Immunohistochemical characterization of a polyclonal antibody against Sphaerospora dicentrarchi (Myxosporea: Bivalvulida), a parasite from sea bass (Dicentrarchus labrax L.) (Teleostei: Serranidae).

Rabbit antibody was raised against Sphaerospora dicentrarchi, a histozoic parasite of sea bass (Dicentrarchus labrax L.). Light and electron immunohistological staining were used to characterize its specificity and possible reactivity toward other fish parasites. In light immunohistochemistry the polar capsules and valves of the S. dicentrarchi spores appeared strongly stained, whereas developmental stages were not. Electron microscopic histochemistry revealed intense labeling in valves and some developmental stages. Cross-reaction was observed with all the myxosporean parasites assayed, even with those belonging to other genera. Polar capsules of all the myxosporean species except Polysporoplasma sparis were the main structures stained by the polyclonal antibody. These observations could reveal the existence of conserved antigenic epitopes in polar capsules of different Myxosporea.