Studies on Antagonism between Exorchis ovariolobularis and Schistosoma japonicum in Oncomelania hupensis
- 生命科学－已发表论文 
目的 探讨在日本血吸虫中间宿主湖北钉螺体内叶巢外睾吸虫和日本血吸虫的对抗性。 方法 通过叶巢外睾吸虫和日本血吸虫对湖北钉螺的双重感染 ,计算血吸虫的感染率和尾蚴逸出量 ,常规石蜡切片观察钉螺组织学变化。 结果 钉螺在感染血吸虫 37d后再感染外睾吸虫 ,经一定时间后检查发现 ,血吸虫的感染率为 5 2 9% ,显著低于同时单独感染日本血吸虫对照组的感染率 (75 9% ) ;先感染叶巢外睾吸虫 ,经 10、 32、6 0、 10 0和 12 0d不同的时间间隔后再感染日本血吸虫的钉螺 ,血吸虫感染率分别为 6 4 %、 6 6 7%、 6 5 2 %、5 6 4 %和 5 7 1% ,而单独感染日本血吸虫对照组钉螺血吸虫感染率为 90 5 % ,经统计检验 ,各双重感染实验组血吸虫与对照组的感染率间差异具有显著或非常显著性意义 (P <0 0 5或P <0 0 1)。对各试验组及对照组钉螺逸出尾蚴试验发现 ,试验组钉螺血吸虫尾蚴逸出量均显著低于对照组的逸出量。组织学观察发现各双重感染组钉螺消化腺萎缩 ,消化腺盲囊间隙只有少量血吸虫子胞蚴 ,血吸虫子胞蚴皱缩、变形及不规则 ,且子胞蚴中只含稀疏的尾蚴胚球 ,有的子胞蚴中已无胚球 ;而单独感染血吸虫的对照组中血吸虫均发育到成熟的子胞蚴或尾蚴。 结论 钉螺体内叶巢外睾吸虫和日本血吸虫之间存Objective To examine the antagonistic interactions between Schistosoma japonicum and Exorchis ovariolobularis in the snail host, Oncomelania hupensis . Methods The infection rate and average number of cercariae of S japonicum were examined in O hupensis which had been superinfected with S japonicum and E ovariolobularis .The experimental snails were histologically observed by paraffin section. Results When snails were fed with eggs of E ovariolobularis 37 days later than S japonicum infection, the infection rate of S japonicum (52 9%) was significantly lower than that of the single S japonicum infected control (75 9%). When E ovariolobularis infected snails were exposed to S japonicum miracidia at different intervals, the infection rates of S japonicum were 64%, 66 7%, 65 2%, 56 4% and 57 1%, respectively. On the other hand, the infection rate of S japonicum in the single infected control was 90 5%. There existed significant differences. Furthermore, the average number of S japonicum cercariae shed from superinfected snails were significantly less than that of single S japonicum infected control. The histological observation showed that the larvae of S japonicum in superinfected snails were sluggish in development, irregular, shrunken, deformed, relatively small in number as compared with the control. The sporocysts contained few germ balls or immature cercariae and most of the digestive glands of superinfected snails were atrophied. Conclusion There is antagonism between E ovariolobularis and S japonicum in O hupensis , and E ovariolobularis is dominant in this situation.