Brit Hjeltnes

The relevance of infectious pancreatic necrosis virus (IPNV) in farmed Norwegian turbot (Scophthalmus maximus)

Abstract In 1989, during a period when high mortalities of turbot fry were recorded in several commercial farms, samples for virus detections were collected in 6 farms. Samples were also collected from two broodstock populations and egg batches from one farm, and from wild fauna in the surroundings of a second farm where infectious pancreatic necrosis virus (IPNV) was isolated from turbot fry with pronounced necrosis in exocrine pancreatic tissue. IPNV was isolated from fry collected in 3 of the farms, from invertebrate fauna and in a few samples from wild fish. Virus was not detected in broodstock or egg batches. Immunohistochemical examination of affected fry revealed severe pancreas necrosis, and a moderate-to-strong, IPNV-specific reaction in the cytoplasm of degenerated exocrine pancreatic cells. This examination indicates that IPNV might cause infectious pancreatic necrosis in turbot fry. After an IPNV bath challenge of turbot fry, IPNV was recovered from viscera of the fry. This transmission of virus indicates that IPNV might infect turbot fry. An increased mortality was recorded in challenged fry, but histological and immunohistochemical examination of moribund and surviving specimens did not reveal any clear pathological changes. The finding of IPNV in wild fish, invertebrate fauna and in Artemia point to several potential virus-sources and ways of transmission.

Vaccination against Vibrio salmonicida: the effect of different routes of administration and of revaccination

Abstract Atlantic salmon (Salmo salar) smolts were vaccinated with a bacterin made from formalin-killed Vibrio salmonicida. Fish vaccinated twice appeared to be better protected than fish vaccinated once, the degree of protection depending on the route of administration of the vaccine.

Immune response and disease resistance in Atlantic salmon (Salmo salar L.) fed three levels of dietary vitamin E and the effect of vaccination on the liver status of antioxidant vitamins

Atlantic salmon were fed 40, 300 or 1100 mgall-rac-α-tocopheryl acetate kg feed−1 for 12 weeks.After 6 weeks half of the fish in each group were marked and vaccinated (i.p.injection) against furunculosis and vibriosis. Liver α-tocopherol levelsreflected the dietary input after 6 and 12 weeks of feeding. Noimmunomodulatoryeffects of dietary vitamin E on baseline levels of the immune parameters beforevaccination were detected in this study, as evaluated by antibody dependent andspontaneous plasma complement activities. In general, vaccination increasedplasma complement activities and the number of antigen specific antibodyproducing cells as compared with unvaccinated control fish, but with nodifferences with respect to the vitamin E regimes. Also the ability ofunvaccinated fish to withstand experimental furunculosis was unaffected bydietary vitamin E. The concentrations of α-tocopherol and ascorbic acidinthe liver were, however, negatively affected 6 weeks post vaccination comparedto respective unvaccinated fish.