日本血吸虫SjIR3 DNA疫苗诱导的抗攻击感染保护力

目的 探讨日本血吸虫SjIR3核酸疫苗诱导小鼠抗日本血吸虫攻击感染的保护效果。 方法 用SjIR3的特异引物构建疫苗SjIR3/pC。54只昆明小鼠随机分为3组：A组（对照组）、 B组（空质粒组）和C组（实验组）分别肌注生理盐水（100 μl）、pcDNA3.0和SjIR3/pC（各50 μg），共免疫3次，每次间隔2周。于每次免疫前和感染前尾静脉采血，ELISA检测血清IgG抗体水平。末次免疫后2周，各组剖杀其中6只小鼠取脾细胞，分别用ConA或rSjIR3重组蛋白诱导，用四甲基偶氮唑盐微量酶反应比色法（MTT）检测脾淋巴细胞增殖情况。各组余下小鼠分别经腹部感染日本血吸虫尾蚴40±1条，45 d后宰杀，观察实验组小鼠的减虫率和肝减卵率。 结果 ELISA结果显示，A组与B组IgG抗体水平变化不明显（P＞0.05），C组于末次免疫后2周（攻击感染前）IgG抗体水平最高为0.78±0.05，且与A、B两组比较差异有统计学意义（P＜0.01）；末次免疫后，实验组小鼠脾淋巴细胞分别在ConA或rSjIR3重组蛋白诱导下可增殖，分别为0.57±0.02、0.68±0.01，与A、B组相比差异有统计学意义（P＜0.01）。经SjIR3/pC免疫的实验组小鼠攻击感染后可产生29.4%的减虫率和36.6%的肝减卵率。 结论 SjIR3/pC核酸疫苗具有较好的免疫原性，可诱导小鼠产生部分免疫保护力。

DNA Vaccine Encoding SjIR3 Induces Partial Immune Protectionagainst Schistosoma japonicum in Mice

OBJECTIVE: To detect the protection in mice induced by DNA vaccine encoding SjIR3 against Schistosoma japonicum (Sj). METHODS: Sj1R3 was amplified by PCR with specific primers and linked to T vector. The reconstructed plasmid was digested by Xho I and BamH I. The target segments were collected and inserted into pcDNA3.0 to construct DNA vaccine SjIR3/pC. Fifty-four female mice were divided into 3 groups: groups A and B received normal saline and pcDNA3.0 respectively as controls, and group C was immunized with SjIR3/pC. All the mice were injected three times with an interval of two weeks. Sera were collected before each inoculation and before challenge infection. Six mice from each group were sacrificed 2 weeks after the final inoculation and spleen cells were collected. Serum IgG was detected by ELISA and the proliferation activity of spleen T lymphocytes induced by ConA or rSjIR3 was detected by MTT assay. The remaining mice were infected by (40+/-1) Sj cercariae per mouse 2 weeks after the final inoculation. Forty-five days later, mice were sacrificed and perfused, numbers of adult worms and of eggs in liver tissue were counted. RESULTS: ELISA showed no significant change of serum IgG level in groups A and B, but considerable increase in group C (0.78+/-0.05) (P<0.01). The proliferation activity of spleen T lymphocytes increased with the induction of ConA or recombinant protein rSjIR3 after the final inoculation. The A570 was 0.57+/-0.02 and 0.68+/-0.01 respectively, showing a significant difference in comparison to the groups A and B (P<0.01). The worm reduction rate and the egg reduction rate in group C were 29.42% and 36.56% respectively. CONCLUSION: DNA vaccine encoding SjIR3 induces humoral and cell-mediated immune response, and shows partial immune protection against Schistosoma japonicum.