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An enzyme-linked immunosorbent assay was used to detect and quantitate the parasporal crystal toxins of Bacillus thuringiensis subspp. kurstaki and israelensis. The assay method described is extremely sensitive, accurate, and highly specific. With this technique, crystalline insecticidal proteins from several subspecies of B. thuringiensis were compared. The dipteran crystal toxin produced by B. thuringiensis subsp. israelensis was shown to share few epitopes with the lepidopteran toxin from B. thuringiensis subspp. kurstaki, tolworthi, berliner, and alesti.

A rapid and sensitive indirect enzyme-linked immunosorbent assay (ELISA) was developed for microsomal epoxide hydrolase of rat liver. The assay, which is easily and readily performed, is significantly more sensitive than most enzymatic epoxide hydrolase assays routinely used and electroimmunoassays previously developed. The limit of sensitivity of the ELISA is between 2-5 ng of microsomal epoxide hydrolase. Using the ELISA microsomal epoxide hydrolases of mouse and rat liver were shown to be antigenically very similar, while microsomal epoxide hydrolases of guinea pig, monkey and human liver are antigenically distinct from those of rat and mouse. The ELISA developed here is capable of detecting microsomal epoxide hydrolase of rat and mouse liver even when significant enzymatic activity is lost. These results indicate that the antigenic sites recognized by the antibodies used are distinct from the catalytic site of the epoxide hydrolase. Approximately 1.9% of rat microsomal protein was quantified as microsomal epoxide hydrolase by the ELISA. Low levels of microsomal epoxide hydrolase were also detected in rat liver cytosol (approximately 0.02% of the cytosolic protein) demonstrating that microsomal epoxide hydrolase is not totally membrane bound or that an immunologically related protein occurs in the cytosol of normal rat liver. The ELISA developed here will be valuable in investigating further the role of microsomal epoxide hydrolase.