中文摘要：

跨膜糖蛋白恒定链在抗原递呈细胞内主要参与主要组织相容性复合体（MHC）Ⅱ类分子与抗原肽复合物的装配,其关键活性基团（Ii-Key）在此过程中发挥重要作用。为了研究Ii-Key携带异种病毒抗原表位能否有效增强机体的免疫应答,本试验首先构建Ii-Key与鸡传染性法氏囊病病毒VP2肽表位（aa197-209）和新城疫病毒HN肽表位（aa345-353）的嵌合体,并将嵌合体基因插入pET-32α原核表达载体,转化E.coli Rosetta诱导表达,用镍柱亲和层析纯化融合蛋白,免疫SPF级BALB/c小鼠,分别通过间接酶联免疫吸附试验和免疫印记试验检测小鼠体内的抗体水平和融合蛋白的反应原性。结果表明,与VP2/HN串联表位对照组相比较,Ii-Key/VP2/HN嵌合体疫苗处理组抗体效价平均提高了13.7倍。通过将嵌合体基因导入pmCherry-C1真核表达载体与pEGFP-N1-MHCⅡα共转染293T细胞,结果表明Ii-Key/VP2/HN嵌合体与VP2/HN和空载体蛋白在细胞内均呈现弥散状,与MHCⅡ类分子共定位无明显差异。综上所述,Ii-Key能够携带异种病毒串联抗原表位有效增强免疫应答,其增强机制还有待于进一步研究。

英文摘要：

Invariant chain（Ii）is a transmembrane glycoprotein that participates in the assembly of MHC classⅡ molecule-peptide complexes in antigen-presenting cells.The key motif of invariant chain named Ii-Key plays an important role in the process.To investigate the immunological responses of Ii-Key hybrid heterologous viral epitopes,we constructed Ii-Key hybrid of VP2（aa197-209）and HN（aa345-353）,from infectious bursal virus and Newcastle disease virus respectively.Then,the hybrid vaccine was injected into SPF BALB/c mice.The antibody titer of the experimental animals were detected by enzyme linked immunosorbent assay（ELISA）,to evaluate the protective effect of the chimeric vaccine.The result showed the Ii-Key hybrid peptide stimulated the immune response and the mean antibody titer enhanced greatly by 13.72 times,compared with the group of epitope-epitope peptide.Moreover,the Ii-Key/VP2/HN hybrid was cloned into a eukaryote expression vector pmCherry-C1,then co-transfected with pEGFP-N1-MHCⅡαinto 293 T cells.There are no apparent difference of location in cells among the epitope-peptide VP2/HN and Ii-Key/VP2/HN.Our study indicated that Ii-Key hybrid heterologous multi-epitopes can enhance the immune reponse effectively,and the mechanism underlying needs further investigation.