Rs 500, 45 mins, just as effective: Why scientists believe FELUDA is simpler alternative to RT-PCR

The FELUDA test developed by the New Delhi-based CSIR-Institute of Genomics and Integrative Biology (IGIB) and the TATA Group that received Drug Controller General of India's (DCGI) approval last week is as effective as the bankable RT-PCR diagnosis, believe scientists. The test changes colour upon the detection of the SARS-CoV-2 virus and is cheaper, faster as well as a simpler alternative, they say. 

The test has been priced at Rs 500 and the results are yielded in 45 minutes. Named after Satyajit Ray's popular private detective, FELUDA can differentiate between the COVID-19 virus and other coronavirus even though the genetic variations between them are minute.

The homegrown test has met high quality benchmarks with 96 per cent sensitivity and 98 per cent specificity. "The CRISPR technology uses a highly specific CAS9 protein to find and bind to the target COVID signature. This is then coupled with paper-strip chemistry to elicit a visual readout on a paper strip," said Debojyoti Chakraborty senior scientist at CSIR-IGIB.

With cases increasing exponentially, it is pertinent to find a test that is not only cheap to ensure widespread utilisation but also something that is faster.

FELUDA or FNCAS9 Editor-Limited Uniform Detection Assay uses an indigenous technology for the detection of the genomic sequence of the SARS-CoV-2 virus, the scientists added. Virologist Upasana Roy, senior scientist at CSIR-IICB, said that FELUDA is a cheaper option to RT-PCR tests. She said that FELUDA is capable of detecting even low quantities of the genetic material of the novel coronavirus, based on the minute differences in their RNA.

CRISPR is a gene editing technology and is used in correcting genetic defects and treating and preventing the spread of diseases. The technology can detect specific sequences of DNA within a gene, and uses an enzyme functioning as molecular scissors to snip it.

"FELUDA is an alternative to the quantitative RT-PCR tests and is highly specific. It is capable of detecting low copy number nucleic acids (less viral RNA quantity) as well as single nucleotide variations," said Ray. "It can distinguish between SARS-CoV-2 and SARS-CoV sequences which differ by a single nucleotide. Unlike RT-PCR which requires expensive machines, FELUDA is simple and can be used in laboratories as well as outside with a quicker turnaround time," she added.

While RT-PCR could take a few hours, trained manpower and a dedicated and expensive machine, FELUDA provides similar sensitivity and specificity but requires only a basic widely available PCR machine and needs extensively trained manpower.

Also read: DCGI nod to commercial launch of India's first low-cost COVID-19 test 'FELUDA'

Also read: Feluda: Satyajit Ray's iconic character who is now COVID-19 detective