Publication Abstract

Isolation of a rhabdovirus during outbreaks of disease in cyprinid fish species at fishery sites in England.

Isolation of a rhabdovirus during outbreaks of disease in cyprinid fish species at fishery sites in England

K. Way, S.J. Bark, C.B. Longshaw, K.L. Denham, P.F. Dixon, S.W. Feist, R. Gardiner, M.J. Gubbins, R-M Le Deuff, P.D. Martin, D.M. Stone, G.R. Taylor.

A rhabdovirus has been isolated during disease outbreaks in bream, tench, roach and crucian carp populations at 6 fishery sites in England in 1999. Mortalities at the sites were, with few exceptions, seen among recently introduced fish and the predominant fish species affected was bream. The fish exhibited few consistent external signs of disease and many of the signs could be attributed to transport and handling stress. However, some of the fish exhibited a clinical disease similar to spring viraemia of carp (SVC) with extensive skin haemorrhages and ulceration on the flanks and internal signs including ascites and petechial haemorrhages in the musculature, visceral organs and adipose tissue. The most prominent histopathological changes were hepatocellular necrosis, interstitial nephritis and splenitis.

The rhabdovirus induced a cytopathic effect in EPC cells at 20°C and produced moderate signals in an enzyme immunoassay (EIA) for the detection of SVC virus. Serologically the virus showed a close relationship to pike fry rhabdovirus in both EIA and serum neutralisation assays and to a rhabdovirus isolated during a disease outbreak in a bream population in the river Bann, Northern Ireland in 1998. The bream stocked at 5 of the 6 English fishery sites were found to have originated from the river Bann.

Experimental infection of juvenile bream and tench to EPC cell-grown rhabdovirus by bath and intraperitoneal (i/p) injections resulted in a 40 % mortality of bream in the i/p injection group only. The virus was re-isolated from pooled kidney, liver and spleen tissue samples from moribund bream. The field observations together with the experimental results indicate that this rhabdovirus is of low virulence but may have the potential to cause significant mortality in fish under stress.

Reference:

K. Way, S.J. Bark, C.B. Longshaw, K.L. Denham, P.F. Dixon, S.W. Feist, R. Gardiner, M.J. Gubbins, R-M Le Deuff, P.D. Martin, D.M. Stone, G.R. Taylor.. 2003. Isolation of a rhabdovirus during outbreaks of disease in cyprinid fish species at fishery sites in England. Diseases of Aquatic Organisms 57: 43 - 50

K. Way*, S.J. Bark*, C.B. Longshaw*, K.L. Denham*, P.F. Dixon*, S.W. Feist*, R. Gardiner*, M.J. Gubbins*, R-M Le Deuff*, P.D. Martin*, D.M. Stone* and G.R. Taylor*

Diseases of Aquatic Organisms 57: 43 - 50