广东省韶关地区戊型肝炎病毒基因型分析

目的了解韶关地区流行的戊型肝炎病毒基因型,并探讨戊型肝炎是否属于人兽共患病。方法通过同源比对HEV四种基因型的戊型肝炎病毒序列,选取其保守序列部分设计两对巢式聚合酶链式反应的简并引物,建立一种可同时扩增戊型肝炎四个基因型病毒RNA的PCR快速检测方法。在广东省韶关地区采集猪粪便标本和非甲非乙型肝炎病人血清,提取病毒RNA,然后进行PCR检测,阳性时对扩增片段进行基因序列测定,并进行基因型分析。结果RT-nPCR检测结果显示99份猪粪便标本中有6份HEVRNA阳性,7份病人血清样本中1份阳性,序列分析显示全部为HEV基因IV型,4份猪标本中的HEV基因序列与GenBank中人HEV的基因序列最相似,同源性为88%~94%,且其中1份猪标本中的HEV与1份病人标本中HEV的序列同源性高达91.5%。结论广东韶关地区HEV流行株为基因IV型,而且猪HEV基因序列与人HEV之间有着高度的相似性,结果证实戊型肝炎是一种人兽共患传染病。     

淮安市戊型病毒性肝炎人畜共患性及病毒基因型研究

目的探讨淮安市戊型病毒性肝炎病例与猪之间的联系,为控制HEV在人畜间的传播提供依据。方法在淮安市收集急性戊肝、肝炎未分型病例血液标本193份,同期在屠宰场收集生猪胆囊标本510份,采用Real-time RT-PCR和RT-PCR提取目标核苷酸,测定序列后进行分析。结果所有标本共分离出HEV-4型毒株20株,分4个亚型,HEV-4d型为优势流行毒株亚型;人源与猪源HEV毒株间的同源性为:80.3%～97.7%。结论淮安市戊肝病例与生猪感染的HEV高度同源,生猪是戊肝传播过程中一种重要的动物宿主。     

华东地区散发性戊型肝炎病毒系统进化分析

目的 了解华东地区散发性戊型肝炎病毒(HEV)的系统进化特征.方法 2005-2008年收集华东地区14家二级或三级医院413份散发戊型肝炎患者血清,应用巢式RT-PCR方法检测HEVRNA并测序.参照GenBank相关序列,分析各序列之间的同源性,并构建进化树.结果 413例患者的男女性别比为1.75:1,40～69岁患者居多(61.5%).413份患者血清有140份分离出HEV RNA,阳性分离率为34%.所有分离的140份病毒株均属于HEV Ⅳ型,与Ⅰ、Ⅱ、Ⅲ和Ⅳ型参考病毒株的核苷酸同源性分别为77.9%～88.3%、80.8%～90.6%、73.4%～85.2%和91.0%～95.4%.结论 基因Ⅳ型HEV是引起华东地区散发性戊型肝炎的优势病毒株,其起源和进化等问题仍需进一步研究.     

北京市郊区八种动物戊型肝炎病毒抗体流行率调查及病毒基因型研究

目的 调查北京地区与人密切接触的猪、牛、羊、马、驴、犬、鸡、鸭8种动物血清中戊型肝炎病毒(HEV)抗体流行率及该地区猪HEV基因型和亚型.方法 收集8种动物的血清标本及幼猪粪便标本,用双抗原夹心ELISA法检测血清中抗-HEV;用巢式反转录聚合酶链反应法(RT-nPCR)检测HEV RNA;对部分PCR产物进行克隆和测序,并对测序结果进行基因分型.结果 在8种动物中抗-HEV阳性率分别为猪80.43%(481/598),其中成猪(>6月龄)为87.86%(369/420),幼猪(2～3月龄)为62.92%(112/178);牛15.02%(52/346);马14.29%(40/280);驴0(0/26);羊9.88%(33/334);犬0(0/21);鸭3.03%(7/231);鸡2.53%(8/316).RT-nPCR检测3月龄以下猪粪便标本HEVRNA阳性率为66.67%(74/111).HEV RNA阳性的标本测序后可归为6株(分别命名为bjsw1、bjsw2、bjsw3、bjsw4、bjsw5和bjsw6),6株HEV开放读码框2(ORF2)部分核苷酸序列的相似性为94.5%～99.6%,与1、2、3、4型HEV的相似性分别为75.6%～78.6%、75.6%～76.2%、77.1%～80.7%和83.7%～94.5%.6株HEV与人HEV 4d亚型的同源性最高,为90.0%～94.5%.结论 北京市郊区猪、牛、马、羊、鸭、鸡中均存在HEV感染,其中猪抗-HEV流行率最高,驴、犬抗-HEV的流行率最低;6株猪HEV属于基因4型、4d亚型.     

Phylogenetic diversity and similarity of active sites of Shiga toxin (stx) in Shiga toxin-producing Escherichia coli (STEC) isolates from humans and animals

Nucleotide sequences of Shiga toxin (Stx) genes in STEC from various origins were determined and characterized by phylogenetic analysis based on Shiga toxin (Stx) with those deposited in GenBank. The phylogenetic trees placed Stx1 and Stx2 into two and five groups respectively, and indicated that Stx1 in sheep-origin STEC were placed into a different group from those in other STEC, and that Stx2 of deer-origin STEC also belonged to the unique group and appeared to be distantly related to human-origin STEC. On the other hand, Stx of STEC isolated from cattle, seagulls and flies were closely related to those of human-origin STEC. Such a diversity of Stx suggested that STEC might be widely disseminated in many animal species, and be dependent on their host species or their habitat. In addition, the active sites in both toxins were compared; the active sites in both subunits of Stx in all the animal-origin STEC were identical to those in human-origin STEC, suggesting that all the toxin of STEC from animals might be also cytotoxic, and therefore, such animal-origin STEC might have potential pathogenicity for humans.     

戊型肝炎病毒基因分型及动物感染率的研究进展

戊型肝炎(戊肝)病毒(HEV)主要经粪-口途径传播,多发生在卫生条件较差的发展中国家,常因水源被污染而造成大规模的流行;发达国家主要是散发病例,多由食入污染的食物引起[1].     

中国发现基因3型戊型肝炎病毒

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。     

Genotype analysis of hepatitis E virus from sporadic hepatitis E cases in northern China

Hepatitis E is an important public health problem in many countries. However, there is no definite conclusion about the zoonotic reservoir, transmission patterns and risk factors of hepatitis E in the human population. The aim of this study was to analyze the epidemiological and viral genotype characteristics of hepatitis E cases in northern China. Surveillance was conducted in two hospitals in Liaoning and Hebei province from July 2010 to June 2012. Out of a total of 116 diagnosed patients, 88 (75.9%) were male and 28 (24.1%) were female and most (73%) were in the age group 40–70 years. In both hospitals, cases were diagnosed more frequently in March than in other months. HEV RNA was amplified from 41 patients and characterized by nucleotide sequencing and phylogenetic analysis. Most of the isolates (37 strains, 90.3%) were genotype 4, including subgenotypes 4a, 4b, 4d, 4h, 4i and a new subgenotype. One subgenotype 3a strain was isolated from Baoding, Hebei province. Three genotype 1b strains were found from patients in Jinzhou, Liaoning province. Most of the genotype 4 strains and the genotype 3 strains were phylogenetically related to known swine isolates. In conclusion, the finding that HEV infects mostly middle-aged and elderly men and that the incidence spiked in March may reflect the zoonotic transmission characteristics of HEV infection. Pigs, but not rabbits, were the important reservoirs in this area, because genotype 4 HEV was found to be responsible for the majority hepatitis E cases. However, genotype 1 is still present in northern China. Also, the first isolation of genotype 3 HEV in this area indicates that alternative routes of HEV transmission might exist.     

戊型肝炎病毒基因Ⅳ型病毒样颗粒的表达和抗原性分析

目的表达戊型肝炎病毒(HEV)基因Ⅳ型(G4)结构蛋白ORF2截短的基因片段,观察病毒样颗粒(VLP)的装配情况,对纯化的VLP进行抗原性分析。方法为了制备HEV病毒样颗粒,将结构蛋白ORF2的N末端111个氨基酸残基截掉,然后将112至660共549个氨基酸残基的基因与杆状病毒基因重组,在昆虫细胞Tn5表达。首先用聚丙烯酰胺凝胶电泳和WesternBlotting检测基因是否正确表达,再用超速离心检测是否形成病毒样颗粒,最后用免疫电镜和ELISA分析病毒样颗粒的抗原特异性。结果含有截掉了N末端111个氨基酸残基的HEVG4的ORF2基因的重组杆状病毒感染昆虫细胞Tn5,除了可以表达最初的产物(相对分子质量为58×103的蛋白分子)外,也产生了一些可能经过宿主细胞酶类处理的蛋白分子,相对分子质量分别为57×103、56×103和54×103,并分泌到培养液中。经超速离心和密度梯度离心,电镜观察发现只有54×103的蛋白分子可以自行组装成VLP,颗粒直径为23~24nm,浮密度为1·285g/cm3,与HEVG1比较,G4VLP具有相同的大小和浮密度,但表达量低。G4VLP与HEV病人血清可以发生抗原抗体反应,用G4VLP作抗原可以检测HEV的G1、G3、G4型特异性IgM和IgG抗体。结论该研究证实截短的HEVG4的ORF2结构蛋白基因可以在重组杆状病毒表达系统高效表达。形成的VLP具有HEV病毒颗粒类似的抗原活性,可用于制备抗HEV诊断试剂和开发预防用疫苗。     

Protection of chickens against avian hepatitis E virus (avian HEV) infection by immunization with recombinant avian HEV capsid protein

Avian hepatitis E virus (avian HEV) is an emerging virus associated with hepatitis-splenomegaly syndrome in chickens in North America. Avian HEV is genetically and antigenically related to human HEV, the causative agent of hepatitis E in humans. In the lack of a practical animal model, avian HEV infection in chickens has been used as a model to study human HEV replication and pathogenesis. A 32 kDa recombinant ORF2 capsid protein of avian HEV expressed in Escherichia coli was found having similar antigenic structure as that of human HEV containing major neutralizing epitopes. To determine if the capsid protein of avian HEV can be used as a vaccine, 20 chickens were immunized with purified avian HEV recombinant protein with aluminum as adjuvant and another 20 chickens were mock immunized with KLH precipitated in aluminum as controls. Both groups of chickens were subsequently challenged with avian HEV. All the tested mock-immunized control chickens developed typical avian HEV infection characterized by viremia, fecal virus shedding and seroconversion to avian HEV antibodies. Gross hepatic lesions were also found in portion of these chickens. In contrast, none of the tested chickens immunized with avian HEV capsid protein had detectable viremia, fecal virus shedding or observable gross hepatitis lesions. The results from this study suggested that immunization of chickens with avian HEV recombinant ORF2 capsid protein with aluminum as adjuvant can induce protective immunity against avian HEV infection. Chickens are a useful small animal model to study anti-HEV immunity and pathogenesis.     

A high hepatitis E virus (HEV) seroprevalence among unpaid blood donors and haemodialysis patients in Egypt

BACKGROUND/AIMS: The aim of this study was to determine the frequency of hepatitis E virus (HEV) infection among unpaid blood donors and haemodialysis patients in Egypt and to find out any possible relationship between HEV and HCV. METHODS: Serum samples collected from 95 unpaid blood donors and 96 haemodialysis patients were screened for HEV and HCV antibodies by enzyme immunoassay techniques. RESULTS: The prevalence of anti-HEV IgG was 45.2% (43/95) in blood donors and 39.6% (38/96) in haemodialysis patients. Anti-HEV IgG was found in 69.2% (18/26) and 28.6% (20/70) in haemodialysis patients positive and negative for HCV, respectively. CONCLUSION: This study emphasizes that HEV is endemic in Egypt and tends to accumulate in certain groups showing evidence of hepatitis C virus infection as in haemodialysis patients suggesting either shared parenteral risk or increased sensitivity to HEV coinfection; that is to say a possibility of combined route of transmission for HEV.     

Induction of antibody response against hepatitis E virus (HEV) with recombinant human papillomavirus pseudoviruses expressing truncated HEV capsid proteins in mice

A hepatitis E virus (HEV) vaccine would be valuable to reduce the morbidity and mortality associated with the infection in endemic areas. HEV pseudocapsids and epidermal delivery of HEV ORF2 DNA vaccine by gene-gun have been shown to confer protection against virus challenge in monkeys. Vectorization of a DNA vaccine by virus-like particles is a new immunization approach. We report here the successful immunization of mice with two ORF2 genes encapsidated into human papillomavirus type 31 virus-like particles. The HEV genes ORF2(112-660) and ORF2(112-608) were optimized for expression in mammalian cells and inserted in a baculovirus-derived vector for expression in insect cells. When expressed in Sf21 insect cells, ORF2(112-660) led to the production of irregular 15 nm particles that accumulated in the cytoplasm of the cells, whereas ORF2(112-608) induced the production of 18nm particles that were present in both the cell culture medium and the cell cytoplasm. Anti-HEV immune responses were higher for the 15 nm particles (HEV112-660) than that for to the 18 nm particles (HEV112-608). Delivery into mice of two HEV ORF2 genes via a papillomavirus VLP was very effective in the induction of anti-HEV antibodies. In addition, an effective immune response to human papillomavirus capsids occurred. These engineered pseudoviruses were thus demonstrated to induce immune responses to both hepatitis E virus and human papillomavirus when they were administered to mice intramuscularly.     

Assessment of the cross-protective capability of recombinant capsid proteins derived from pig, rat, and avian hepatitis E viruses (HEV) against challenge with a genotype 3 HEV in pigs

Hepatitis E virus (HEV), the causative agent of hepatitis E, is primarily transmitted via the fecal-oral route through contaminated water supplies, although many sporadic cases of hepatitis E are transmitted zoonotically via direct contact with infected animals or consumption of contaminated animal meats. Genotypes 3 and 4 HEV are zoonotic and infect humans and other animal species, whereas genotypes 1 and 2 HEV are restricted to humans. There exists a single serotype of HEV, although the cross-protective ability among the animal HEV strains is unknown. Thus, in this study we expressed and characterized N-terminal truncated ORF2 capsid antigens derived from swine, rat, and avian HEV strains and evaluated their cross-protective ability in a pig challenge model. Thirty, specific-pathogen-free, pigs were divided into 5 groups of 6 pigs each, and each group of pigs were vaccinated with 200μg of swine HEV, rat HEV, or avian HEV ORF2 antigen or PBS buffer (2 groups) as positive and negative control groups. After a booster dose immunization at 2 weeks post-vaccination, the vaccinated animals all seroconverted to IgG anti-HEV. At 4 weeks post-vaccination, the animals were intravenously challenged with a genotype 3 mammalian HEV, and necropsied at 4 weeks post-challenge. Viremia, fecal virus shedding, and liver histological lesions were compared to assess the protective and cross-protective abilities of these antigens against HEV challenge in pigs. The results indicated that pigs vaccinated with truncated recombinant capsid antigens derived from three animal strains of HEV induced a strong IgG anti-HEV response in vaccinated pigs, but these antigens confer only partial cross-protection against a genotype 3 mammalian HEV. The results have important implications for the efficacy of current vaccines and for future vaccine development, especially against the novel zoonotic animal strains of HEV.     

Identification of European-type hepatitis E virus subtype 3e isolates in Japanese wild boars: Molecular tracing of HEV from swine to wild boars

Nucleotide sequences of hepatitis E virus (HEV) isolates infecting wild boars in Mie prefecture, which is located in the central region of Japan and is far from the most prevalent regions of HEV infection in Japan, were determined and characterised. Among 144 serum samples of wild boars captured in Mie prefecture, 7 were positive for HEV-RNA. The nucleotide sequence of nearly the entire genome was determined for 4 of the 7 positive samples. Phylogenetic tree analyses indicated that 6 samples were subtype 3e and 1 was subtype 3a among the 7 isolates. We identified the indigenization of subtype 3e isolates in Japanese wild boars. Furthermore, 5 subtype 3e isolates were closely related and were located in the peripheral branch of subtype 3e isolates from European countries in the phylogenetic tree. The structure indicated that the ancestor of the 5 subtype 3e isolates originated in Europe. The phylogenetic structure and coalescent analyses suggested that the subtype 3e isolates entered Japan from Europe by importation of large-race pigs around 1966. The results also indicated that several lineages of subtype 3e expanded to a wide area of Japan around 1992 and 1 of the lineages was indigenized in wild boars in Mie prefecture between 1992 and 2009. The appearance of a wild boar cluster in the peripheral branch in the phylogenetic lineage may indicate the direction of gene flow of HEV subtype 3e from swine to wild boars. Clarification of the transmission direction or route should be helpful to prevent a future endemic or epidemic of HEV infection.     

深圳地区HEV流行基因型及动物宿主带毒状况分析

目的了解深圳地区戊型肝炎病毒(HEV)流行基因型及动物宿主带毒状况。方法通过同源比对HEV四种基因型的戊型肝炎病毒序列,选取其保守序列部分设计两对巢式聚合酶链式反应的简并引物,建立一种可同时扩增戊型肝炎四个基因型病毒RNA的PCR快速检测方法。对深圳市采集的80份猪粪便标本和6份戊型肝炎病人血清,提取病毒RNA,然后进行PCR检测,阳性时对扩增片段进行基因序列测定,并进行基因型分析。结果80份猪粪便标本5份HEV—RNA阳性,6份病人血清样本中4份阳性。序列分析显示全部为HEV基因IV型,5份猪标本中的HEV基因序列与GenBank中人HEV的基因序列最相似,同源性为88%～94%。结论深圳地区HEV流行株为基因IV型,而且猪HEV基因序列与人HEV之间有着高度的相似性,证实猪是HEV的宿主,戊型肝炎是一种人兽共患传染病。     

Close similarity between sequences of hepatitis E virus recovered from humans and swine, France, 2008-2009

Frequent zoonotic transmission of hepatitis E virus (HEV) has been suspected, but data supporting the animal origin of autochthonous cases are still sparse. We assessed the genetic identity of HEV strains found in humans and swine during an 18-month period in France. HEV sequences identified in patients with autochthonous hepatitis E infection (n = 106) were compared with sequences amplified from swine livers collected in slaughterhouses (n = 43). Phylogenetic analysis showed the same proportions of subtypes 3f (73.8%), 3c (13.4%), and 3e (4.7%) in human and swine populations. Furthermore, similarity of >99% was found between HEV sequences of human and swine origins. These results indicate that consumption of some pork products, such as raw liver, is a major source of exposure for autochthonous HEV infection.     

Phylogenetic analysis of Hepatitis E virus strains isolated from slaughter-age pigs in Colombia

Hepatitis E virus (HEV) is a zoonotic virus that causes acute hepatitis in humans, and can be transmitted via the fecal–oral route. Pigs are considered to be a reservoir for this infection—mainly where the disease is not endemic. In a previous study conducted in Antioquia, which is a region in Colombia where the production and consumption of pork meat is higher than in the rest of the country, the presence of anti-HEV IgG-type antibodies was reported in slaughter-age pigs. Aiming to identify the HEV genotype circulating in swine, animal liver, and feces samples from five swine cattle slaughterhouses located in six different sub-regions of Antioquia were collected. A nested RT-PCR (nRT-PCR) was used in order to amplify the HEV ORF-1 (170 bp) and ORF-2 (348, and 958 bp). The amplicons yielded in this study were sequenced, and a molecular phylogeny analysis based on the maximum likelihood method, including HEV sequences reported in several countries, was performed. Phylogeny analysis revealed that HEV amplification fragments from Antioquia's pigs were grouped in three clades within the sub-genotype 3a without a specific geographical structure, and were also genetically related to Japanese and American HEV sequences. This analysis provides the first approach on the genetic diversity and circulation dynamics of HEV in Colombian herds.