To study anti-soluble egg antigen egg yolk immunoglobulin ( anti-SEA IgY) as a therapeutic vaccine against Schistosoma japonicum, BALB/c mice were divided into 5 groups each with 8 mice. Anti-SEA IgY was orally administered at 2 h, 4 d, 7 d and 15 d after the infection with 40 ± 1 S. japonicum cercariae per mouse, respectively. PBS was orally administered as control group. Six weeks later, mice were killed and perfused, and the adult worms and eggs were counted. The mean size of single-egg granuloma in each group was measured in the pathological sections of livers. The results showed that the worm reduction rates and egg reduction rates of IgY passive transfer groups at 2 h , 4 d, 7 d and 15 d after infection were 19. 59% , 18. 19% , 32. 58% , 6. 31% and 58. 33% , 49. 56% , 82. 46% , 5. 26% , respectively. Compared to those of other groups, IgY passive transfer group at 7 d after infection showed higher worm reduction rates and egg reduction rates , and the difference was significant ( P < 0. 05 ). Histopathological examination revealed the mean size of single-egg granulomas of IgY passive transfer groups at 2 h, 4 d, 7 d and 15 d after infection were (38.04 ±20.97) × 10 3 , (30.05 ±15.42) xl0', (21. 55 ± 13. 35 ) × 10 3 , (39. 67 ± 13. 87 ) × 10 3 and (40. 12 ± 24. 13 ) × 10 3 mm3, respectively, which showed that the mean size of single-egg granulomas of IgY passive transfer group at 7 d after infection were significantly smaller than those of all the other groups (P <0. 05). Moreover, IgY passive transfer group at 7 d after infection had higher level of specific IgG in sera (0. 16 ±0. 10, 0. 30 ±0. 15, 0.58 ±0. 15 and 0. 38 ±0. 16 in IgY passive transfer groups at 2 h, 4 d, 7 d and 15 d after infection, respectively. ). Those results demonstrate passive immunization of anti-SEA IgY could induce the immune protection against challenge infection, and the time of passive transfer was important.%为探讨抗日本血吸虫可溶性虫卵抗原的卵黄免疫球蛋白(anti-SEA IgY)作为抗血吸虫治疗性疫苗的可行性,将实验鼠分为5组,每组8只小鼠,分别在感染后2 h、4天、7天和15天进行 IgY 口服被动免疫,并以PBS作为对照.每鼠经腹部皮肤感染日本血吸虫尾蚴40±1条,感染后6周剖杀小鼠,从门脉中收集成虫和记数肝组织中的虫卵数,计算减虫率和减卵率.并做肝脏连续病理切片观察病变程度,测量并比较各组平均虫卵肉芽肿的体积大小.结果表明,感染后2 h、4天、7天和15天IgY被动免疫组的减虫率分别为19.59%、18.19%、32.58%和6.31%;减卵率分别为58.33%、49.56%、82.46%和5.26%.感染后7天IgY被动免疫组的减虫率和减卵率均明显高于其他实验组,并有统计学差异(P<0.05).感染后2 h、4天、7天和15天IgY被动免疫组的平均单卵肉芽肿体积分别为(38.04±20.97)×10-3、(30.05±15.42)×10-3、(21.55±13.35)×10-3、(39.67±13.87)×10-3和(40.12±24.13)×10-3 mm3,血清中血吸虫特异性IgG滴度分别为0.16±0.10、0.30±0.15、0.58±0.15、0.38±0.16.与对照组和其他实验组相比,感染后7天IgY被动免疫组的肝脏平均单卵肉芽肿体积明显减小,血清中日本血吸虫特异性抗体IgG水平明显升高(P<0.05).研究结果提示,特异性IgY被动免疫可诱导小鼠产生一定水平的抗血吸虫感染作用,但以感染后第7天的免疫效果最好,其相关机制值得进一步研究.
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