What is Feluda Test? How does it work? All you need to know about Tata CRISPRCOVID-19 test

India now has its own COVID-19 test. The Tata CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) COVID-19 test, has been approved by the Drugs Controller General of India. This test uses an indigenously developed, cutting-edge CRISPR technology for detection of the genomic sequence of SARS-CoV-2 virus, according to the CSIR. 

The test has been developed over the past five months by two scientists at the Institute of Genomics and Integrative Biology (IGIB).The Tata Group, which has signed an agreement with Council of Scientific and Industrial Research (CSIR), will soon launch the test kit. 

The kits of this test are claimed to be faster than the existing Real-Time Reverse Transcription – Polymerase Chain Reaction test (rRT-PCR). The rRT-PCR test is considered as the gold standard for detecting SARS-CoV-2. 

What is Feluda Test? 

Feluda--an acronym for FNCAS9 Editor-Limited Uniform Detection Assay, is an indigenous COVID-19 testing mechanism that was created at the Council of Scientific and Industrial Research’s constituent lab, the Institute of Genomics and Integrative Biology (CSIR-IGIB) in New Delhi. 

According to the Ministry of Science and Technology, it adapts the Cas9 protein to detect the Coronavirus during the test. The entire process of the test takes lesser time compared to the rRT-PCR test and also requires less expensive and skilled manpower. The test kit has been developed by IGIB scientists Souvik Maiti, senior principal scientist and Debojyoti Chakaraborty, senior scientist. 

Feluda is a fictitious character created by noted filmmaker and writer Satyajit Ray - a detective.  

"Paper-based tests have also been developed in some other parts of the world and one of the groups have given name Sherlock so we thought Sherlock is another fictitious character so we thought Feluda would actually match that. Feluda is an Indian name Satyajit Rays very showcase name so we thought we give Feluda name to this test strip," said CSIR Director-General Dr Shekhar Mande. 

How does the test work? 

The testing with Feluda happens in four steps - 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 using 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 amplification process to generate a colorimetric reaction on the paper strip. In the last step, the paper strip or dipstick is immersed in the Feluda mix. The paper strip generates the test result in the form of two lines for a positive and one line in the case of a negative test. 

What are the benefits? 

Dr Mande explained that Feluda test kit only takes 45 minutes whereas an RT-PCR takes long hours. Also, this COVID-19 testing kit is cheaper than RT-PCR based test kit. Another advantage is that it does not require any heavy equipment like RT-PCR. 

"Feluda test kit is very cost-effective because many things it doesn`t require costly equipment, unlike RT-PCR. It does not require any chemical which is costly. It is very cost-effective and in terms of time, it is very quick. It can literally, in 45 minutes, finish the test," he said.