ReseARchers NeW CRISPR TOol for diagNosing disEAses

It is called SHERLOCK and never acronym was more apt: it is an application of the CRISPR technique (the name stands for Specific High Sensitivity Enzymatic Reporter UnLOCKing) that allows to quickly identify nucleic acids of viruses and bacteria in samples of blood, urine and saliva , and to trace the genetic material referable to "crazed" cells and tumors in progress.

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This low-cost diagnostic method, based on a modified version of an enzyme that finds the anomaly and then "gives the alarm", was presented last year April. Now an article published in Science describes the latest, most advanced version, which boasts a better sensitivity and the ability to identify the amount of viral material or mutated cells in a sample, as well as to assess the presence of multiple infections or cell mutations. simultaneously.

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ELEMENTARY

Both versions of SHERLOCK, developed by researchers at Broad Institute, MIT and Harvard (USA), are based on a variant of the Cas13 protein that can be programmed to target specific parts of DNA or RNA: it may be a viral genome, genes that help bacteria develop resistance to antibiotics or genetic mutations that anticipate the onset of a tumor. This protein has been equipped with tools to release a fluorescent molecule that signals whether the target is present or not.

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DIFFICULT TO CIRCUMVENT

In the previous version, SHERLOCK could identify one genetic sequence at a time - so a target of only one type. Now it can analyze more than one at a time, and in samples of more modest quantities. If the previous version could identify a single molecule in one millionth of a liter, this has a sensitivity 100 times greater: this could make it particularly useful in identifying traces of tumor cells in a blood tube, in preliminary phases where their concentration is still very low.

The new version can release fluorescent signals for several anomalies at a time (up to 4): this means that a single test could determine if a single biological sample contains traces of Zika or dengue virus, which have similar symptoms.

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POSITIVE OR NEGATIVE?

The outcome will also be visible to the naked eye: the team has developed a strip of reagent paper that, immersed in the sample, indicates the presence or absence of the genetic material with a dash, as in a pregnancy test. The new version of SHERLOCK brought it closer to a practical application, but the platform is not yet ready for diagnostic use.

References For Further Reading

Futurism

Broad Institute

MIT

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