title: Gene expression comparison of resistant and susceptible Atlantic salmon fry challenged with Infectious Pancreatic Necrosis virus reveals a marked contrast in immune response.
abstract: BACKGROUND
  Infectious Pancreatic Necrosis (IPN) is a highly contagious birnavirus disease of farmed salmonid fish, which often causes high levels of morbidity and mortality. A large host genetic component to resistance has been previously described for Atlantic salmon (Salmo salar L.), which mediates high mortality rates in some families and zero mortality in others. However, the molecular and immunological basis for this resistance is not yet fully known. This manuscript describes a global comparison of the gene expression profiles of resistant and susceptible Atlantic salmon fry following challenge with the IPN virus.
  
  
  RESULTS
  Salmon fry from two IPNV-resistant and two IPNV-susceptible full sibling families were challenged with the virus and sampled at 1 day, 7 days and 20 days post-challenge. Significant viral titre was observed in both resistant and susceptible fish at all timepoints, although generally at higher levels in susceptible fish. Gene expression profiles combined with gene ontology and pathway analyses demonstrated that while a clear immune response was observed in both resistant and susceptible fish, there were striking differences between the two phenotypes. The susceptible fish showed marked up-regulation of genes related to cytokine activity and inflammatory response that evidently failed to protect against the virus. In contrast, the resistant fish demonstrated a less pronounced immune response including up-regulation of genes relating to the M2 macrophage system.
  
  
  CONCLUSIONS
  While only the susceptible phenotype shows appreciable mortality levels, both resistant and susceptible fish can become infected with IPNV. Susceptible fish are characterized by a much larger, yet ineffective, immune response, largely related to cytokine and inflammatory systems. Resistant fish demonstrate a more moderate, putative macrophage-mediated inflammatory response, which may contribute to their survival.
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK.|Departamento de Genética, Facultad de Biología, Universidad de Santiago de Compostela, Santiago de Compostela, 15782, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Robledo
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK.
authors.forename: John B
authors.initials: JB
authors.lastname: Taggart
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK.
authors.forename: Jacqueline H
authors.initials: JH
authors.lastname: Ireland
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK.
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: McAndrew
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK.
authors.forename: William G
authors.initials: WG
authors.lastname: Starkey
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK.
authors.forename: Chris S
authors.initials: CS
authors.lastname: Haley
authors.affiliation: Landcatch Natural Selection Ltd., 15 Beta Centre, Stirling University Innovation Park, Stirling, FK9 4NF, UK.
authors.forename: Alastair
authors.initials: A
authors.lastname: Hamilton
authors.affiliation: Landcatch Natural Selection Ltd., 15 Beta Centre, Stirling University Innovation Park, Stirling, FK9 4NF, UK.
authors.forename: Derrick R
authors.initials: DR
authors.lastname: Guy
authors.affiliation: Landcatch Natural Selection Ltd., 15 Beta Centre, Stirling University Innovation Park, Stirling, FK9 4NF, UK.
authors.forename: Jose C
authors.initials: JC
authors.lastname: Mota-Velasco
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK.|Landcatch Natural Selection Ltd., 15 Beta Centre, Stirling University Innovation Park, Stirling, FK9 4NF, UK.
authors.forename: Almas A
authors.initials: AA
authors.lastname: Gheyas
authors.affiliation: Landcatch Natural Selection Ltd., 15 Beta Centre, Stirling University Innovation Park, Stirling, FK9 4NF, UK.
authors.forename: Alan E
authors.initials: AE
authors.lastname: Tinch
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth, DT4 8UB, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Verner-Jeffreys
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth, DT4 8UB, UK.
authors.forename: Richard K
authors.initials: RK
authors.lastname: Paley
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth, DT4 8UB, UK.
authors.forename: Georgina S E
authors.initials: GS
authors.lastname: Rimmer
authors.affiliation: Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth, DT4 8UB, UK.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Tew
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Bishop
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK.
authors.forename: James E
authors.initials: JE
authors.lastname: Bron
authors.affiliation: The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, EH25 9RG, UK. ross.houston@roslin.ed.ac.uk.
authors.forename: Ross D
authors.initials: RD
authors.lastname: Houston
mesh_terms: D000818:Animals; D018175:Birnaviridae Infections / Q000235:genetics / Q000276:immunology / Q000662:veterinary*; D016207:Cytokines / Q000276:immunology; D060467:Disease Resistance / Q000235:genetics*; D005393:Fish Diseases / Q000235:genetics* / Q000276:immunology / Q000821:virology; D018061:Infectious pancreatic necrosis virus; D008264:Macrophages / Q000276:immunology; D020317:Salmo salar / Q000235:genetics* / Q000276:immunology* / Q000821:virology; D059467:Transcriptome
chemical_list: D016207:Cytokines
keywords: Salmo salar; aquaculture; disease resistance; infectious pancreatic necrosis; innate immunity; interferon; transcriptome; virus