2011—2012年四川省猪流行性腹泻病毒的遗传变异分析

Genetic variation analysis of porcine epidemic diarrhea virus isolated in 2011-2012 of Sichuan province

为分析猪流行性腹泻病毒(PEDV)的遗传变异情况,本试验从四川省11个市19个不同地区发生仔猪腹泻疾病的猪场采集的病料中分别扩增到8个PEDV(SC-8)ORF3和部分S基因序列,将其进行比对和遗传演化分析。结果显示,SC-8的ORF3基因包含674~676个碱基,编码224个氨基酸,与GenBank中登录的国内外地方流行株的核苷酸序列同源性为95.7%~99.9%,氨基酸序列同源性为98.2%~100%,与标准毒株CV777相比,核苷酸序列和氨基酸序列除存在点突变现象外,部分序列还存在核苷酸的插入和缺失性突变;部分S基因扩增长度为981bp,编码327个氨基酸,与国内外参考毒株的核苷酸序列同源性为93.2%~99.5%,氨基酸序列同源性为93.5%~100%,与标准毒株CV777相比,四川-绵阳(SCMY)分离株在92~93nt之间存在1个核苷酸插入,在2~29aa之间也有18个氨基酸发生了突变;系统进化树分析表明,8株PEDV ORF3基因均与野毒株亲缘关系较近,而与弱毒疫苗株亲缘关系较远;SC-8的部分S基因均与国内地方流行毒株亲缘关系较近,而与国外分离株的亲缘关系较远。

Porcine epidemic diarrhea virus(PEDV)causes an acute and highly contagious enteric disease in swine.To investigate the variation of PEDV,eight sequences of ORF3 and partial S gene,respectively,were amplified from clinical samples in nineteen pig farms with refractory diarrhea from different city of eleven in Sichuan.The ORF3 consisted of 674-676 nucleotides,encoding a 224-amino acid protein.These eight PDEV strains shared 95.7%-99.9% nucleotide and 98.2%-100%amino acid identities with the PEDV strains in GenBank.Compared with CV777,nucleotide sequence and amino acid sequence except for point mutation phenomenon,partial sequence still exists nucleotide insertion and deletion mutant.The partial S gene consisted of 981 nucleotides,encoding a 327-amino acid protein.These eight PDEV strains shared 93.2%-99.5% nucleotide and93.5%-100% amino acid identities with the PEDV strains in GenBank.Compared with CV777,there was 1nucleotide insertion between 92-93 nt and 18 amino acid mutations in 2-29 aa in Sichuan-Mianyang(SCMY)strains.Based on genetic evolution,ORF3 of the eight PEDV strains were close to velogenic strain and distant with the attenuated DR13strain;and the partial S gene of which were close to strains in China and distant with strains in foreigner.