SARS-CoV-2 pandemics: An update of CRISPR in diagnosis and host-virus interaction studies

Since December 2019, the Coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has spread rapidly around the world, overburdening healthcare systems and creating significant global health concerns. Rapid detection of infected individuals via early diagnostic tests and administration of effective therapy remains vital in pandemic control, and recent advances in the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins (Cas) system may support the development of novel diagnostic and therapeutic approaches. Cas-based SARS-CoV-2 detection methods (FnCAS9 Editor Linked Uniform Detection Assay (FELUDA), DNA endonuclease-targeted CRISPR trans reporter (DETECTR), and Specific High-sensitivity Enzymatic Reporter Unlocking (SHERLOCK)) have been developed for easier handling compared to quantitative polymerase chain reaction (qPCR) assays, with good rapidity, high specificity, and reduced need for complex instrumentation. Cas-CRISPR-derived RNA (Cas-crRNA) complexes have been shown to reduce viral loads in the lungs of infected hamsters, by degrading virus genomes and limiting viral replication in host cells. Viral-host interaction screening platforms have been developed using the CRISPR-based system to identify essential cellular factors involved in pathogenesis, and CRISPR knockout (CRISPRKO) and activation screening results have revealed vital pathways in the life cycle of coronaviruses, including host cell entry receptors (ACE2, DPP4, and ANPEP), proteases involved in spike activation and membrane fusion (cathepsin L (CTSL) and transmembrane protease serine 2 (TMPRSS2)), intracellular traffic control routes for virus uncoating and budding, and membrane recruitment for viral replication. Several novel genes (SWI/SNF Related, Matrix Associated, Actin Dependent Regulator of Chromatin, subfamily A, member 4 (SMARCA4), ARIDIA, and KDM6A) have also been identified via systematic data mining analysis as pathogenic factors for severe CoV infection. This review highlights how CRISPR-based systems can be applied to investigate the viral life cycle, detect viral genomes, and develop therapies against SARS-CoV-2 infection.