Molecular Studies of Immunoparasitology in Snails

描述（申请人提供）：淡水蜗牛光螺在传播人类血吸虫——曼氏血吸虫中起着不可或缺的作用。增加我们对这种蜗牛内部防御的基本机制的理解可以帮助开发控制血吸虫病的新方法，全世界仍有2亿人感染血吸虫病。关于血吸虫和它们的蜗牛宿主之间的分子相互作用，还有很多未知的地方，到目前为止，光斑螺-曼森螺模型系统是评估潜在的抗性和相容性机制的最佳方法。拟议的研究是建立在先前的研究基础上的，这些研究表明蜗牛血液中被称为FREPs（纤维蛋白原相关蛋白）的蛋白质在抗血吸虫防御中的功能作用。我们的发现表明，B. glabrata通过点突变和重组产生了惊人的FREP基因多样性，这一发现与其他实验室的工作一起引发了对无脊椎动物产生多样化防御反应能力的普遍重新考虑，这进一步启发了他们。在这一应用中，我们开发了一种通用的方法来评估假定的免疫效应器（FREPs是主要的，但不是唯一的，可以用这种方法测试的效应器）在影响曼氏s.m ansoni在光斑双胞杆菌中成功发展的能力方面的功能。在这样做的过程中，重要的是从它们参与抗感染的角度来检查候选效应分子，以及作为相容性的一般决定因素。具体来说，我们将进一步开发RNA干扰（RNAi）和重组蛋白/抗体方法，使用体内和体外方法来研究FREPs在影响不相容宿主中寄生虫发育的功能作用。我们最近发现的其他候选物，即革兰氏阴性细菌结合蛋白（GNBP）和肽聚糖识别蛋白（PGRPs），以及控制上游Toll/Imd途径的关键分子的蜗牛同源物也可用于研究，从而进一步拓宽了我们对蜗牛免疫的理解。最后，我们将尝试破坏曼索尼血吸虫对相容蜗牛的成功寄生。这种破坏的能力将是一项重要进展，因为兼容性确保了血吸虫病在流行地区的持续传播。这项研究将使我们能够对frep和其他候选分子的功能获得有价值的见解，更重要的是，开发一个普遍适用的系统，用于评估任何蜗牛候选分子在影响S. mansoni与其蜗牛宿主相遇结果中的作用。

DESCRIPTION (provided by applicant): The freshwater snail Biomphalaria glabrata plays an indispensible role in transmission of the human blood fluke, Schistosoma mansoni. Increasing our understanding of the fundamental mechanisms of internal defense of this snail could help develop novel methods of control of schistosomiasis which still infects 200 million people world-wide. Much remains unknown regarding the molecular interplay between schistosomes and their snail hosts, and the B. glabrata - S. mansoni model system is by far the best for assessing underlying mechanisms of resistance and compatibility. The proposed investigations are built on previous studies suggestive of a functional role of snail blood proteins called FREPs (fibrinogen-related proteins) in anti-schistosome defenses. They are further inspired by our discoveries showing that B. glabrata generates a surprising diversity of FREP genes through point mutation and recombination, a discovery that along with work in other labs has provoked a general reconsideration of the capacity of invertebrates to generate diversified defense responses. In this application, which has been extensively revised in response to the previous review, we develop a general approach for assessing the functionality of putative immune effectors (FREPs are the main, but not the sole, effectors available to be tested using this approach) in influencing the ability of S. mansoni to develop successfully in B. glabrata. In so doing, it is important to examine candidate effector molecules both from the perspective of their involvement in resistance to infection, and as general determinants of compatibility. Specifically, we will further develop RNA interference (RNAi) and recombinant protein/antibody approaches to examine the functional role of FREPs in affecting the development of parasites in incompatible hosts, using both in vivo and in vitro approaches. Other candidates we have recently identified, namely gram-negative bacteria binding protein (GNBP) and peptidoglycan recognition proteins (PGRPs), the snail homologs of key molecules controlling upstream Toll/Imd pathways, are also available for study, thus further broadening our understanding of snail immunity. Finally, we will attempt to disrupt the successful parasitization of compatible snails by S. mansoni. The ability to effect such disruption would be an important advance because compatibility ensures the continued transmission of schistosomiasis in endemic areas. This study will enable us to gain valuable insights into the functionality of FREPs and other candidates, and even more importantly, to develop a system of general applicability for evaluating the role of any snail candidate molecules in influencing the outcome of an encounter between S. mansoni and its snail host.