Vibrio harveyi Infection in Farmed Greater Amberjack Seriola dumerili

Abstract

Mortalities accompanied with symptoms similar to vibriosis were observed in farmed greater amberjack Seriola dumerili immunized with a commercial Vibrio anguillarum vaccine (serotype J-O-3). The symptoms of infection included exfoliation of the head epithelium, ragged caudal fin, accumulated ascites, and ophthalmitis. Bacteria isolated from infected fish were positive in species-specific PCR assays for V. harveyi. A phylogenic analysis based on topA (DNA topoisomerase I) and mreB (rod shape-determining protein mreB) concatenated gene sequence provided further confirmation of the isolated bacteria as V. harveyi. Experimental infection revealed that the isolate was pathogenic to greater amberjack. In a vaccine trial, mortality of fish immunized with formalin-killed cells (FKC) of the isolate was significantly lower than that of control fish, suggesting that FKC of the isolate prevents greater amberjack from V. harveyi infection.