浙江省猪圆环病毒2型流行株遗传变异分析

Genetic Variation Analysis of Porcine Circovirus Type 2 Epidemic Strains in Zhejiang Province

为了解浙江省猪圆环病毒2型(PCV2)基因型和遗传变异情况,本试验对2021年采自浙江省不同地区的27份PCV2阳性病料进行PCV2全基因组扩增、克隆和测序,并将其全基因组、ORF 2基因核苷酸序列及其推导的Cap蛋白氨基酸序列与不同国家和地区的流行株进行遗传变异分析。结果显示,27株PCV2流行株之间全基因组和ORF 2基因核苷酸序列同源性分别为91.0%~99.9%和81.7%~99.9%,与不同国家和地区的PCV2参考株之间全基因组和ORF 2基因核苷酸序列同源性为90.7%~99.9%和81.8%~100%。遗传进化树分析显示,27株PCV2流行株分别处于4个分支,其中8株为PCV2a基因型,6株为PCV2b基因型,12株为PCV2d基因型,1株为PCV2e基因型。27株PCV2流行株Cap蛋白的糖基化位点和核定位信号区氨基酸序列呈高度保守,B细胞抗原表位和T细胞抗原表位存在多个氨基酸突变。结果表明,浙江省多种基因型PCV2共存,以PCV2d基因型流行为主。本试验结果对于了解浙江省PCV2流行毒株的基因型和变异状况具有重要的意义。

In order to understand the genotypes and genetic variations of porcine circovirus type 2(PCV2)in Zhejiang province,this study performed amplification,cloning,and sequencing of the full genome of 27 PCV2-positive samples collected from different regions of Zhejiang province in 2021.The genetic variations of full genome,nucleotide sequences of ORF 2 gene,and deduced Cap protein amino acid sequences were analyzed among these isolates and compared with prevalent strains from different countries and regions.The results showed that the nucleotide sequence homology among the 27 PCV2 epidemic strains was 91.0%-99.9%for the full genome and 81.7%-99.9%for the ORF 2 gene,and the homology with PCV2 reference strains from different countries and regions was 90.7%-99.9%for the full genome and 81.8%-100%for the ORF 2 gene.The phylogenetic analysis revealed that the 27 PCV2 epidemic strains belonged to 4 different branches,including 8 PCV2a genotypes,6 PCV2b genotypes,12 PCV2d genotypes,and 1 PCV2e genotype.The glycosylation sites and nuclear localization signal amino acid sequences of the Cap protein of the 27 PCV2 strains were highly conserved,while multiple amino acid mutations were observed in B-cell and T-cell antigenic epitopes.These findings indicate the coexistence of various genotypes of PCV2 in Zhejiang province,with PCV2d being the predominant genotype.The results of this study are of great significance for understanding the genotypes and variations of PCV2 epidemic strains in Zhejiang province.