title: Innate and adaptive immune responses in migrating spring-run adult chinook salmon, Oncorhynchus tshawytscha.
abstract: Adult Chinook salmon (Oncorhynchus tshawytscha) migrate from salt water to freshwater streams to spawn. Immune responses in migrating adult salmon are thought to diminish in the run up to spawning, though the exact mechanisms for diminished immune responses remain unknown. Here we examine both adaptive and innate immune responses as well as pathogen burdens in migrating adult Chinook salmon in the Upper Willamette River basin. Messenger RNA transcripts encoding antibody heavy chain molecules slightly diminish as a function of time, but are still present even after fish have successfully spawned. In contrast, the innate anti-bacterial effector proteins present in fish plasma rapidly decrease as spawning approaches. Fish also were examined for the presence and severity of eight different pathogens in different organs. While pathogen burden tended to increase during the migration, no specific pathogen signature was associated with diminished immune responses. Transcript levels of the immunosuppressive cytokines IL-10 and TGF beta were measured and did not change during the migration. These results suggest that loss of immune functions in adult migrating salmon are not due to pathogen infection or cytokine-mediated immune suppression, but is rather part of the life history of Chinook salmon likely induced by diminished energy reserves or hormonal changes which accompany spawning.
authors.affiliation: Department of Biomedical Sciences, 105 Magruder Hall, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97333, USA. Electronic address: Brian.Dolan@oregonstate.edu.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Dolan
authors.affiliation: Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Fisher
authors.affiliation: Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Colvin
authors.affiliation: Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Benda
authors.affiliation: U.S. Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA.
authors.forename: James T
authors.initials: JT
authors.lastname: Peterson
authors.affiliation: Department of Microbiology, Oregon State University, 220 Nash Hall, Corvallis, OR, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Kent
authors.affiliation: U.S. Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA.
authors.forename: Carl B
authors.initials: CB
authors.lastname: Schreck
mesh_terms: D056704:Adaptive Immunity; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D005260:Female; D029941:Fish Proteins / Q000276:immunology; D007113:Immunity, Innate; D016753:Interleukin-10 / Q000276:immunology; D008297:Male; D012474:Salmon / Q000276:immunology*; D012621:Seasons; D016212:Transforming Growth Factor beta / Q000276:immunology
chemical_list: D029941:Fish Proteins; D016212:Transforming Growth Factor beta; D016753:Interleukin-10
keywords: Immune response; Parasite burden; Salmon