Comparative studies on the specificity and sensitivity of rabbit and laying-hen antisera to ochratoxin A

Polyclonal antisera specific for ochratoxin A (OA) were developed in laying-hens and rabbits immunized with OA conjugated to bovine serum albumin. The rabbits and laying-hens were immunized and tested under parallel conditions. OA-specific antiserum activity was monitored using an indirect, competitive enzyme-linked immunosorbent assay (cELISA). Rabbits and hens produced OA-specific antisera within the first 51 clays of the immunization schedule. The rabbits consistently produced OA antisera in 10-fold higher amounts than the laying-hens. Rabbit and laying-hen antisera were found to be equally specific at most times in the immunization schedule for ochratoxins B and C, but not a. Antisera from both sources could be used to quantify OA in spiked wheat. The rabbit antisera could reproducibly detect OA at concentrations of 3 mu g kg(-1) or more, whereas antisera from hens could only detect 50 mu g kg(-1) or more. Similar results were obtained when OA was quantified in spiked wheat with both antisera when assayed at three different pH values (pH 6.0, 7.0 and 8.0). The optimal assay pH for the specific quantification of OA in wheat was 7.0. These studies suggest that rabbit antiserum is superior to hen antiserum in its ability to: quantify OA in wheat. The sera from both animals, however had similar cross-reactivities with structurally related compounds.