An indigenously developed testing kit for coronavirus disease (Covid-19) based on the gene-editing technology CRISPR – called Feluda – will be launched in Delhi on Thursday by the Tata group in collaboration with the Apollo group of hospitals, people familiar with the matter said on Wednesday.
Earlier this month, Tata Medical and Diagnostics Ltd (TataMD) announced that the paper-strip kit would be marketed as “TataMD’s CHECK”.
The test is likely to be cheaper than the current gold standard RT-PCR and equally accurate, helping in scaling up Covid-19 testing as it would need a machine that is widely available with laboratories and science institutions.
The new kit has a high sensitivity of 96% and specificity of 98%, meaning it can accurately detect both positive and negative cases. It was approved for use by the Indian Council of Medical Research in September. A team of researchers from the Institute of Genomics and Integrative Biology named the test Feluda after the eponymous Bengali fictional detective.
Similar CRISPR based Covid-19 tests have been approved for emergency use by the US Food and Drug Administration. Called “Sherlock” after the English fictional detective Sherlock Holmes, the American test uses Cas-13 (Fledua instead uses Cas-9) to detect the virus.
Once a swab sample is collected from a patient, the RNA is extracted from it and amplified using a thermocycler. The sample is then tested using a paper strip that is barcoded with the Cas-9 protein coded to recognise genetic material of the Sars-CoV-2 virus to get the result. The strip displays lines to show whether a person has the virus that causes Covid-19, just like a home-based pregnancy testing kit.
The test result can be obtained in about 40 minutes.
“Although the process of sample collection and extracting RNA remains the same as that in RT-PCR, only a thermocycler machine is needed for processing the sample. Only big laboratories and scientific institutions usually have maybe one traditional RT-PCR machine. Whereas thermocyclers are cheap and most labs have them and many scientific institutions will have several. These machines can be utilised to scale up testing,” said Dr Debjyoti Chakraborty, one of the scientists who developed the kit.
Sample processing still has to be in a laboratory as technicians have to work with the viral RNA that can cause infection. In comparison, rapid antigen tests can be done at the point-of-care because the sample is immediately dipped in a solution to destroy the viral RNA and only proteins are detected in the test. But, it makes the test less sensitive, potentially missing several positive cases.
“The workflow has been simplified with this kit. Although a lab is still needed, it can be performed in small mobile labs,” said Dr Chakraborty.
This comes at a time when Delhi is in the process of increasing the number of molecular tests such as RT-PCR, CBNAAT, and TrueNat, with 10 mobile vans being deployed by the central government in an effort to control the spread of the infection.
“It is the world’s first CRISPR Cas-9 based diagnostic tool to be launched globally. Within a short span of 100 days from licensing the technology to its commercial launch, intense collaboration between the CSIR-IGIB team, other reputed scientific research bodies and the Tata MD R&D team helped develop, a compelling end-to-end diagnostic solution that will set the new standard in testing…” TataMD had said in a statement.
