猪圆环病毒2型天津及周边地区分离株的遗传演化分析

为了解天津及周边地区猪圆环病毒2型（porcine circovirus 2，PCV2）的流行毒株遗传变异情况，本研究应用基因克隆技术和生物信息学分析软件对24株PCV2分离株全基因及ORF2基因分别进行克隆、测序、同源性比对和遗传进化分析。全基因组序列分析结果显示，24株PCV2分离株全基因组序列有14株为1 767 bp，10株为1 768 bp。用DNAStar软件对全基因组序列同源性比对表明，24株PCV2分离株与NCBI上的PCV2参考株的全基因序列同源性为93.6%~99.8%，24株分离株之间的全基因组序列差异很小，同源性为94.0%~99.9%。同时，用DNAStar对PCV2分离株的ORF2基因序列同源性分析表明，其与NCBI上的PCV2 ORF2基因参考序列的核苷酸序列同源性为87.3%~99.3%，24株分离株ORF2基因核苷酸序列同源性为89.0%~100.0%，3株分离株（10084F4、R14040及R14086）的核苷酸序列同源性为100.0%。对全基因和ORF2基因的遗传进化分析表明，24株分离株的系统进化树被分为2个大分支，其中23株分离毒株属于PCV2b亚型，1株属于PCV2a亚型，未分离出PCV2c亚型。综上所述，天津及周边地区PCV2的流行模式仍以PCV 2b亚型为主，本研究为该地区PCV2的流行变异情况研究提供了一定的理论依据。

Phylogenetic Analysis of Porcine Circovirus Type 2 Isolated from Tianjin and Its Surrounding Areas

To investigate the genetic variation of porcine circovirus type 2 (PCV2) in Tianjin and its surrounding areas,PCV2 whole genes and ORF2 genes of 24 PCV2 strains from the infected pigs in different regions were cloned,sequenced,and nucleotide sequence homology and genetic evolution were analyzed.The results showed that 24 strains had the full length of 1 767 or 1 768 bp,and the homology of complete genomic nucleotides among 24 strains and reference strains on NCBI was from 93.6% to 99.8%,and the homology of 24 strains was from 94.0% to 99.9%.At the same time,the homology of ORF2 gene among 24 strains and reference strains on NCBI was from 87.3% to 99.3%,and the homology of 24 strains was from 89.0% to 100.0%,and the sequence homology of three isolates of 10084F4,R14040 and R14086 was 100.0%.Phylogenetic analysis showed that the PCV2 strains could be classified into two groups,among which 23 strains belonged to PCV2b,1 strain belonged to PCV2a,which showed that PCV2b group strain was predominant prevailing strain in Tianjin and its surrounding areas,this provided some theory for the study of prevalence and variation of PCV2.