弓形虫SAG1单基因疫苗与SAG1-ROP2复合基因疫苗的免疫效果观察

目的构建弓形虫主要表面抗原SAG1单价基因疫苗及其与棒状体蛋白ROP2的复合基因疫苗,接种BALB/c小鼠,观察疫苗的免疫保护性。方法构建重组质粒pcDNA3.1SAG1及pcDNA3.1SAG1ROP2。将两核酸疫苗分别免疫小鼠,ELISA法检测血清IgG抗体、IFNγ、IL4;流式细胞仪测定T细胞亚群;弓形虫速殖子腹腔攻击感染观察小鼠生存时间。结果获得pcDNA3.1SAG1、pcDNA3.1SAG1ROP2重组质粒;pcDNA3.1SAG1ROP2组小鼠IgG抗体(P<0.05)、IFNγ(P<0.01)及CD8+细胞比例(P<0.05)均高于pcDNA3.1SAG1组;实验组组均未测到IL4;复合基因组感染弓形虫后生存时间较单基因组延长(P<0.01)。结论弓形虫不同生活阶段的抗原基因复合疫苗较单基因疫苗具有更好的免疫保护性。

Observation on the efficiency of the monvalent SAG1 and compound SAG1-ROP2 DNA vaccine against Toxoplasma gondii infections

To construct the monovalent SAG1 and compound SAG1-ROP2 DNA vaccines against Toxoplasma gondii infection and to observe the protective immune responses induced in BALB/c mice. The sequences of genes encoding SAG1 and ROP2 protein were inserted into the eukaryotic expression vector pcDNA3.1 in order to construct the monovalent and the compound vaccines. Mice were immunized intra-muscularly with the recombinant plasmid. Serum IgG antibodies and cytokines were demonstrated by ELISA and the T lymphocyte subsets assayed by flow cytometry challenge experiment was exploited with tachyzoites of T.gondii and the survival times of the challenged mice were observed. In the present study, the recombinant plasmid pcDNA3.1-SAG1 and pcDNA3.1-SAG1-ROP2 were constructed. The productions of IgG antibodies and IFN-γ were more obvious in mice immunized with pcDNA3.1-SAG1-ROP2 compound DNA vaccine than those in mice immunized with pcDNA3.1-SAG1 monovalent vaccine. No IL-4 could be detected in all experimental groups. In both experiments of mice immunized with monovalent and compound DNA vaccine there were decrease of CD+_4 cells and increase of CD+_8 cells resulting in an elevation of CD_4/CD_8 ratio. The survival time of mice immunized with the compound DNA vaccine was considerably prolonged in comparison with that of mice immunized with monovalent DNA vaccine. It is evident from the present study that the compound DNA vaccine elicit a better immuno-protection in mice than the monovalent DNA vaccine.