感染外睾吸虫钉螺的分泌物和血淋巴细胞对日本血吸虫幼虫被击毁的免疫反应机理研究

Schistosoma japonicum is the pathogen of a grave zoonosis in China. Oncomelania hupensis is the snail medium of S. japonicum, and it also is the intermediate host of Exorchis trematodes of freshwater fish Parasilurus asotus. The results of our former experiments have indicated that all larval S. japonicum were blocked in the O. hupensis snails which were pre-infected with larval Exorchis trematode. And the attack degrees on larval S. japonicum in experimental O. hupensis snails dually infected by the two species trematodes, Exorchis spp. and S. japonicum larvae with longer intervals were stronger than that of shorter intervals. Present project would do works to find and identify the species and their structures of snail secretion and lymphocytes, and their transcription、proteomics、functional genomic、the changes in protein and functional genes expression in O.hupensis snails with different experimental conditions (singly infected with larval S. japonicum, singly infected with larval Exorchis trematode, dually infected with larval Exorchis trematode and larval S. japonicum, and negative control snails). To clarify and analyze the molecular mechanism of S. japonicum larvae to be destroyed in O.hupensis snail infected ahead by larval Exorchis trematode.

日本血吸虫病是我国严重的人兽共患寄生虫病。钉螺是日本血吸虫病媒介，也是鲶鱼外睾吸虫的中间宿主。申请者此前已经实验阐明先感染外睾吸虫的钉螺，能使再进入其体内的全部日本血吸虫幼虫不能发育并解体死亡；此两种吸虫双重感染钉螺，间隔时间愈长血吸虫幼虫被击毁的强度愈大。本项目拟进一步探讨不同条件钉螺（单独感染日本血吸虫、单独感染外睾吸虫、双重感染外睾吸虫和日本血吸虫、阴性对照钉螺）体内的分泌物与血淋巴细胞的种类和结构；它们的转录组学、蛋白质组学、相关功能基因的情况；及它们与被击毁的日本血吸虫幼虫间免疫反应关系；并阐明它们的分子机制、找出拮抗日本血吸虫幼虫的物质。

本项目是在此总项目即科学上首次成功地利用一种无害的吸虫先感染血吸虫病媒介钉螺,进而能有效地生物控制并杀灭全部再侵入螺体的血吸虫幼虫的实验基础上开展的工作。目前本项目在科学上首次观察到实验钉螺免疫防御系统的血淋巴细胞在寄生虫感染钉螺前后的变化情况,结果显示出它们开始对血吸虫病原有抵抗作用,而此作用随着时间的延长逐渐减弱。除此之外，本项目亦在科学上首次展示了实验钉螺体内外分泌物的结构复杂性、数量不断增加、会侵入血吸虫病原体内并杀害它们等情况。本项目亦在科学上首次应用微观工作对四种不同条件的钉螺(阴性钉螺、血吸虫阳性钉螺、外睾吸虫阳性钉螺、外睾吸虫与血吸虫先后不间隔时间双重感染阳性钉螺)进行转录组和蛋白质组的测序及差异表达分析，并成功地对湖北钉螺巨噬细胞迁移抑制因子（OhMIF）进行了克隆、表达及其生物活性分析，探究了OhMIF在寄生虫感染前后表达量的变化以及其在钉螺免疫细胞抵制寄生虫入侵过程中的关键作用。另外，我们还对钉螺体内的人体TRP14基因同系物也进行了克隆、表达与序列分析,以及应用组织学的方法观察分析其在钉螺体内的分布及感染前后的变化情况。接下来我们还筛选出许多对血吸虫病原具免疫反应有关的蛋白质,也见到其中的差异。.有关贝类的免疫防御系统的资料很欠缺,尤其是有关湖北钉螺及其体内对血吸虫病原进行生物控制的机理,范围很大,无人研究过。需要后人慢慢去探讨。