华东地区猪基因4型戊肝病毒的季节变化及与人同源性的分析

Seasonal pattern and phylogenetic analysis with human isolates of genotype-IV hepatitis E virus in swine herds, eastern China

目的戊型肝炎病毒的人兽共患特征被认可，本研究检测华东地区猪群在不同季节中基因4型戊肝病毒（HEV）的感染情况，了解猪病毒株之间以及与人病毒株的同源性关系。方法2007年9月—2008年6月在华东地区浙江、安徽和江苏的3家屠宰场中共采集猪胆汁标本1200份，应用巢式RT—PCR方法检测HEVRNA，对阳性标本测序并结合同-地区人HEV序列进行同源性分析。结果猪胆汁标本中HEVRNA总检出率为4．5％，各季节猪群的检出率为9-10月平均检出率6％，12-1月4．33％，3-4月4．33％，5-6月3．33％，各地区的平均检出率为江苏6％、安徽5％、浙江2．5％。不同地区猪与猪、猪与人基因4型HEV病毒株的同源性都较高（猪株之间核苷酸序列约为80％-100％，氨基酸序列约为96％～100％；猪与人株之间核苷酸序列约为76％～99％，氨基酸序列约为95％-100％）。部分猪HEV与人HEV构成独立的同源性分支，进化起源关系密切。结论基因4型HEV在华东地区猪群中常年广泛流行，且可能拥有共同的进化与传播起源。猪群携带HEV可能会对人群戊肝的流行趋势产生影响。

Objective To determine the seasonal prevalence of genotype-IV hepatitis E virus （HEV） in swine herds in Eastern China and explore the phylogenetic relationship between swine HEV and human HEV in the situation that zoonotic features of HEV had been confirmed. Methods From September 2007 to June 2008 ,a total of 1200 swine bile specimens were collected from three slaughter houses located in Zhejiang,Anhui and Jiangsu, the Eastern China, and detected for HEV RNA by using nested RT-PCR. The positive PCR products were sequenced. Then the swine HEV were phylogenetically determined with human HEV isolated in Eastern China. Results The positive rate for HEV RNA in swine herds was 4. 5% totally. Significant differences of HEV detection were not observed among seasonal pattern （ Sep - Oct： 6% , Dec - Jan： 4. 33 % , Mar - Apr： 4. 33%, May - Jun： 3.33 % ） but in geographic distribution （ Jiangsu ： 6% , Anhui： 5% ,Zhejiang： 2. 5% ）. Regardless of isolation from different areas, swine and human genotype-IV HEV shared a high similarity. Phylogenetically,there were 80% -100% and 96% -100% identities within swine genotype-lV HEV at the nucleotide and amino acid levels respectively. Between swine HEV and human HEV ,there were also similarities of 76% -99% and 95% -100%. It was noted that some human and swine isolates were clustered with bootstrap values of 〉 90%. Conclusion Genotypo-Ⅳ HEV is widely prevalent in swine herds in Eastern China and original common ancestor of evolution and transmission was implied. The sustaining prevalence within swine herds should have a probable influence on the epidemic situation of hepatitis E in human beings.