13 April 2020

Introduction:

In a major breakthrough, a team of Indian scientists have successfully developed a low-cost, paper-strip test which can detect the new coronavirus within an hour and address India’s urgent need for rapid-testing. This is the first of its kind in the world.

Salient Features of the test:

• The test uses the cutting-edge gene-editing tool- Crispr-Cas9 to target and identify the genomic sequences of the novel coronavirus in the samples of suspected individuals.
• The kit is similar to a portable paper-strip test used to confirm pregnancy and does not require any different specialized skill to perform and is relatively less-sophisticated.
•  Most rapid tests require dedicated machinery,  but this can be performed using standard equipments available in every pathological laboratory or even Mohalla Clinics in Delhi.
  •  This is important, because if number of infections shoot up drastically, it would need tests which can be done in local facilities as this will reduce transmission.

• The team led by Dr Souvik Maiti and  Dr Debjyoti Chakraborty, from the Institute of Genomic and Integrative Biology (IGIB), CSIR’s premier laboratory in New Delhi is currently testing the kit in a patient cohort for its accuracy and sensitivity and hope to seek validation from a regulatory body of the Indian Council of Medical Research (ICMR) within a week.
• Unlike the real time PCR(Polymerase Chain Reaction) test currently being used for diagnosis of Covid-19 in India, costing about ₹4500, the paper-strip test costs less than ₹500.
• It also does not depend on expensive real-time PCR machines for RNA isolation, DNA conversion and amplification, which are already in limited supply.
• It is the first such indigenous testing kit based on CRISPR technology to be developed in India.
• Result is almost 100% accurate.
• A simple seven day training can suffice to impart skills needed to conduct these tests.

How the test works:

• The sample is taken from the nasal swab.
• First the RNA in the sample  is converted into genetic material or complimentary DNA (cDNA). Then it is amplified using a polymerase chain reaction (done on a simple PCR machine) and mix with a complex Cas9 protein.
• The Cas9 protein specifically binds to the DNA signature of the Covid-19 virus.
• Finally, this mixture is applied on a paper strip. Depending on the presence of Covid-19 DNA, a line appears on the paper strip, apart from a control line that appears regardless of whether the virus is present or not.
• If there is presence of even low amounts of viral RNA, it will detect it. The results are known within 1.5 hours.

Why the test is named ‘Feluda’?

• It is ‘Feluda’ because a competitive paper-strip test being developed by MIT and Harvard goes by the name ‘Sherlock’, after the famous [fictional] detective.
• So to give it an Indian twist it was decided to call it ‘Feluda’, after Bengal’s most famous detective character created by Satyajit Ray.
• Also ‘Feluda’ is an acronym for the scientific name of the test — Fncas9 Editor Linked Uniform Detection Assay.