A scientist presents an antibody test to use with a blood sample for the coronavirus in a laboratory. (Photo: AP)
The Feluda CRISPR Test Kit has a less complicated process and can detect the presence of coronavirus faster than an rRT-PCR test.
- News18.com
- Last update: September 21, 2020 5:55 PM IST
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Five months after it was developed by two scientists from the Institute for Genomics and Integrative Biology (IGIB), the Feluda CRISPR test for the presence of Coronavirus has received a go-ahead from the Controller General of Drugs of India for a commercial launch.
The Tata Group, which has signed an agreement with the Council for Scientific and Industrial Research (CSIR), will soon launch the test kit, which is touted as faster than the real-time reverse transcription polymerase chain reaction test. (rRT-PCR). The rRT-PCR test is considered the gold standard for detecting SARS-CoV-2.
News18 explains how the Feluda-CRISPR test works and how it differs from the rRT-PCR test.
What is the new Feluda test developed by CSIR-IGIB?
The test uses CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technology which has been hailed as a cutting edge technology used for genomic sequence detection and gene editing. According to the Ministry of Science and Technology, it adapts the Cas9 protein to detect the Coronavirus during the test. The entire test process takes less time compared to the rRT-PCR test and also requires less expensive and skilled labor. The test kit has been developed by IGIB scientists Souvik Maiti, Senior Principal Scientist, and Debojyoti Chakaraborty, Senior Scientist.
How does the Feluda test work?
The testing process is completed in approximately four steps. Viral RNA is extracted from pharyngeal and nasal swab samples collected from a suspected patient. 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 multiple copies.
According to Debjoyi Chakaraborty, the Feluda mixture is prepared that contains the Cas9 protein, which can bind to the DNA of the virus. Chemicals are added to the CRISPR complex and DNA during the amplification process to generate a colorimetric reaction on the paper strip.
In the last step, the strip of paper or stick is dipped in the Feluda mixture. The paper strip generates the test result in the form of two lines for a positive test and one line for a negative test, similar to a home pregnancy test. However, this is a nucleic acid test and not a protein-based test.
How is the Feluda test different from the rRT-PCR test?
The Feluda-CRISPR test does not require the machinery required for a real-time reverse transcription polymerase chain reaction and the skilled manpower required to use it. Standard PCR machines can be used for the CRISPR test and is most readily available in laboratories. “We detected the signal using the CRISPR complex, which is very specific. Find out if the viral signature is the SARS-CoV-2 signature, and then join it and the readout is in the form of a strip of paper, in the shape of a band. It takes less time than rRT-PC, ”said Chakaraborty.
Will governments use it in field settings and what is the cost of the kit?
According to Chakaraborty, the Tata Group is handling the industrial and commercial operations of the kit and the commercial availability of the kit will be announced soon along with its final market price. However, given the less complicated process followed to use the kit, it is likely that it will soon be used in field settings.
According to the Ministry of Science and Technology, the test kit had a sensitivity of 96% and a specificity of 98% for detecting the SARS-CoV-2 virus. Sensitivity is related to the rate at which you can correctly detect positive cases (true-positive rate) and specificity is the rate at which you can correctly detect negative cases (true-negative rate).
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