Enzyme immunoassay for detection of Drosophila melanogaster antigens in the juice of various foods.

An enzyme immunoassay (EIA) was developed to identify and quantitate soluble antigens originating from Drosophila melanogaster eggs. Polystyrene microtiter plates were coated with anti-egg antibody. Egg antigen standards or samples were reacted with the sensitized wells. The immobilized antigen was reacted with biotinylated antibody, and the complex was quantitated by an avidin-horseradish peroxidase conjugate. The assay can detect egg antigens equivalent to 0.03 eggs/mL. The antibody was directed against a number of antigens and cross-reacted with extracts of adult Drosophila melanogaster flies. Homogenized eggs diluted in various juice samples were detectable by EIA. Heating the antigen diluted in buffer or juice at a temperature used in processing of juice reduced the immunological response approximately 40-45%. Brine separated from fresh-packed sauerkraut showed EIA responses equivalent to 0.3-3 eggs/mL. Electrophoretic, chromatographic, and immunological analyses suggested that the EIA responses for sauerkraut brine were related to the Drosophila melanogaster egg antigens.