Asia I型口蹄疫病毒中和表位与羊IgG重链恒定区的融合表达及免疫原性测定

Fusion expression of Asia I type FMDV neutralizing epitope with heavy chain constant region of sheep IgG and the assessment of its immunogenicity

摘要:

VP1蛋白是口蹄疫病毒 (Foot-and-Mouth Disease Virus，FMDV) 诱导机体产生抗病毒感染免疫的主要蛋白，含有病毒的若干中和表位。本研究设计和合成了由Asia I型FMDV VP1蛋白136~160aa和198~211aa两个表位组成的重复串联表位的编码基因，并克隆了羊IgG重链恒定区编码基因。利用BamH I、EcoR I和Xho I位点将2个基因片段依次克隆到pPROExHTb载体，构建成重组质粒pPRO-FshIgG，将其转化大肠杆菌BL21(DE3)感受态细胞，以IPTG诱导表达得到融合蛋白FshIgG。100 μg FshIgG蛋白免疫豚鼠后刺激豚鼠产生了高效价的FMDV中和抗体，而且使这些免疫豚鼠在用200 ID50剂量FMDV攻击时得到了完全保护。由此证明，羊IgG重链恒定区蛋白能够作为FMDV表位肽的载体，而融合蛋白FshIgG可成为一种口蹄疫表位疫苗候选物用于口蹄疫的预防。

Abstract:

VP1 is a major antigenic protein of foot-and-mouth disease virus(FMDV), which induces the immune response against FMDV infection, and contains several epitopes of the virus. we designed and chemically synthesized a DNA fragment which encoding a tandem repeat protein of 136?160aa and 198?211aa of a strain of type Asia I FMDV, and cloned the gene of heavy chain constant region of sheep IgG. By using the BamH I, EcoR I and Xho I sites, both genes were cloned into pPROExHTb vector in turn to form a recombinant plasmid pPRO-FshIgG. A chimeric protein, named FshIgG, was obtained after transforming the pPRO-FshIgG into Escherichia coli BL21 (DE3) host cell and induced by IPTG. Inoculation with 100 μg FsIgG induced strong neutralizing antibody response in guinea pigs, and FshIgG inoculated guinea pigs were also protected against 200 ID50 FMDV challenge. Our study indicated that the heavy chain constant region of sheep IgG can act as the carrier protein for FMDV peptide epitopes, and FshIgG is a potential multiepitope peptide vaccine candidate to prevent FMDV infection.