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Two distinct phylogenetic clades of infectious hematopoietic necrosis virus overlap within the Columbia River basin

Diseases of Aquatic Organisms

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Abstract

Infectious hematopoietic necrosis virus (IHNV), an aquatic rhabdovirus, causes a highly lethal disease of salmonid fish in North America. To evaluate the genetic diversity of IHNV from throughout the Columbia River basin, excluding the Hagerman Valley, Idaho, the sequences of a 303 nt region of the glycoprotein gene (mid-G) of 120 virus isolates were determined. Sequence comparisons revealed 30 different sequence types, with a maximum nucleotide diversity of 7.3% (22 mismatches) and an intrapopulational nucleotide diversity of 0.018. This indicates that the genetic diversity of IHNV within the Columbia River basin is 3-fold higher than in Alaska, but 2-fold lower than in the Hagerman Valley, Idaho. Phylogenetic analyses separated the Columbia River basin IHNV isolates into 2 major clades, designated U and M. The 2 clades geographically overlapped within the lower Columbia River basin and in the lower Snake River and tributaries, while the upper Columbia River basin had only U clade and the upper Snake River basin had only M clade virus types. These results suggest that there are co-circulating lineages of IHNV present within specific areas of the Columbia River basin. The epidemiological significance of these findings provided insight into viral traffic patterns exhibited by IHNV in the Columbia River basin, with specific relevance to how the Columbia River basin IHNV types were related to those in the Hagerman Valley. These analyses indicate that there have likely been 2 historical events in which Hagerman Valley IHNV types were introduced and became established in the lower Columbia River basin. However, the data also clearly indicates that the Hagerman Valley is not a continuous source of waterborne virus infecting salmonid stocks downstream.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Two distinct phylogenetic clades of infectious hematopoietic necrosis virus overlap within the Columbia River basin
Series title:
Diseases of Aquatic Organisms
Volume
55
Issue:
3
Year Published:
2003
Language:
English
Publisher:
Inter-Research
Description:
p.187-203
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Diseases of Aquatic Organisms
First page:
187
Last page:
203