DEVELOPMENT OF AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR ANALYSIS OF SPORIDESMIN-A AND ITS METABOLITES IN OVINE URINE AND BILE

Monoclonal and polyclonal antibodies have been produced for the develo pment of competitive enzyme-linked immunosorbent assays for sporidesmi n A, the mycotoxin that causes facial eczema in grazing livestock. Hem isuccinyl derivatives of sporidesmin conjugated to a number of protein s were used as immunizing and coating antigens. Two immunoassays have been developed. Each detects the presence of a different region of the sporidesmin molecule, therefore allowing the two major sporidesmins f ound in grass or in culture to be distinguished as well as allowing th e detection of metabolites in ovine urine and bile. An analytical proc edure that did not include organic solvent extraction was developed so that water-soluble metabolites would also be detected. Matrix effects occurring in the immunoassay of bile have been overcome by dilution o f samples in 1% Tween 20 followed by heat treatment at 70 degrees C fo r 30 min. Sporidesmin A in bile measured by immunoassay was compared w ith that measured by HPLC. The coefficient of determination R(2) was 0 .97.