Characterization of Antibodies and Development of an Indirect Competitive Immunoassay for Detection of Deamidated Gluten

Diversification of gluten applications in the food and cosmetics industries was achieved through the production of water-soluble gluten that can be obtained by deamidation. Current analytical methods dedicated to gluten detection failed to detect deamidated gluten. After immunizing mice with the peptide LQPEEPFPE conjugated to keyhole limpet hemocyanin, five mouse monoclonal antibodies (mAbs) were produced and sequences of bound epitopes were determined as XPXEPFPE, where X is Q or E. The mAbs exhibited high specificity for deamidated gliadins and low molecular weight glutenin subunits. A competitive enzyme-linked immunosorbent assay (ELISA) based on INRA-DG1 mAb was developed with an IC50% of 85 ng/mL and a limit of detection of 25 ng/mL. The intra- and interassay coefficients of variation (CV) were <10% except for the interassay CV of the low-level control (40 ng/mL), which was 20%. This assay was capable of detecting three of the four deamidated gluten samples spiked in rice flour at 20 mg/kg.