Effect of mutations in carbohydrate-active enzymes on virulence of Aliivibrio salmonicida

Cold water vibriosis has been one of the most important bacterial diseases in salmon aquaculture. Despite 30 years of research, there is still limited knowledge on the virulence and pathogenesis of the causing agent, Aliivibrio salmonicida. The main purpose of the current experiment is to investigate the role of the carbohydrate-active enzymes (CAEs) on virulence of Aliivibrio salmonicida in Atlantic salmon. The current experiment is a continuation from a pilot experiment (FOTS 11380), and will outline the magnitude of the effects of mutations in CAE on pathogenicity of Al. salmonicida. In the present experimental setup, a maximum of 1750 Atlantic salmon smolts will be used to investigate the role of three CAEs in Al. salmonicida virulence. Based on prior experience, the distress expected for the fish is expected to be moderate since the animals will not experience any mechanical damage and all manipulations will be terminal and done under anesthesia. We expect the data collected to reveal new knowledge on the infection mechanism used by Al. salmonicida, which may result in new ways of preventing bacterial infections (e.g. novel vaccines) and thereby improved fish welfare. In order utilize the research animals to their full potential, we will also collect samples for analysis of the general host response to infection (host metabolomics and transcriptomics and analysis of the gut microbial community). By using the current challenge experiment to answer multiple research questions, we may reduce the need of doing similar separate studies in the future.