Resistance and protective immunity in Redfish Lake sockeye salmon exposed to M type infectious hematopoietic necrosis virus (IHNV).
Differential virulence of infectious hematopoietic necrosis virus (IHNV) isolates from the U and M phylogenetic subgroups is clearly evident in the Redfish Lake (RFL) strain of sockeye salmon Oncorhynchus nerka. In these fish, experimental immersion challenges with U isolates cause extremely high mortality and M isolates cause low or no mortality. When survivors of M virus immersion challenges were exposed to a secondary challenge with virulent U type virus they experienced high mortality, indicating that the primary M challenge did not elicit protective immunity. Delivery of a moderate dose (2 x 10(4) plaque-forming units [PFU]/fish) of virus by intraperitoneal injection challenge did not overcome RFL sockeye salmon resistance to M type IHNV. Injection challenge with a high dose (5 X 10(6) PFU/fish) of M type virus caused 10% mortality, and in this case survivors did develop protective immunity against a secondary U type virus challenge. Thus, although it is possible for M type IHNV to elicit cross-protective immunity in this disease model, it does not develop after immersion challenge despite entry, transient replication of M virus to low levels, stimulation of innate immune genes, and development of neutralizing antibodies in some fish.
Kurath
Gael
G
U.S. Geological Survey, Western Fisheries Research Center, 6505 Northeast 65th Street, Seattle, Washington 98115, USA. gkurath@usgs.gov
Garver
Kyle A
KA
LaPatra
Scott E
SE
Purcell
Maureen K
MK
D000818:Animals; D004198:Disease Susceptibility; D005393:Fish Diseases / Q000276:immunology / Q000821:virology*; D005618:Fresh Water; D029142:Infectious hematopoietic necrosis virus / Q000145:classification; D018353:Rhabdoviridae Infections / Q000276:immunology / Q000662:veterinary*; D012474:Salmon