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Thanks to advances in molecular biology and biochemistry, scientist have been able to consistently detect lower and lower concentration of molecules, to the point that, to date, single molecules can be reliably recognised with methods such as polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH). This has opened doors for better and more accurate diagnostic tests that biomarkers like nucleic acids and proteins as targets. Through such advances, the field of molecular diagnostics developed. Unfortunately, current standard methods require expensive equipment or trained personnel, which generally limits their usability to hospitals or laboratories. Only in recent times has there been a push to develop new tests that fuse the reliability of standard methods with affordable platforms such as gene chips or paper strips. We wanted to help close this gap and set out to engineer a diagnosis principle for the detection of a wide array of targets that could be used without difficult technical requirements.
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Molecular cloning
Our project, which we dubbed Cas13a controlled assay for infectious diseases (CascAID) features the recently identified CRISPR/Cas effector Cas13a. Unlike other proteins in the familiy, Cas13a has the unique ability to bind and cleave specific RNA targets rather than DNA ones. Moreover after cleaving its target, Cas13a presents collateral activity i.e. it can unspecifically cleave RNA molecules. By using Cas13a, our system can detect virtually detect any RNA target. This is done by changing the crRNA in the protein, that is a short RNA sequence that determines what is recognized as target.
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