CRISPR-Cas target recognition for sensing viral and cancer biomarkers

Nucleic acid-based diagnostics is a promising venue for detection of pathogens causing infectious diseases and mutations related to cancer. However, this type of diagnostics still faces certain challenges, and there is a need for more robust, simple and cost-effective methods. Clustered regularly interspaced short palindromic repeats (CRISPRs), the adaptive immune systems present in the prokaryotes, has recently been developed for specific detection of nucleic acids. In this review, structural and functional differences of CRISPR-Cas proteins Cas9, Cas12 and Cas13 are outlined. Thereafter, recent reports about applications of these Cas proteins for detection of viral genomes and cancer biomarkers are discussed. Further, we highlight the challenges associated with using these technologies to replace the current diagnostic approaches and outline the points that need to be considered for designing an ideal Cas-based detection system for nucleic acids.