MONOCLONAL-ANTIBODY AND LECTIN PROBES RECOGNIZE DEVELOPMENTAL AND SPOROGONIC STAGES OF PKX, THE CAUSATIVE AGENT OF PROLIFERATIVE KIDNEY-DISEASE IN EUROPEAN AND NORTH-AMERICAN SALMONID FISH

The lectin GS-I (Griffonia simplicifolia agglutinin-I) and a recently developed monoclonal antibody (Mab12) both recognized extrasporogonic (interstitial) and sporogonic (intraluminal) stages of the PKX myxosporean causing proliferative kidney disease (PKD) in salmonid fish. In histochemical and immunostains the lectin and antibody recognized PKX from North American and European salmonids including Atlantic salmon Salmo salar, chinook salmon Oncorhynchus tshawytscha, coho salmon Oncorhynchus kisutch, brown trout Salmo trutta, and grayling Thymallus thymallus. Although the specific structures recognized by the lectin and Mab12 were not determined, double fluorescent staining techniques showed similar staining patterns with extrasporogonic or interstitial stages of the PKX myxosporean. An apparent inhibition between the lectin and Mab12 in these double stains suggests that they recognize similar structures of the parasite. Sporogonic stages of PKX, some containing polar capsules, were detected with the lectin and Mab12 stains in fish with typical extrasporogonic (interstitial) PKX providing further confirmation of the relatedness of these stages. Both the lectin and Mab12 provide useful tools for further study of the epidemiology of the PKX myxosporean, for future development of tests to detect anti-parasite antibodies in fish serum and for the identification of potential immunogens for vaccination of trout.