DAO 58:111-115 (2004)  -  doi:10.3354/dao058111

Experimental horizontal transmission of viral hemorrhagic septicemia virus (VHSV) in Japanese flounder Paralichthys olivaceus

K. Muroga1,4,*, H. Iida1, K. Mori2, T. Nishizawa3, M. Arimoto2

1Graduate School of Biosphere Sciences, Hiroshima University, Higashihiroshima 739-8528, Japan
2The Kamiura Station, Japan Sea-Farming Association, Kamiuracho, Oita 879-2602, Japan
3Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
4Present address: Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan

ABSTRACT: Infection by viral hemorrhagic septicemia virus (VHSV) has recently occurred among wild and farmed Japanese flounder Paralichthys olivaceus in Japan. In the present study, horizontal transmission of VHSV among Japanese flounder was experimentally demonstrated by immersion challenge. Exposure to a flounder isolate (Obama25) of VHSV revealed a dose-response, with higher mortality (81 and 70%) at the 2 higher exposure levels (6.0 and 4.0 log10 TCID50 ml-1). In a second experiment, high titers of VHSV were expressed from moribund and dead flounder based on virus detection in holding-tank waters 2 to 3 d prior to death of the fish and 1 d after death. The virus could not be detected in tank waters 2 d after death. Finally, a third cohabitation experiment in small tanks demonstrated horizontal transmission of VHSV from experimentally infected to uninfected fish.


KEY WORDS: Viral hemorrhagic septicemia virus · Paralichthys olivaceus · Horizontal transmission · Immersion challenge · Waterborne route


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