日本血吸虫极低密度脂蛋白结合蛋白重组抗原的免疫保护性研究

Protective Immunity of the Recombinant Schistosoma japonicum Specific Very Low Density Lipoprotein Binding Protein as a Vaccine Candidate

目的探讨日本血吸虫极低密度脂蛋白结合蛋白(SVLBP)重组抗原的免疫保护性及其作为候选疫苗的潜在价值。方法用异丙基-β-D-硫代半乳糖苷(IPTG)诱导克隆菌大量表达SVLBP重组抗原,以镍-次氮基三乙酸琼脂糖树脂(Ni-NTA)亲和层析法纯化制备SVLBP重组抗原;将纯化的重组抗原加福氏佐剂经皮下免疫C57BL/6小鼠,每隔2周免疫1次,在第3次免疫后10d,经腹部皮肤攻击感染日本血吸虫尾蚴35±1条,感染后45d剖杀,计数检获虫数和每克肝虫卵数(LEPG)。小鼠在免疫前和攻击感染后分别采眶窦血,用ELISA测定特异性IgG及其亚群抗体水平。结果相对于佐剂对照组,免疫组小鼠的减虫率为33.4%,减卵率为47.6%;免疫后小鼠产生高水平的特异性IgG(>1:6400);抗体亚类检测结果显示,免疫组小鼠IgG2a、IgG2b、IgG1明显高于免疫前和佐剂对照组。结论日本血吸虫皮层蛋白SVLBP重组抗原能诱导小鼠产生一定的保护性免疫,是潜在的疫苗候选抗原分子。

Objective To investigate the protective immunity against Schistosoma japonicum in mice immunized with recombinant specific very low density lipoprotein binding protein (SVLBP) and its potential as vaccine candidate. Methods Recombinant SVLBP antigen was over-expressed under IPTG induction and purified by Ni-NTA affinity chromatography. C57BL/6 mice were immunized three times with purified reSVLBP complexed with Freund's adjuvant, at biweekly intervals. Then 35±1 cercariae of S. japonicum were given to each mouse by abdominal skin 10 days after the 3rd immunization. 45 days later, all mice were sacrificed to collect adult worms and count liver eggs. serum samples were collected before immunization and after challenge respectively, and were probed the antigen-specific antibodies using a panel of ELISAs. Results The worm burden and the egg deposition in liver tissue were reduced by 33.4% and 47.6% respectively in the immunized group, in comparison with the adjuvant control group (P<0.05). Higher titer (>1:6 400) of total IgG was observed after challenge infection. The vaccinated mice developed significantly higher levels of IgG2a, IgG2b,IgG1 than those of control mice. Conclusion The recombinant tegumental SVLBP antigen could induce partial protection against S. japonicum infection. These data demonstrate the potential of SVLBP as a schistosome vaccine candidate.