Anti-idiotypic single-chain variable fragment antibody partially mimic the functionally spatial structure of Cry2Aa toxin

The anti-idiotypic antibody is widely used in the field of immunology to simulate structural features or even induce the biological activity of antigens. In this study, we obtained seven anti-idiotypic single-chain variable fragments (scFv) antibodies of Cry2Aa toxin from a phage-displayed mutant library constructed using errorprone PCR technique. A mutant designated 2-12B showed the best binding ability amongst all anti-idiotypic scFv isolates to Plutella xylostella brush border membrane vesicles (BBMVs). 2-12B and Cry2Aa toxin shared a potential receptor of polycalin in P. xylostella BBMVs. Homology modeling and molecular docking demonstrated that 2-12B and Cry2Aa toxin have seven common binding amino acid residues in polycalin. Insect bioassay results suggested that 2-12 had insecticidal efficacy against P. xylostella larvae. These results indicated that the Cry2Aa anti-idiotypic scFv antibody 2-12B partially mimicked the structure and function of Cry2Aa toxin. The anti-idiotypic scFv antibody provides the basic material for the future study of surrogate molecules or new insecticidal materials.

Automated summary

The study obtained seven anti-Cry2Aa toxin anti-idiotypic scFv antibodies from a phage-displayed mutant library, with mutant 2-12B showing the best binding ability. 2-12B and Cry2Aa toxin shared a potential receptor of polycalin in P. xylostella BBMVs and had seven common binding amino acid residues in polycalin. Insect bioassay results indicated that 2-12 had insecticidal efficacy against P. xylostella larvae, suggesting that the 2-12B antibody partially mimics the structure and function of Cry2Aa toxin.