The fumonisins (B1, B2, and B3) are a group of mycotoxins produced by Fusarium moniliforme. Fumonisins have been found world-wide as a contaminant of maize (corn) and have been shown to cause liver cancer in experimental rats, pulmonary edema in pigs and leukoencephalomalacia in horses. High levels of fumonisins in locally grown maize have been found in areas of the world which have a high prevalence of human esophageal cancer, for instance, in South Africa and China.
The Helica Biosystems' fumonisin ELISA is a solid phase direct competitive enzyme immunoassay. A fumonisin-specific antibody optimized to cross react with the three fumonisin subtypes is coated to a polystyrene microwell. Toxins are extracted from a ground sample with 90% methanol. The extracted sample and HRP-conjugated fumonisin are mixed and added to the antibody-coated microwell. Fumonisin from the extracted sample and HRP-conjugated fumonisin compete to bind with the antibody coated to the microwell. Microwell contents are decanted and non-specific reactants are removed by washing. An enzyme substrate (TMB) is added and color (blue) develops. The intensity of the color is directly proportional to the amount of bound conjugate and inversely proportional to the concentration of fumonisin in the sample or standard. Therefore, as the concentration of fumonisin in the sample or standard increases, the intensity of the blue color will decrease. An acidic stop solution is added which changes the chromagen color from blue to yellow. The microwells are measured optically by a microplate reader with an absorbance filter of 450nm (OD450). The optical densities of the samples are compared to the OD's of the kit standards and an interpretative result is determined.
The Helica Biosystems' fumonisin ELISA is a competitive enzyme-linked immunoassay intended for the quantitative detection of fumonisins in maize.