Production and characterization of monoclonal antibodies to estrogen-related receptor alpha (ERRα) and use in immunoaffinity chromatography

Development of a sensitive monoclonal antibody-based sandwich ELISA to detect Vip3Aa in genetically modified crops

Objectives

To develop a sensitive monoclonal antibody-based sandwich enzyme-linked immunosorbent assay (ELISA) to detect Vip3Aa in genetically modified (GM) crops and their products.

Results

Vegetative insecticidal proteins (Vips) are secreted by Bacillus thuringiensis (Bt) and are known to be toxic to Lepidoptera species. Vip3Aa family proteins, Vip3Aa19 and Vip3Aa20, were successfully applied in GM crops to confer an effective and persistent insecticidal resistance. A sensitive monoclonal antibody-based sandwich ELISA was developed to detect Vip3Aa in GM crops and their products. Two monoclonal antibodies were raised against the overexpressed and purified His-Vip3Aa20, were purified from mouse ascites and characterized. A sandwich ELISA method was developed using the 2G3-1D7 monoclonal antibody for capture and the biotin-labeled 1F9-1F5 monoclonal antibody for detection of Vip3Aa20. The linear detection range of the method was found to be approximately 31.25–500 pg/ml, with a sensitivity of 10.24 pg/ml.

Conclusions

The established ELISA was effective for detecting Vip3Aa family proteins other than Vip3Aa8, and was successfully applied in the detection of Vip3Aa20 and Vip3Aa19 expressed in transgenic maize and cotton.

Secretory expression, immunoaffinity purification and metal-binding ability of recombinant metallothionein (ShMT) from freshwater crab Sinopotamon henanense

Metallothioneins (MTs) are a super-family of ubiquitous, low-molecular-weight, cysteine-rich and metal-binding proteins. They are thought to play a predominant role in mediating metal metabolism and antioxidation. However, the accurate functions of MTs remain unclear in the physiological processes due to native proteins deficiency and little information of their metal-binding character. Freshwater crab Sinopotamon henanense is a decapod crustacean widely distributed in northern China, in which only one MT isoform (ShMT) has been reported so far. In order to shed light on the accurate role of ShMT, a novel recombinant ShMT in native form was over-expressed by phoA secreted expression system in Escherichia coli (E. coli). Then the ShMT proteins were purified using a one-step gentle immunoaffinity chromatography with a polyol-responsive mAb (PR-mAb) to ShMT, which was generated by conventional hybridoma technology followed by ELISA-elution. The Zn-, Cu-, and Cd-ShMT complexes were prepared by recombinant synthesis in metal-enriched media and reconstitution with metal ions, respectively. Further analysis about metal-binding capacity showed recombinant ShMT has high ability to bind Zn, Cu and Cd metals, although the recombinantly expressed and reconstituted metal-ShMT complexes have different metal-to-protein stoichiometry. Moreover, the affinity of recombinant protein for metal ions has been analyzed using competitive reaction with 5, 5-dithiobis (2-nitrobenzoic acid) (DTNB). The results demonstrated the affinity of recombinant ShMT for metals was as follows: Cu＞Cd＞Zn. In summary, the experimental procedure we have developed facilitates production of recombinant ShMT with native characteristics for further research and the study of metal-binding ability could help further clarify the accurate functions of ShMT.