中文摘要：

【目的】探讨犬白细胞介素-2（cIL-2）与犬IL-7（cIL-7）基因对犬细小病毒（CPV）VP2蛋白DNA疫苗免疫增强的协同作用。【方法】利用含内部核蛋白体进入位点（IRES）的真核表达载体构建cIL-2和cIL-7双基因表达载体。然后利用本实验室构建的CPV VP2、cIL-2和cIL-7表达载体及本文构建的双基因表达载体,以不同组合对小鼠进行免疫,即VP2单免疫,VP2＋cIL-2、VP2＋cIL-7和VP2＋cIL-2/cIL-7共免疫。通过ELISA方法检测免疫后不同时间小鼠血清VP2的抗体水平,并分析中和抗体的效价,通过细胞增殖实验检测免疫后小鼠脾脏淋巴细胞的增殖反应,并用ELISA方法测定小鼠淋巴细胞γ干扰素的表达水平。【结果】本实验构建的双基因表达载体结构正确,并能够介导cIL-2与cIL-7基因在真核细胞中进行同步分泌表达。小鼠免疫结果表明,VP2＋cIL-2/cIL-7共免疫组小鼠血清的抗体滴度和中和抗体效价均显著高于VP2＋cIL-2和VP2＋cIL-7共免疫组（P〈0.05）。VP2＋cIL-2/cIL-7共免疫组小鼠的淋巴细胞刺激指数比其它免疫组略有升高但尚未达到显著水平,然而γ干扰素的表达水平显著高于其它免疫组（P〈0.05）。【结论】cIL-2和cIL-7基因对CPV VP2 DNA疫苗免疫原性的增强作用具有明显的协同效应。

英文摘要：

[Objective] To investigate the effects of canine interleukin-2（cIL-2） and cIL-7 genes on enhancing the immunogenicity of canine parvovirus（CPV） VP2 DNA vaccine.[Methods] The bicistronic vectors of cIL-2 and cIL-7 genes were constructed using the eukaryotic expression vector containing internal ribosome entry site（IRES）.The cIL-2/clL-7 dicistronic vector plus previously constructed vectors,including CPV VP2 DNA vaccine vector,cIL-2 vector and cIL-7 vector,were used to co-immunize mice with different combinations,consisting of VP2 alone,VP2＋cIL-2,VP2＋cIL-7 and VP2＋cIL-2/cIL-7.The VP2-specific antibody levels in immunized mice were measured by ELISA at different time post-immunization.The proliferation indices and interferon-γ expression were measured by lymphocyte proliferation assay and ELISA,respectively.[Results] The cIL-2/cIL-7 bicistronic vector was correct and could mediate cIL-2 and cIL-7 gene expression in eukaryotic cells.Immunization results revealed that the antibody titers and the neutralizing antibody levels of the mice co-immunized with VP2＋cIL-7/cIL-2 vectors were significantly higher than that with either VP2＋cIL-2 vectors or VP2＋cIL-7 vectors（P0.05）.The lymphocyte proliferation indices of VP2＋cIL-7/cIL-2 vector-immunized mice were also higher than that of other two groups although not statistically significant.However,the IFN-γexpression levels of VP2＋cIL-7/cIL-2 vector-immunized mice were significantly higher than other immunized mice（P0.05）.[Conclusion] The cIL-2 and cIL-7 genes showed the significant synergic effects on enhancing the immunogenecity of CPV VP2 DNA vaccine.