Grant: Engage Grants Program

Winter ulcer disease has mainly affected salmonids in Norway and Iceland, but also in Scotland, the Faroe Islands, Canada and Ireland. Outbreaks occur most commonly in Atlantic salmon, Salmo salar L., but also in rainbow trout, Oncorhynchus mykiss (Walbaum). The Gram-negative bacterium, Moritella viscosa is the main aetiological agent of winter ulcer disease at cold water temperatures (8-12°C) in seawater, however, Aliivibrio wodanis [formerly Vibrio wodanis] is often co-isolated with M. viscosa or as the only isolate from fish with the disease. Although winter ulcer disease was recognised more than 20 years ago, the pathogenesis of this disease is not yet fully understood and only a few virulence features have been characterized in Moritella viscosa. For knowledge-based development of vaccines and vaccine strategies, this is a considerable disadvantage. These outbreaks represent a serious threat to the industry, both directly in terms of the cost of aquatic health products and monitoring costs, and indirectly through impacts on production management decisions and, as with winter ulcer disease, in reduced carcass quality). This disease is the primary reason for antibiotic usage in aquaculture on the east coast of Canada and anecdotal reports suggest mortality from this disease is increasing although it is unclear as to why. The goals of the current work are to develop a challenge model for the study of M. viscose and characterize ulcer development so that future vaccine targets can be tested against this disease on a controlled setting. Furthermore, we will determine the impacts of common co-infection on pathology of winter ulcer disease.