用移植胞蚴技术建立日本血吸虫克隆的研究

STUDY OF SCHISTOSOMA JAPONICUM CLONING BY TRANSPLANTATION OF SPOROCYSTS 

目的：尝试不使用脊椎动物宿主，在钉螺内建立日本血吸虫单性克隆。方法：应用Ｊｏｕｒ－ｄａｎｅ显微外科移植胞蚴技术将单个毛蚴感染钉螺发育而获得的血吸虫子胞蚴供体连续植入正常钉螺头足窦内。结果：被移植的子胞蚴供体能继续无性繁殖产生新一代胞蚴，然后产生尾蚴，成功地建立了日本血吸虫雄性克隆ＡＨＳＰ和雌性克隆ＡＨＳＰ♀。植入雄血吸虫的雌、雄受体螺存活率分别为８０％和７８％。植入雌血吸虫的雌、雄受体螺存活率为８３％和８５％。雌、雄血吸虫克隆的尾蚴逸出前期分别为７１±６．３ｄ和６８±４．１ｄ。ＡＨＳＰ的移植感染率为６０％，ＡＨＳＰ♀的感染率为４２％。结论：供体子胞蚴性别与移植感染率有关，ＡＨＳＰ的感染率明显高于ＡＨＳＰ♀的感染率。而受体螺的性别、供体虫龄和移植的代序都与移植感染率无关。本技术不使用脊椎动物，有希望用于在实验室建立并保持不同生物特性的虫株。

AIM:To establish unisexual Schistosoma japonicum clone without using vertebrate host. Methods: The donor sporocysts originally derived from a monomiracidial infected snail were serially transplanted into the cephalopedal sinus of parasite free snails by using Jourdanes microsurgical transplantation of sporocyst technique. RESULTS: After transplantation, donor sporocysts replicated into a new generation of sporocysts and then reproduced normal infective cercariae. Both a male and a female Schistosoma japonicum clone named AHSP  and AHSP♀ were maintained only in its intermediate host Oncomelania hupensis. The survival rate of recipient snails was over 78%. The first onset of cercarial emergence began at 64 days after operation. The infection rates of snails by using the male and the female clones were 60% and 42%, respectively. CONCLUSION: The infection rate of snails by using the clone AHSP  was higher than by using the clone AHSP♀. However, the sex of recipient snails did not influence cloning success. There was no evidence of correlation between the percentage of snails which released cercariae and the order of the passage by transplantation or the age of donor sporocyst. Cloning unisexual Schistosome in Oncomelania without participation of vertebrate host is thus possible and the coloning technique offers a practical means of providing genetically homogenous cercariae with interesting phenotypes.