Studies of factors related to susceptibility or resistance in IPN virus infection in Atlantic salmon throughout the production cycle

Infectious pancreatic necrosis (IPN) in Atlantic salmon is today considered to be the disease causing the highest losses in Norwegian salmon farming. It causes unpredictable conditions and has an impact on the profitability of the production. This project will aim at characterizing in detail isolates of IPNV from two different categories of freshwater and seawater operations. The fish will be followed all the way from the broodstocks through to harvest. The categories chosen have either a record of chroni c IPN problems (throughout the cycle) and one category with few problems reported. Through collaboration with Marine Harvest Norway, the project will have access to the different categories as described. Isolates of IPN virus will be subject to serotyping and sequencing for detailed characterization at the genomic level and subsequent challenge studies in fry. Selected isolates with high and low virulence will also be tested in challenge experiments using par/smolt stages. To address the issue of potential differences in virulence between IPNV isolates of freshwater and seawater origin, a limited study will be included to characterize isolates from cod, with regard to serotype, genomic profile and virulence in challenge experiments.