规模化猪场脐带血猪瘟病原检测及遗传变异分析

Detection and genetic variation analysi of classical swine fever virus from umbilical cord blood in large-scale pig farms

为了了解某规模化猪场母猪猪瘟病毒(CSFV)带毒及病原遗传变异情况,应用荧光定量PCR对117份分娩母猪的脐带血进行猪瘟病原检测,对阳性样品进行CSFV E2基因RT-PCR扩增,研究CSFV遗传变异特性。结果表明,该猪场猪瘟病原阳性率为7.69%(9/117),5株CSFVE2基因之间的核苷酸同源性为97.8%~100%,与参考株的同源性为80.0%~97.5%,与C株和HCLV株的同源性分别为95.6%~96.7%、96.4%~97.5%;5株CSFVE2基因推导的氨基酸同源性为97.8%~100%,与参考株之间同源性为83.5%~96.7%,与C株和HCLV株同源性均为95.5%~96.7%。遗传进化树分析表明,5株CSFV E2基因属于1.1亚群,与疫苗株HCLV亲缘性最近;氨基酸变异位点分析表明,5株CSFV E2基因在位于抗原决定区内氨基酸发生较小程度的变异。表明该猪场通过胎盘屏障感染仔猪的猪瘟病毒可能来源疫苗株,这种现象应该引起重视。

In order to understand the epidemiology and genetic variation of classical swine fever virus(CSFV)in large-scale pig farms,we collected 117 umbilical cord blood samples from parturient?sows.And then all of the samples were detected by real-time fluorescence quantitative PCR(RT-qPCR).The results showed that 9 samples were positive by RT-qPCR and the positive rate was 7.69%.All of the positive products were analyzed by RT-PCR,and all 9 samples were amplified to get a 272 bp band.Five of these 9 positive products were sequenced and analyzed.The results showed that the nucleotide homology of CSFV E2 gene between five strains were 97.8% ~100%,the homology with the reference strain was 80.0% ~97.5%,and the homology with the C and HCLV strain was 95.6% ~96.7% and 96.4% ~97.5%,respectively.The amino acid homology of CSFV E2 gene between five strains were 97.8% ~100%,the homology with the reference strain was 83.5% ~96.7%,and the homology with the C and HCLV strain was 95.5% ~96.7%.The phylogenetic tree analysis showed that five CSFV E2 gene belonged to subgroup 1.1,and were closely related to HCLV.Amino acid variation site analysis showed that amino acids of five CSFV E2 genes occurred at low degree variation in the antigenic determining region.The present study revealed that piglets infected with classical swine fever virus may be derived from vaccine strains through the placental barrier.