Oystein Evensen

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In contrast to the roles played by monocytes/macrophages, neutrophils and lymphocytes, the presence and functions of basophils, mast cells/eosinophilic granule cells, eosinophils and rodlet cells in teleosts are areas of controversy. The tissue distribution of mast cells/eosinophilic granule cells in species from a certain genus shows a characteristic(More)
Cardiomyopathy syndrome (CMS) of farmed and wild Atlantic salmon (Salmo salar L.) is a disease of yet unknown etiology characterized by a necrotizing myocarditis involving the atrium and the spongious part of the heart ventricle. Here, we report the identification of a double-stranded RNA virus likely belonging to the family Totiviridae as the causative(More)
During the last few years, the use of vaccines for disease prevention in aquaculture has expanded both with regard to the number of fish species and number of microbial diseases. According to the responses to a questionnaire received from 41 countries, vaccination is used in the commercial aquaculture of species like Atlantic salmon (Salmo salar), rainbow(More)
Heart and skeletal inflammation (HSMI) of farmed Atlantic salmon (Salmo salar L.) is a disease characterized by a chronic myocarditis involving the epicardium and the compact and spongious part of the heart ventricle. Chronic myositis of the red skeletal muscle is also a typical finding of HSMI. Piscine reovirus (PRV) has been detected by real-time PCR from(More)
During the last 10 to 20 years vaccination has become established as an important method for prevention of infectious diseases in farmed fish, mainly salmonid species. So far, most commercial vaccines have been inactivated vaccines administered by injection or immersion. Bacterial infections caused by Gram-negative bacteria such as Vibrio sp., Aeromonas(More)
Lysozyrne activity was studied in vanous species of fish (13 mild species and cultured rainbow trout Salmo gairdnen and Atlantic salmon Salmo salar). Marked interspecies variation prevailed, most strikingly between rainbow trout and Atlantic salmon; lysozyme activity in the former was at least 20 times greater than in the latter. Tissue distribution was(More)
Infectious pancreatic necrosis virus serotype Sp was identified by immunohistochemistry in formaldehyde-fixed and paraffin-embedded tissue of Atlantic salmon (Salmo salar). The immunoreaction was present in degenerating and necrotic cells in exocrine pancreatic cells. Cross reactions were observed with rabbit antisera against serotypes Sp, Ab, and VR-299 in(More)
Live and dead Atlantic salmon eyed eggs were challenged with eight different Saprolegnia isolates, selected because of their varied origins, known morphological characteristics and growth/germination pattern. Some isolates were also tested for pathogenicity to Atlantic salmon parr. Challenge of eggs was performed by exposure to spores in suspension or by(More)
Infectious pancreatic necrosis, an important problem of the salmon industry worldwide, is caused by Infectious pancreatic necrosis virus (IPNV). Fish surviving an IPNV infection become virus carriers, and the identification of infected fish is highly relevant to disease control. The target organ for IPNV diagnosis is the kidney, where the virus persists,(More)
The uptake and handling of Vibrio salmonicida in phagocytes of the head kidney of Atlantic salmon (Salmo salar L.) were evaluated by light and electron microscopy, including in situ identification of the bacterium by immunolabeling at the light microscopical and the ultrastructural level. Fish were injected with live bacteria, and 4, 24, 48, and 72 hours(More)