Abstract:

Epizootic Ulcerative Syndrome (EUS) is a seasonal and widely spread ulcerative condition of fresh and brackishwater fishes in Asia caused by a complex of etiological agents. Viral agents have been found to be associated with EUS, but their role in the complex etiology still has to be identified. Further virological examinations were, therefore, conducted in this study. Twenty viral isolations were achieved from three epizootics in Thailand. In the 1993-1994 epizootic, nine rhabdoviruses were successfully isolated from EUS snakehead (Channa striata) and three-spot gourami (Trichoglaster trichopterus). Another nine rhabdoviruses were also isolated from 11 tissue extracts from affected snakeheads collected in the 1995-1996 outbreak. Two other viral isolates were obtained from affected giant gourami (Osphronemus gouramy) and climbing perch (anabas testudineus) in the 1996-1997 outbreak. These viruses were isolated only from samples collected during the early period of the outbreaks. The tissue samples collected from moribund fish, processed and inoculated from the samples collected after the early period of the EUS from Thailand and Pakistan gave no cytopathic effect on the host cells. In this study, BF-2 cells seemed to be the best cell line for viral isolation followed by SSN-1 and HCK lines, while no virus could be obtained using the EPC and BB lines. The results of this study suggest that the viruses, especially rhabdovirus, are readily isolated from diseased fishes during the early period of an outbreak, and that they may have a significant role in a complex of etiological agents of EUS.

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Date 1999/12/01

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