ISA resistance in Atlantic salmon: Defining new phenotypes for accurate breeding

Infectious diseases continue to pose major problems for aquaculture in Norway, resulting in large economic losses and negatively impacting animal welfare and their living habitats. Selective breeding to enhance pathogen resistance has been a successful strategy, although for some diseases, such as chronic or subclinical infections, the best selection criteria or ‘phenotypes’ are yet to be defined. Recent developments of various genomic resources in Atlantic salmon have now provided the opportunity to exploit these advances to both improve the understanding of the underlying genetic basis of disease resistance, and to provide tools to more accurately and efficiently select them in breeding programs. It is the aim of this project to use these advances to complement and enhance the current practices for identifying and selecting the best candidates by applying a multidisciplinary approach, while breeding against infectious salmon anaemia (ISA), a deadly contagious disease of farmed Atlantic salmon. Selection will be based on the newly defined phenotype(s) and the tools and methodologies will be developed for measuring them, to provide the supporting industry partner, SalmoBreed AS, with a highly valued product. Furthermore, the underlying idea could be further applied to many other diseases of economic importance.

The main objective of the iSABreed project is to address the need of the industry to identify new phenotypes for efficient selection against ISAV infection and to implement these phenotypes in breeding programs. To achieve this objective, the sub-goals of the project are:

  • In both vaccinated and unvaccinated fish, to identify genes and genetic networks that are associate with higher tolerance/resistance against ISAV;
  • Develop a quantitative real-time PCR assay for simultaneous assessment of an individual’s resistance and rate of virus shedding based on skin mucus;
  • Develop an enzyme-linked immunosorbent assay (ELISA) for easy assessment of an individual’s responsiveness to vaccination and to infection based on skin mucus;
  • Investigate the kinetics of virus transmission, and determine the effects of host genetics and vaccination on it;
  • Estimate genetic parameters for the newly defined traits, identify genetic markers associated with “resistant” phenotype and compute the gain in accuracy of selection and genetic gain compared to the currently used practice;
  • Develop a software that can be used by the industry to assess the epidemiological and economic benefits of implementing the new phenotypes into ISA breeding programs.

The iSABreed project is an innovation project in the HAVBRUK2 program of the Norwegian Research Council (NFR 281797), 2018 – 2021. Project owner is SalmoBreed AS. Other partners include Pharmaq AS, Nofima, the Norwegian Veterinary Institute, and the University of Edinburgh.

The Toxinology Research Group is participating with metabolomic and proteomic analyses in iSABreed.