Function/optimization of a nematicidal Cry toxin arsenal

描述（由申请人提供）：数十年来，苏云金芽孢杆菌（Bt）晶体（Cry）蛋白一直用于杀死昆虫害虫，包括传播人类疾病的蚊子和黑蝇。与那些杀死昆虫的蛋白质相关的Cry蛋白质现在已经被发现可以杀死线虫，尽管它们目前还没有用于线虫控制。Cry蛋白对哺乳动物无毒，使其成为杀虫剂和潜在杀线虫剂的绝佳选择。杀线虫Cry蛋白可使多种线虫中毒，包括C.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的人群，使其成为Cry蛋白的重要医学靶标。这个应用程序建议利用C语言提供的优秀工具。这是一个非常重要的研究项目，旨在深入研究Cry蛋白如何发挥作用，对Cry蛋白的抗性如何发展（甚至对昆虫来说也是一个重要的问题），并首次解决Cry蛋白是否可用于控制哺乳动物寄生线虫。将进化出对线虫具有更好毒性的一种Cry蛋白的变体，然后测试其改变的功能，以将毒素的结构与毒素的功能相关联（特异性目的I）。本申请还提出探索C. elegans和确定这种杀线虫蛋白是否可能是其他Cry蛋白的优秀伴侣治疗剂（特异性目的II）。在特定目标I和II中生成和研究的信息和Cry蛋白变体将随后应用于哺乳动物寄生虫的治疗。Cry蛋白、野生型和改良变体将口服给予感染肠道寄生虫（包括可以感染人类的寄生虫）的啮齿动物，以优化治疗方案并确定哪些Cry蛋白可以对线虫具有治疗效果。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.