CRISPR-Cas13 test kit for detection of Covid19
Scientists are beginning to unlock the potential of powerful biological tools. Sherlock Biosciences, a genetic engineering company recently received emergency use authorization from US FDA for Sherlock CRISPR SARS-CoV-2 kit to detect virus which causes Covid19, providing results in approximately an hour.
What is CRISPR?
It is a specialized region of DNA that has two distinct characteristics: the presence of nucleotide repeats and spacers. Nucleotide repeats are building blocks of DNA and spacers are bits of DNA that are scattered among these repeated sequences.
Cas9 is an enzyme capable of cutting DNA strands. It acts as a pair of molecular scissors. CRISPR -Cas9 and CRISPR- Cas13 are genome editing tools having wide range of potential applications. CRISPR-Cas9 is a powerful gene-editing technology to treat diseases. Scientists have found that Cas13 can be used to detect diseases. Cas9 targets DNA whereas Cas13 targets single-stranded RNA and cleaves it.
How does Cas13 work in the natural environment?
It uses the RNA guide and looks for viral RNA. Cas13 becomes activated on finding a viral target. Sometimes, it cuts any RNA it comes across. This is known as collateral cleavage.
Scientists at Broad Institute of MIT and Harvard, and McGovern Institute for Brain Research at MIT used this mechanism to create ‘Sherlock’- sensitive tool for detecting infectious diseases in humans.
How does the CRISPR-Cas13 testing kit work?
Sample is taken from a patient who has a viral infection(sample is obtained from respiratory swabs). For example, Flu. Then amplification of RNA levels in it is done and Cas13 sensitive reporters are added. Then, an engineered CRISPR- Cas13 is added to the sample. The Cas13 is programmed with a guide RNA. This guide RNA is designed to only detect virus RNA and bind to it. Then Cas13 starts the cleaving mechanism and it starts splicing nearby RNA randomly and also the reporter. Each end of the reporter has a different label. Cas13 separates this and creates a unique signal in the sample. Then the sample is applied to a flow detection system. If the sample is negative for flu, the reporter will remain intact and is collected at the first detection line. If it is positive, then it collects at a different site making it easy for diagnosis.
Sherlock Biosciences has made history with the very first FDA-authorized use of CRISPR technology that will be used to rapidly identify the Covid19 virus.
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