The histopathological effects of a levamisole-adjuvanted Vibrio anguillarum vaccine on Atlantic salmon (Salmo salar L.)

Atlantic salmon (Salmo salar L.) were administered a levamisole-adjuvanted or non-adjuvanted Vibrio anguillarum vaccine by either bath or intraperiton eal (IP) injection. The potential side effects of vaccination were investig ated at a histological level, with the skin, gills, anterior kidney and spl een all examined. At a gross level, no pathological changes were evident in any organs. Observations of histological structures found that the skin, a nterior kidney and spleen were not affected by vaccination. However patholo gical changes were observed in the gills of fish treated with the adjuvante d vaccine by both routes of administration. Pathology of the gills was mult ifocal and included hyperplasia of mucous cells, lamellar oedema, prolifera tion of chloride cells, inflammation and necrosis. Hyperplasia and hypertro phy of epithelial cells resulted in lamellar fusion. The abundance of lamel lar associated mucous cells significantly increased in the gills of fish fr om groups administered the levamisole-adjuvanted vaccine (IP and bath) (P < 0.05). However, the effect of the treatments on lamellar fusion was not si gnificant (P > 0.05). (C) 2001 Elsevier Science B.V. All rights reserved.