Efficacy of Direct Immersion Vaccination of Ayu Plecoglossus altivelis with Vibrio anguillarum Bacterin

Abstract

There was no mortality in ayu (Plecoglossus altivelis) which had mean body weight of 4.2 or 9.2 g during the rearing period after direct immersion in underground water containing lyophilized formalin-killed cells or sonicated cells of Vibrio anguillarum. A high level of protection against vibriosis was found in fish immersed directly in 0.94 or 9.4 (wet) g/l lyophilized or sonicated bacterin. The efficacy was no different for fish with a mean body weight of 4.2 g immersed for 1, 3, or 10 min in 1 (wet) g/l lyophilized bacterin. The duration of protective immunity in fish with a mean body weight of 8.0 g lasted 60 days after direct immersion in 0.94 or 9.4 (wet) g/l of lyophilized bacterin.