2005-2008年浙江省生猪主产区猪戊型肝炎血清流行病学调查

Sero-prevalence of Hepatitis E Virus Infections in Pigs from Zhejiang Province During 2005-2008

本研究旨在建立检测猪戊型肝炎病毒(HEV)感染的间接ELISA方法,并将其用于分析浙江省生猪主产区猪群的HEV感染状况。首先人工合成并原核表达了HEV ORF2蛋白的主要抗原表位区,免疫印迹显示表达产物对HEV抗体阳性的猪血清具有良好的反应性。以此纯化蛋白为包被抗原建立了猪血清中HEV特异性抗体的ELISA检测方法,检测结果显示其与商品化HEV抗体诊断试剂盒的检测符合率达91.5%。对2005-2008年采集自浙江省不同地区46个猪场的1330份血清进行了检测,有741份血清检测为猪HEV抗体阳性,平均阳性率为55.7%。其中2005和2006年HEV抗体阳性率分别为62.7%(175/279)和61.4%(301/490),明显高于2007年的43.1%(59/137)和2008年的48.6%(206/424)。同时,66-100日龄中猪的血清HEV抗体阳性率(58.2%,110/189)显著高于30-65日龄小猪(39.7%,73/184)和101-160日龄大猪(44.1%,83/188)。从猪场水平来看,仅有3个猪场未检测到HEV抗体,场阳性率93.2%。结果表明本研究建立的ELISA方法切实可行,检测结果显示浙江省猪场中HEV感染相当普遍。

The study was aimed to establish an indirect ELISA for epidemiological investigation of hepatitis E virus（HEV） infections in pigs from the major pig--producing regions of Zhejiang Province. The gene fragment covering immunogenic epitopes of HEV ORF2 was synthesized and expressed in Escherichia coll. Western blot analysis revealed that the purified protein reacted to HEV positive sera, but not to positive sera of other common viruses infecting pigs. An indirect ELISA system was then developed using truncated HEV ORF2 protein as the coating antigen and had diagnostic accuracy of 91.5 % as compared with a diagnostic kit for HEV antibodies. A total of 1 330 serum samples were collected from 46 pig farms in Zhejiang province during 2005--2008 and tested for sero-prevalence of HEV using the indirect ELISA. The average HEV-positive rate was 55.7% （741/1 330）. The positive rate of 2005 and 2006 was 62.7% （175/279） and 61.4% （301/490） respectively, much higher than those of 2007 （43.1%, 59/137） and 2008 （48.6%, 206/424）. Meanwhile, the pigs aged 66- 100 days had a statistically higher positive rate （58.2%, 110/189）as compared with that of pigs of 30--65 （39.7%, 73/184） and 101--160 （44.1%, 83/188） days. Only three herds in the study were HEV antibody-negative, indicating high sero-prevalenee of HEV in the pig populations in Zhejiang Province.