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Melanized focal changes in skeletal muscle in farmed Atlantic salmon after natural infection with Piscine orthoreovirus (PRV).

https://arctichealth.org/en/permalink/ahliterature301317
Source
J Fish Dis. 2019 Jun; 42(6):935-945
Publication Type
Journal Article
Date
Jun-2019
Author
Håvard Bjørgen
Randi Haldorsen
Øyvind Oaland
Agnar Kvellestad
Dhamotharan Kannimuthu
Espen Rimstad
Erling Olaf Koppang
Author Affiliation
Institute of Basic Science and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
Source
J Fish Dis. 2019 Jun; 42(6):935-945
Date
Jun-2019
Language
English
Publication Type
Journal Article
Keywords
Animals
Aquaculture
Fish Diseases - pathology - virology
Melanins
Muscle, Skeletal - pathology - virology
Norway
Orthoreovirus - pathogenicity
RNA, Viral - genetics
Reoviridae Infections - pathology - veterinary
Salmo salar - virology
Abstract
Melanized focal changes in skeletal muscle of farmed Atlantic salmon (Salmo salar) are a major quality problem. The aetiology is unknown, but infection with Piscine orthoreovirus (PRV) has been associated with the condition. Here, we addressed the pathogenesis of red and melanized focal changes and their association with PRV. First, a population of farmed fish (PRV-negative prior to sea transfer) was sequentially investigated throughout the seawater period. The fish were autopsied and tested for PRV infection. Muscular changes were described by macroscopy and histology, and a classification system was established. Second, in an experimental infection trial, PRV was injected intramuscularly to induce changes. The farmed fish was gradually infected with PRV. Red focal changes occurred throughout the observation period with a low prevalence regardless of PRV status. Melanized changes were highly diverse and their prevalence increased during the trial. Changes of low macroscopic grade and histological category were more prevalent in PRV-negative fish. Diffuse granulomatous melanized changes only occurred after PRV infection. No muscular changes were observed in the experimentally challenged fish. Our studies do not indicate that PRV infection causes red focal changes, but seems important in the development of granulomatous melanized changes.
PubMed ID
30972792 View in PubMed
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Piscine orthoreovirus (PRV) in red and melanised foci in white muscle of Atlantic salmon (Salmo salar).

https://arctichealth.org/en/permalink/ahliterature271725
Source
Vet Res. 2015;46:89
Publication Type
Article
Date
2015
Author
Håvard Bjørgen
Øystein Wessel
Per Gunnar Fjelldal
Tom Hansen
Harald Sveier
Håkon Rydland Sæbø
Katrine Bones Enger
Eirik Monsen
Agnar Kvellestad
Espen Rimstad
Erling Olaf Koppang
Source
Vet Res. 2015;46:89
Date
2015
Language
English
Publication Type
Article
Keywords
Animals
Aquaculture
Fish Diseases - epidemiology - virology
Muscle, Skeletal - virology
Norway - epidemiology
Orthoreovirus - isolation & purification
Prevalence
Reoviridae Infections - epidemiology - veterinary - virology
Salmo salar
Abstract
Melanised focal changes (black spots) are common findings in the white skeletal muscle of seawater-farmed Atlantic salmon (Salmo salar). Fillets with melanised focal changes are considered as lower quality and cause large economic losses. It has been suggested that red focal changes (red spots) precede the melanised focal changes. In the present work, we examined different populations of captive and wild salmon for the occurrence of both types of changes, which were investigated for the presence of different viruses by immunohistochemistry and RT-qPCR. The occurrence of red or melanised foci varied significantly between the populations, from none in wild fish control group, low prevalence of small foci in fish kept in in-house tanks, to high prevalence of large foci in farm-raised salmon. Large amounts of Piscine orthoreovirus (PRV) antigen were detected in all foci. No other viruses were detected. Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals. Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation. We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.
Notes
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PubMed ID
26346256 View in PubMed
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Protection of atlantic salmon Salmo salar against infectious pancreatic necrosis after DNA vaccination.

https://arctichealth.org/en/permalink/ahliterature51641
Source
Dis Aquat Organ. 2004 Jul 5;60(1):11-20
Publication Type
Article
Date
Jul-5-2004
Author
Aase B Mikalsen
Jacob Torgersen
Peter Aleström
Anne-Lill Hellemann
Erling-Olaf Koppang
Espen Rimstad
Author Affiliation
Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, PO Box 8146 Dep, 0033 Oslo, Norway.
Source
Dis Aquat Organ. 2004 Jul 5;60(1):11-20
Date
Jul-5-2004
Language
English
Publication Type
Article
Keywords
Animals
Antibodies, Monoclonal - metabolism
Aquaculture - methods
Base Sequence
Birnaviridae Infections - immunology - prevention & control - veterinary
Blotting, Western
Cells, Cultured
Comparative Study
Fish Diseases - immunology - virology
Infectious pancreatic necrosis virus - genetics
Norway
Plasmids - genetics - metabolism
Research Support, Non-U.S. Gov't
Salmo salar
Sequence Alignment
Sequence Analysis, DNA
Vaccination - veterinary
Vaccines, DNA - immunology
Viral Structural Proteins - genetics - metabolism
Zebrafish
Abstract
Although vaccines against infectious pancreatic necrosis (IPN) based on inactivated virus or recombinant structural viral proteins are commercially available, the protection is not complete and the disease is still a problem for the Atlantic salmon Salmo salar farming industry. In the present study, 5 different plasmids that expressed whole or parts of the large open reading frames (ORF) of Segment A of the IPN virus (IPNV) were constructed. The plasmids were shown to express proteins in cell cultures and in zebrafish Danio rerio in vivo. The specificities of the expressed proteins were confirmed by staining with IPNV-specific monoclonal antibodies (MAb) The plasmids were then used alone or in different combinations to vaccinate groups of Atlantic salmon, which subsequently were challenged in an experimental assay for IPN. A high level of protection was induced only by the plasmid combination that contained a plasmid expressing all the large ORF polyprotein.
PubMed ID
15352520 View in PubMed
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Variations in mucous cell numbers in gills of Atlantic salmon (Salmo salar) presmolt in commercial freshwater farms in Norway.

https://arctichealth.org/en/permalink/ahliterature311989
Source
J Fish Dis. 2021 Jan; 44(1):25-32
Publication Type
Journal Article
Date
Jan-2021
Author
David Persson
Håvard Bjørgen
Alexander Figenschou
Linn-Anett Hillestad
Erling Olaf Koppang
Ane Nødtvedt
Marit Stormoen
Author Affiliation
Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
Source
J Fish Dis. 2021 Jan; 44(1):25-32
Date
Jan-2021
Language
English
Publication Type
Journal Article
Keywords
Animals
Aquaculture
Cell Count
Fisheries
Fresh Water
Gills - cytology
Immunohistochemistry
Mucus - cytology
Norway
Salmo salar
Abstract
Fish gills are heavily exposed to the external milieu and may react against irritants with different cellular responses. We describe variations in mucous cell counts in gills from healthy Atlantic salmon (Salmo salar) presmolts in five recirculating aquaculture system (RAS) farms and one flow-through farm. Based on certain criteria, mucous cells were histologically quantified in a defined lamellar region of the gills and the counts were analysed. Immunohistochemistry (IHC) was used to investigate epithelial responses. The median number of total mucous cells in the defined region was 59 per fish. Between the farms, the medians varied from 31 to 101 with the lowest in the flow-through farm. A regression model was fitted with "total mucous cells" as the dependent variable and with "fish length" and "fish farm" as independent variables. The proportion of variation in mucous cell counts explained by the model was twice as high when "fish farm" was included compared to only "fish length." IHC revealed proliferative responses in coherence with high mucous cell numbers. Conclusively, the variation in mucous cell counts depends on combined farm-related factors. Establishing a baseline for mucous cell counts is fundamental in the development of high-throughput monitoring programmes of gill health in farmed fish.
PubMed ID
33070329 View in PubMed
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Vertebral column deformity with curved cross-stitch vertebrae in Norwegian seawater-farmed Atlantic salmon, Salmo salar L.

https://arctichealth.org/en/permalink/ahliterature307203
Source
J Fish Dis. 2020 Mar; 43(3):379-389
Publication Type
Journal Article
Date
Mar-2020
Author
Cathrine Trangerud
Håvard Bjørgen
Erling Olaf Koppang
Randi Nygaard Grøntvedt
Hege Kippenes Skogmo
Nina Ottesen
Agnar Kvellestad
Author Affiliation
Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway.
Source
J Fish Dis. 2020 Mar; 43(3):379-389
Date
Mar-2020
Language
English
Publication Type
Journal Article
Keywords
Animals
Fish Diseases - epidemiology - pathology
Norway - epidemiology
Prevalence
Salmo salar - abnormalities
Spinal Diseases - epidemiology - pathology - veterinary
Spine - abnormalities
Abstract
Pathological changes in the vertebral column of farmed Atlantic salmon in Norway have been reported since the 1990s. Based on the characteristic radiographic findings, we here present a vertebral column deformity named "curved cross-stitch vertebrae" that mainly affects the middle aspect of the vertebral column. Sixty fish, from the west/northwest coast of mid-Norway, were sampled at slaughter and examined by radiography, computed tomography (CT), necropsy, macrophotography, and histology. The vertebral deformities were radiographically graded as mild, moderate, or marked. The main differences between these grades of changes were defined by increased curving of the peripheries of endplates, reduced intervertebral spaces, and vertical displacement of the vertebrae. The curved rims of endplates were located peripheral to a continuous and approximately circular borderline. The CT studies revealed small, multifocal, hypo-attenuating, round to crescent-shaped areas in the notochord, compatible with the presence of gas. Additionally, histology revealed that the axial parts of endplates had circular zones with perforations, through which either notochordal tissue prolapsed into the vertebrae or vascularized fibrochondroid proliferations extended from the vertebrae into the notochord. Inflammation was present in many vertebral bodies. To the best of our knowledge, this is the first report of gas in the notochord of fish.
PubMed ID
31970816 View in PubMed
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