Towards lice-resistant salmon: functional genetics and genome editing to enhance disease resistance in aquaculture

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Improving genetic resistance of farmed salmon stocks is a promising but underutilised component of preventing the economic and animal welfare burden caused by sea lice. While selective breeding incrementally increases host resistance, it is restricted to utilising genomic variants segregating in the broodstock. Genome editing approaches offer new opportunities to create de novo resistance alleles, or to introgress resistance alleles from closely related species. Therefore, understanding and harnessing within and across species variation in sea lice resistance in salmonids is a key goal.

While Atlantic salmon are susceptible to lice, certain Pacific salmon such as coho are highly resistant. This resistance is mediated by a localised epithelial hyperplasia coupled with immune cell infiltration in the first few days after louse attachment. This project focusses on understanding and exploiting the functional mechanisms underpinning this response. Harnessing large scale disease challenge and pedigree data provided by the industrial partner Benchmark, the team will map and characterise genes underpinning host resistance in Atlantic salmon. This will be coupled by a detailed temporal profiling of the localised host response using single cell RNA sequencing of attachment sites in resistant and susceptible fish, within and across species. Putative targets for immunomodulation by the parasite will also be identified using a yeast-two-hybrid approach with known louse secretory proteins.

The high-throughput genomic data will provide a list of putative key resistance genes and pathways for further filtering using CRISPR editing in a primary cell culture model system. This will culminate in high priority targets for in vivo editing, followed by assessment of the relative resistance to sea lice in edited salmon versus unedited controls. A successful outcome of an edited Atlantic salmon with resistance to sea lice has potential to transform global aquaculture.