马乳头瘤病毒7型的鉴定及遗传进化分析

Identification and Phylogenetic Analysis of EcPV-7

乳头瘤病毒(Papillomaviruses,PVs)是一类入侵上皮细胞的病原体,可感染人、马等多种动物,已鉴定的马乳头瘤病毒(Equus caballus papillomavirus,EcPV)有9种,包括EcPV-1~9型,国内仅报道马携带EcPV-1。为调查EcPV在北疆地区纯血马中的流行情况,对北疆3个不同地区采集的242份纯血马鼻拭子和精液样品进行PCR检测,结果显示,在3份马匹精液样品中检出EcPV-7,阳性率为1.2%(3/242),提示该病毒可通过垂直传播。利用特异性引物PCR扩增得到其中1份阳性样品中EcPV-7的全基因组序列,并将该样品中的相应毒株命名为XJ-ZS1。同源性分析结果显示,鉴定的XJ-ZS1与瑞士EcPV-7参考株(登录号JX035935)全基因组中不同基因核苷酸序列同源性在98.9%~100%之间,氨基酸序列同源性在98.2%~100%之间,其中XJ-ZS1 L1基因与EcPV-7参考株L1基因核苷酸同源性为98.2%~98.9%,表明XJ-ZS1为EcPV-7新变异株。遗传进化分析结果表明,鉴定的XJ-ZS1与瑞士EcPV-7亲缘关系较近,处于独立进化分支,与瑞士EcPV-3、德国EcPV-6参考株同处于Dyorho乳头瘤病毒属进化分支,提示EcPV-7可能是通过纯血马贸易进入我国。结果首次报道国内马匹中存在EcPV-7,为我国EcPV-7的流行病学研究提供了基础数据。

Papillomaviruses(PVs)are pathogens that invade epithelial cells and infect a variety of animals such as humans and horses.Nine species of Equus caballus papillomavirus(EcPV)have been identified,including EcPV-1-9 types,and only horses carried EcPV-1 have been reported in China.To investigate the prevalence of EcPV-7 in thoroughbred horses in the northern Xinjiang,this study collected 242 nasal swabs and semen samples of thoroughbred horses in three different areas of the northern Xinjiang,and the samples were tested by PCR.The results showed that EcPV-7 was detected in three equine semen samples with a positive rate of 1.2%(3/242),indicating that this virus might spread through vertical transmission.The complete genome sequence of EcPV-7 was obtained by PCR amplification using specific primers,named XJ-ZS1 strain.The results of homology analysis showed that the homologies of nucleotide sequences and amino acid sequences of different genes between the XJ-ZS1 strain and the Swiss EcPV-7 reference strain(accession number:JX035935)were 98.9%-100%and 98.2%-100%,respectively.The XJ-ZS1 shared a nucleotide identity of 34.4%-77.9%and an amino acid identity of 7.3%-82.3%with genes of EcPV other types of reference strains.Homology of the L1 gene between the XJ-ZS1 strain and the EcPV-7 reference strain was 98.2%-98.9%,indicating that XJ-ZS1 strain is a new variant.Genetic evolution analysis showed that the EcPV-7 XJ-ZS1 strain was closely related to Swiss EcPV-7 and was in an independent branch,and it was in the same branch of the genus Dyorho papillomavirus with the Swiss EcPV-3 and German EcPV-6 reference strains,suggesting that EcPV-7 may enter China through the thoroughbred horse trade.This study is the first report of EcPV-7 in Chinese horses.These findings provide fundamental data for the epidemiological study of EcPV-7.