日本血吸虫组织蛋白酶B2在小鼠抗血吸虫再感染中的作用

目的 构建日本血吸虫组织蛋白酶B（Sjcb2）真核表达载体,检测日本血吸虫组织蛋白酶B2单独和联合吡喹酮（PZQ）在小鼠抗血吸虫再感染中的作用.方法 将60只BALB/c雌性小鼠随机均分为六组,建立日本血吸虫感染动物模型：感染组、感染攻击组、空质粒处理组、Sjcb2免疫组、吡喹酮处理组、Sjcb2联合吡喹酮处理组.Sjcb2免疫组和Sjcb2联合吡喹酮组分别在初次尾蚴感染前第21天、14天及7天接种pcDNA3.1（＋）/Sjcb2重组质粒,空质粒处理组接种pcDNA3.1（＋）空质粒.初次尾蚴感染后第六周,对吡喹酮处理组和Sjcb2联合吡喹酮处理组小鼠给予PZQ治疗.除感染组外其它各组在第八周再次进行尾蚴攻击感染.分别于第8周和第14周取各组小鼠肝脏组织做病理切片,观察虫卵肉芽肿大小;采用间接ELISA法检测血清中特异性IgE和IgG亚型（IgG1,IgG2和IgG3）;检测各组小鼠荷成虫数,计算抗血吸虫再感染率.结果 Sjcb2免疫组、联合组与其它组分别比较,小鼠荷虫数显著性减少,抗血吸虫再感染率显著升高,虫卵肉芽肿直径显著减小,IgG1水平显著下降和IgE水平显著升高（P〈0.01）.结论 Sjcb2在小鼠模型中具有抗日本血吸虫再感染作用,抗血吸虫再感染率为70.3%,抗再感染作用机制可能与特异性IgE水平升高和IgG1水平下降有关.

The Effect of Sjcb2 in Resistance to Re-infectionof Schistosoma Japonicum

ObjectiveTo construct the eukaryotic expression plasmid pcDNA3.1(+)/Sjcb2 and evaluate the effect of Schistosoma japonicum cathepsin B2 alone or combined with praziquantel (PZQ)in resisting the reinfection of Schistosoma japonicum.MethodsThe infected mouse model of Schistosoma japonicum was constructed and employed.Female BALB/ c mice were divided into six groups:the infected group of Schistosoma japonicum,the re-infected challenged group with cercaria after first infected,the pcDNA3.1(+) treated group,the pcDNA3.1(+)/Sjcb2 treated group,the PZQ treated group,the pcDNA3.1(+)/Sjcb2 combined with PZQ treated group.The mice of pcDNA3.1(+) group and pcDNA3.1(+)/Sjcb2 group were respectively treated with pcDNA3.1(+) or pcDNA3.1(+)/Sjcb2 in 21day,14day and 7day before primary infection with schistosoma japonicum cercaria.The PZQ was administered in the sixth week after primary infection.The re-infected challenged was in the eighth week after primary infection.The mice were sacrificed in the sixth week after re-challenged with cercaria.The worms were collected by portal vein perfused method,the quantities of adult worm burden of each mice were counted and the percentage of resistance to re-infection was calculated.The diameter of the hepatic eggs granuloma was measured,and IgG subclasses (IgG1,IgG2 and IgG3) and IgE were assayed by indirect enzyme-linked immunosorbent assay (ELISA).ResultsCompared with other groups,the Sjcb2 (pcDNA3.1 (+)/Sjcb2) group and the Sjcb2 combined with PZQ group,produced decreased adult worm burden and hepatic eggs granuloma as well as lower level of IgG1 but higher IgE.Further,these two group showed higher percentage of resistance to re-infection with statistical significance(P<0.01).ConclusionSchistosoma japonicum cathepsin B2 could significantly resist to re-infection of Schistosoma japonicum.The percentage of Sjcb2 resistance to re-infection of Schistosoma japonicum was 70.3%.The mechanism of resistance to re-infection was possibly associated with IgE and decreased IgG1.