Analysis of the nucleoprotein gene identifies distinct lineages of viral haemorrhagic septicaemia virus within the European marine environment

A ribonuclease (RNase) protection assay (RPA) has been used to detect nucle otide sequence variation within the nucleoprotein gene of 39 viral haemorrh agic septicaemia virus (VHSV) isolates of European marine origin. The class ification of VHSV isolates based on RPA cleavage patterns permitted the ide ntification of ten distinct groups of viruses based on differences at the m olecular level. The nucleotide sequence of representatives of each of these groupings was determined and subjected to phylogenetic analysis. This reve aled grouping of the European marine isolates of VHSV into three genotypes circulating within distinct geographic areas. A fourth genotype was identif ied comprising isolates originating from North America. Phylogenetic analys es indicated that VHSV isolates recovered from wild caught fish around the British isles were genetically related to isolates responsible for losses i n farmed turbot. Furthermore, a relationship between naturally occurring ma rine isolates and VHSV isolates causing mortality among rainbow trout in co ntinental Europe was demonstrated. (C) 1999 Elsevier Science B.V. All right s reserved.