Efficacy of Oil-adjuvanted Vaccine for Coldwater Disease in Ayu Plecoglossus altivelis

Abstract

We investigated the potency of two oil adjuvants, Montanidae ISA 763A (763A) and a squalene emulsion (Squalene), to enhance the response of ayu Plecoglossus altivelis to a formalin-killed bacterin (FKB) made from the coldwater disease etiologic agent, Flavobacterium psychrophilum. Ayu were challenged 4 wk after vaccination by an intramuscular injection with live pathogenic F. psychrophilum. Mortalities of fish injected with FKB of F. psychrophilum combined with either adjuvant showed that the adjuvanted vaccines had significantly higher (P<0.05) potencies than the FKB vaccine alone or sterile distilled water. Moreover, both adjuvanted vaccines produced significantly higher antibody titers than the FKB vaccine without adjuvant. From these investigations it is concluded that the use of Squalene and 763A adjuvants provides enhanced protection against coldwater disease in ayu compared to the use of FKB alone.