Influence of seven immunostimulants on the immune response of coho salmon to Aeromonas salmonicida

A study was conducted to evaluate the efficacy of 7 substances at potentiating a formalinlulled Aeromonas salmonicida bacterin in juvenile coho salmon Oncorhynchus kisutch.The substances were injected into the fish along with the bacterin.The fish were challenged 27 d later with viable A. salmonicida cells by 2 methods (cohabitation and immersion).The cumulative mortalities in each of the experimental groups was then determined.A significant and consistent increase in protection over the groups receiving only the A. sal~nonicida bacterin was observed with 3 of the substances tested.These were VitaStinl-Taito, lentinan and formalin-killed Renibacterium salmoninarum cells.One of these materials, VitaStim-Taito (a 8-1,3 glucan), showed particular promise for further studies.' Dose refers to the dried cells of Mycobacterium butyricum present in the adjuvant emulsion administered