Novel strategies for immunisation against intracellular pathogens of Atlantic salmon

The aim of this project is to develop improved formulations and optimised antigen delivery strategies to elicit protective immune responses against intracellular pathogens of Atlantic salmon. The introduction of adjuvanted vaccines in the salmon industry over the last decade has been a key factor for reduced antibiotics consumption and increased cost efficiency in production, in Norway and internationally. Since the introduction of oil-adjuvanted vaccines in the salmon industry, no new concepts of antige n formulation or delivery has been presented. While oil-adjuvanted vaccines confer protection against furunculosis, they have been found to elicit sub-optimal immunity against virus infections (IPN virus) and some intracellular bacteria like Pisciricket tsia salmonis. The immune responses induced by oil-adjuvants are not known in detail but there are indications for a Th2 bias for some antigens. Under any circumstances the general understanding that the most appropriate adjuvant or antigen delivery metho d for a given vaccine antigen will depend to a large extent on the type of immune response that is required for protective immunity. To be able to design an improved vaccine against intracellular pathogens, more detailed knowledge about the protective i mmune mechanisms are needed as well as more optimised methods of vaccine design/formulation. The use of defined nanoparticles in conjunction with ligands and antigens as vaccines would allow us to, in a reductive term, control the immune response towards either Th1 or Th2 response. The quality of the immune responses achieved will be assessed by gene expression analysis, vaccine potency and efficacy measurements. By this project a fundamentally new and novel vaccine strategies will be developed for fish - aiming to vaccinate fish against intracellular pathogens.