吉林省猪圆环病毒3型的分子流行病学调查及遗传演化分析

为了解猪圆环病毒3型(porcine circovirus type 3,PCV3)在吉林省的流行情况和分子生物学特性,本研究通过PCR方法对吉林省2015-2017年的484份血清样品进行PCV3检测,将PCV3检测阳性的样品进行ORF2基因扩增和测序,并利用生物信息学软件DNAStar和Mega 6.06对ORF2基因的分子生物学特性进行分析。结果显示,吉林省2015-2017年PCV3样品总感染率和猪场感染率分别为28.1%(136/484)和65.8%(25/38),且呈逐年上升趋势。同源性分析结果表明,本研究获得的4株PCV3 ORF2基因的核苷酸和氨基酸序列同源性分别为98.3%～98.9%和97.7%～99.5%,4株PCV3 ORF2基因与国内外参考毒株ORF2基因的核苷酸和氨基酸序列同源性分别为97.7%～99.7%和96.7%～100%。遗传进化分析表明,PCV3存在2个亚群:PCV3a和PCV3b。本试验分离的PCV3毒株分别位于2个亚群上,1株属于PCV3a亚群,3株属于PCV3b亚群。PCV3毒株Cap蛋白第24(A、V)和27位(R、K)氨基酸的不同可能与PCV3毒株的进化相关。本试验结果表明,PCV3在吉林省猪群和猪场中存在很高的感染率,PCV3毒株之间高度保守,本研究结果为PCV3的分子特性研究提供了参考依据。

Molecular Epidemiological Investigation and Genetic Evolution Analysis of Porcine Circovirus Type 3 in Jilin Province

To understand the prevalence and molecular biology of porcine circovirus type 3 (PCV3) in Jilin province,a total of 484 serum samples in Jilin province from 2015 to 2017 were detected by PCR in this study.The ORF2 gene sequence of PCV3 positive samples was sequenced,the molecular characterization of ORF2 gene sequences was analyzed using bioinformatics softwares of DNAStar and Mega 6.06.The results showed that the total infection rates of PCV3 were 28.1% (136/484) at serum samples and 65.8% (25/38) at pig farms,and showed increased infection rates from 2015 to 2017.The homology alignment analysis showed that the nucleotide and amino acid homology of the 4 ORF2 gene sequences in this study shared 98.3% to 98.9% and 97.7% to 99.5% homologies,respectively,and also shared 97.7% to 99.7% and 96.7% to 100% homologies in the nucleotide and amino acid with reference ORF2 gene sequences in GenBank.The results of phylogenetic showed that there were two major branches of PCV3 strains,PCV3a and PCV3b.The PCV3 strains isolated in Jilin province were distributed on the two major branches,PCV3a (1 isolate) and PCV3b (3 isolates).The difference between the amino acid at sites 24 (A,V) and 27 (R,K) of the Cap protein might be generated during the evolutionary of PCV3 strains.These results showed that PCV3 had a high infection rates in pig herds and pig farms in Jilin province.The molecular characterization of PCV3 showed that PCV3 strains were highly conserved in natural evolution.This study provided an important reference for the molecular characteristics of PCV3.