PeptidEx aimed at developing a pathogen epitope prediction programme and evaluating it's usefulness in the design of a viral pathogen peptide vaccine for use in fish. Salmonids are of great economical importance for aquaculture and sport fishing in Europe. In the European countries farming of Atlantic salmon and rainbow trout has been predicted to rise to 379,900 and 193.600 tons/year, respectively. Brown trout, a close relative, is a major farmed species in other parts of Europe, and exploitation of other non-salmonid species such as seabass and seabream is presently expanding. Conventional bacterial vaccines seem to be working just fine, but the available viral vaccines have so far not been optimal. Thus, finding new successful approaches to viral vaccines will be a major contribution to disease control in fish. The approach of developing viral pathogen epitope prediction programmes will benefit all future fish vaccine design, administered in a peptide form. The project has provided methods and approaches easily transferable to a variety of farmed fish species. Efficient vaccines against viral pfish pathogens can reduce the costs of disease outbreaks, both in terms of economical benefits, and in terms of environmental impact due to reduced spread of disease also to wild populations. It will stimulate similar studies in other cultured fish species, and has the potential of greatly increasing productivity. The approach can also serve as a model and provide tools for similar studies in emerging industries involving new fish species such as turbot, seabass, and seabream. Fish farming is mainly performed in rural areas and is seen as one of the major industries of the future. Any projects which may improve the economic situation for fish farming will thus also benefit rural parts of Europe. This may also increase rural employment. If the fish farmers have less production loss, this will reduce their costs and improve their economical margins, which again may be reflected in reduced prices to the consumers. Peptide-based vaccines have a clear advantage over currently used vaccines. Most vaccines used today in aquaculture contain oil-based adjuvants. These cause problems to the fish, in the form of side effects, such as granuloma's. In addition, administration of these vaccines can cause harm to humans, who are injecting the vaccine manually. The proposed new generation of peptide-based vaccines will overcome both problems, creating safer working conditions for humans. In addition, the welfare of the fish will benefit from vaccines, causing less side effects. Food safety is a major concern both from a governmental point of view as well as with the consumers. Today's DNA-vaccine constructs present several points of concern such as the viral promoters used and the antibiotic resistances residing in the vectors. These issues will have to be resolved before DNA-vaccines becomes commercially exploitable. Peptide vaccines circumvent those safety hazards by being administered in a non-replicative peptide form.