Application of CRISPR-Cas9 Technology in Visceral Leishmaniasis Research: Current Understanding and Future Perspective

Visceral leishmaniasis (VL) is a severe disease that affects millions of people in the endemic areas due to Leishmania donovani parasites. There are no licensed vaccines, and chemotherapy is the mainstay to combat the disease. The clinical value of commonly used chemotherapeutic agents for the treatment of VL is now threatened due to the emergence of acquired drug resistance and toxicity. The CRISPR-Cas9 genome editing system have significantly advanced Leishmania research in terms of drug target validation and vaccine development. The CRISPR-Cas9 system is an adaptive immune system in bacteria, and it uses Cas9, an endonuclease guided by single-guide RNA (sgRNA) to introduce double-strand breaks at specific genomic loci. It is therefore more efficient for gene knockout, knock-in or base editing via HDR pathways, which makes it a better tool of gene editing than other currently available tools such as ZFNs and TALENs because of its flexibility, simplicity and scalability. To date, in Leishmania, CRISPR-Cas9 has helped in dissecting the drug resistance mechanisms, for example, RING-variant and transmembrane proteins in miltefosine resistance and the sterol 24 C methyltransferase (C24SMT) in amphotericin B resistance. It has also exposed new genes involving parasitic qualities that help it survive, multiply, and be virulent, and helped create new shapes of weakened strains for use in vaccines. Therefore, CRISPRCas9 proves to be an indispensable weapon in the assault on Leishmania biology and the development of VL treatment.