Big win amid testing times PDF Print E-mail
Friday, 09 October 2020 16:30
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Sarthak edit 

Emmanuelle Charpentier and Jennifer Doudna’s chemistry Nobel win for the invention of the Crispr Cas9—the gene-editing tool that has opened up a world of wondrous potential and moral landmines—is significant for many reasons. The most obvious, yet by no means trifle, is the fact that Charpentier and Doudna are only the sixth and the seventh women chemistry Nobel honorees (not in that order, given it is a joint award) in a list of 184 so far. The Nobel committee’s less than perfect record of recognising women’s contribution to science needs correction, and this win, without taking away from the seminal nature of the honorees’ work, is a step forward.

Beyond that, the invention of Crispr Cas9 is a turning point in the history of science; it vests in humans the power over their genetic future in ways that can’t perhaps be fully imagined at present. To be sure, gene-editing was possible even before the invention of Crispr Cas9, but it was incredibly complicated, high-cost, with a large room for errors. With Crispr Cas9, gene-editing has become more accurate and relatively easier and cheaper. It has a range of use cases—the primary being control of genetic diseases and disorders. It has already been harnessed against sickle-cell anaemia and certain cancers. The promise for the treatment of a host of genetic diseases—from cystic fibrosis to congenital blindness or gene-linked dementia—and in the long run, their elimination, is a paradigm shift for human health in the league of the discovery of vaccination and penicillin.

The invention, though, is particularly noteworthy in the context of the Covid-19 pandemic. Crispr, which is a primordial immune system that prokaryotes evolved in response to viral attacks over billions of years, is now being steered by researchers to detect and battle the virus. The US became the first country to approve Crispr-based testing for SARS-CoV-2 in May this year—the diagnostic kit was based on the approach described by Crispr researcher Geng Zhang. Ever since, many countries have joined the bandwagon, including India, with the diagnostic kit developed by the CSIR-Institute of Genomics and Integrative Biology that received regulatory approval last month and is being produced for commercial deployment by the Tata Group. Crispr-based testing will be a quantum leap, since it mirrors the RT-PCR’s high accuracy of detection, even as it is much cheaper and has a turnaround time that is a fraction of the genetic material amplification-based testing (like RT-PCR). Crispr recognises specific DNA sequences within a gene, while Cas proteins can be guided to snip the gene at a particular point.

While other Crispr-based testing use Cas12 and Cas13 proteins, India’s strip-based ‘Feluda’ kit uses Cas9. The Crispr sequence is coded to recognise viral genetic material in a patient sample, and the Cas9 protein snips the RNA recognised by Crispr. The kit’s diagnostic strip uses flow detection—where one filter stops uncut RNA if there is no virus and another stops the snipped RNA if the virus is present in the sample. Given it needs neither the expensive reagents of RT-PCR nor its specific lab requirements, it is ideal for field testing with results in under half an hour. None of this would have been possible without Charpentier and Doudna.


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