DAO 61:11-21 (2004)  -  doi:10.3354/dao061011

Genetic population structure of marine viral haemorrhagic septicaemia virus (VHSV)

M. Snow1,*, N. Bain1, J. Black1, V. Taupin1, C. O. Cunningham1, J. a. King1, H. F. Skall2, R. S. Raynard1

1Fisheries Research Services (FRS) Marine Laboratory, PO Box 101, 375 Victoria Road, Aberdeen, AB11 9DB, Scotland, UK
2Department of Poultry, Fish and Fur Animals, Danish Institute for Food and Veterinary Research, Hangøvej 2, 8200 Århus N, Denmark
Nucleotide sequences reported in this paper have been submitted to the GenBank database and designated the accession numbers detailed in Table 1. Sequences may also be retrieved in FASTA format from www.fishpathogens.net (Snow et al. 2004). Alignment available on request

ABSTRACT: The nucleotide sequences of a specific region of the nucleoprotein gene were compared in order to investigate the genetic population structure of marine viral haemorrhagic septicaemia virus (VHSV). Analysis of the sequence from 128 isolates of diverse geographic and host origin renders this the most comprehensive molecular epidemiological study of marine VHSV conducted to date. Phylogenetic analysis of nucleoprotein gene sequences confirmed the existence of the 4 major genotypes previously identified based on N- and subsequent G-gene based analyses. The range of Genotype I included subgroups of isolates associated with rainbow trout aquaculture (Genotype Ia) and those from the Baltic marine environment (Genotype Ib) to emphasise the relatively close genetic relationship between these isolates. The existence of an additional genotype circulating within the Baltic Sea (Genotype II) was also confirmed. Genotype III included marine isolates from around the British Isles in addition to those associated with turbot mariculture, highlighting a continued risk to the development of this industry. Genotype IV consisted of isolates from the marine environment in North America. Taken together, these findings suggest a marine origin of VHSV in rainbow trout aquaculture. The implications of these findings with respect to the future control of VHSV are discussed. The capacity for molecular phylogenetic analysis to resolve complex epidemiological problems is also demonstrated and its likely future importance to disease management issues highlighted.

KEY WORDS: Viral Haemorrhagic Septicaemia Virus · VHSV · VHS · Nucleoprotein · Phylogenetics

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