日本血吸虫未成熟卵可溶性抗原诱导小鼠抗雌虫生殖免疫的研究

Anti-fecundity Effect of Soluble Immature Egg Antigen of Schistosoma japonicum in Mice

目的探讨日本血吸虫云南株未成熟卵可溶性抗原(SIEA)免疫小鼠产生的抗雌虫生殖效果及作用机制。方法3000条日本血吸虫尾蚴经腹部皮肤感染家兔,第34天收集兔肝中的未成熟卵制备SIEA。20只ICR小鼠随机分为两组,免疫组(11只)每鼠背部皮下多点注射SIEA(100μg/只),对照组(9只)给予等量生理盐水,每2周免疫1次,共5次。末次免疫后1周,用(30±2)条血吸虫尾蚴攻击感染每只鼠。第45天收集小鼠粪便,第46天剖杀小鼠,心脏灌注法收集成虫,比较成虫数及粪便、肝组织、雌虫子宫内虫卵数和肝表面虫卵结节密度;透射电镜观察雌虫卵黄腺及雄虫睾丸组织。结果免疫组与对照组检获成虫数差异无统计学意义(P>0.05)。免疫组小鼠每克粪便每条雌虫虫卵数、每克肝组织每条雌虫虫卵数、每条雌虫子宫内虫卵数及肝表面虫卵结节密度分别为(56.68±24.78)个、(5826±437)个、(49.94±12.53)个和(10.04±1.13)个/0.25cm2;对照组分别为(89.93±32.18)个、(10016±3541)个、(76.54±19.77)个和(19.22±2.45)个/0.25cm2,差异均具有统计学意义(P<0.05)。透射电镜观察显示,与对照组相比,免疫组小鼠体内雌虫卵黄腺内成熟卵黄细胞和脂滴减少,雄虫睾丸组织内支持细胞多见而精细胞较少,且卵黄细胞和支持细胞胞质内出现空泡。结论SIEA可能通过抑制日本血吸虫生殖细胞的成熟而产生抗雌虫生殖免疫效应。

Objective To study anti-female fecundity effect in mice immunized with soluble immature egg antigen（SIEA） of Schistosoma japonicum, and observe possible mechanism. Methods Immature eggs were collected from the liver of a rabbit 34 days after being infected with 3000 cercariae of S. japonicum, and soluble antigen was prepared routinely. 20 ICR mice were divided randomly to 2 groups. 11 mice were immunized with SIEA （100μg per mouse） and Freund adjuvant and the other 9 were injected with equal volume of sterile normal saline and Freund adjuvant as control. All mice received injection 5 times in 2 weeks interval. One week following the last vaccination, mice were challenged with 30±2 cercariae of S.japonicum Yunnan isolate. Feces were collected on day 45. All mice were sacrificed on day 46. The number of worms collected, number of eggs in feces, female uterus and liver, and the number of egg granulomas on the liver surface were eompared between the 2 groups. Tile vitelline gland of female and testes of male worms were examined by transmission electron microscopy. Results There was no significant difference on the worm number between the immunized group and control （P〉0.05）. The eggs per gram feces and liver, eggs in uterus per female, and egg granulomas on the liver surface were （56.68±24.78）, （5 826±437）, （49.94±12.53） and （10.04±1.13）/0.25 cm2, respectively in immunized group, while in control group these were （89.93±32.18）, （10016±3 541）, （76.54± 19.77） and （ 19.22±2.45）/0.25 em2 respectively, all with significant difference （P〈0.05）. Uhrastructure of the reproductive organs of paired adult worms showed that mature vitelline cells and lipid droplets in the eytoplasm of the eells decreased in the vitelline glands of immunized mice. More sustentaeular cells and fewer spermatids were seen in testes of immunized mice. Vacuoles were seen in the cytoplasm of vitelline cells and sustentaeular cells. Conclusion The results indicated that SIEA may have an anti-fecundity effect possibly through inhibiting the maturation of germinal cells.