约氏疟红内期细胞颗粒疫苗免疫保护性机制

Protective Immune Mechanisms Induced by Cellular Vaccine Made of the Erythrocytic Plasmodium yoelii

目的探讨约氏疟红内期细胞疫苗保护性免疫作用的特点。方法分别用Saponin和双蒸水溶血后的约氏疟原虫感染的鬼形红细胞作疫苗、腹腔免疫接种BALB/c小鼠,并设正常小鼠为空白对照,分别以致死性同源虫株攻击后比较各组小鼠的感染率和存活率。采用间接免疫荧光检测法,ELISA法测定血清特异性抗体及其亚类。RT-PCR法比较各组小鼠脾细胞白细胞介素-4(IL-4),γ-干扰素(IFN-γ)表达的差异,用SDS-PAGE及直接免疫荧光染色法分析感染红细胞膜蛋白。结果用Saponin皂化构建的疟疾红内期细胞颗粒疫苗(SPRBC)与水化的红内期细胞颗粒疫苗(DPRBC)及对照组相比,可使免疫鼠获得对致死性攻击的非常显著的免疫保护,表现为低原虫血症、短病程和高存活率(P<0.01),并呈现有高滴度抗体,其亚类有先以IgG1,后以IgG2a为主的趋势;同时经SPRBC免疫鼠的脾细胞其IL-4,IFN-γ均有高表达;感染红细胞表面呈现有相对分子质量为47000的小鼠MHC-Ⅰα链分子表达。结论皂化处理的约氏疟红内期细胞颗粒疫苗对同源致死性攻击有显著的免疫保护,其作用与疫苗诱导、对攻击产生的IgG1、IgG2a类抗体以及免疫细胞分泌的IL-4,IFN-γ类细胞因子相关,呈现细胞免疫和体液免疫的共同作用。正常与感染小鼠红细胞表面的MHCclassⅠ类分子可能有重要的免疫学意义。

Objective To explore the characteristics of protective immunity against Plasmodium yoelii(P.y.)infection by asexual blood-stages cellular vaccine.Methods The particulate vaccines were constructed by saponin or double-distilled-water lysed parasitic red blood cells and inoculated into BALB/c mice by intraperitoneal injection (i.p.).Each group was challenged by the lethal erythrocytic P.y.parasites,and then their parasitemia and survival rates were detected.Expressions of interleukin-4(IL-4)and interferon-γ(IFN-γ)were detected by RT-PCR.ELISA showed the serum antibodies against the malaria challenge and their subclasses.Special membrane protein was recognized by immunofluorescence assay.Results The vaccination with saponified erythrocytic parasites protected the immunized mice against P.y.challenge,while double-distilled-water lysed vaccine did not(P<0.01).This protection was characterized by the increase of both IFN-γ/IgG2a and IL-4/IgG1.Meanwhile,MHC classⅠαchain molecule was recognized on the membrane of infected-erthythrocyte.Conclusion Saponified P.y.asexual blood-stage cellular vaccine has a significantly high protective immunity against this lethal P.y.malaria,and the immunity may be associated with the expression levels of IgG2a and IFN-γ.MHC classⅠαchain on infected erythrocytes may play an important role in the successful immunization.