Production and characterization of polyclonal antibodies against norsolorinic acid reductase involved in aflatoxin biosynthesis

Polyclonal antibodies against norsolorinic acid reductase (NSR), an enzyme responsible for the conversion of norsolorinic acid to averantin in the early stage of aflatoxin biosynthesis, were produced after immunizing rabbits with a semi‐purified NSR preparation. Immunochemical analysis of the enzyme extracts from Aspergillus parasiticus revealed that the antibodies reacted with several protein species, including bands corresponding to NSR activity. The ammonium sulfate‐cut IgG was further purified by passing it through a column armed with protein fractions containing immunoreactivity, but no enzyme activity, isolated from the A. parasiticus extracts that had been subjected to Sepharose gel filtration. After subtractive affinity chromatography, the purified antiserum reacted primarily with two protein bands (of molecular weight 43 and 48 kDa) and was capable of neutralizing the NSR activity. Enzyme‐linked immunosorbent assay (ELISA) analysis of various fungal extracts showed that the purified antiserum was highly specific for the enzyme.