CRISPR-BASED FUNCTIONAL GENOMICS OF IMMUNE GENES UNDERLYING PATHOGEN RESISTANCE IN AQUACULTURE SPECIES

Emerging infectious diseases are a major threat to aquatic animal health, productivity and sustainable food production in aquaculture. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein 9 (CRISPR-Cas9) technology has now become a useful genome editing tool to study the functional role of immune-related genes in pathogen resistance. The recent advances in functional characterisation of immune genes in economically important fishes and crustacean’s species through the CRISPR system are critically assessed here. There is an emphasis on gene knockout, targeted mutagenesis and functional validation approaches for the study of innate immune signaling, host-pathogen interactions and disease susceptibility. Toll-like receptor, Jak/Stat and NF-kB are important immune pathways that are studied in relation to antimicrobial responses and pathogen defence. While the application of CRISPR in the characterization of the genes involved in immune function holds great promise, there are several areas of concern that must be addressed, including off target mutations, mosaicism, the variable efficiency of genome editing, genome annotation and the establishment of reliable genotype–phenotype relationships. The transferring laboratory results to disease-proof variants of aquaculture is difficult for ecological safety, animal welfare, and regulatory approval and genetic stability. Integration of CRISPR and transcriptomic/proteomic analysis and with advanced pathogen challenge models may further improve functional validation and mechanism of action. To conclude, CRISPR technologies have tremendous potential in the field of aquaculture, particularly for disease resistance research, but their successful application in aquaculture development requires proper validation and responsible use.