中国发现基因3型戊型肝炎病毒

Identification of the genotype Ⅲ hepatitis E virus from swine herds in China

目的通过对中国华东地区分离出的2株基因3型戊型肝炎病毒株进行同源性分析，探讨其分子起源和传播问题。方法收集华东某地区13个养猪场的133份猪粪便标本，利用巢式RT—PCR技术扩增戊肝病毒基因组的开放读码区2（ORF2）和RNA依赖的RNA聚合酶区（RdRp，ORF1），并进行基因同源性分析。结果戊肝病毒RNA检出率为43．61％（58／133）。其中，在同一个养猪场检出的2份阳性标本与23条戊肝病毒基因3型全长序列在ORF2和ORF1区的同源性分别为77．10％～92．64％和77．49％～91．14％，被划分为基因3型。另外12个养猪场的56份阳性标本均为基因4型。同时发现，某些日本分离的基因3型病毒株比其他基因3型株更接近本次分离的病毒株。结论这是在中国大陆地区首次发现基因3型戊肝病毒。同时证明在一个较为局限的群体中基因3型和4型病毒可以共存。

Objective To determine the phylogenetic reconstruction of two genotype-Ⅲ HEV strains isolated in Eastern China and investigate the molecular ancestor and source for transmission, Methods A total of 133 swine fecal specimens was collected randomly from 13 local swine farms in Eastern China. The fragments in Open Reading Frame 2 （ORF2） and RNA-dependent RNA polymerase （RdRp） domain in ORF1 of hepatitis E virus genome were amplified with nested RT-PCR. Phylogenetic reconstruction of partial sequences was then performed based on them, Results HEV RNA was detected from 43.61% （58/133） of fecal specimens. In one swine farm, 2 HEV isolates were close to the 23 reference genotype Ⅲ HEV full-length strains available from GerLBank, with 77, 10%-92,64% and 77.49% -91.14% identities in ORF2 and RdRp domain at nucleotide level, respectively. These two isolates were both grouped into genotype Ⅲ. The rest 56 HEV strains isolated from the other 12 farms were all classified into genotype Ⅳ. The wbJYG1 strain, which was isolated from the liver specimen of a wild-caught boar in Japan in 2005, had always the highest similarity with the swCNZJB2 and swCNZJB10 isolates both at nucleotide and amino acid levels （except for the secondary highest in amino acid analysis in ORF1 ）. These three strains constitute a distinct cluster with bootstrapping support values of 〉90%. Conclusions It is the first time that genotype Ⅲ HEV has been identified in China. The identification of genotype Ⅲ and Ⅳ HEV in the same region may imply feasible concurrent circulations in a restricted colony.