Double-antibody sandwich ELISA for the quantitative detection of Cry1Ac protein in transgenic plants

In this study, CrylAc protein, encoded by insect-resistance gene CrylAc, was selected as the target antigen and its monoclonal antibody and horseradish peroxidase labeled anti-monoclonal antibody were prepared. Using optimized antibody purification techniques, the purified antibody was obtained and double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for detection of CrylAc protein in corn. CrylAc monoclonal antibody was used as the coating antibody and horseradish peroxidase-labeled CrylAb monoclonal antibody was used as the detection antibody. The results showed that the newly developed ELISA had good stability and the coefficient of variation was within 3%. In the concentration range of 10~200 ng/mL, the linear regression equation was y = 0.0114x + 0.0768 (R² = 0.9989), while the detection limit of the assay was 9.49 ng/mL. The recoveries of Cry1Ac in corn extract ranged from 102.5% to 103%. The established sandwich ELISA provides an effective method for the quantitative detection of Cry1Ac protein in corn and is therefore a promising detection method for the inspection and quarantine of transgenic products and may have high application value in entry-exit inspection and quarantine.