Function/optimization of a nematicidal Cry toxin arsenal

描述（由申请人提供）：苏云金芽孢杆菌（Bt）晶体（Cry）蛋白几十年来一直被用于杀死害虫，包括传播人类疾病的蚊子和黑蝇。与杀虫蛋白相关的Cry蛋白现在已经被发现可以杀死线虫，尽管它们目前还没有被用于控制线虫。Cry蛋白对哺乳动物是无毒的，使其成为杀虫剂和潜在的杀线虫剂的绝佳选择。杀线虫的Cry蛋白使多种线虫中毒，包括秀丽隐杆线虫和两种感染肠道的哺乳动物寄生线虫。肠道线虫感染超过1/4的人口，使其成为Cry蛋白的重要医学靶点。该应用程序提出利用秀丽隐杆线虫的优秀工具来深入研究Cry蛋白的功能，对Cry蛋白的抗性如何发展（即使对昆虫来说也是一个重要的问题），并首次解决Cry蛋白是否在控制哺乳动物寄生线虫方面具有实用性。一种对线虫具有更好毒性的Cry蛋白的变体将被进化，然后测试其功能的改变，以将毒素的结构与毒素的功能联系起来（Specific Aim I）。该应用还提出了探索线虫对不同的杀线虫Cry蛋白的抗性机制，并确定该杀线虫蛋白是否可能成为其他Cry蛋白的良好伴侣治疗（Specific Aim II）。在Specific Aims I和II中产生和研究的信息和Cry蛋白变体将随后应用于哺乳动物寄生虫的治疗。将对感染肠道寄生虫（包括可感染人类的寄生虫）的啮齿动物口服Cry蛋白（野生型和改良变种），以优化治疗方案，并确定哪种Cry蛋白可以对线虫产生治疗效果。这些试验的目的是为未来的人体研究奠定基础。

DESCRIPTION (provided by the applicant): Bacillus thuringiensis (Bt) crystal (Cry) proteins have been used for decades to kill insect pests, including mosquitoes and black flies that transmit human diseases. Cry proteins related to those that kill insects have now been discovered to kill nematodes, although they are not currently used for nematode control. Cry proteins are non-toxic to mammals, making them excellent choices as insecticides and potentially as nematicides. Nematicidal Cry proteins intoxicate a wide range of nematodes, including C. elegans and two mammalian parasitic nematodes that infect the intestine. Intestinal nematodes infect over 1/4 of the human population making them an important medical target for Cry proteins. This application proposes to take advantage of the excellent tools available with C. elegans to study in depth how Cry proteins function, how resistance to Cry proteins develop (an important question even for insects), and, for the first time, address whether Cry proteins have utility in controlling mammalian parasitic nematodes. Variants of one Cry protein with better toxicity towards nematodes will be evolved and then tested for altered functions to correlate structure of toxin with function of toxin (Specific Aim I). This application also proposes to explore the mechanism of resistance to a different nematicidal Cry protein in C. elegans and determine whether this nematicidal protein may be an excellent companion therapeutic for other Cry proteins (Specific Aim II). The information and Cry protein variants generated and studied in Specific Aims I and II will then be applied towards therapy of mammalian parasites. Cry proteins, wild type and improved variants, will be orally administered to rodents infected with intestinal parasites (including one that can infect humans) to optimize therapeutic regimens and to determine which Cry proteins can have a therapeutic effect against the nematodes. The goal of these trials is to lay a foundation for future human studies.