The importance of bacterial interactions for winter ulcer and the potential use in control of fish diseases

Investigation of bacterial interaction within and between pathogens involved in the disease Winter ulcer will be the main object since this disease is the main unsolved bacterial infection in salmonid farming and the problem has so far not been solved by vaccination, antibiotics or any management factors. The increased knowledge will be a scientific base for effective control of Winter ulcer and other infectious fish diseases. The investigation will start with a broad approach involving many different cr iteria for the growth of the bacteria and any detection of new factors will be further investigated in detail. Culturing and co-culturing of V. wodanis and M. viscosa with investigation of extracellular factors, surface features, intracellular changes og changes in behaviour related to interactions between the two bacteria will be performed. The various components and factors in the interaction will be studied with molecular proteomic and genetic methods. Bacterial strains with genes of importance in the bacterial interaction will be "knocked out" by molecular methods and tested for in vitro effect including complementating strains in small-scale challenge experiments with fish. The results from the project will be a good background for developing optim al control of Winter ulcer by improved vaccines or new strategies of preventing disease outbreaks.