Detection in one hour, as sensitive as PCR test: Debojyoti Chakraborty

Senior scientist Dr Debojyoti Chakraborty, who has developed Feluda along with Dr Souvik Maiti, spoke to Sanchita Sharma about test strip.

A precise and cost-effective test strip named after Feluda, a detective in a series of novels by filmmaker Satyajit Ray, has been developed at Council of Scientific & Industrial Research’s Institute of Genomics and Integrative Biology (CSIR-IGIB) in New Delhi to detect coronavirus disease (Covid-19) within one hour. Feluda, the acronym for FNCAS9 Editor Linked Uniform Detection Assay, uses CRISPR gene-editing technology to identify and target the genetic material of Sars-CoV2, the virus that causes Covid-19. Senior scientist Dr Debojyoti Chakraborty, who has developed Feluda along with Dr Souvik Maiti, spoke to Sanchita Sharma about test strip. Edited excerpts:

A passenger is thermal screened after Indian Railways resumed services partially, at Howrah Junction railway station in Kolkata, West Bengal. (Photo by Samir Jana / Hindustan Times)

How does the CRISPR-based Feluda rapid test work?

The CRISPR-based Feluda testing works by combining CRISPR biology and paper strip chemistry. Briefly, Cas9 protein, a component of the CRISPR system, is barcoded to interact specifically with CoV2 sequence in a patient’s genetic material. The complex of Cas9 with CoV2 is then applied to a paper strip where by using 2 lines [one control, one test], it is possible to determine if the original sample was infected with Covid-19.

Are you a Satyajit Ray fan? Who came up with the acronym?

Yes, I am a Satyajt Ray fan and the name was given by my wife, who is not a Bengali but is well aware of the sentiments. The name Feluda is also an acronym of FnCas9 Editor Linked Uniform Detection Assay.

The sensitivity is similar or sometimes better than quantitative realtime PCR [polymerase chain reaction]-based tests...

How long did it take to develop the test?

Feluda is not limited to Covid-19. We were working on Feluda for the past two years to develop an assay that can work on detecting any DNA-RNA or their mutations. In end of January 2020, we started working on adapting it for Covid-19

How long does it take to produce results?

This process of detection takes about one hour to complete if the starting material is RNA, and gives a visual readout on the strip.

What will be the cost of each test? Can it be used outside labs in under-resourced settings?

At the lab level, the cost of each test is around Rs 500. Our efforts are directed for its use at places with very basic lab setups such as pathology labs, universities, health centres, etc.

When will it be ready for the market? What is the role of Tata Sons in it?

The CSIR-IGIB is an academic institute. The marketing will be done by industry. Tata Sons has recently signed an agreement with us for the same to take it to the masses. We hope this should be ready for the first phase of testing in four weeks.