The phylogenetic relationship of nervous necrosis virus from halibut (Hippoglossus hippoglossus).

Viral nervous necrosis was detected on larval and juvenile turbot in Norway as early as in 1987-1989 and on halibut (Hippoglossus hippoglossus) in 199 5. At present this disease is a very constant finding in cultures of larval and juvenile halibut. This study is a report on the presence of viral nerv ous necrosis in adult and mature halibut. In addition, the coat protein gen e from nervous necrosis virus isolated from halibut was sequenced and compa red with similar sequences available from nodaviruses isolated from other m arine finfish. The molecular phylogenetic trees deduced from analysis of ex isting nucleotide sequences of the coat protein gene and the sequence from halibut, confirm previous phylogenies. The isolate from halibut is closely related to isolates from other cold water species, barfin flounder (Veraspe r moseri) and pacific cod (Gadus macrocephalus). It is suggested that the o bserved pattern of four major clusters of NNV isolates which all occur in J apanese waters, may be a result of transportation of isolates between Europ e and the Pacific.