Vaccination experiments in the gadoid haddock, Melanogrammus aeglefinus L., against the bacterial pathogen Vibrio anguillarum

Vibrio anguillarum is one of the primary pathogens responsible for high levels of fish mortality in the aquaculture industry, and among gadoids O2a and b are the most common pathogenic serotypes. In this paper a variety of studies were performed to assess the optimal route by which to challenge haddock against this pathogen, and an optimal regime to vaccinate haddock. The most efficient method to challenge haddock with V. anguillarum in this study was immersion in a bath containing 107 cfu/ml, where 60% mortality was seen. Subsequent experiments showed that juvenile haddock could be protected against bacterial challenge with V. anguillarum, with a significant reduction in mortalities observed amongst the vaccination treatments when compared to the unvaccinated controls. However, as seen previously in cod studies, vaccination did not induce a specific antibody response.