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目的研究日本血吸虫硫氧还蛋白谷胱甘肽还原酶(Thioredoxin Glutathione Reductase of Schistosoma japonicum,SjTGR)的免疫原性及抗日本血吸虫感染的免疫保护性作用。方法 75只小鼠随机分为5组:空白组、PBS组、CpG2免疫组、TGR免疫组和TGR+CpG2联合免疫组,免疫3次。首次免疫前及第3次免疫后2周经尾静脉采血,采用酶联免疫法分别检测血清中抗SjTGR蛋白IgG、IgG1和IgG2a的抗体水平。第3次免疫后2周,每只小鼠经腹部感染日本血吸虫尾蚴40±2条,42 d后剖杀,收集成虫和虫卵,计算减虫率和减卵率;制备各组小鼠单个脾淋巴细胞,采用流式细胞术检测脾细胞表面标志物CD44high、CD4+CD44high或CD8+CD44high水平;用SjTGR刺激免疫小鼠脾细胞72 h,采用酶联免疫法检测脾细胞的IL-2、IL-4、IL-10和IFN-γ的水平。结果第3次免疫后2周TGR与CpG2+TGR免疫组小鼠血清抗SjTGR抗体的IgG滴度均达1:200 000以上,IgG2a与IgG1的比值(IgG2a/IgG1)随时间的延长缓慢增高。TGR免疫组和TGR+CpG2联合免疫组细胞上清中的IFN-γ和IL-2水平与空白组、PBS组、CpG2免疫组相比明显增高(P<0.05)。TGR免疫组与TGR+CpG2免疫组小鼠脾细胞的CD44high、CD8+CD44high及CD4+CD44high与空白组和PBS组相比细胞比值增加(P<0.05)。TGR免疫组和CpG2+TGR免疫组的减虫率分别为9.4%,10.5%,减卵率分别为9.2%和32.8%。结论 SjTGR具有较强的免疫原性,可诱导小鼠免疫反应向Th1型极化,但不足以产生抗日本血吸虫感染的保护效应。CpG2 ODN可能是一种有效的Th1型免疫佐剂。
Objective To study the immunogenicity of Thioredoxin Glutathione Reductase of Schistosoma japonicum (SjTGR) and the protective immunity against Schistosoma japonicum infection. Methods 75 mice were randomly divided into 5 groups: blank group, PBS group, CpG2 immunized group, TGR immunized group and TGR + CpG2 combined immunized group, immunized three times. Serum anti-SjTGR IgG, IgG1 and IgG2a antibody levels were detected by enzyme-linked immunosorbent assay before and after the first immunization two weeks after the third immunization. Two weeks after the third immunization, each mouse was infected with 40 ± 2 Schistosoma japonicum cercariae by abdomen. After 42 days, the mice were killed and the adults and eggs were collected to calculate the worm reduction rate and the egg reduction rate. Splenic lymphocytes were detected by flow cytometry splenic cell surface markers CD44high, CD4 + CD44high or CD8 + CD44high level; with SjTGR stimulated spleen cells in mice for 72 h, the enzyme-linked immunosorbent assay IL-2, IL-4, IL-10 and IFN-γ levels. Results The IgG titer of anti-SjTGR antibody in mice immunized with TGR and CpG2 + TGR 2 weeks after the third immunization was over 1: 200 000, and the ratio of IgG2a to IgG1 (IgG2a / IgG1) was slowly increased with time. The levels of IFN-γ and IL-2 in the supernatant of TGR and TGR + CpG2 combined immunized groups were significantly higher than those in blank group, PBS group and CpG2 immunized group (P <0.05). The ratio of CD44high, CD8 + CD44high and CD4 + CD44high of TGR and TGR + CpG2 immunized mice was higher than that of blank group and PBS group (P <0.05). The worm reduction rates of TGR and CpG2 + TGR vaccines were 9.4% and 10.5%, respectively, and the rates of egg reduction were 9.2% and 32.8% respectively. Conclusion SjTGR has strong immunogenicity and can induce the immune response of mice to Th1 type polarization, but not enough to produce the protective effect against Schistosoma japonicum infection. CpG2 ODN may be a potent Th1 immune adjuvant.