tests can detect the virus even at an early or late stage of the disease.
We are now working towards developing tests that can be performed at the point of care, in a sense bringing the test closer to home. The work is ongoing for that.