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目的了解编码SAG3的重组质粒和IL-2基因佐剂在小鼠体内的免疫反应,为进一步的核酸疫苗及免疫学研究创造条件。方法将编码SAG3的质粒和鼠源性IL-2表达载体以100μg的剂量感染小鼠,3周中两次以相同的剂量加强免疫,分别以PBS和空质粒pcDNA3.1感染。采用ELISA法测定抗体水平、亚型、IFN-γI、L-4和IL-2的含量,RT-PCR方法检测注射部位目的基因的转录,所有鼠均由强毒力ZS2株弓形虫感染。结果SAG3表达质粒3次免疫后鼠体内特异IgG水平明显上升,IL-2表达质粒的联合使用导致IgG2a水平的升高和IFN-γ的产生,提高了其分泌IL-2的水平,但对IL-4的水平产生轻微的影响;RT-PCR显示首次使用导致IgG2a水平的升高和IFN-γ的产生,提高了其分泌IL-2的水平,但对IL-4的水平产生轻微的影响;RT-PCR显示首次免疫15天后,目的基因在肌肉组织中仍有表达;混合质粒注射和小鼠抗弓形虫感染的存活时间延长。结论由SAG3 DNA诱导的免疫应答因IL-2表达质粒的共同注射而增强,DNA疫苗和适当细胞因子的共注射对抵抗弓形虫感染的效果值得进一步研究。
Objective To understand the immune response of SAG3 recombinant plasmid and IL-2 gene adjuvant in mice, and to create conditions for further nucleic acid vaccine and immunological research. Methods SAG3-encoding plasmids and murine IL-2 expression vectors were infected at a dose of 100 μg and immunized twice at the same dose in three weeks, infected with PBS and empty plasmid pcDNA3.1, respectively. Antibody levels, subtypes, IFN-γI, L-4 and IL-2 levels were measured by ELISA. Transcription of the target gene at injection site was detected by RT-PCR. All mice were infected with Toxoplasma gondii virulent strain ZS2. Results The specific IgG level of SAG3 expression plasmids was significantly increased after three immunizations. The combined use of IL-2 expression plasmids resulted in the increase of IgG2a level and IFN-γ production, -4 levels; RT-PCR showed that first-time use led to elevated IgG2a levels and IFN-γ production, increased levels of IL-2 secretion but had a slight effect on IL-4 levels; RT-PCR showed that the target gene was still expressed in muscle tissue 15 days after the first immunization; the survival time of mixed plasmid injection and anti-Toxoplasma infection in mice was prolonged. Conclusions The immune response induced by SAG3 DNA is enhanced by the co-injection of IL-2 expression plasmid. The co-injection of DNA vaccine and appropriate cytokines should be further investigated for its resistance to Toxoplasma gondii infection.