The isolation and identification of a pathogenic Vibrio neocaledonicus from Yesso scallop (Patinopecten yessoensis)
Keywords:Yesso scallop, isolation and identification, pathogenicity, bacterial infection, Vibrio neocaledonicus
Yesso scallop (Patinopecten yessoensis) is one of the most important cultured mollusc in China. However, the diseases of Yesso scallops, especially abscess disease, occurred frequently and led to massive mortality in recent years. In the present study, 20 bacterial strains were isolated and characterized from the adductor muscle of moribund Yesso scallops in the North Yellow Sea to identify the potential pathogens, and 14 of them were grouped into genus Vibrio. Vibrio neocaledonicus (M-08 strain) was found to be the most dominant strain, and it was able to survive and exhibit haemolytic activity from 8 °C to 36 °C with the highest activity at 32 °C. The pathogenicity of M-08 in Yesso scallops was further investigated by intravalvar injection and immersion challenges, and the cumulative mortality rates were calculated to be 93 % and 53 %, respectively. The activities of superoxide dismutase (SOD) and catalase (CAT) increased after M-08 intravalvar injection, and peaked at 3 h and 6 h, respectively. The MDA contents increased and were significantly higher than that in the control group at 3 h after M-08 intravalvar injection. Immediately afterwards, immune response and haemocyte apoptosis were observed in Yesso scallops. Therefore, V. neocaledonicus is the pathogen of abscess disease in the Yesso scallops, which was able to activate the antioxidant system and immune response, and cause haemocyte apoptosis, tissue damage and death sequentially. The information would provide helpful contribution to the prevention and control of abscess disease in Yesso scallop aquaculture.