ASFV pp62 Protein Has 9 Dominant B-T Cell Combined Epitopes

[Objective]The paper was to study the basic characteristics of the pp62 protein of the African swine fever virus strain Pig/HLJ/2018,and to provide more basic data for the study of the virus.[Method]We used the ProtParam program to analyze the physical and chemical properties of the pp62 protein.TMHMM-2.0 and SignalP-5.0 were used to analyze protein transmembrane region and signal peptide,and Lasergene 7.0 Protean program was used to study protein antigen index,hydrophilicity,surface accessibility and titration curve.Protein N-glycosylation site and O-glycosylation site came out with NetNGlyc-1.0 and NetOGlyc-4.0 online servers.Then,PSIPRED-4.0,NetSurfP-2.0,and PSRSM were used to analyze protein secondary structure,BepiPred1.0 and IEDB tools were used to analyze protein B-cell epitopes,and NetMHC 4.0 and NetMHCpan tools were used to analyze protein T-cell epitopes.And we used Swiss-Model to analyze the high-level structure of the protein,the EzMol tool to visually analyze B-T cell combined epitopes,and finally,MEGA 7.0 to analyze the genetic evolutionary relationship of the protein.[Result]The pp62 protein of African swine fever viral strain Pig/HLJ/2018 had a molecular weight of 60.5 kDa.It was a hydrophilic acid labile protein,and had no transmembrane region and signal peptide.There were 5 N-glycosylation sites and 4 O-glycosylation sites.Analysis of the secondary structure of the protein showed that the proportions of helix,coil and strands were 45.5%,41.7%and 12.8%,respectively.The study of dominant epitopes revealed that there were 14 dominant B-cell epitopes and 16 dominant T-cell epitopes.And 9 dominant B-T cell combined epitopes located on the surface of the protein molecule were found.The phylogenetic tree constructed with the pp62 protein showed that the evolutionary relationship of Pig/HLJ/2018 strain was the closest to Georgia/2007/1,which belonged to genotype II.[Conclusion]The results will provide basic information for pp62 research.

管式磁微粒非洲猪瘟病毒pp62蛋白化学发光抗体检测方法的建立

【背景】非洲猪瘟(African swine fever,ASF)作为高致病性传染病,给我国生猪养殖业造成了严重的经济损失,因此建立快捷、灵敏的诊断方法至关重要。【目的】建立一种管式非洲猪瘟病毒pp62蛋白化学发光抗体检测方法。【方法】以重组pp62蛋白作为包被抗原,羧基磁珠(carboxylic magnetic beads)作为固相载体,碱性磷酸酶(alkaline phosphatase,AP)标记的兔抗猪IgG作为酶标二抗,通过对反应条件进行优化,采用非洲猪瘟国家参考品作为溯源血清绘制出标准曲线,建立基于ASFV pp62蛋白的化学发光抗体检测方法。【结果】用建立的化学发光方法检测277份临床样品血清,通过受试者工作特征(receiver operating characteristic,ROC)曲线分析确定阴性、阳性临界值,并确定判定标准:浓度值>140.02 U时为抗体阳性,浓度值<140.02 U时为抗体阴性。此方法对6种不同的病原血清抗体进行检测均无交叉反应,且批内和批间变异系数均在10%以内,与商品化非洲猪瘟抗体检测试剂盒的符合率达96.7%。【结论】本研究建立的管式非洲猪瘟病毒化学发光抗体检测方法具有良好的特异性、敏感性和重复性,可为非洲猪瘟早期监测及试剂盒研发提供参考。

非洲猪瘟病毒pp62蛋白单克隆抗体的制备和鉴定

pp62蛋白是非洲猪瘟病毒(ASFV)CP530R基因编码的多聚蛋白前体,可被蛋白水解酶切割形成成熟蛋白p35、p15和p8,与pp220多聚蛋白前体的加工产物组装成病毒核壳。本研究参考ASFV China/2018/AnhuiXCGQ毒株基因序列,分析后选取CP530R基因N端(1—612 bp)及C端(784—1593 bp),分别构建原核表达质粒pET-28a-pp62-N和pET-28a-pp62-C;转化Rosetta感受态细胞,IPTG诱导表达pp62蛋白;再用纯化蛋白免疫BALB/c小鼠,经细胞融合和阳性克隆筛选后,获得4株可稳定分泌pp62单克隆抗体的杂交瘤细胞。Western-blot检测ASFV感染PAM细胞中pp62剪切体的结果显示,1株仅识别pp62蛋白,1株仅识别p35蛋白,1株仅识别p15蛋白,1株可识别pp62和p8蛋白。IFA鉴定结果显示,4株均能与ASFV感染PAM细胞产生特异性绿色荧光。本研究为建立ASFV诊断方法和研究pp62的生物学功能奠定了生物材料基础。

非洲猪瘟病毒PP62蛋白在昆虫细胞中的表达与鉴定

为表达非洲猪瘟病毒PP62蛋白,将非洲猪瘟病毒pp62基因克隆至pFastBac-HTA载体,经转座、转染后获得重组杆状病毒rBac-pp62。将该重组病毒感染Sf9细胞后,采用间接免疫荧光(IFA)检测PP62蛋白的表达,通过亲和层析纯化重组蛋白PP62,以Western-blot和间接ELISA方法鉴定纯化的重组蛋白PP62的免疫反应活性。结果显示,重组杆状病毒rBac-pp62感染的Sf9细胞可以大量表达PP62蛋白,纯化的PP62重组蛋白能够与非洲猪瘟阳性血清发生特异性反应,以重组蛋白PP62为包被抗原建立的间接ELISA方法可以区分非洲猪瘟阳性血清和阴性血清。结果表明,表达的重组蛋白PP62具有良好的反应活性,可作为开发非洲猪瘟抗体检测试剂盒的抗原以及用于PP62蛋白的结构和生物学功能研究。