嵌合流行毒株G-H环基因重组口蹄疫病毒的拯救及其免疫原性分析

Rescue and Immunogenicity Analysis of Recombinant Foot-and-Mouth Disease Virus with the Chimera of G-H Loop Gene of the Epidemic Strain

为了研究能有效免疫防控当前流行的O型3个拓扑型口蹄疫病毒(foot-and-mouth disease virus,FMDV)的疫苗候选株,本研究利用FMDV反向遗传操作技术,通过基因替换,构建同时含当前流行的O型三个拓扑型病毒株结构蛋白基因的重组全长克隆,转染表达T7RNA聚合酶的细胞后拯救重组FMDV,分析结构蛋白基因的重构对病毒生物学特性的影响;拯救病毒制备灭活疫苗,免疫猪和牛,用体外中和试验初步研究其作为O型FMD疫苗候选株的潜力。结果表明FMD流行毒株结构蛋白VP1 G-H环基因的替换没有明显影响重组病毒的噬斑表型和复制能力,但不同FMDV G-H环抗原表位对猪诱导机体产生交叉中和抗体水平影响较大,对牛诱导机体产生交叉中和抗体的影响较小,表明FMDV G-H抗原表位是猪免疫优势的表位。本研究为未来FMDV疫苗的设计提供了重要参考。

In order to develop FMD vaccine candidate strain that could effectively prevent and control recently epidemic strains belonging to three topotypes of serotype O FMDV,we constructed recombinant full-length clone containing the structural protein genes belonging to three topotypes of type O FMDV by gene replacement based on FMDV reverse genetic manipulation technique.The recombinant FMDV was rescued after transfection the full-length plasmid into BSR/T7 cells expressing T7 RNA polymerase.The effect of gene reconstruction on the biological characteristics of the recombinant virus was analyzed,pigs and cattle were vaccinated with the vaccines prepared from the recombinant virus and parental virus,the potential of the recombinant virus as a vaccine candidate strain for type O FMD was preliminarily studied by in vitro neutralization test.The results showed that the replacement of G-H loop gene of structural protein VP1 of FMD epidemic strain did not significantly affect the plaque phenotype and replication ability of the recombinant virus,but different G-H has obvious effect on production the cross-neutralizing antibody in pigs,and has little effect on production the cross-neutralizing antibody in cattle,indicating that FMDV G-H loop is the immune dominance epitope for pigs.This study will provide important reference for the design of FMDV vaccine in future.