DAO 64:13-22 (2005)  -  doi:10.3354/dao064013

Efficacy of an infectious hematopoietic necrosis (IHN) virus DNA vaccine in Chinook Oncorhynchus tshawytscha and sockeye O. nerka salmon

Kyle A. Garver1,2,*, Scott E. LaPatra3, Gael Kurath1,2

1Department of Pathobiology, University of Washington, Seattle, Washington 98195, USA
2Western Fisheries Research Center, United States Geological Survey, Biological Resources Division, 6505 NE 65th St, Seattle, Washington 98115, USA
3Clear Springs Foods, Inc., Research Division, PO Box 712, Buhl, Idaho 83316, USA

ABSTRACT: The level of protective immunity was determined for Chinook Oncorhynchus tshawytscha and sockeye/kokanee salmon (anadromous and landlocked) O. nerka following intramuscular vaccination with a DNA vaccine against the aquatic rhabdovirus, infectious hematopoietic necrosis virus (IHNV). A DNA vaccine containing the glycoprotein gene of IHNV protected Chinook and sockeye/kokanee salmon against waterborne or injection challenge with IHNV, and relative percent survival (RPS) values of 23 to 86% were obtained under a variety of lethal challenge conditions. Although this is significant protection, it is less than RPS values obtained in previous studies with rainbow trout (O. mykiss). In addition to the variability in the severity of the challenge and inherent host susceptibility differences, it appears that use of a cross-genogroup challenge virus strain may lead to reduced efficacy of the DNA vaccine. Neutralizing antibody titers were detected in both Chinook and sockeye that had been vaccinated with 1.0 and 0.1 µg doses of the DNA vaccine, and vaccinated fish responded to viral challenges with higher antibody titers than mock-vaccinated control fish.

KEY WORDS:DNA vaccine · Infectious hematopoietic necrosis virus · IHNV · Chinook salmon · Sockeye salmon · Cross-genogroup and intragenogroup challenge

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