Immunohistochemistry, ultrastructure and pathology of gills of Abramis brama from the lake Mondsee, Austria, infected with Ergasilus sieboldi (Copepoda)

Immunohistochemical, ultrastructural and pathological studies were carried out on thegills of bream Abramis brama (L.) from Lake Mondsee, Austria, that were naturally infected withErgasilus sieboldi Nordmann, 1832. Of a total of 14 specimens of bream examined, the gills of 7 (50%)were parasitized with this copepod and the intensity of infection ranged from 1 to 23 crustaceans perhost. Histopathological investigations of infected gill showed extensive tissue damage due to attachmentand feeding of the crustacean. Parasites attached close to the base of filaments near the gillarch. Pressure exerted by the ectoparasite attached to the lateral margin of the gill filaments inducedatrophy of the secondary lamellae. Tissue reactions included hyperplasia and mucous cell proliferationof the respiratory epithelium. Mucous cells displayed an intense immunohistochemical reactivitywith the anti-nitric oxide synthase antibody. In parasitized primary and secondary lamellae, a highnumber of eosinophilic granular cells and rodlet cells were noticed. Rodlet cells represent an inflammatorycell type closely linked to other piscine inflammatory cells. Presence of a high number ofinflammatory cells at the site of E. sieboldi attachment is related to intense host cellular reaction.[...]