幽门螺杆菌靶向核酸疫苗的构建及免疫学评价

目的:为了提高幽门螺杆菌DNA疫苗的免疫原性,构建具有靶向作用于APC细胞的核酸疫苗.方法:利用基因工程技术,将靶向基因片段和过氧化氢酶基因融合构建了核酸疫苗.体外转染293T细胞,间接免疫荧光和ELISA检测其基因表达情况.用该核酸疫苗肌肉免疫注射BALB/c小鼠后,测定其血清IgG、IgG1和IgG2a水平.结果:间接免疫荧光检测转染DNA疫苗的293T细胞,表明该疫苗能在真核细胞中表达目的抗原,通过ELISA方法测定表明其仍具有IgG抗体结合能力.BALB/c小鼠免疫后血清测定结果表明,该靶向核酸疫苗诱导的抗体水平高于对照质粒pDNAkat,抗体分型实验显示靶向核酸疫苗pcDNAkathIgz和pcDNAkat,促进了免疫反应类型由Th2向Th1的部分偏转.结论:成功构建了靶向APC细胞的幽门螺杆菌核酸疫苗,并在小鼠体内诱导了较高的抗体水平.

Construction of targeted DNA vaccine of H pylori and immune test in BALB/c mice

AIM:To construct DNA vaccine targeted on antigen-presenting cells for the purpose of increasing the immunogenecity of Helicobacter pylori DNA vaccine. METHODS:DNA vaccine was constructed by combining the targeted DNA sequence with katA.Whether or not the DNA vaccine could be expressed in the mammalian cells was detected by indirect immunofluorescence assay of 293T cells transfected with DNA vaccine.The IgG, IgG1 and IgG2a antibody titers of BALB/c mice immunized with DNA vaccine were also deter- mined. RESULTS:It was indicated in the immuno- fluorescence assay of 293T cells transfected with DNA vaccine that the KatA protein could be expressed in these cells.Enzyme-linked im- munosorbent assay(ELISA)also showed that the transfected cells with pcDNAkathIgz had a higher affinity for IgG.The IgG antibody ti- ter of BALB/c mice immunized with targeted DNA vaccine was significantly higher than that of mice immunized with pcDNAkatA,and a shift form(Th2 response to Th1 response)was achieved in the mice immunized with DNA vac- cine. CONCLUSION:DNA vaccine targeted on anti- gen-presenting cells is constructed successfully, which can evoke a higher IgG antibody titer than non-targeted DNA vaccine.