Lectin histochemical studies on Sphaerospora sp. (Myxosporea) from Italian brown trout, Salmo trutta L.

A Sphaerospora sp. (Myxosporea) infection (presumably S. truttae) was identified on a trout farm in northeastern Italy. Parasites were detected in kidneys from infected brown trout, Salmo trutta L., over a 2-year period. Extrasporogonic, sporogonic stages and mature spores were simultaneously detected in the same fish. Traditional diagnostic methods for Sphaerospora spp. rely on the detection of the myxosporean developmental stages in Giemsa-stained kidney smears or haematoxylin-eosin stained tissue sections.A histochemical method was employed where 10 biotinylated lectins (Con-A, DBA, SBA, GS-I, PHA-P, LEA, PWM, RCA1, WGA and UEA-I) and the avidin-biotin-peroxidase complex (ABC) were used on Sphaerospora-infected brown trout renal tissues and kidney imprints. Five monoclonal antibodies against PKX (Mab12, MabA3, MabC5, MabD4 and MabB4) were also tested. A lectin glycoconjugate binding pattern for Sphaerospora spp. is presented. This staining method shows that SBA lectin (Glycine max agglutinin) is a useful tool for the detection of the Sphaerospora spp. Only MabB4 bound some of the most mature sporogonic stages. In contrast Mabs12, A3, C5 and D4, and GS-I lectin (Griffonia simplicifolia agglutinin) did not stain any of the Sphaerospora spp. stages, but did bind very specifically to the sporogonic and extrasporogonic stages of PKX, the causative agent of proliferative kidney disease (PKD).