DAO 71:267-272 (2006) - doi:10.3354/dao071267
Nucleotide diversity of Japanese isolates of infectious hematopoietic necrosis virus (IHNV) based on the glycoprotein gene
T. Nishizawa, S. Kinoshita, W.-S. Kim, S. Higashi, M. Yoshimizu*
ABSTRACT: Infectious hematopoietic necrosis virus (IHNV), a member of the genus Novirhabdovirus, causes a highly lethal disease of salmonid fish. In the present study, G gene nucleotide sequences of 9 Japanese IHNV isolates obtained from 1971 to 1996 were analyzed to evaluate the genetic diversity and compared with IHNV isolates from North America and Europe. A radial phylogenetic tree revealed 5 major clusters including 3 genogroups (U, M and L) for North American isolates and 1 genogroup for European isolates. Five Japanese isolates from 1971 to 1982 appeared in the cluster for genogroup U, while the remaining Japanese isolates from 1980 to 1996 formed a new genogroup, JRt (Japanese rainbow trout). Maximum nucleotide diversity among the Japanese isolates was 4.5%, which was greater than that within the North American isolates (3.6%), and the degree of nucleotide diversity within Japanese isolates was increased by inclusion of the genogroup JRt isolates. It was concluded that Japanese isolates shared a common source with the genogroup U of the North American isolates and that there were large divergences between Japanese isolates before and after the 1980s.
KEY WORDS: IHNV · Fish rhabdovirus · Glycoprotein gene · Phylogenetic relatedness · Evolution
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