Comparative Susceptibilities of Selected California Chinook Salmon and Steelhead Populations to Isolates of L Genogroup Infectious Hematopoietic Necrosis Virus (IHNV).

Salmonid species demonstrate varied susceptibility to the viral pathogen infectious hematopoietic necrosis virus (IHNV). In California conservation hatcheries, juvenile Chinook salmon ( have experienced disease outbreaks due to L genogroup IHNV since the 1940s, while indigenous steelhead (anadromous appear relatively resistant. To characterize factors contributing to the losses of California salmonid fish due to IHNV, three populations of Chinook salmon and two populations of steelhead native to California watersheds were compared in controlled waterborne challenges with California L genogroup IHNV isolates at viral doses of 10-10 pfu mL.

New disease records for hatchery-reared sturgeon. I. Expansion of frog virus 3 host range into Scaphirhynchus albus.

In 2009, juvenile pallid sturgeon Scaphirhynchus albus, reared at the Blind Pony State Fish Hatchery (Missouri, USA) to replenish dwindling wild stocks, experienced mass mortality. Histological examination revealed extensive necrosis of the haematopoietic tissues, and a virus was isolated from affected organs in cell culture and then observed by electron microscopy. Experimental infection studies revealed that the virus is highly pathogenic to juvenile pallid sturgeon, one of several species of sturgeon currently listed as Endangered.

Protective immunity of a modified-live cyprinid herpesvirus 3 vaccine in koi (Cyprinus carpio koi) 13 months after vaccination.

Objective: To evaluate the long-term protective immunity of a cyprinid herpesvirus 3 (CyHV3) vaccine in naïve koi (Cyprinus carpio koi).

Animals: 72 koi. Procedures-Vaccinated koi (n = 36) and unvaccinated control koi (36) were challenge exposed to a wild-type CyHV3 strain (KHVp8 F98-50) 13 months after vaccination.

Efficacy and safety of a modified-live cyprinid herpesvirus 3 vaccine in koi (Cyprinus carpio koi) for prevention of koi herpesvirus disease.

Objective: To investigate safety and efficacy of a cyprinid herpesvirus type 3 (CyHV3) modified-live virus vaccine for the prevention of koi herpesvirus disease (KHVd).

Animals: 420 healthy koi (Cyprinus carpio koi).

Procedures: Fish were vaccinated with a 1× dose or 10× overdose of CyHV3 modified-live virus vaccine or a placebo through bath exposure in tanks at 22°C.

Genetic diversity of infectious hematopoietic necrosis virus from Feather River and Lake Oroville, California, and virulence of selected isolates for Chinook salmon and rainbow trout.

Infectious hematopoietic necrosis virus (IHNV) is a significant pathogen of young salmonid fishes worldwide but particularly within the historical range of the Pacific Northwest and California. In the Sacramento and San Joaquin River drainages of California, IHNV outbreaks in juvenile Chinook salmon Oncorhynchus tshawytscha have been observed regularly at large production hatcheries, including Coleman National Fish Hatchery (established in 1941) and Feather River State Fish Hatchery (FRH; established in 1967), since facility operations began. Recent severe epidemics at the FRH in 1998 and 2000-2002 prompted investigations into the characteristics and potential sources of virus at this facility.

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

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.