Susceptibility of ocean- and stream-type Chinook salmon to isolates of the L, U, and M genogroups of infectious hematopoietic necrosis virus (IHNV).
This study examined the susceptibility of Chinook salmon Oncorhynchus tshawytscha to viral strains from the L, U, and M genogroups of infectious hematopoietic necrosis virus (IHNV) present in western North America. The goal of this investigation was to establish a baseline understanding of the susceptibility of ocean- and stream-type Chinook salmon to infection and mortality caused by exposure to commonly detected strains of L, U, and M IHNV. The L IHNV strain tested here was highly infectious and virulent in both Chinook salmon populations, following patterns previously reported for Chinook salmon. Furthermore, ocean- and stream-type Chinook salmon fry at 1 g can also become subclinically infected with U and M strains of IHNV without experiencing significant mortality. The stream-type life history phenotype was generally more susceptible to infection and suffered greater mortality than the ocean-type phenotype. Between the U and M genogroup strains tested, the U group strains were generally more infectious than the M group strains in both Chinook salmon types. Substantial viral clearance occurred by 30 d post exposure, but persistent viral infection was observed with L, U, and M strains in both host populations. While mortality decreased with increased host size in stream-type Chinook salmon, infection prevalence was not lower for all strains at a greater size. These results suggest that Chinook salmon may serve as reservoirs and/or vectors of U and M genogroup IHNV.
University of Washington, School of Aquatic and Fishery Sciences, Box 355020, Seattle, WA 98195, USA.
Daniel G
DG
Hernandez
Maureen K
MK
Purcell
Carolyn S
CS
Friedman
Gael
G
Kurath
D000818:Animals; D004198:Disease Susceptibility; D005393:Fish Diseases / Q000821:virology*; D029142:Infectious hematopoietic necrosis virus / Q000235:genetics*; D010140:Pacific Ocean; D018353:Rhabdoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D045483:Rivers; D012474:Salmon; D019562:Viral Load; D010948:Viral Plaque Assay