Huang F F, Haqshenas G, Guenette D K, Halbur P G, Schommer S K, Pierson F W, Toth T E, Meng X J
Center for Molecular Medicine and Infectious Diseases, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0342, USA.
J Clin Microbiol. 2002 Apr;40(4):1326-32. doi: 10.1128/JCM.40.4.1326-1332.2002.
Hepatitis E virus (HEV) is an important public health concern in many developing countries. HEV is also endemic in some industrialized counties, including the United States. With our recent discovery of swine HEV in pigs that is genetically closely related to human HEV, hepatitis E is now considered a zoonotic disease. Human strains of HEV are genetically heterogenic. So far in the United States, only one strain of swine HEV has been identified and characterized from a pig. To determine the extent of genetic variations and the nature of swine HEV infections in U.S. pigs, we developed a universal reverse transcription-PCR (RT-PCR) assay that is capable of detecting genetically divergent strains of HEV. By using this universal RT-PCR assay, we tested fecal and serum samples of pigs of 2 to 4 months of age from 37 different U.S. swine farms for the presence of swine HEV RNA. Thirty-four of the 96 pigs (35%) and 20 of the 37 swine herds (54%) tested were positive for swine HEV RNA. The sequences of a 348-bp region within the ORF2 gene of 27 swine HEV isolates from different geographic regions were determined. Sequence analyses revealed that the 27 U.S. swine HEV isolates shared 88 to 100% nucleotide sequence identities with each other and 89 to 98% identities with the prototype U.S. strain of swine HEV. These U.S. swine HEV isolates are only distantly related to the Taiwanese strains of swine HEV, with about 74 to 78% nucleotide sequence identities; to most known human strains of HEV worldwide, with <79% sequence identities; and to avian HEV, with 54 to 56% sequence identities. Phylogenetic analysis showed that all the U.S. swine HEV isolates identified in this study clustered in the same genotype with the prototype U.S. swine HEV and the two U.S. strains of human HEV. The data from this study indicated that swine HEV is widespread and enzoonotic in U.S. swine herds and that, as is with human HEV, swine HEV isolates from different geographic regions of the world are also genetically heterogenic. These data further raise potential concerns for zoonosis, xenozoonosis, and food safety.
戊型肝炎病毒（HEV）在许多发展中国家都是一个重要的公共卫生问题。HEV在包括美国在内的一些工业化国家也呈地方性流行。随着我们最近在猪身上发现与人类HEV基因密切相关的猪HEV，戊型肝炎现在被认为是一种人畜共患病。人类HEV毒株在基因上具有异质性。到目前为止，在美国，仅从一头猪身上鉴定并表征了一种猪HEV毒株。为了确定美国猪中猪HEV感染的基因变异程度和性质，我们开发了一种通用逆转录聚合酶链反应（RT-PCR）检测方法，该方法能够检测基因不同的HEV毒株。通过使用这种通用RT-PCR检测方法，我们检测了来自美国37个不同养猪场的2至4月龄猪的粪便和血清样本中猪HEV RNA的存在情况。96头猪中有34头（35%）以及37个猪群中有20个（54%）的检测结果显示猪HEV RNA呈阳性。测定了来自不同地理区域的27株猪HEV分离株ORF2基因内一个348 bp区域的序列。序列分析表明，27株美国猪HEV分离株彼此之间的核苷酸序列同一性为88%至100%，与美国猪HEV原型毒株的同一性为89%至98%。这些美国猪HEV分离株与台湾猪HEV毒株的亲缘关系较远，核苷酸序列同一性约为74%至78%；与世界上大多数已知的人类HEV毒株的序列同一性<79%；与禽HEV的序列同一性为54%至56%。系统发育分析表明，本研究中鉴定的所有美国猪HEV分离株与美国猪HEV原型毒株以及两株美国人类HEV毒株聚集在同一基因型中。这项研究的数据表明，猪HEV在美国猪群中广泛存在且呈地方性流行，并且与人类HEV一样，来自世界不同地理区域的猪HEV分离株在基因上也具有异质性。这些数据进一步引发了对人畜共患病、异种人畜共患病和食品安全的潜在担忧。
