Incidence of Vibriosis disease of Cultured Asian seabass (Lates calcarifer) in Iran

It is considered as one of the main challenges for the production of marine fish and Asian seabass, causing significant losses, especially in cage culture systems. Many researchers point out that vibrios is a major cause of bacterial disease in marine aquaculture, and pointed out that in order to prevent the onset of vibriosis, a serious effort should be made to determine the virulence of various species of vibrio, their pathogenicity and the production of vaccine strains. In this study, a total number of 110 Asian seabass (80, with clinical sings of disease and 30, apparently healthy fish) with different body weight ranging 50 - 700g were sampled. Isolation was done from internal organs (kidney, heart, spleen and liver) in common method of bacterial isolation and isolates subjected to phenotypic and molecular characteristics using duplex PCR amplification of the 16SrDNA & vhh genes respectively genus & species-specific gene. The results of PCR showed that of the 95 phenotypically identified isolates, only65 isolates belong to the genus vibrio and 46(70.76%) of them were identified as V. harveyi. The results of this study indicate a high prevalence of V. harveyi in marine Asian seabass fish farms, Therefore, prophylactic measures should be consider to prevent vibriosis disease (especially vaccination). Also On the basis of molecular and phonotypic virulent assay, challenge experiment was designed by selecting two of 46 isolate. It was found that V. harveyi VHAM1 highly virulent to seabass at LD50 1.2x108 c.f.u. g- 1 fish that it was used as bacterine.

کلیدواژه ها:

Asian seabass ، Vibriosis ، virulence ، Bacterine ، duplex PCR