title: Effects of functional feeds on the lipid composition, transcriptomic responses and pathology in heart of Atlantic salmon (Salmo salar L.) before and after experimental challenge with Piscine Myocarditis Virus (PMCV).
abstract: BACKGROUND
  Cardiomyopathy syndrome (CMS) is a severe cardiac disease of Atlantic salmon (Salmo salar) recently associated with a double-stranded RNA virus, Piscine Myocarditis Virus (PMCV). The disease has been diagnosed in 75-85 farms in Norway each year over the last decade resulting in annual economic losses estimated at up to €9 million. Recently, we demonstrated that functional feeds led to a milder inflammatory response and reduced severity of heart lesions in salmon experimentally infected with Atlantic salmon reovirus, the causal agent of heart and skeletal muscle inflammation (HSMI). In the present study we employed a similar strategy to investigate the effects of functional feeds, with reduced lipid content and increased eicosapentaenoic acid levels, in controlling CMS in salmon after experimental infection with PMCV.
  
  
  RESULTS
  Hepatic steatosis associated with CMS was significantly reduced over the time course of the infection in fish fed the functional feeds. Significant differences in immune and inflammatory responses and pathology in heart tissue were found in fish fed the different dietary treatments over the course of the infection. Specifically, fish fed the functional feeds showed a milder and delayed inflammatory response and, consequently, less severity of heart lesions at earlier and later stages after infection with PMCV. Decreasing levels of phosphatidylinositol in cell membranes combined with the increased expression of genes related with T-cell signalling pathways revealed new interactions between dietary lipid composition and the immune response in fish during viral infection. Dietary histidine supplementation did not significantly affect immune responses or levels of heart lesions.
  
  
  CONCLUSIONS
  Combined with the previous findings on HSMI, the results of the present study highlight the potential role of clinical nutrition in controlling inflammatory diseases in Atlantic salmon. In particular, dietary lipid content and fatty acid composition may have important immune-modulatory effects in Atlantic salmon that could be potentially beneficial in fish balancing the immune and tissue responses to viral infections.
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK. laura.martinez@stir.ac.uk.
authors.forename: Laura
authors.initials: L
authors.lastname: Martinez-Rubio
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Evensen
authors.forename: Aleksei
authors.initials: A
authors.lastname: Krasnov
authors.forename: Sven Martin
authors.initials: SM
authors.lastname: Jørgensen
authors.forename: Simon
authors.initials: S
authors.lastname: Wadsworth
authors.forename: Kari
authors.initials: K
authors.lastname: Ruohonen
authors.forename: Jose L G
authors.initials: JL
authors.lastname: Vecino
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Tocher
mesh_terms: D000818:Animals; D005227:Fatty Acids / Q000378:metabolism; D005393:Fish Diseases / Q000235:genetics* / Q000378:metabolism* / Q000821:virology; D020869:Gene Expression Profiling; D006321:Heart / Q000821:virology; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism / Q000473:pathology / Q000821:virology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D020317:Salmo salar / Q000235:genetics* / Q000378:metabolism* / Q000821:virology; D015398:Signal Transduction; D013997:Time Factors; D019196:Totiviridae / Q000502:physiology; D059467:Transcriptome; D019562:Viral Load
chemical_list: D005227:Fatty Acids