Last Updated: 24th July, 2022

Feluda refers to FNCAS9 Editor Linked Uniform Detection Assay. The name is in addition an homage in a series of Bengali novels of Satyajit Ray‘s prominent fictional character of the corresponding name, a private detective.

What Is Feluda COVID-19 Test?

This is a low-cost paper-strip based COVID-19 test that is used to detect the virus that causes COVID-19 (SARS-CoV-2) in a sample. The Feluda COVID-19 test works much like a pregnancy test kit (explained later in detail).

How Does Feluda COVID-19 Test Work?

At a gross level, the Feluda COVID-19 test works similar to a pregnancy test strip that will just change color upon detection of the coronavirus genetic material in the test sample.

Feluda refers to FNCAS9 Editor Linked Uniform Detection Assay. This novel COVID-19 testing kit employs a gene-editing technology to identify and target the genetic material of SARS-CoV2. This technology is known as CRISPR.

Is This Test Accurate And Reliable For COVID-19 Testing?

Just like the RT-PCR test, the Feluda COVID-19 looks for the genetic material of the SARS-CoV-2 virus in a sample. Hence, it tends to give a more directive and specific result than the currently available antibody and antigen tests.

According to the Council of Scientific and Industrial Research (CSIR), the Feluda test matches accuracy levels of RT-PCR tests, which are considered the gold standard for COVID-19 diagnosis. It is reported to have a 96% sensitivity and 98% specificity. While “Sensitivity” reflects a test’s ability to correctly identify all people who harbor the disease, specificity measures a test’s ability to correctly generate a negative result for uninfected people.

What Sample Type Is Required For Feluda COVID-19 Testing?

This test uses a swab sample from the throat and/or nose. The mucous from these body areas carries the coronavirus on the swab, which is then utilized to identify the infection-causing virus.

When Should This Test Be Undergone?

A few days may pass before the virus starts replicating in the throat and nose, so the test won’t identify someone who has recently been affected. The Feluda COVID-19 test can be undergone on days 5-10 of getting infected when you are experiencing an active Coronavirus infection.

How Much Time Does It Require To Generate A Report?

As per currently obtainable information, it can produce a result in less than an hour. It has a quicker turnaround time and requires less valuable equipment.

How Does The CRISPR Technology Work?

CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. This is a gene-editing technique which is naturally employed by the immune system of some bacteria to combat Coronavirus. The same mechanism is being used to identify disease-causing viruses in humans under an artificial set-up.

There are two integral parts of the CRISPR technique: Cas9 Protein and guide RNA (gRNA). The CRISPR complex (Cas9-gRNA) is extremely specific. It identifies the SARS-CoV-2 genetic material, and then binds to it and the readout is in the form of a paper strip, in the form of a band. This visual signal is analyzed on a cloud-based system.

The Feluda test-Tata CRISPR test-is the world’s first diagnostic test to deploy Cas9 protein to successfully detect the virus causing Coronavirus, it said. More primarily, remote cousins of this protein, Cas12 and Cas13 have been used in some of the kits made in the US.

Step 1: Swab sample is collected from throat and/or nose.
Step 2: RNA is extracted from the cells collected in the sample.
Step 3: Feluda mix is added, which contains: Reporter fluorescent dye: to color the viral RNA.
Cas9: Act as scissor or paper shredder on the targeted genes.
gRNA: Required for Cas9 activation.
Step 4: Cas9-gRNA complex identify the SARS-CoV-2 RNA and cut it along with the reporter molecule.
Step 5: This sample is then added onto the paper test strip.
Step 6: Visual readout is generated.

If the sample is negative: The reporter dye remains intact and collects at the first detection line-the control capture line. Only a unique line is present.

If the sample is positive: The Cas-gRNA complex will cut the target and the reporter molecules. The cleaved target RNA will collect at a separate location as well and generate a signal towards the target capture line, generating two lines on the strip.

What Is The Cost Of The Feluda Test?

The Feluda test will be priced at around Rs 500. Currently, the RT-PCR test can cost anywhere between Rs 1,600 and Rs 2,000 whereas a rapid antigen test kit, which interprets a positive or negative test in 30 minutes, costs Rs 450. TruNat test provides results within 60 minutes, and a kit comes for about Rs 1,300. Antibody tests, which check for previous infections, are priced between Rs 500 and Rs 600 and can generate the results in 20-30 minutes.

How Is The Feluda Test Different From The RT-PCR Test?

The Feluda-CRISPR test does not require the machinery required for a RT-PCR test and the skilled manpower required to operate it. Standard PCR machines can be used for the CRISPR test and it is more readily available in labs. The sample collection process remains the same.

The Feluda COVID-19 test achieves accuracy levels of traditional RT-PCR tests with quicker turnaround time, less valuable equipment and better ease of use.