Genome editing is a technology that allows humans to change an organism’s DNA behaviours; These technologies allow the basic genetic material of an organism to be altered. Several approaches to genome editing have been developed over the past few years. A recent one is known as CRISPR-Cas9, which is short for clustered regularly interspaced short palindromic repeats and CRISPR related protein 9. The CRISPR-Cas9 system has composed a lot of enthusiasm in the scientific community because it is faster, cheaper, accurate, and more efficient than any other existing gene-editing technology.
The CRISPR-Cas9 technology originates from type II CRISPR-Cas systems, which provide bacteria with adaptive immunity to viruses and plasmids. CRISPR-Cas is a microbial adaptive immune system that uses RNA-guided nucleases to cleave foreign genetic elements. Three types (I–III) of CRISPR systems have been identified across a wide range of bacterial and archaeal hosts, wherein each system comprises a cluster of CRISPR-associated genes, non-coding RNAs and a distinctive array of repetitive elements. These repeats are interspaced by short variable sequences derived from exogenous DNA targets known as protospacers, and together they constitute the CRISPR RNA (crRNA) array. Within the DNA target, each protospacer is always associated with a protospacer adjacent motif (PAM), which can vary depending on the specific CRISPR system.
In the last few years, the simple-designed CRISPR/Cas9 system has greatly expanded its application scopes in life science, and now, it is still in its rapidly developing stage. As an effective, highly specific and robust tool, CRISPR/Cas9 machinery holds great promise for targeting infectious viruses and removing their reservoirs to enhance human health. The CRISPR/Cas9 technology can be used not only to target any special nucleotide sequences in the human genome but also to edit the double-stranded DNA (dsDNA) of viral invaders in vivo and in vitro systems. Moreover, the technologies of Cas9 equipped with multiple single guide RNAs have enabled the Cas9 endonucleases to target several different genomic loci in a single cell. the CRISPR Cas9 methodology holds huge potential promise for targeting different developmental phases of the viral life cycle and possess the ability to mediate an effective and sustained genetic therapy against human viruses. Herein, CRISPR/Cas9-based antiviral approach to manipulate major human infectious viruses including HIV, HBV, HPV, and other viruses will be discussed in the coming years.
CRISPR/Cas9 technology is still in the outset stage, and many technical problems remain to be solved. However, the utilization of CRISPR/Cas9 systems towards clinical applications will be faced with some ethical questions. Firstly, the misuse of this technology could likely create certain ethical disputes. Secondly, the safety produced by unwanted gene editing of CRISPR/Cas9 should be carefully improved and evaluated while clinically applying this system. However, in the UK, scientists have gained a license to edit human embryos with the use of CRISPR/Cas9 technology, which potentially shows the technical strengths of this system in prospective clinical applications. Nevertheless, CRISPR/Cas9-associated clinics in the future must be strictly overseen with newly established laws to boost CRISPR gene-editing technology to help humans achieve new results.
References : https://en.wikipedia.org/wiki/CRISPR
https://www.yourgenome.org/facts/what-is-crispr-cas9
https://www.livescience.com/58790-crispr-explained.html
Additional Resources: https://www.science.org/doi/10.1126/science.1258096
https://www.sciencedirect.com/science/article/pii/S0092867414006047
