An RNA sensitive approach to CRISPR technology could be the answer to early detection of the Zika virus and much more.
A CRISPR-Cas9 diagnostic test might be the key to confirming the presence of low-concentration Zika virus in blood, urine, or even saliva. There is hope that using the tool could become an accurate, fast and affordable way to screen for Zika outside of a clinical lab setting and at point-of-care.
The test, which was created by a team at the Broad Institute, will be RNA-guided and work using RNA-targeting CRISPR effector Cas13 (formerly known as C2c2). The test, which is being called SHERLOCK (Specific High-sensitivity Enzymatic Reporter unLOCKing) differs from typical CRISPR applications in that it picks up on RNA as opposed to DNA, based on the damage the enzyme causes to any RNA that is nearby, or as the findings call it “collateral.”
The SHERLOCK detection test is able to confirm which strain of Zika a patient is infected with, and the abilities of the RNA-sensitive diagnostic don’t stop there. The test might hold the answer to cancer screening, as it can pick up on cell-free DNA fragments in the blood, which are indicative of specific mutations. SHERLOCK is even able to identify genes for antibiotic resistance, which will be critical as this problem continues.
Jim Collins of The Broad Institute spoke about the possibilities of the test. “This tool offers the sensitivity that could detect an extremely small amount of cancer DNA in a patient’s blood sample, for example, which would help researchers understand how cancer mutates over time,” he explained. “For public health, it could help researchers monitor the frequency of antibiotic-resistant bacteria in a population. The scientific possibilities get very exciting very quickly.”
To make SHERLOCK work, The Broad team picked up where CRISPR Therapeutics and the team at UC Berkely left off, taking their studies of Cas13a for RNA detection and amplifying it. That research was unable to detect the RNA in the samples because it was not sensitive enough. To combat this, Collins was able to raise the RNA or DNA levels in the samples. This was achieved using body heat and then undergoing another amplification, which converted the DNA to RNA. After this alteration in sensitivity, the test improved.
CRISPR has garnered a huge amount of attention due to the seemingly endless possibilities that the tool could offer. Researchers feel that promising treatments for a number of ailments including sickle cell disease, acute myeloid leukemia and retinitis pigmentosa might be underway.
SHERLOCK has great potential as well because it is so accessible—the test does not require cold chain storage and can be disseminated on site in a number of conditions. This makes it ideal for situations in developing nations during outbreaks for speedy results, rapidly. The test can be packaged as paper-based, meaning it will not need cold storage or refrigeration.
CRISPR Therapeutics has earned a $64 million Series A and is backed by both Celgene and GlaxoSmithKline.