Salmon lice (Lepeophtheirus salmonis) represents the single most economically important animal welfare problem threatening both the sustainability and expansion of salmon aquaculture. In many countries, sea lice have become endemic to farmed salmon and may be transmitted to and harm local wild salmonids. In the natural environment, the heaviest lice infestations are found on brown trout and Atlantic salmon, with both species displaying weak or absent local inflammatory response and high parasite burden. In contrast both pink and especially Coho salmon display high resistance. The LiceRESIST project is designed to identify genes, pathways and causal variants responsible for these species differences in immune response, especially at epigenetic and functional levels, which today are poorly understood. With a more detailed understanding of lice resistance mechanism in place, it is feasible to translate project outcomes into gene editing based precision breeding and identifying target molecules for therapeutic control, which may in turn may lead to improved production and animal welfare in salmon aquaculture.
So far in the project, we have established highly demanded methodology for functional analyses (RNA-, ATAC- and ChIP-Seq) from skin samples. The methodology will be used on samples from a "challenge" experiment with lice to be carried out in Canada first half of November 2021. In parallel with the laboratory work, we are working on establishing a bioinformatic pipeline to analyse these data.
Sea lice (Lepeophtheirus salmonis) is the single greatest biological threat to the development of sustainable salmonid farming. Despite extensive international research efforts, our understanding of the functional genetic basis for host immune responses to sea lice infestations in Atlantic salmon, the main farmed species in Norway, remains unclear, largely due to the complex genetic architecture of the trait. By comparing the functional genomic changes occurring in response to sea lice attack in several salmonid species exhibiting diversity in resistance, LiceRESIST will (i) reveal novel functional mechanisms underlying immunity that have evolved in independent lineages, and (ii) facilitate the identification of key causative genetic variants responsible for lineage-specific resistance to lice burden. Our approach, combining comparative and functional genomics with CRISPR/Cas gene editing for discovery and validation of functional differences, will create opportunities to devise novel therapeutics to combat the sea lice threat. Given the pressing nature of the sea lice problem for aquaculture, in terms of economic losses, animal welfare concerns, and the threat to wild salmon, generating such advanced knowledge as a basis for improved lice management is both urgently required and in full alignment with the vision of the HAVBRUK2 program.