DAO 77:29-40 (2007)  -  DOI: https://doi.org/10.3354/dao01811

Genotypes and phylogeographical relationships of infectious hematopoietic necrosis virus in California, USA

Garry O. Kelley1, Christin M. Bendorf1, Susan C. Yun1, Gael Kurath2, Ronald P. Hedrick1,*

1Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA 2 Western Fisheries Research Center, United States Geological Survey, Biological Resources Discipline, 6505 NE 65th St., Seattle, Washington 98115, USA
*Corresponding author. Email:

ABSTRACT: Infectious hematopoietic necrosis virus (IHNV) contains 3 major genogroups in North America with discreet geographic ranges designated as upper (U), middle (M), and lower (L). A comprehensive genotyping of 237 IHNV isolates from hatchery and wild salmonids in California revealed 25 different sequence types (a to y) all in the L genogroup; specifically, the genogroup contained 14 sequence types that were unique to individual isolates as well as 11 sequence types representing 2 or more identical isolates. The most evident trend was the phylogenetic and geographical division of the L genogroup into 2 distinct subgroups designated as LI and LII. Isolates within Subgroup LI were primarily found within waterways linked to southern Oregon and northern California coastal rivers. Isolates in Subgroup LII were concentrated within inland valley watersheds that included the Sacramento River, San Joaquin River, and their tributaries. The temporal and spatial patterns of virus occurrence suggested that infections among adult Chinook salmon in the hatchery or that spawn in the river are a major source of virus potentially infecting other migrating or resident salmonids in California. Serum neutralization results of the California isolates of IHNV corroborated a temporal trend of sequence divergence; specifically, 2 progressive shifts in which more recent virus isolates represent new serotypes. A comparison of the estimates of divergence rates for Subgroup LI (1 × 10–5 mutations per nucleotide site per year) indicated stasis similar to that observed in the U genogroup, while the Subgroup LII rate (1 × 10–3 mutations per nucleotide site per year) suggested a more active evolution similar to that of the M genogroup.


KEY WORDS: Infectious hematopoietic necrosis virus · IHNV · Rhabdovirus · Chinook salmon


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Cite this article as: Kelley GO, Bendorf CM, Yun SC, Kurath G, Hedrick RP (2007) Genotypes and phylogeographical relationships of infectious hematopoietic necrosis virus in California, USA. Dis Aquat Org 77:29-40. https://doi.org/10.3354/dao01811

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