AN ELISA ASSAY FOR AVIAN SERUM BUTYRYLCHOLINESTERASE - A BIOMARKER FOR ORGANOPHOSPHATES

A competitive enzyme-linked immunosorbent assay (ELISA) for the quanti fication of butyrylcholinesterase (BChE) (EC 3.1.1.8) substance concen tration in avian serum samples is described. The assay is based on pol yclonal (rabbit) anti-pigeon BChE coupled with biotin. The binding of the biotinylated antibody to immobilized antigen is competitively inhi bited by an added standard or test antigen, and the amount of label-bo und antibody is inversely related to the concentration of antigen. The assay yields positive reactions with as little as 0.15 ng/ml of antig en. The assay was employed to investigate changes in the quantities of BChE in avian serum, following exposure to organophosphorus insectici des, which are not measured by the standard bioassay of this enzyme. T he applicability of the assay to metabolic and toxicological studies i s demonstrated, and the determination of the specific activity of BChE is recommended as a rational diagnostic tool after measurement of bot h activity and concentration of the enzyme.