日本血吸虫童虫细胞免疫母鼠的子代抗攻击感染的保护性研究

Protection against challenge infection in the offspring mice born to immunized mother mice with schistosomulum cells

目的以2种日本血吸虫易感小鼠为动物模型,探讨日本血吸虫(Schistosoma japonicum,S.j)童虫细胞免疫母鼠的子代鼠抗日本血吸虫攻击感染的应答水平。方法用S.j童虫细胞分别免疫昆明母鼠和Balb/c母鼠,将免疫母鼠或正常母鼠与相应鼠种的正常公鼠进行配对饲养,用其子代鼠建立2个感染模型共4组(A1:免疫昆明子代感染组;B1:正常昆明子代感染对照组;A2:免疫Balb/c子代感染组;B2:正常Balb/c子代感染对照组);计数A1、B1、A2、B2组经日本血吸虫尾蚴攻击感染后从其子代鼠体内收获的虫荷和每克肝卵荷(liver eggs per gram,LEPG);测量上述4组小鼠经HE染色后的肝组织切片内虫卵肉芽肿的大小;间接ELISA检测血清中抗S.j可溶性童虫抗原(soluble juvenile worm antigens,SJWA)IgG(H+L)水平。结果与正常昆明株、Balb/c株子代对照组B1、B2组相比,2组S.j童虫活细胞免疫母鼠子代A1、A2组均表现出不同程度的抗攻击感染的免疫力,尤其抗生殖效果显得尤为突出。其中,A1获得35.6%的减虫率和59.4%的LEPG减卵率;A2获得29.8%的减虫率和47.4%的LEPG减少率。从肝脏外表来看,B1、B2组子代对照鼠肝脏的坏死程度明显高于A1、A2免疫子代鼠。此外,A1组肝脏虫卵肉芽肿平均直径和面积比B1组分别减少23.8%和43.4%,A2组肝脏虫卵肉芽肿平均直径和面积较B2组减少28.4%和50.3%。A1、A2与B1、B2各指标结果的组间差异均具有统计学意义(P<0.05)。间接ELISA结果显示,不同时间点采集的2株免疫子代鼠血清中的抗SJWA-IgG水平高于同期相应对照组血清中的特异性IgG水平。结论用S.j童虫细胞接种母鼠所诱生的保护性免疫能传给子代,进而使子代鼠产生针对后天初次感染的保护性免疫。

To explore the resistance against challenge infection in the two susceptible strains of the offspring mice born to mother mice immunized with schistosomulum cells. Both susceptible female Kunming strain and Balb/c strain of mice to schiostosome were immunized with Schistosomulum japonicum cells for 3 time, respectively. After mating with the corresponding strain of male mice, the offspring mice either born to immunized mothers or to untreated mothers were divided into 4 groups, A1：experiment offspring mice born to immunized Kunming strain of mother mice, B1： control offspring mice born to untreated Kunming strain of mothers, A2： experiment offspring mice born to immunized Balb/c strain of mother mice, B2： control offspring mice born to untreated Balb/c strain of mothers. About 6-8 weeks post neutralization rearing（both strains of mice in weight of 16-20 g）, the two strains of offspring mice either born to immunized mothers（A1 and A2 group）or born to untreated normal mothers（B1 and B2 group）were challenged with S. j cercariae and the protection efficiency was evaluated with parasitological and immunological indicators. The worm burdens and liver egg loads collected from above 4 groups were counted and compared; The liver sections were prepared and stained with HE, and the diameters and areas of liver egg granulomas were estimated; The levels of Ig G against soluble juvenile worm antigen（SJWA）in the sera of the progenies collected at different time points were detected by ELISA. Compared with two strains of control groups B1 and B2, both strains of experiment offspring mice（A1 and A2）possessed certain level of protection against challenge infection with either Kunming strain of offspring mice exhibiting 35.6% reduction in worm burden and 59.4% reduction of liver egg burden or Balb/c strain of offspring mice showing 29.8% reduction in worm burden and 47.4% reduction in liver egg burden. The liver appearances of A1 and A2 mice were relatively normal as compared with that of control mice. At the same time, the mean diamaters and areas of granulomas in the sections of livers from A1 and A2 groups were significantly smaller than that in the sections of livers from B1 and B2 groups. Furthermore, ELISA results showed that the levels of specific Ig G against SJWA in the sera from A1 and A2 group of mice were higher than the Ig G levels in the sera from corresponding strain of control groups. By employing two susceptible strains of mice to S. j infection as models, the experiment results indicated that the mother mice immunized with live schistosomulum cells could deliver the protective immunity to next generation and make them to inherit immune protection against initial acquired challenge of Schistosoma japonicum.