title: Immune gene profiles in Atlantic salmon (salmo salar L.) post-smolts infected with SAV3 by bath-challenge show a delayed response and lower levels of gene transcription compared to injected fish.
abstract: Salmonid alphavirus (SAV) causes pancreatic disease (PD) in salmonids in Northern Europe which results in large economic losses within the aquaculture industry. In order to better understand the underlying immune mechanisms during a SAV3 infection Atlantic salmon post-smolts were infected by either i.m.-injection or bath immersion and their immune responses compared. Analysis of viral loads showed that by 14 dpi i.m.-injected and bath immersion groups had 95.6% and 100% prevalence respectively and that both groups had developed the severe pathology typical of PD. The immune response was evaluated by using RT-qPCR to measure the transcription of innate immune genes involved in the interferon (IFN) response as well as genes associated with inflammation. Our results showed that IFNa transcription was only weakly upregulated, especially in the bath immersion group. Despite this, high levels of the IFN-stimulated genes (ISGs) such as Mx and viperin were observed. The immune response in the i.m.-injected group as measured by immune gene transcription was generally faster, and more pronounced than the response in the bath immersion group, especially at earlier time-points. The response in the bath immersion group started later as expected and appeared to last longer often exceeding the response in the i.m-injected fish at later time-points. High levels of transcription of many genes indicative of an active innate immune response were present in both groups.
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway.
authors.forename: L J
authors.initials: LJ
authors.lastname: Moore
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway; Department of Biology, University of Bergen, P.O. Box 7803, 5020 Bergen, Norway.
authors.forename: J
authors.initials: J
authors.lastname: Jarungsriapisit
authors.affiliation: Uni Research Environment, Uni Research, Thormøhlensgt, 49B 5006 Bergen, Norway.
authors.forename: T O
authors.initials: TO
authors.lastname: Nilsen
authors.affiliation: Department of Biology, University of Bergen, P.O. Box 7803, 5020 Bergen, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Stefansson
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway.
authors.forename: G L
authors.initials: GL
authors.lastname: Taranger
authors.affiliation: Scottish Fish Immunology Research Centre, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, Scotland, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Secombes
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway.
authors.forename: H C
authors.initials: HC
authors.lastname: Morton
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway. Electronic address: sonal.patel@imr.no.
authors.forename: S
authors.initials: S
authors.lastname: Patel
mesh_terms: D000284:Administration, Oral; D000524:Alphavirus / Q000502:physiology*; D018354:Alphavirus Infections / Q000235:genetics / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D000818:Animals; D005393:Fish Diseases / Q000235:genetics* / Q000276:immunology / Q000821:virology; D007113:Immunity, Innate; D007273:Injections, Intramuscular / Q000662:veterinary; D010182:Pancreatic Diseases / Q000235:genetics / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D016133:Polymerase Chain Reaction / Q000662:veterinary; D020317:Salmo salar; D014158:Transcription, Genetic
keywords: Bath immersion; Gene expression; Infection route; Interferon; Pancreas disease; Salmonid alphavirus