猪圆环病毒2型和3型混合感染与遗传进化分析

Co-infection detection and phylogenetic analysis of PCV2 and PCV3

为了解临床猪圆环病毒混合感染及其遗传进化情况,利用PCV检测试剂盒对10份疑似感染PCV的患病猪的病料进行检测,并对阳性样品进行全基因组克隆与测序分析。结果显示:10份样品中,PCV1均为阴性,PCV2阳性率为90%,PCV3阳性率为30%,PCV2与PCV3混合感染率为30%。全基因组遗传进化结果显示:9株PCV2毒株全序列间的核苷酸同源性为94.5%—100.0%,分属PCV2a、PCV2b、PCV2d和PCV2e基因型,其中PCV2d为优势基因型,占比达55.56%。3株PCV3毒株全序列之间核苷酸同源性为99.2%—99.8%。对Cap蛋白氨基酸序列分析发现,PCV3毒株与PCV2毒株的亲缘性较远,氨基酸同源性仅为43.9%—45.1%。PCV3毒株的Cap蛋白抗原指数与参考菌株间差异较小,5株PCV2d毒株的Cap蛋白抗原指数较疫苗株有明显差异。综上,在临床PCV2患病猪中PCV2d为优势基因型,且存在一定比例的PCV2与PCV3混合感染现象。

In order to investigate the co-infection detection and phylogenetic analysis of porcine circovirus,a total of 10 samples with PCV-like syndrome were collected and detected by PCR.Positive samples were selected to whole genome cloning and sequencing analysis.The results showed that all samples were PCV1 negative,the positive rates of PCV2 and PCV3 were 90%and 30%,respectively,the co-infection rates of PCV2 and PCV3 were 30%.Phylogenetic analysis results showed that the homology of complete genome between 9 isolated PCV2 strains were 94.5%—100.0%.These PCV2 strains were PCV2a,PCV2b,PCV2d and PCV2e genotype,and the dominant genotype of PCV2d was 55.56%.The homology of the whole genome nucleotide sequences of three PCV3 isolated strains were 99.2%—99.8%.Through the amino acid sequence analysis of Cap,low homology was found when compare with PCV2 and PCV3,which was 43.9%—45.1%.The antigenic index of PCV3 Cap protein showed relatively low variation compared with reference strains,and which of PCV2d Cap protein contained the obvious differences compared with vaccine strains.The results indicated that PCV2d was prevalent genotype and there was still a certain proportion of co-infection with PCV2 and PCV3 in the PCV2 infected pigs.