苏云金芽孢杆菌Cry毒素靶标受体众多、毒理机制尚存争议，致其新资源开发难以实现靶向筛选和理性设计。项目依据Cry毒素受体结合区与抗体可变区结构及功能相似性特点，拟利用抗独特型抗体的分子模拟功能，制备能模拟Cry2Aa毒素活性关键表位的抗独特型纳米抗体，分析其对靶标昆虫的受体结合活性及杀虫活性，进而探讨其生物活性形成规律。.研究内容包括:（1）Cry2Aa毒素活性关键区的免疫原性分析与设计。（2）高丰度抗独特型纳米抗体库构建与筛选。（3）抗独特型纳米抗体的生物活性分析。（4）抗独特型纳米抗体的体外定向进化及杂交毒素构建。（5）毒素活性关键表位定位以及抗独特型纳米抗体的生物活性形成规律分析。.项目将揭示Cry2Aa毒素抗独特型纳米抗体的生物活性形成规律，创制具有自主知识产权的新型杀虫蛋白及基因，定位Cry2Aa毒素活性关键表位，并为其他类型Cry毒素及生物农药的模拟创制提供新思路及理论指导。

Bacillus thuringiensis Cry toxins have a lot of putative receptors in target insects, and their mode of action is still controversial, which makes it difficult to achieve targeted screening and rational design for its new resource development. Based on the structure and function similarity between receptor binding region of Cry toxins and variable region of antibodies, this project intends to use the molecular mimicry technology to prepare anti-idiotypic nanobodies which could mimic the critical epitopes of Cry2Aa toxin and determine their receptor binding and insecticidal activities, the formation of their biological activities were also investigated..The research work is designed as follows: (1) Immunogenicity analysis and design of critical epitopes of Cry2Aa toxins. (2) Construction of anti-idiotypic nanobody libraries with high abundance, isolation and characterization of anti-idiotypic nanobodies from the libraries. (3) Determination of the biological activities of anti-idiotypic nanobodies. (4) In vitro directed evolution of anti-idiotypic nanobodies and construction of hybrid toxins. (5) Mapping the critical epitopes of Cry2Aa toxin and analysis of the formation of biological activities of anti-idiotypic nanobodies..This project would reveal the regularity for the biological activities formation of anti-idiotypic nanobodies, create high insecticidal proteins and genes with independent intellectual property rights, and map the critical epitopes of Cry2Aa toxin. It would also provide a new approach and theoretical guidance for exploration of new insecticidal resources for other Cry toxins or biopesticides.