高致病性猪繁殖与呼吸综合征病毒GP5蛋白B表位诱导中和抗体能力的研究

摘要

为证实GP5蛋白B表位是否具有诱导抗猪繁殖与呼吸综合征病毒(PRRSV)中和抗体的能力,本实验合成了PRRSV CH-la株和高致病性PRRSV(HP-PRRSV)HuN4株B表位的短肽,分别免疫家兔制备两份特异性多肽抗血清.此外,将12头PRRSV及其抗体均为阴性的健康仔猪以HP-PRRSV HuN4疫苗毒株(HuN4-F112)进行基础免疫,然后用强毒株(HuN4-F5)进行多次接种,制备猪高免血清.间接免疫荧光检测(IFA)结果显示,两份多肽抗血清均能与PRRSV经典株和变异株发生特异性反应,IFA抗体效价无差异,表明两份血清没有显著差异.病毒中和试验结果表明,两份多肽抗血清均不具有中和PRRSV活性.间接ELISA和病毒中和试验结果表明,猪高免血清中针对B表位肽的ELISA抗体水平与血清抗PRRSV中和抗体之间没有正相关关系,而且B表位肽不能抑制中和抗体.以上结果表明HP-PRRSV B表位不能诱导产生中和抗体.%B epitope was considered as a major linear neutralizing epitope in the GP5 protein of porcine reproductive and respiratory syndrome virus (PRRSV) classical strains. Compared with the classical strains, however, one amino acid mutation (L39I)was found in the B epitope of highly pathogenic PRRSV (HP-PRRSV) strains. To study the ability of the B epitope to induce neutralizing antibody (NA) against HP-PRRSV, the B epitope peptides with and without the mutation (L39I) were synthesized and immunized in rabbits to prepare the anti-peptide serums, respectively. Pig hyperimmune serums with high titer of NAs against PRRSV were prepared by hyperimmunization of swine with HP-PRRSV HuN4 vaccine strain (HuN4-F1 12) and virulent strain (HuN4-F5). Indirect immunofluorescence assay (IFA) showed that both rabbit anti-peptide serums had positive reactivity to PRRSV CH-la strain and HP-PRRSV HuN4 strain in the infected cells, but didn't have virus neutralizing activity. Indirect ELISA and virus neutralization results indicated that there was no significant correlation between the anti-B epitope peptide antibodies and NA in pig hyperimmune serums. Base on these findings, we conclude that the B epitope of GP5 protein in HP-PRRSV can not induce NA.