Science & Technology

COVID-19: New tool through CRISPR tech to aid quicker coronavirus tests

The technology confirms presence of viral DNA in samples faster and more accurately  

By Vibha Varshney
Published: Tuesday 12 May 2020

A new kit — based on clustered regularly interspaced short palindromic repeats (CRISPR) technology — that tests for the novel coronavirus (SARS-CoV-2) in an hour’s time and the results for which can be seen through the naked eye, is now available, at a time when an increase in the quantum of testing is highly sought after to combat the COVID-19 disease.

The diagnostic kit received Emergency Use Authorisation by the United States’ Food and Drug Administration on May 7, 2020.

The testing kit — developed by biotechnology firm Sherlock Biosciences — does not give false negative or false positive results and has high sensitivity and specificity, unlike Reverse Transcription Polymerase Chain Reaction (RT-PCR) and immunoassays tests. The genetic material from the Ribonucleic acid (RNA) of the virus does not need to be converted to Deoxyribonucleic acid (DNA), unlike RT-PCR based tests.

This technology has so far been used to find genes along a strand of DNA, snip them out and replace them with alternative genes. Researchers in China used CRISPR technology to edit genes from a pair of twins in a womb, a year ago.

This is the first time a CRISPR-based tool has been used as a diagnostic.

The Sherlock CRISPR SARS-CoV-2 kit is based on the CRISPR-based SHERLOCK (Specific High Sensitivity Enzymatic Reporter UnLOCKing) technique.

The test has three steps. Genetic material is extracted from the patients’ sample and is amplified using a commercially available polymerase amplification kit. This step takes around 25 minutes.

The amplified viral sample is then incubated with and detected with Cas13 (an RNA editing technique), which takes 30 minutes.

A commercially available paper dipstick is then used to confirm the presence of the virus. This confirmation can be done through the naked eye and takes around two minutes.

The test only needs basic equipment found in most labs.

The technology for the kit was developed by a team led by CRISPR pioneer Feng Zhang at the Eli and Edythe L Broad Institute operated by the Massachusetts Institute of Technology and Harvard University at Cambridge, Massachusetts and is marketed by Sherlock Biosciences.

When Zhang’s team tested the technology using synthetic COVID-19 virus RNA fragments, it could consistently detect COVID-19 target sequences in a range between 10-100 copies per microliter of amplified sample.

“We have made history with the very first FDA-authorised use of CRISPR technology, which will be used to rapidly identify the virus that causes COVID-19,” said Rahul Dhanda, co-founder, president and CEO of Sherlock Biosciences in a press release.

“We are committed to providing this initial wave of testing kits to physicians, laboratory experts and researchers worldwide to enable them to assist frontline workers leading the charge against this pandemic,” the release said.

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