Based on important disease models, this project concerns development of a technological knowledge platform for a future improved immunity to infectious pathogens in the major aquacultured species in Europe (Atlantic salmon, rainbow trout, sea bream, sea b ass, carp, mussel and oyster). Focus will be put on use of vaccines, immuno-stimulants, immuno-diagnostic surveillance as well as markers for selection of the most immuno-competent individuals. Assays for qualitative and quantitative monitoring of key ele ments of the innate and adaptive immune system at genetic and functional levels will be established and used for determination of response profiles which correlate with protective immunity. For all species, infection trials with various types of pathogens , including re-challenge of survivors, will be used to determine reference response profiles of naïve and primed animals. For finfish, vaccination trials with efficiently working commercial and experimental vaccines and corresponding control reagents will be used to identify critical response elements/profiles for vaccine efficacy. Variability both in terms of gene polymorphism and occurrence of isoforms among the immunological key elements and their regulation will be related to the functional response i n in vitro assays as well as in vivo in terms of disease susceptibility of naïve and primed/vaccinated animals. Assays for direct functional determination of gene functions will also be developed. The outcome of the project will be versatile gene array an d immune response assays which can be implemented in development of efficient vaccines and immuno-stimulants for the finfish species and for genetic typing, monitoring of immuno-competence and immuno-diagnostic surveillance in both finfish and shellfish. In combination with the know-how established during the project these tools will represent a strong platform for immunity-based reduction of losses caused by infectious diseases in future aquaculture.