单性血吸虫带虫免疫对继发血吸虫病的影响

EFFECT OF INFECTION OF SINGLE-SEX SCHISTOSOMA ON SECONDARY SCHISTOSOMIASIS

研究表明,辐照致弱血吸虫尾蚴疫苗能够诱导宿主产生较高的免疫保护作用,是所有血吸虫候选疫苗中保护力最强的,且辐照致弱尾蚴在宿主体内不能发育成熟,不会对宿主造成严重的病理损害。单性感染的血吸虫同样不能在宿主体内发育成熟,其发育状态停留在童虫阶段,也不会对宿主造成严重的病理损害,在童虫状态下对宿主持续进行的免疫刺激,是否也能诱导宿主对继发血吸虫病产生较高的免疫保护作用呢?为此,本研究通过让宿主携带单性血吸虫雄虫的带虫免疫方式来检测其对继发血吸虫病的影响。选用雄性血吸虫尾蚴感染BALB/c小鼠(100条/只),于单性血吸虫尾蚴攻击后第5、7 w用吡喹酮进行治疗(300mg/kg),第9 w进行雌雄血吸虫混合尾蚴攻击实验动物(40条/只),第15 w剖杀实验动物,收集宿主荷虫、宿主肝卵负荷、肝卵孵化、宿主肝单卵肉芽肿体积数据,并检测宿主血清特异性抗体变化趋势。结果表明单性带虫免疫可以引起宿主肝虫卵孵化率及组织病理损伤显著降低,对宿主有一定的免疫保护效果。

Previous studies have shown that irradiated schistosome cercariae can induce higher immunoprotection. In the hosts, the radiation attenuated cercariae can neither mature nor cause serious pathological damage. Single-sex schistosoma perform similar behaviors but induce uninterrupted immune stimulation. Whether or not single-sex schistosoma can induce immune protection in hosts is unknown. To explore this problem, we first infected male BALB/c mice with single-sex male schistosoma and then examined its impact on the secondary schistosomiasis. BALB/c mice were randomly divided into two groups. Each mouse in test group was infected with 100 male cercariae and untreated mice used as controls. At 5 and 7 weeks post-infection, all mice in two groups were treated with praziquantel （300 mg/kg）. Then at 9 weeks post-infection, all mice were infected with 40 sex-mixed cercariae. At 15 weeks post-infection, all mice were sacrificed and liver tissues and blood samples were collected for detection of eggs, pathological changes and seroconversion. The results showed that single-sex male worm caused significant reduction in eggs hatching rate and pathological damages in livers, indicating a certain immunoprotective effect in hosts.