Production and characterization of monoclonal antibodies against sterigmatocystin o‐methyltransferase

Abstract

Monoclonal antibodies (MAbs) against sterigmatocystin (ST) O‐methyltransferase (OMTase), an enzyme responsible for the conversion of ST to O‐methylsterigmatocystin (OMST) in the late stage of aflatoxin biosynthesis, were produced by fusion of P3/NS‐1/1‐AG4–1 myeloma cells with spleen cells isolated from Balb/c mice that had been immunized with a purified ST‐OMTase preparation. Two clones, 1D9 and 8F11, which produced antibodies showing highest affinity toward ST‐OMTase, were chosen for antibody production and characterization. Enzyme‐linked immunosorbent assay (ELISA) analysis of various fungal extracts showed that the MAbs obtained from either ID9 or 8F11 were highly specific for the ST‐OMTase. Results of ELISA analysis using MAb obtained from clone 8F11 correlated well with those of ST‐OMTase activity in fungal extracts determined by spectrofluorometry, and only MAb 8F11 was capable of neutralizing part of the ST‐OMTase activity. Immunochemical analysis of various fungal extracts with MAb 1D9 revealed that the antibodies primarily reacted with the 40‐kDa ST‐OMTase purified with DEAE‐Sephadex chromatography, but reacted with the 46‐kDa ST‐OMTase species in the crude protein extracts of Aspergillus parasiticus.

Keywords:

• Sterigmatocystin
• O‐
• methylsterigmatocystin
• Aspergillus flavus
• A. parasiticus, aflatoxin
• antibodies