22株猪圆环病毒2型安徽分离株全基因组遗传进化分析

Phylogenetic Analysis of Complete Genome of 22 Porcine Circovirus Type 2 Isolated from Anhui Province

为了解安徽地区猪圆环病毒2型(PCV2)的分子流行病学及流行毒株遗传变异情况,本研究应用DNA Star软件,针对22株PCV2安徽分离株和26株Gen Bank登录的PCV2参考毒株,进行全基因组核苷酸序列、ORF1和ORF2核苷酸序列及其推导的氨基酸序列的同源性分析,并运用MEGA 6.0软件构建系统进化树。结果显示,22株PCV2安徽分离株基因组全长均为1 767 bp,相互之间的核苷酸序列相似度为94.6%~99.8%,与Gen Bank登录的26株PCV2参考毒株之间的核苷酸序列相似度为92.4%~99.8%。PCV2安徽分离株的ORF1核苷酸序列及其推导的氨基酸序列与参考毒株之间的相似度分别为94.3%~100%和85.4%~100%,ORF2核苷酸序列及其推导的氨基酸序列相似度分别为85.9%~99.9%和76.9%~100%。ORF2编码的Cap蛋白氨基酸序列在8~30、44~91、121~140及190~224几个区域存在突变,且有部分变异位点位于抗原表位区。22株PCV2安徽分离株分布于两个基因亚型,8株属于PCV2b,14株属于PCV2d。结果表明,PCV2安徽分离株的全基因组核苷酸序列较稳定且彼此间亲缘关系密切。ORF2的变异程度远高于ORF1,PCV2d基因亚型已经逐渐过渡成为安徽地区的主要流行毒株。Cap蛋白氨基酸序列在免疫反应区域内的变异可能影响PCV2的免疫原性。本研究结果丰富了安徽地区猪圆环病毒病的分子流行病学资料,同时也为有效防控该病提供了一定的参考依据。

To investigate the molecular epidemiology and genetic variation of porcine circovirus type 2(PCV2) in Anhui province, DNA Star software was used to perform homology analysis of genome-wide nucleotide sequences,ORF1 and ORF2 nucleotide sequences and their derived amino acid sequences for 22 Anhui iso-lates of PCV2 and26 PCV2 reference strains of Gen Bank, and MEGA6.0 software was used to construct phylogenetic tree. The results showed that the complete genome of 22 PCV2 Anhui isolates consisted of 1 767 nucleotides, and the similarity of the complete genomes was 92.4% to 99.8% compared with 26 PCV2 reference strains. The similarity of ORF1 nucleotide sequences and derived amino acid sequence between PCV2 Anhui strains and reference strains was 94.3%~100% and 85.4%~100%, and the similarity of ORF2 nucleotide sequences and derived amino acid sequence was 85.9% ~99.9% and 76.9% ~100%, respectively. The amino acid sequence of Cap protein encod ed by ORF2 was mutated in several regions including 8~30, 44~91, 121~140 and 190~224, and some of the mutation sites were located in epitope region. The 22 PCV2 Anhui isolates were classified into two gene subtypes, 8 strains belonging to PCV2 b, 14 strains belonging to PCV2 d. The results showed that the complete genome nucleotide se quences of PCV2 Anhui isolates were stable and closely related to each other. The variation degree of ORF2 was much higher than that of ORF1, PCV2 d gene subtype has gradually become the major epidemic strains in Anhui.The variation of the amino acid sequence of Cap protein in the immune response region may affect the immunogenicity of PCV2. The results of this study enriched the molecular epidemiology of porcine circovirus disease in Anhui province and provided some references for the effective prevention and control of porcine circovirus disease.