Title: Development of Monoclonal Antibodies against the Myxosporean, Ceratomyxa shasta, and Characterization of the Salmonid Host Response

myxosporean parasite, Ceratomyxa shasta, and were characterized by indirect immunofluorescent techniques, western blot analysis, and immunoelectron microscopy. The resulting Mabs reacted specifically with the trophozoite and sporoblast stages of the parasite, but not with the mature spore, indicating that certain antigens are stage-specific. Two of the Mabs produced also reacted with trout white blood cells as evidenced by indirect fluorescent antibody techniques (IFAT) and Western blot analysis. Further characterization of these cross-reacting antibodies showed that they were directed against carbohydrate epitopes on both the parasite and trout immunoglobulin heavy chain. One hybridoma produced antibodies of high specificity for prespore stages of C. shasta. Ultrastructural analysis of the parasite using immunogold labeling showed that the Mab specifically bound antigen located in the cytoplasm of the trophozoites