一种新型T细胞免疫原的原核表达及对口蹄疫疫苗的免疫增强作用

Enhanced immune response of a novel T-cell immunogen in vaccinefor foot-and-mouth disease

摘要:

主要探讨了T细胞免疫原TI对口蹄疫疫苗的免疫增强作用。设计并原核表达产生了一种包含口蹄疫病毒VP1，VP4，3A和3D蛋白上多个T细胞表位与两个通用T细胞表位的T细胞免疫原，命名为TI；同时表达了O和Asia 1两个型口蹄疫病毒 VP1 蛋白的串联编码基因，表达产物命名为OA-VP1。将上述T细胞免疫原分别与OA-VP1和口蹄疫灭活疫苗按不同剂量组合免疫小鼠，于免疫后不同时间测定各组小鼠的体液与细胞免疫应答情况。采用微量中和试验检测小鼠O型和Asia1型中和抗体，采用流式细胞检测技术和测定γ-干扰素的水平来分析不同免疫组小鼠细胞免疫的水平。结果显示，与灭活疫苗或OA-VP1单独免疫组相比，添加TI抗原后灭活疫苗 (P＜0.01) 和OA-VP1免疫组(P＜0.05)小鼠均能产生高水平的特异性中和抗体；且CD4+ T细胞数量显著增多，IFN-γ产生水平显著升高 (P＜0.01)。说明TI抗原具有很好的诱导特异性体液与细胞免疫应答的作用，是一种很好的免疫增效剂，可作为口蹄疫蛋白亚单位疫苗和灭活疫苗中的一种有效成分，以提高疫苗的免疫效果。

Abstract:

We investigated the enhanced immune response of a recombinant T cell immunogen as an effective cellular immune adjuvant. The T cell immunogen named TI contained several T cell epitopes from the VP1, VP4, 3A and 3D proteins of foot-and-mouth disease virus (FMDV) and two pan-T helper (TH) cell site to broaden the immunogenicity of the protein. Meanwhile, another fusion protein named OAVP1 was expressed in bacteria, which contained two VP1 proteins of O and Asia1 type FMDV. Mice were vaccinated with commercially inactivated vaccine or OAVP1 protein with or without the TI immunogen. The results show that mice inoculated with inactivated vaccine or OAVP1 protein supplemented with TI immunogen produced significantly higher level of neutralizing antibodies (P<0.01 or P<0.05) than the mice only inoculated with inactivated vaccine or OAVP1 protein by microneutralization assay. An obvious increase in T cell number by flow cytometric analysis and significantly higher concentration of IFN-γ secreted in culture media of spleen lymphocytes were observed in groups supplemented with TI immunogen (P<0.01). TI immunogen was an effective stimulator for humoral and cellular immunity and could help improve the immunogenicity of inactivated vaccine or protein subunit vaccine.