重组副肌球蛋白联合ISA206佐剂诱导抗日本血吸虫保护力

Protective immunization against Schistosoma japonicum by recombinant paramyosin and ISA206 as adjuvant in C57BL/6 mice

目的探讨重组的全长日本血吸虫副肌球蛋白(rSj97)的免疫保护作用以及作为疫苗的适用佐剂组合。方法重组副肌球蛋白分别与弗氏佐剂(rSj97-FA)、ISA206(rSj97-ISA206)、CpGODN(rSj97-CpGODN-IFA)联合免疫C57BL/6小鼠,在0、2、4周共进行3次免疫注射,剂量为每只每次25μgrSj97。第3次免疫后2周,经腹部贴片感染日本血吸虫尾蚴(40±2)条。第12周剖杀冲虫,计算减虫率与减卵率。同时,在0、2、6、8、12周对各组小鼠采血,检测血清中特异性IgG1与IgG2a抗体。结果相对于未免疫组,rSj97-FA组的减虫率为27.6%、减卵率为-2.3%,rSj97-ISA206组的减虫率为45.3%(P<0.01)、减卵率为35.4%(P<0.05),rSj97-CpGODN-IFA组的减虫率为7.3%、减卵率为6.4%,对照组(仅注射CpGODN)减虫率为13%、减卵率为3%。rSj97-FA、rSj97-ISA206与rSj97-CpGODN-IFA组在首次免疫后2周,rSj97特异性IgG1与IgG2a水平较免疫前显著升高(P<0.01),攻击感染后仍维持在同一水平;对照组与未免疫对照组,其特异性IgG1水平至感染后6周方显著升高(P<0.01),但仍为较低水平(A值<0.1),而IgG2a一直保持在基线水平,无显著变化。结论重组副肌球蛋白分别与3种佐剂联合使用均能诱导小鼠产生特异性IgG1和IgG2a,但仅ISA206佐剂组诱导C57BL/6小鼠产生显著的抗日本血吸虫保护力,rSj97-ISA206是潜在用于大动物免疫的疫苗组合。

Objective To investigate protective effects of recombinant paramyosin （rSj97） against Schistosoma japonicum infection with different adjuvant combinations. Methods rSj97 were used with Freund＇s adjuvant （ rSj97-FA）, ISA206 （ rSj97- ISA206） and Freund＇s adjuvant and CpG ODN mixture （rSj97-CpG ODN-IFA）. C57BL/6 mice were injected at week 0, 2 and 4 with 25μg of rSj97 per injection, s. c.. Two weeks after the final injection （week 6） , mice were challenged with 40±2 ＆histosoma japonicum cercaria percutaneously and sacrificed for perfusion 6 weeks after the challenge to calculate the worm and egg reduction rates. Serum samples were collected at week 0, 2, 6, 8 and 12 for detection of rSj97 specific IgG1 and IgG2a by ELISA. Results Compared with the unimmunized group, the worm reduction rate and egg reduction rate of the rSj97-FA group were 27.6% and -2.3%, respectively; rSj97-ISA206 were 45.5% （ P 〈 0.01 ） and 35.4% （ P 〈 0.05 ）, respectively; rSj97-CpG ODN-IFA were 7.3% and 6.4% , respectively. Two weeks after the first injection, rSj97 specific IgG1 and IgG2a levels were significantly higher than those pre-injection in the rSj97-FA, rSj97-ISA206 and rSj97-CpG ODN-IFA groups （P 〈 0.01 ） and no significant changes were observed after the challenge infection, rSj97 specific IgG1 in the CpG ODN and unimmunized groups showed a significant increase only at 6 weeks after the challenge infection comparing with baseline （P 〈0.01 ）, but at a low level （A 〈 0.1 ）. rSj97 specific IgG2a did not change significantly during the observation time points. Conclusions This full length recombinant paramyosin could induce specific IgG1 and IgG2a responses in C57BL/6 mice after immunization with three adjuvants used in this experiment. However, only the combination of rSj97-ISA206 showed effective protection against Schistosoma japonicum in C57BL/6 mice. rSj97-ISA206 may have potential as the schistosomiasis vaccine for domestic animals and merit further investigation.