Detection of Ergot Alkaloids in tall fescue by competitive immunoassay with a monoclonal antibody

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Abstract
Ergonovine was coupled to human serum albumin by a modification of the carbodiimide procedure. The conjugate was used to immunize mice, one of which developed specific anti‐ergonovine antibodies as measured by a competitive indirect (CI) enzymelinked immunosorbent assay (ELISA). Lymphocytes from this mouse were used to produce a hybridoma cell line which continued to produce specific anti‐ergonovine monoclonal antibody (MAb); the MAb was then used to develop an assay for ergot alkaloids associated with fescue (Festuca arundinacea) infected with the endophytic fungus Acremonium coenophialum. In this CI‐ELISA, the 50% inhibition value of the MAb by ergonovine was approximately 0.5 ng ml−1. The MAb recognized clavine, ergopeptine and lysergic acid derivatives. In tall fescue plants, the assay identified pastures with infection percentages as low as 3% and could be used to determine infection in a single plant, using as little as 0.5 g of material. Infection in seed was similarly detectable at infection levels as low as 4%. The assay offers significant advantages over diagnosis by microsopy or high‐performance liquid chromatography in terms of time, cost and special conditions required.