Determinants of snail-trematode associations

蜗牛作为中间宿主，支持所描述的10,000种同基因吸虫中几乎每一种的幼虫发育。这些感染中的大多数会导致人或动物的疾病，造成严重的医疗和农业负担。蜗牛对吸虫施加了很大的选择性压力，对它们遇到的东西起到了过滤器的作用。在许多情况下，只有一种蜗牛适合作为吸虫物种的宿主。这种特异性的结果是，由成体吸虫引起的人和动物疾病的地理分布是由易感蜗牛宿主的存在决定的。免疫学因素在决定钉螺和吸虫之间的兼容性方面发挥着核心作用。蜗牛的免疫反应既有细胞成分，也有循环成分，如果蜗牛要成功抵御吸虫的攻击，这两种成分都必须正常发挥作用。提高我们对钉螺对吸虫感染抵抗力的免疫学决定因素的理解是我的NSERC发现赠款的主要重点。拟议的具体目标涉及针对吸虫的蜗牛防御反应的两个基本方面。第一个目标是进一步确定蜗牛中一类关键的免疫分子：纤维蛋白原相关蛋白(FREPs)。我们知道FREP是蜗牛免疫反应的重要介质，但我们对它们如何协调寄生虫防御和清除知之甚少。第二个目标是提高我们对蜗牛免疫细胞(血细胞)的理解，包括它们的发育是如何调节的，以及每种血细胞类型的特定功能是什么。我们知道血细胞对杀死入侵的吸虫是必不可少的，但我们仍然不知道它们是如何被招募的，以及它们在防御中扮演什么角色。这一NSERC DG将促进我们对宿主-寄生虫关系的理解，这种关系对人类和动物的健康具有重大影响。导致了新的疾病控制策略的发展，重点是打破蜗牛和吸虫之间的亲密联系，从而防止吸虫疾病的传播。

Snails serve as intermediate hosts supporting the larval development of almost every one of the 10,000 described species of digenetic trematodes. The majority of these infections result in diseases of humans or animals that cause profound medical and agriculture burdens. Snails place significant selective pressure on tremaotdes, acting as a filter for those that they encounter. In many cases, only a single species of snail is suitable as a host for a trematode species. A result of this specificity is that the geographic distribution of the human and animal diseases caused by adult trematodes is defined by the presence of susceptible snail hosts. Immunological factors play a central role in determining compatibility between snails and trematodes. Snails have both cellular and circulating components to their immune response, both of which must function properly if a snail is to successfully defend against trematode challenge. Advancing our understanding of the immunological determinants of snail resistance to trematode infection is the primary focus of my NSERC Discovery Grant. The specific objectives proposed address two essential aspects of the snail defence response against trematodes. The first objective aims to further characterize a critical group of immunological molecules in the snail: the fibrinogen related proteins (FREPs). We know that FREPs are important mediators of the snail immune response, however we know very little about how they function to coordinate parasite defence and clearance. The second objective aims to improve our understanding about snail immune cells (hemocytes), including how their development is regulated, and what the specific functions of each hemocyte type is. We know that hemocytes are essential for killing invading trematodes, however we remain ignorant regarding how they are recruited and what roles they play in defence. This NSERC DG will advance our understanding of a host-parasite relationship that has significant impact on human and animal health. Resulting in the development of novel disease control strategies focused on breaking the intimate bond between snails and trematodes, thereby preventing trematode disease transmission.