目的观察表没食子儿茶素-3-没食子酸酯(Epigallocatechin-3-gallate,EGCG)对日本血吸虫尾蚴的体外杀伤作用及其超微组织结构的变化,探讨EGCG预防日本血吸虫尾蚴感染的效果,为进一步开展血吸虫尾蚴感染预防措施的研究提供实验数据。方法将日本血吸虫尾蚴分别置于空白对照组蒸馏水、药物处理组0.2%EGCG和1%EGCG溶液中,各处理0、30和60min,解剖镜下观察并摄像;分别选取以上3组处理30min的尾蚴进行扫描电镜观察。设置蒸馏水对照组、0.1%和1%EGCG溶液处理30min组尾蚴感染小白鼠,饲养43d后解剖小鼠,冲虫,观察感染情况。结果解剖镜下观察,蒸馏水对照组在0min和30min时尾蚴体态柔和,自由运动;60min时尾蚴虫体完整,蜷缩成团,活动停止。0.2%和1%EGCG处理组在30min时尾蚴剧烈运动,尾部急剧摆动、挛缩,体部发生变形,且1%EGCG处理组比0.2%EGCG处理组尾蚴运动更为剧烈,形态变形更明显;60min时,两组尾蚴尾部都已脱落且死亡。扫描电镜观察对照组尾蚴形态修长且虫体完整,口吸盘、头器和腹吸盘的结构正常,体部与尾部连接紧密,尾蚴体被表面光滑,体棘遍布全身,且头部和躯干部体棘的排列和棘的尖端都朝向身体后方。0.2%和1%EGCG处理30min组尾蚴体部高度收缩且皱褶不平,尾蚴口吸盘变形、肿大,腹吸盘肿胀、变窄,其中1%EGCG处理组比0.2%EGCG处理组尾蚴体部的收缩皱褶和腹吸盘变形更明显;两组EGCG处理组尾蚴体部与尾部连接松弛,尾端呈皱褶状变化,其中1%EGCG处理30min组尾蚴的尾部都已脱落,体表体棘散在分布,体棘紊乱、朝向不一,部分体棘脱落。动物感染试验显示对照组和0.1%EGCG处理组尾蚴感染小鼠的感染率均为100%,但0.1%EGCG处理组的减虫率为33.52%;1%EGCG处理组尾蚴感染小鼠的感染率为16.7%,减虫率81.87%。结论 EGCG对日本血吸虫尾蚴具有体外杀伤作用,发生的形态结构可能影响其侵袭宿主皮肤的能力。 Objective To observe the effects of epigallocatechin-3-gallate (EGCG) on the cytotoxicity and ultrastructure of Schistosoma japonicum cercariae in vitro and the effect of EGCG on the prevention of cercariae infection of Schistosoma japonicum To further carry out prevention and treatment of schistosome cercariae infection provide experimental data. Methods Schistosoma japonicum cercariae were placed in the blank control group, distilled water, drug-treated group 0.2% EGCG and 1% EGCG solution for 0, 30 and 60 min, respectively, observed and photographed under the microscope; Scanning electron microscopy. Distilled water control group, 0.1% and 1% EGCG solution for 30min group cercariae infected mice, 43d after feeding the mice, red worms, observe the infection. Results The dissected microscope showed that the cercariae in the distilled water control group were soft and free-moving at 0 min and 30 min. At 60 min, the cercaria larvae were intact and crouched into clusters with the activity stopped. At 30 min, the cercariae in the 0.2% and 1% EGCG groups were strenuous and the tail was swirling, contracting and deforming, and the cercariae in the 1% EGCG treatment group were more vigorous than those in the 0.2% EGCG treatment group. The morphological changes were more obvious after 60 minutes , The tail of both groups of cercariae has been shed and died. Scanning electron microscopy showed that the cercariae of the control group were slender and full of worms. The structure of the mouth sucker, head and abdominal sucker was normal, the body and the tail were closely connected, the surface of the cercariae was smooth, the body spines covered the whole body, The spines are arranged and the tips of the spines are toward the back of the body. The cercaria larvae were highly contracted and irregularly covered by 0.2% and 1% EGCG for 30min. The sucker of cercariae was deformed and swollen, and the abdominal sucker was swollen and narrowed. In the 1% EGCG treatment group, Shrinkage folds and abdominal suction disc deformation more obvious; two groups of EGCG treatment group cercaria larvae and the tail part of the connection, the tail was wrinkled changes, 1% EGCG treatment 30min cercariae tail have been shed, body surface spines scattered Distribution, body spine disorders, different directions, some body spine off. Animal infection test showed that the infection rate of mice infected by cercariae of control group and 0.1% EGCG group was 100%, but the worm reduction rate of 0.1% EGCG treatment group was 33.52%; infection rate of mice infected by 1% EGCG treatment group cercariae 16.7% and worm reduction rate 81.87%. Conclusion EGCG has an in vitro killing effect on Schistosoma japonicum cercariae, and its morphological structure may affect its ability to invade the host skin.