山西省2018-2020年猪圆环病毒3型的检测及Cap基因遗传演化分析

Survey detection and Cap genetic variation of porcine circovirus-3from 2018to 2020in Shanxi,China

为了掌握近年来山西省猪圆环病毒3型(PCV3)的分子流行病学情况,运用PCR技术对2018-2020年在山西省猪场采集的1125份血清和病、死猪组织样品进行PCV3检测,然后对获得的5份PCV3阳性样品ORF2序列进行测序,并对ORF2序列和推导出的Cap蛋白氨基酸序列进行遗传进化分析。结果发现,PCV3在山西省猪场感染严重,山西省2018-2020年PCV3平均阳性率为21.42%,猪场平均阳性率为44.17%,且猪场PCV3型的平均阳性率有呈逐年上升的趋势;测序发现山西省5株PCV3的ORF2核酸序列均为645bp,编码214个氨基酸,5株PCV3 ORF2之间核苷酸和Cap蛋白氨基酸同源性分别为99.2%~100.0%和98.1%~100.0%,与36株参考株之间核苷酸和氨基酸同源性分别为98.1%~99.8%和97.2%~100.0%;PCV3的ORF2核酸序列遗传进化分析表明,山西省5株PCV3流行株都属于PCV3b亚型,由此可见目前山西省PCV3流行株主要为PCV3b亚型。5株PCV3Cap蛋白氨基酸序列较为保守,没有出现不同于其他毒株的特异性突变。本研究结果为了解PCV3在山西省的流行和遗传进化特点提供了理论依据,也为山西省PCV3的科学防控奠定了基础。

A total of 1125serums and tissue samples of sick or dead pigs were collected in Shanxi from 2018to 2020and detected by PCR,hoping to master the molecular epidemiology of porcine circovirus type 3(PCV3)in Shanxi in recent years.Then ORF2sequences obtained from five positive samples of PCV3were sequenced,and the genetic variation analysis of the ORF2sequences and the amino acid sequences of the Cap protein deduced were performed.The results showed that the average positive rate of PCV3and the pig farms were 21.42%and 44.17%in Shanxi from 2018 to 2020.Further more,the infection of PCV3was more serious with an increasing trend year by year from 2018to 2020in Shanxi.The results of sequencing revealed that the ORF2nucleic acid sequence of five PCV3strains was 645bp in Shanxi,encoding for 214amino acids.The homologies of ORF2nucleotide sequences and Cap amino acid of the five strains were 99.2%-100.0%and 98.1%-100.0%respectively,the homologies of ORF2nucleotide sequences and Cap amino acid of the five strains to the 36isolates from different regions of the world PCV strain were 98.1%-99.8%and 97.2%-100.0%respectively.The phylogenetic analysis from the ORF2nucleic acid sequence of five PCV3strains in Shanxi indicated they belonged to genotype PCV3b,thus it proved that PCV3bwere the dominant influenza strain in Shanxi.And the Cap protein amino acid of thesefive strains were conserved and no specific mutations different from other strains.The results of this study provided theoretical reference for the prevalence and genetic evolution of PCV3in Shanxi.It wanted to provide basis for the scientific immune prevention of PCV3in Shanxi.