猪瘟病毒基因2型流行毒株和疫苗C株抗血清与相应E2蛋白交叉免疫反应性分析

摘要

To investigate the difference of cross-reactivity of E2 proteins in classical swine fever vius (CSFV) vaccine C-strain and field isolates with corresponding antisera,the recent and early CSFV Zhejiang isolates of QZ-14,JH-14,QZ-07 and HZ-08 as well as C-strain were compared on the variations of their E2 genes.The antisera to C-strain and field isolates (QZ-14,QZ-07 and HZ-08) were prepared in pigs with recombinant E2 proteins (rE2) of CSFV expressed from baculovirus expression systems and used to examine cross-reactivity with rE2.The monoclonal antibody (MAb) 4F4 prepared against E2 of field isolates was used for detection of CSFVs in cells in vitro.The phylogenetic analysis based on E2 gene sequences of CSFV shown that isolate of QZ-14 and JH-14 belonged to subgroup 2.1d,and the isolates of QZ-07 and HZ-08 were subgroup 2.1b,which were 82-84％ nucleotide identity to C-strain.lmmunofluorescence assay indicated that MAb 4F4 recognized the 4 field isolates,but not the C-strain.All pigs inoculated with field isolates displayed certain degree of clinical symptoms and their antisera had lower level of reactivity with E2 of C-strain.ELISA showed that reactivity of anti-C-strain sera collected at day 28 post inculcation with E2 of subgroup 2 isolates was only 27％-49％ of its homologous E2,while that of antisera from field isolates to the C-strain E2 was 34％ -50％ of the homologous E2 proteins.Western blot detection also had the similar results.These results suggest that the variations of the E2 proteins between the group 2 CSFV isolates and C-strain could affect cross-reactivity with heterolgous antisera.Further research is needed to examine if such decreased immuno-reactivity is related to reduce protection of C-strain-based vaccine.%为研究猪瘟病毒(CSFv)2.1基因亚型病毒株和疫苗C株E2蛋白与相应抗血清的免疫反应性差异,本研究在分析4株CSFV浙江流行株(QZ-14、JH-14、QZ-07和HZ-08)与疫苗C株E2变异程度的基础上,制备了流行病毒株和疫苗C株全病毒猪抗血清以及针对流行株E2的单克隆抗体(MAb) 4F4,比较了它们与同源株和异源株重组杆状病毒表达的E2蛋白的亲和性.结果显示,4株浙江分离株中2株(QZ-14和JH-14)属于亚型2.1d,另2株(QZ-07和Hz-08)为亚型2.1b,它们与C株E2的核苷酸同源性在82％～84％;间接免疫荧光鉴定显示MAb 4F4能够识别4株流行株,但不与C株反应;接种流行株的动物均出现不同程度临床症状;ELISA分析显示疫苗C株血清与流行株E2蛋白的反应性约为C株E2蛋白的27 ％～49％,2株流行株感染血清与C株E2蛋白反应性约为流行株E2蛋白的34％～50％,免疫印迹分析显示类似结果.以上结果表明CSFV基因2型流行株与疫苗C株E2蛋白的差异显著影响其与相应抗血清的交叉免疫反应性,这一现象是否与C株猪瘟疫苗免疫保护效果下降有关还有待于进一步研究.