Characterization and zoonotic potential of endemic hepatitis E virus (HEV) strains in humans and animals in Hungary

First report of hepatitis E virus infection in sika deer in China

Hepatitis E virus (HEV), a single stranded RNA, nonenveloped virus, belongs to the genus Hepevirus, in the family of Hepeviridae. In this study, 46 (5.43%) out of the 847 serum samples from sika deer (Cervus nippon) were detected as seropositive with hepatitis E virus (HEV) by enzyme linked immunosorbent assay (ELISA). These samples were collected from Inner Mongolia and Jilin and Heilongjiang provinces in China, between October 2012 and October 2013. Seroprevalence of HEV infection in male and female deer was 4.82% and 6.52%, respectively. HEV seroprevalence in sika deer from different geographical locations varied from 3.13% to 6.73%. There was no significant difference in HEV seroprevalence between sika deer collected in autumn (5.65%) and winter (4.85%). This is the first report of HEV seroprevalence in sika deer in China, which will provide foundation information for estimating the effectiveness of future measures to control HEV infection in sika deer in China and assessing the potential risk of humans infected with HEV after consumption of undercooked or raw meat from infected sika deer.

Hepatitis E in hemodialysis and kidney transplant patients in south-east Italy

AIM: To investigate the serovirological prevalence and clinical features of hepatitis E virus (HEV) infection in end-stage renal failure patients and in the healthy population.

METHODS: HEV infection is a viral disease that can cause sporadic and epidemic hepatitis. Previous studies unexpectedly showed a high prevalence of HEV antibodies in immunosuppressed subjects, including hemodialysis (HD) patients and patients who had undergone kidney transplant. A cohort/case-control study was carried out from January 2012 to August 2013 in two hospitals in southern Italy (Foggia and S. Giovanni Rotondo, Apulia). The seroprevalence of HEV was determined in 801 subjects; 231 HD patients, 120 renal transplant recipients, and 450 health individuals. All HD patients and the recipients of renal transplants were attending the Departments of Nephrology and Dialysis at two hospitals located in Southern Italy, and were included progressively in this study. Serum samples were tested for HEV antibodies (IgG/IgM); in the case of positivity they were confirmed by a Western blot assay and were also tested for HEV-RNA, and the HEV genotypes were determined.

RESULTS: A total of 30/801 (3.7%) patients were positive for anti-HEV Ig (IgG and/or IgM) and by Western blot. The healthy population presented with a prevalence of 2.7%, HD patients had a prevalence of 6.0%, and transplant recipients had a prevalence of 3.3%. The overall combined HEV-positive prevalence in the two groups with chronic renal failure was 5.1%. The rates of exposure to HEV (positivity of HEV-IgG/M in the early samples) were lower in the healthy controls, but the difference among the three groups was not statistically significant (P > 0.05). Positivity for anti-HEV/IgM was detected in 4/30 (13.33%) anti-HEV Ig positive individuals, in 2/14 HD patients, in 1/4 transplant individuals, and in 1/12 of the healthy population. The relative risk of being HEV-IgM-positive was significantly higher among transplant recipients compared to the other two groups (OR = 65.4, 95%CI: 7.2-592.7, P < 0.001), but the subjects with HEV-IgM positivity were numerically too few to calculate a significant difference. No patient presented with chronic hepatitis from HEV infection alone.

CONCLUSION: This study indicated a higher, but not significant, circulation of HEV in hemodialysis patients vs the healthy population. Chronic hepatitis due to the HEV virus was not observed.

Prevalence of Hepatitis E Virus in Populations of Wild Animals in Comparison with Animals Bred in Game Enclosures

Hepatitis E virus (HEV) is now accepted as a zoonotic virus, and domestic pigs, wild boars and deer are recognised as natural reservoirs of the pathogen. In this study, 762 animals (wild boars, fallow deer, red deer, sika deer, roe deer and mouflons) originating from the wild and from game enclosures were tested for the presence of HEV RNA by qRT-PCR. HEV RNA was detected in wild boars (96/450), red deer (2/169), roe deer (1/30) and mouflons (5/39). The sequence relationship between HEV isolates from wild boars and domestic pigs or humans indicate a circulation of HEV in the Czech Republic.

Preliminary molecular epidemiological investigation of hepatitis E virus sequences from Québec, Canada

Our study objective was to describe the Canadian Hepatitis E virus (HEV) sequences currently cataloged in GenBank from three populations: commercially raised pigs, retail pork, and locally acquired Hepatitis E cases, and to interpret the molecular evidence they provide. We searched the GenBank for any/all Canadian HEV sequences from these populations, and identified highly similar matches using the Basic Local Alignment Search Tool (BLAST) algorithm, studying sequences of the partial ORF2 gene. We validated the findings made using Multiple Sequence Comparison by Log-Expectation (MUSCLE) and Clustal 2 programs for multiple sequence alignments, as inputs to estimate dendrograms using both neighbour-joining and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) methods. The GenBank search yielded 47 sequences collected from pigs: 32 sequences from two to four month old commercial pigs in Québec, one from three to four month old pigs at a research station in Ontario, one from two month old pigs in a commercial Saskatchewan herd, and 13 collected from finisher pigs in a national survey. Additionally, 14 sequences were collected from a national survey of Canadian retail pork livers, and seven sequences from two Canadian pediatric patients with locally acquired Hepatitis E, both from the province of Québec. All sequences belonged to genotype 3. Eight of the 14 sequences from retail pork livers had human-derived sequences in their top ten BLAST matches; six did not. Those eight sequences having close human BLAST matches clustered within a dendrogram, as did those with no close human BLAST matches. Human sequences with close matches to the eight retail sequences included both of the Québec Hepatitis E cases, as well as sequences from Japanese Hepatitis E cases, and Japanese blood donors. Seven of the eight HEV sequences from retail liver with close human BLAST matches originated in Québec. Kulldorff's spatial scan statistic showed a significant (P<0.05) spatial cluster of these sequences, but not of the overall dataset of 12 HEV sequences collected from Québec retail livers. All seven retail liver sequences with close human matches were processed in-store. We conclude that some Canadian sequences of HEV collected from pigs/pork are more closely related to human sequences than others, and hypothesize that detection of some HEV sequences recovered from Canadian retail pork livers may be associated with exposure to human shedding. More research needs to be conducted at the processing level to help understand the molecular epidemiology of HEV in Canadian retail pork.

Hepeviridae: an expanding family of vertebrate viruses

The hepatitis E virus (HEV) was first identified in 1990, although hepatitis E-like diseases in humans have been recorded for a long time dating back to the 18th century. The HEV genotypes 1-4 have been subsequently detected in human hepatitis E cases with different geographical distribution and different modes of transmission. Genotypes 3 and 4 have been identified in parallel in pigs, wild boars and other animal species and their zoonotic potential has been confirmed. Until 2010, these genotypes along with avian HEV strains infecting chicken were the only known representatives of the family Hepeviridae. Thereafter, additional HEV-related viruses have been detected in wild boars, distinct HEV-like viruses were identified in rats, rabbit, ferret, mink, fox, bats and moose, and a distantly related agent was described from closely related salmonid fish. This review summarizes the characteristics of the so far known HEV-like viruses, their phylogenetic relationship, host association and proposed involvement in diseases. Based on the reviewed knowledge, a suggestion for a new taxonomic grouping scheme of the viruses within the family Hepeviridae is presented.

Optimization of the elution buffer and concentration method for detecting hepatitis E virus in swine liver using a nested reverse transcription-polymerase chain reaction and real-time reverse transcription-polymerase chain reaction

The aim of this study was to develop an optimal technique for detecting hepatitis E virus (HEV) in swine livers. Here, three elution buffers and two concentration methods were compared with respect to enhancing recovery of HEV from swine liver samples. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and nested RT-PCR were performed to detect HEV RNA. When phosphate-buffered saline (PBS, pH 7.4) was used to concentrate HEV in swine liver samples using ultrafiltration, real-time RT-PCR detected HEV in 6 of the 26 samples. When threonine buffer was used to concentrate HEV using polyethylene glycol (PEG) precipitation and ultrafiltration, real-time RT-PCR detected HEV in 1 and 3 of the 26 samples, respectively. When glycine buffer was used to concentrate HEV using ultrafiltration and PEG precipitation, real-time RT-PCR detected HEV in 1 and 3 samples of the 26 samples, respectively. When nested RT-PCR was used to detect HEV, all samples tested negative regardless of the type of elution buffer or concentration method used. Therefore, the combination of real-time RT-PCR and ultrafiltration with PBS buffer was the most sensitive and reliable method for detecting HEV in swine livers.

Autochthonous Hepatitis E Virus Infection in Europe: A Matter of Concern for Public Health?

Human hepatitis E virus (HHEV) is the proposed name for a diverse group of RNA viruses from the family Hepeviridae that cause acute hepatitis among humans. Waterborne strains are regularly imported into Europe by international travelers, and virus transmission of zoonotic strains via contaminated aliments is involved in autochthonous cases. Therefore, in Europe, hepatitis E displays a unique dual character, having features of both imported and autochthonous infections. Environmental involvement of waterborne and zoonotic diseases puts alimentary safety at risk. In addition, it may lead to serious health problems derived from persistent infection among patients with immune impairment due to organ transplant, cancer, or human immunodeficiency virus infection. Although the European health authorities know at present that HHEV represents a problem worthy of consideration, the actual incidence of the disease in Europe is unknown, and attempts to ascertain the prevalence of the infection is hampered by unresolved technical issues. In order to determine the burden of hepatitis E in Europe, the World Health Organization Regional Office and the European Centre for Disease Prevention and Control should pay specific attention to hepatitis E, and research efforts in the continent should be transnational and collaborative. Development of a specific European network for hepatitis E would help to achieve these goals.

Features of hepatitis E virus infection in humans and animals in Japan

In Japan, hepatitis E had long been considered to be a rare liver disease which can be accidentally imported from endemic countries in Asia and Africa, where the sanitation conditions are suboptimal. However, since the identification of the first autochthonous hepatitis E case and hepatitis E viremic domestic pigs in Japan in 2001, our understanding of hepatitis E virus (HEV) infection in this country has been changing markedly. This has largely been due to the development of serological and gene-based diagnostic assays, the accumulation of molecular epidemiological findings on HEV infection in humans and animals (as potential reservoirs for HEV in humans) and the recognition of the importance of zoonotic food-borne and other routes of transmission of HEV, including blood-borne transmission. Although it is now evident that autochthonous hepatitis E in Japan is far more common than was previously thought, clinical and subclinical HEV infections indigenous to Japan remain underdiagnosed and their prevalence is still underestimated due to the presence of unknown transmission routes and a low awareness of the infection status by many physicians in Japan. This review focuses on the features of HEV infection in humans and animals, as definitive or potential reservoirs for HEV, in Japan, and updates the current knowledge on the routes of transmission, including zoonotic routes, which are important for the maintenance and spread of HEV in Japan.

Light and Darkness: Prevalence of Hepatitis E Virus Infection among the General Population

Human hepatitis E virus (HHEV) spreads early in life among the population in areas endemic for genotype 1 and infects mainly adults in areas endemic for genotype 3, where it would be responsible for about 10% of cases of suspected acute viral hepatitis of unknown etiology and for a number of subclinical, unrecognized infections. The overall prevalence of antibody to HHEV is high in most of the former areas and low in most of the later ones, but wide regional differences have been recorded in both cases. "Hot spots" of HHEV infection would exist for both types of strains in particular regions or among particular populations of the world. Studies on pork derivatives, shellfish bivalves, and vegetables for HHEV contamination at the sale point need to be extended for evaluating the impact of the agent on food safety, and the meaning of the finding of HHEV genotype 1 genomes in urban sewage from developed countries should be established through active surveillance. Consensus about technical issues in regard to anti-HEV testing would improve the knowledge of the HHEV epidemiology. Studies in particular regions and populations, and introduction of molecular diagnosis in the clinical setting as a routine tool, would also be required.

Host immune status and response to hepatitis E virus infection

Hepatitis E virus (HEV), identified over 30 years ago, remains a serious threat to life, health, and productivity in developing countries where access to clean water is limited. Recognition that HEV also circulates as a zoonotic and food-borne pathogen in developed countries is more recent. Even without treatment, most cases of HEV-related acute viral hepatitis (with or without jaundice) resolve within 1 to 2 months. However, HEV sometimes leads to acute liver failure, chronic infection, or extrahepatic symptoms. The mechanisms of pathogenesis appear to be substantially immune mediated. This review covers the epidemiology of HEV infection worldwide, the humoral and cellular immune responses to HEV, and the persistence and protection of antibodies produced in response to both natural infection and vaccines. We focus on the contributions of altered immune states (associated with pregnancy, human immunodeficiency virus [HIV], and immunosuppressive agents used in cancer and transplant medicine) to the elevated risks of chronic infection (in immunosuppressed/immunocompromised patients) and acute liver failure and mortality (among pregnant women). We conclude by discussing outstanding questions about the immune response to HEV and interactions with hormones and comorbid conditions. These questions take on heightened importance now that a vaccine is available.

Molecular characterization of a novel hepatitis E virus (HEV) strain obtained from a wild boar in Japan that is highly divergent from the previously recognized HEV strains

Although a consensus classification system for hepatitis E virus (HEV) genotypes is currently unavailable, HEV variants (JBOAR135-Shiz09 and wbJOY_06) from wild boars (Sus scrofa leucomystax) have provisionally been classified into two novel genotypes (5 and 6). While performing a survey of HEV infections among 566 wild boars that were captured in Japan between January 2010 and August 2013, we found 24 boars (4.2%) with ongoing HEV infections: 13 had genotype 3 HEV, 10 had genotype 4 HEV and the remaining boar possessed a novel HEV variant (designated wbJNN_13). The entire wbJNN_13 genome comprised 7247 nucleotides excluding the poly(A) tail, and was highly divergent from known genotype 1 to 4 HEV isolates derived from humans, swine, wild boars, deer, mongoose and rabbits by 22.4-28.2%, JBOAR135-Shiz09 and wbJOY_06 by 19.6-21.9% and rat, ferret, bat and avian HEV isolates by 40.9-46.1% over the entire genome. Phylogenetic trees confirmed that wbJNN_13 is distantly related to all known HEV isolates. A Simplot analysis revealed no significant recombination among the existing HEV strains. These results indicate the presence of at least three genetic lineages of presumably boar-indigenous HEV strains. Further studies to fully understand the extent of the genomic heterogeneity of HEV variants infecting wild boars are warranted.

Detection and characterisation of hepatitis E virus in naturally infected swine in Croatia

Hepatitis E is a viral zoonotic disease infecting swine worldwide. Since pigs represent a likely animal reservoir for the hepatitis E virus, the epidemiology of naturally occurring hepatitis E was investigated in Croatian swine herds. Nearly all tested animals were seropositive for antibodies against the hepatitis E virus (55/60, 91.7%). Active infection was detected in all age groups by RT-PCR of viral RNA in serum (8/60, 13.3%) and bile samples (3/37, 8.1%), which was further confirmed by histopathological findings of characteristic lesions in the livers of the infected animals. Three new strains of hepatitis E virus were isolated from Croatian pig herds. Phylogenetic analysis using median-joining networks clustered those Croatian strains with isolates from various parts of the world, indicating their likely origin in international trade. Similarity to human isolates implies a zoonotic potential of Croatian strains, which raises a public health concern, especially in the light of the high prevalence of hepatitis E in the herds studied.

Hepatitis E virus: foodborne, waterborne and zoonotic transmission

Hepatitis E virus (HEV) is responsible for epidemics and endemics of acute hepatitis in humans, mainly through waterborne, foodborne, and zoonotic transmission routes. HEV is a single-stranded, positive-sense RNA virus classified in the family Hepeviridae and encompasses four known Genotypes (1–4), at least two new putative genotypes of mammalian HEV, and one floating genus of avian HEV. Genotypes 1 and 2 HEVs only affect humans, while Genotypes 3 and 4 are zoonotic and responsible for sporadic and autochthonous infections in both humans and several other animal species worldwide. HEV has an ever-expanding host range and has been identified in numerous animal species. Swine serve as a reservoir species for HEV transmission to humans; however, it is likely that other animal species may also act as reservoirs. HEV poses an important public health concern with cases of the disease definitively linked to handling of infected pigs, consumption of raw and undercooked animal meats, and animal manure contamination of drinking or irrigation water. Infectious HEV has been identified in numerous sources of concern including animal feces, sewage water, inadequately-treated water, contaminated shellfish and produce, as well as animal meats. Many aspects of HEV pathogenesis, replication, and immunological responses remain unknown, as HEV is an extremely understudied but important human pathogen. This article reviews the current understanding of HEV transmission routes with emphasis on food and environmental sources and the prevalence of HEV in animal species with zoonotic potential in humans.

A longitudinal study revealing hepatitis E virus infection and transmission at a swine test station

Hepatitis E virus (HEV) is a zoonotic agent that causes acute hepatitis in humans, and infects several animal species, most importantly swine. In the current study, that presents the first evidence of HEV infections in pigs in Finland, genetic divergence and transmission of HEV was investigated among pigs at a swine test station at two occasions. In 2007, HEV RNA was found in 25% of pens, and 35% of 2-3 month-old pigs at the station. Three different isolates, comprising 13 sequences of HEV genotype 3 e that were imported from different farms were detected. In 2010, 39% of pigs were HEV RNA positive on weeks 1, 3, or 5 of a 3-month follow-up, and 11 sequences, all representing one of the isolates that was also present in 2007, were detected. The isolate was considered to be either re-introduced to, or to persist at the station, and it was transmitted between the pigs. The study sheds light on the rate and time of HEV transmission in swine, and describes the epidemiologic variability of HEV isolates over time.

Hepatitis E virus in wild boar in the central northern part of Italy

Hepatitis E virus (HEV) is responsible for sporadic acute hepatitis in developed countries, where the infection is acquired probably through ingestion of contaminated food, in addition to travel-related cases. In this study, the circulation of HEV in wild boar from nine Italian provinces was evaluated. An overall seroprevalence of 10.2% was found, although there were differences among the provinces, while no samples were positive for HEV RNA detection. This study indicates an active circulation of HEV in the Italian wild boar populations and suggests to consider the zoonotic risk in handling and eating meat from this animal.

Rabbit and human hepatitis E virus strains belong to a single serotype

Hepatitis E virus (HEV) is a zoonotic pathogen and all four established genotypes of HEV belong to a single serotype. The recently identified rabbit HEV is antigenically and genetically related to human HEV. It is unclear whether rabbit HEV belongs to the same serotype as human HEV. The purpose of this study was to determine the serotypic relationship between rabbit and human HEVs. HEV ORF2 recombinant capsid protein p166 (amino acids 452-617) of four known HEV genotypes and rabbit HEV were used to induce immune serum, which were evaluated for their ability to neutralize human HEV genotype 1, 4, and rabbit HEV strains by an in vitro PCR-based HEV neutralization assay. Immune sera of five kinds of p166 proteins were all found to neutralize or cross-neutralize the three different HEV strains, suggesting a common neutralization epitope(s) existing between human and rabbit HEV. Rabbit models of a second-passage rabbit HEV strain, JS204-2, and a genotype 4 human HEV strain, NJ703, were established as evidenced by fecal virus shedding, viremia and anti-HEV IgG seroconversion. Six rabbits, recovered from JS204 infection, were challenged with NJ703, and another six recovered from NJ703 infection were challenged with JS204-2. After challenge, viremia was not detected, shorter fecal virus shedding durations and obvious early stage declines in anti-HEV IgG values were observed. The results from this study indicate that rabbit HEV belongs to the same serotype as human HEV.

Epidemiological and clinical features of HEV infection: a survey in the district of Foggia (Apulia, Southern Italy)

In this study we assessed the seroprevalence of hepatitis E virus (HEV) infection in both the Italian population and immigrants from developing countries in Foggia (Apulia, Southern Italy). The seroprevalence of HEV was determined in 1217 subjects [412 (34%) immigrants and 805 Italian subjects (blood donors, general population, HIV-positive, haemodialysis patients)]. Serum samples were tested for anti-HEV and confirmed by Western blot assay; in positive patients HEV RNA and genotype were also determined. There were 8·8% of patients that were positive to anti-HEV, confirmed by Western blot. The prevalence in immigrants was 19·7%, and in Italians 3·9% (blood donors 1·3%, general population 2·7%, HIV-positive patients 2·0%, haemodialysis patients 9·6%). Anti-HEV IgM was found in 38/107 (35·5%) of the anti-HEV-positive serum samples (34 immigrants, four Italians). This study indicates a higher circulation of HEV in immigrants and Italian haemodialysis patients, whereas a low prevalence of HEV antibodies was seen in the remaining Italian population.

Genetic variability of HEV isolates: inconsistencies of current classification

Many HEV and HEV-like sequences have been reported during the last years, including isolates which may represent a number of potential new genera, new genotypes or new subtypes within the family Hepeviridae. Using the most common classification system, difficulties in the establishment of subtypes have been reported. Moreover the relevance of subtype classification for epidemiology can be questioned. In this study we have performed phylogenetic analyses based on whole capsid gene and complete HEV genomic sequences in order to evaluate the current classification of HEV at genotype and subtype levels. The results of our analyses modify the current taxonomy of genotype 3 and refine the established system for typing of HEV. In addition we suggest a classification for hepeviruses recently isolated from bats, ferrets, rats and wild boar.

Culture systems for hepatitis E virus

The lack of an efficient cell culture system for hepatitis E virus (HEV) has greatly hampered detailed analyses of this virus. The first efficient cell culture systems for HEV that were developed were capable of secreting infectious HEV progenies in high titers into culture media, using PLC/PRF/5 cells derived from human hepatocellular carcinoma and A549 cells derived from human lung cancer as host cells. The success achieved with the original genotype 3 JE03-1760F strain has now been extended to various HEV strains in fecal and serum samples obtained from hepatitis E patients and to HEV strains in fecal and serum samples and liver tissues obtained from pigs and wild boar across species barriers. In addition, infectious HEV cDNA clones of the wild-type JE03-1760F strain and its variants have been engineered. Cell culture-generated HEV particles and those in circulating blood were found to be associated with lipids and open reading frame 3 (ORF3) protein, thereby likely contributing to the assembly and release of HEV from infected cells both in vivo and in vitro. The ORF3 protein interacts with the tumor susceptibility gene 101, a critical cellular protein required for the budding of enveloped viruses, through the Pro, Ser, Ala, and Pro (PSAP) motif in infected cells; ORF3 is co-localized with multivesicular bodies (MVBs) in the cytoplasm of infected cells, thus suggesting that HEV requires the MVB pathway for the egress of virus particles. This article reviews the development of efficient cell culture systems for a wide variety of infectious HEV strains obtained from humans, pigs, and wild boar, and also provides details of a new model for virion egress.

Epidemiology of mammalian hepatitis E virus infection

Mammalian hepatitis E virus (HEV), the etiological agent of hepatitis E in humans, is a recently discovered infectious agent. It was identified for the first time in 1983 using electron microscopy on a faecal specimen of a person infected with non-A, non-B enterically-transmitted hepatitis. Based on retrospective and prospective studies, HEV was long described as one of the leading causes of acute viral hepatitis in tropical and subtropical countries, whereas in developed countries hepatitis E was considered an imported disease from HEV hyperendemic countries. Data from studies conducted during the past decade have greatly shifted our knowledge on the epidemiology and clinical spectrum of HEV. Recently, it has been shown that contrary to previous beliefs, hepatitis E is also an endemic disease in several developed countries, particularly in Japan and in Europe, as evidenced by reports of high anti-HEV immunoglobulin G prevalence in healthy individuals and an increasing number of non-travel-related acute hepatitis E cases. Moreover, a porcine reservoir and growing evidence of zoonotic transmission have been reported in these countries. This review summarizes the current knowledge on the epidemiology and prevention of transmission of mammalian HEV.

Virus hazards from food, water and other contaminated environments

Numerous viruses of human or animal origin can spread in the environment and infect people via water and food, mostly through ingestion and occasionally through skin contact. These viruses are released into the environment by various routes including water run-offs and aerosols. Furthermore, zoonotic viruses may infect humans exposed to contaminated surface waters. Foodstuffs of animal origin can be contaminated, and their consumption may cause human infection if the viruses are not inactivated during food processing. Molecular epidemiology and surveillance of environmental samples are necessary to elucidate the public health hazards associated with exposure to environmental viruses. Whereas monitoring of viral nucleic acids by PCR methods is relatively straightforward and well documented, detection of infectious virus particles is technically more demanding and not always possible (e.g. human norovirus or hepatitis E virus). The human pathogenic viruses that are most relevant in this context are nonenveloped and belong to the families of the Caliciviridae, Adenoviridae, Hepeviridae, Picornaviridae and Reoviridae. Sampling methods and strategies, first-choice detection methods and evaluation criteria are reviewed.

Molecular epidemiology and genetic history of European-type genotype 3 hepatitis E virus indigenized in the central region of Japan

In Mie prefecture in Japan, 12 cases of sporadic hepatitis E occurred from 2004 to 2011. Mie prefecture is located in the central region of Japan, far from the most prevalent regions of hepatitis E virus (HEV) infection in Japan, the north and northeastern part. These 12 cases did not have any common risk factors of HEV infection. We analyzed the molecular epidemiology of the cases in Mie prefecture. We obtained the nucleotide sequences of the HEV strains and analyzed them with the sequences of other HEV strains by phylogenetic and coalescent analyses. Japan-indigenous genotype 3 HEV strains were divided into two major subtypes, namely, 3a and 3b; one minor subtype, 3e; and a few other unassigned lineages. The Japan-indigenous subtype 3e strains were closely related to European subtype 3e HEV strains and were comparatively rare in Japan; however, eight strains of the 12 cases we examined belonged to subtype 3e, indicating a close phylogenetic relationship, despite the lack of common risk factors. Coalescent analyses indicated that the Mie 3e strains seemed to have intruded into Mie prefecture about 10 years ago. Sporadic acute hepatitis E cases caused by the 3e strains occurred consistently from 2004 to 2011 in Mie prefecture. This is the first report of unexpected persistent occurrence of hepatitis by the European-type genotype 3 HEV, subtype 3e, in a country outside of Europe. Phylogenetic and coalescent analyses traced the history of the indigenization of the Mie 3e strains from Europe. Because hepatitis E cases caused by 3e strains are relatively rare in Japan, molecular evolutionary analyses of HEV infection in Mie prefecture is important for preventing a future hepatitis endemic or epidemic by 3e strains in Japan.

The epidemiology of hepatitis E virus infections in developed countries and among immunocompromised patients

Hepatitis E virus (HEV) is an important cause of acute hepatitis in humans worldwide, both as epidemic and sporadic disease. Since the virus was identified in 1983, epidemics have occurred regularly in many countries across South and Southeast Asia when seasonal floods have contaminated drinking water supplies and in Africa during humanitarian crises among refugee populations without access to clean water. In addition, sporadic cases and small clusters of HEV infections have been recognized throughout the world in developed countries over the past couple of decades. This review will focus on emerging evidence of HEV infection as an under-recognized pathogen in Europe, the USA and other industrialized countries. We will discuss some of the issues associated with the recognition, diagnosis and treatment of these sporadic cases. We will also summarize the recent literature on autochthonous HEV infection among populations in developed countries in industrialized Europe, the USA, Japan and other industrialized Asian countries. We will review recent reports of acute and chronic HEV infections among transplant recipients and other immunocompromised individuals including HIV/AIDS patients.

New findings regarding the epidemic history and population dynamics of Japan-indigenous genotype 3 hepatitis E virus inferred by molecular evolution

BACKGROUND

Since previous studies have investigated the population dynamics of Japan-indigenous genotype 3 hepatitis E virus (HEV) using virus sequences, more nucleotide sequences have been determined, and new techniques have been developed for such analysis.

AIMS

To prevent future hepatitis E epidemic in Japan, this study aimed to elucidate the cause of past HEV expansion.

METHODS

The epidemic history of Japan-indigenous genotype 3 HEV was determined using the coalescent analysis framework. Bayesian skyline plot (BSP) and Bayesian estimate of phylogeny with relaxed molecular clock models were calculated using Markov chain Monte Carlo sampling.

RESULTS

Japan-indigenous strains consist of New World strains (subtype 3a), Japanese strains (3b) and European strains (3e). The oldest lineage, 3b, appeared around 1929. Lineages 3a and 3e appeared around 1960. BSPs indicated similar radical population growth of the 3a and 3b lineages from 1960 to 1980.

CONCLUSIONS

Population dynamics of the three lineages shared some common characteristics, but had distinguishing features. The appearance of 3a and 3e lineages coincides with the increase of large-race pig importation from Europe and the USA after 1960. The epidemic phase of 3a and 3b strains from 1960 to 1980 could be related to increased opportunity for HEV infection arising from large-scale pig breeding since 1960. Our observations revealed new findings concerning the close relationship between the epidemic history of Japan-indigenous genotype 3 HEV and the improvement of the Japanese pig industry. Infection control in pig farms should be an effective method of preventing HEV infection in humans.

Potential risk of zoonotic transmission from young swine to human: seroepidemiological and genetic characterization of hepatitis E virus in human and various animals in Beijing, China

The aim of this study was to further investigate the prevalence of infection and genotype of hepatitis E virus (HEV) among different species of animals, people whose works are related to pigs and the general population in the suburb of Beijing, China. Serum and faecal samples were collected from 10 animal species and humans. Anti-HEV was detected by enzyme immunoassays (EIA); HEV RNA was amplified by reverse transcription-nested polymerase chain reaction (RT-nPCR) method. PCR products were cloned and sequenced. The isolated swine HEV sequences were analysed phylogenetically. The positive rates of serum anti-HEV in swine, cattle, milk cow, horse, sheep, donkey, dog, duck, chicken, pig farm workers and slaughterhouse workers, and general population were 81.17% (802/988), 25.29% (66/261), 14.87% (40/269), 14.29% (40/280), 9.30% (53/514), 0 (0/25), 0 (0/20), 2.53% (8/316), 3.03% (7/231), 58.73% (37/63), 35.87% (66/184) and 20.06% (538/2682), respectively. The anti-HEV prevalence in adult swine (≥ 6 months) and younger swine (≤ 3 months) was 91.49% (591/646) and 61.7% (211/342), respectively. The positive rate of HEV RNA in young swine faeces was 47.94% (93/194). All 93 isolates from the younger swine shared 87.8-100% nucleotide homology with each other and had identities of 75.6-78.9%, 73.9-76.1%, 76.4-80.6% and 83.1-95.0% with the corresponding regions of genotypes 1-4 HEV, respectively. Phylogenetic analysis showed that all HEV isolates belong to genotype 4, subgenotype 4d. These results suggest a potential risk of zoonotic transmission of HEV from younger swine to farmers who rear pigs.

A survey of the transmission of infectious diseases/infections between wild and domestic ungulates in Europe

The domestic animals/wildlife interface is becoming a global issue of growing interest. However, despite studies on wildlife diseases being in expansion, the epidemiological role of wild animals in the transmission of infectious diseases remains unclear most of the time. Multiple diseases affecting livestock have already been identified in wildlife, especially in wild ungulates. The first objective of this paper was to establish a list of infections already reported in European wild ungulates. For each disease/infection, three additional materials develop examples already published, specifying the epidemiological role of the species as assigned by the authors. Furthermore, risk factors associated with interactions between wild and domestic animals and regarding emerging infectious diseases are summarized. Finally, the wildlife surveillance measures implemented in different European countries are presented. New research areas are proposed in order to provide efficient tools to prevent the transmission of diseases between wild ungulates and livestock.

The molecular epidemiology of hepatitis E virus infection

Molecular characterization of various hepatitis E virus (HEV) strains circulating among humans and animals (particularly swine, deer and boars) in different countries has revealed substantial genetic heterogeneity. The distinctive four-genotype distribution worldwide of mammalian HEV and varying degrees of genetic relatedness among local strains suggest a long and complex evolution of HEV in different geographic regions. The population expansion likely experienced by mammalian HEV in the second half of the 20th century is consistent with an extensive genetic divergence of HEV strains and high prevalence of HEV infections in many parts of the world, including developed countries. The rate and mechanisms of human-to-human transmission and zoonotic transmission to humans vary geographically, thus contributing to the complexity of HEV molecular evolution.

Hepatitis E virus infection in developed countries

Hepatitis E was considered to be endemic infectious disease in developing countries in tropical or subtropical regions with poor sanitary conditions. Large, previously reported outbreaks were mainly due to contaminated water or heavy flooding. Prototype hepatitis E viruses of genotypes I and II were obtained from such endemic cases. In developed countries, in contrast, hepatitis E was rare and diagnosed only in travelers or imported cases. However, the development of accurate diagnostic tests, mainly PCR detection elucidated that autochthonous hepatitis E in developed countries is far more common than previously thought. Although the main route of transmission is food-borne, other routes including blood-borne have been suggested. Recent developments of gene-based diagnostic assays and molecular epidemiology have disclosed the significance of hepatitis E virus infection in developed countries.

Increasing contact with hepatitis E virus in red deer, Spain

To describe the epidemiology of hepatitis E virus (HEV) in red deer in mainland Spain, we tested red deer for HEV RNA and antibodies. Overall, 10.4% and 13.6% of serum samples were positive by ELISA and reverse transcription–PCR, respectively. The increasing prevalence suggests a potential risk for humans.

From barnyard to food table: the omnipresence of hepatitis E virus and risk for zoonotic infection and food safety

Hepatitis E virus (HEV) is an important but extremely understudied pathogen. The mechanisms of HEV replication and pathogenesis are poorly understood, and a vaccine against HEV is not yet available. HEV is classified in the family Hepeviridae consisting of at least four recognized major genotypes. Genotypes 1 and 2 HEV are restricted to humans and associated with epidemics in developing countries, whereas genotypes 3 and 4 HEV are zoonotic and responsible for sporadic cases worldwide. The identification and characterization of a number of animal strains of HEV from pigs, chickens, rabbits, rats, mongoose, deer, and possibly cattle and sheep have significantly broadened the host range and diversity of HEV. The demonstrated ability of cross-species infection by some animal strains of HEV raises public health concerns for zoonotic HEV infection. Pigs are a recognized reservoir for HEV, and pig handlers are at increased risk of zoonotic HEV infection. Sporadic cases of hepatitis E have been definitively linked to the consumption of raw or undercooked animal meats such as pig livers, sausages, and deer meats. In addition, since large amounts of viruses excreted in feces, animal manure land application and runoffs can contaminate irrigation and drinking water with concomitant contamination of produce or shellfish. HEV RNA of swine origin has been detected in swine manure, sewage water and oysters, and consumption of contaminated shellfish has also been implicated in sporadic cases of hepatitis E. Therefore, the animal strains of HEV pose not only a zoonotic risk but also food and environmental safety concerns.

Hepatitis E virus cell culture models

Early studies reported the propagation of hepatitis E virus (HEV) in either primary hepatocytes or several established cell lines, but replication was inefficient. Efficient cell culture systems for HEV in PLC/PRF/5 and A549 cells have recently been established, using inoculum of fecal suspensions with high HEV loads, originally obtained from patients with genotype 3 HEV (the JE03-1760F strain, 2.0×10(7) copies/ml) or genotype 4 HEV (the HE-JF5/15F strain, 1.3×10(7) copies/ml), and many generations were successfully propagated in serial passages of culture supernatant. In addition, a full-length infectious cDNA clone (pJE03-1760F/wt) of the JE03-1760F strain was constructed, which can replicate efficiently in PLC/PRF/5 and A549 cells. A derivative ORF3-deficient mutant revealed that the ORF3 protein of HEV is responsible for virion egress from infected cells and is present on the surface of released HEV particles, which is associated with lipids. Various HEV strains with high loads of ≥10(5) copies/ml in circulating blood were also propagated efficiently in PLC/PRF/5 and A549 cells. This paper reviews the road map toward the development of efficient cell culture systems for a wide variety of HEV strains and introduces the current knowledge on virion egress obtained by cell culture models.

Evolutionary history and population dynamics of hepatitis E virus

Background

Hepatitis E virus (HEV) is an enterically transmitted hepatropic virus. It segregates as four genotypes. All genotypes infect humans while only genotypes 3 and 4 also infect several animal species. It has been suggested that hepatitis E is zoonotic, but no study has analyzed the evolutionary history of HEV. We present here an analysis of the evolutionary history of HEV.

Methods and Findings

The times to the most recent common ancestors for all four genotypes of HEV were calculated using BEAST to conduct a Bayesian analysis of HEV. The population dynamics for genotypes 1, 3 and 4 were analyzed using skyline plots. Bayesian analysis showed that the most recent common ancestor for modern HEV existed between 536 and 1344 years ago. The progenitor of HEV appears to have given rise to anthropotropic and enzootic forms of HEV, which evolved into genotypes 1 and 2 and genotypes 3 and 4, respectively. Population dynamics suggest that genotypes 1, 3 and 4 experienced a population expansion during the 20^th century. Genotype 1 has increased in infected population size ∼30–35 years ago. Genotype 3 and 4 have experienced an increase in population size starting late in the 19^th century until ca.1940-45, with genotype 3 having undergone additional rapid expansion until ca.1960. The effective population size for both genotype 3 and 4 rapidly declined to pre-expansion levels starting in ca.1990. Genotype 4 was further examined as Chinese and Japanese sequences, which exhibited different population dynamics, suggesting that this genotype experienced different evolutionary history in these two countries.

Conclusions

HEV appears to have evolved through a series of steps, in which the ancestors of HEV may have adapted to a succession of animal hosts leading to humans. Analysis of the population dynamics of HEV suggests a substantial temporal variation in the rate of transmission among HEV genotypes in different geographic regions late in the 20^th Century.

Hepatitis E in high-income countries

PURPOSE OF REVIEW

To discuss recent advances in characterising viral Hepatitis E (HEV) in nonendemic regions, with a special focus on epidemiology in high-income countries, different clinical aspects of the disease, possible zoonotic origin of these cases and the improvement of Hepatitis E diagnosis.

RECENT FINDINGS

In high-income countries, most cases of Hepatitis E are acquired locally and not imported from endemic regions. Different genotypes are involved in indigenous cases than those in endemic regions. Particular population groups, such as transplant recipients, can be persistently infected by hepatitis E and develop chronic diseases. Viral hepatitis E is frequently observed in people in animal care occupations. Indeed, HEV has a large animal reservoir and this emerging disease in developed countries has probably a zoonotic origin.

SUMMARY

Recent studies on viral Hepatitis E have shown that the epidemiology of the disease differs between endemic and nonendemic regions. Several lines of evidence suggest that Hepatitis E is more frequent than was suspected and that it has a possible animal origin. Particular attention must be paid to the possible chronic evolution of various forms of the disease. Surveillance of human cases and animal reservoirs must be developed further.

Diagnosis of acute hepatitis E by antibody and molecular testing: a study on 277 suspected cases

BACKGROUND

Acute hepatitis due to hepatitis E virus (HEV) infection is both indigenous and imported to Europe. Few studies provide information about the role of HEV as an agent for acute hepatitis in Spain.

OBJECTIVES

To investigate the frequency of the HEV infection among patients displaying acute hepatitis of unexplained origin in Spain, comparing the performance of two different diagnostic approaches.

STUDY DESIGN

Specific IgM antibody and HEV RNA tests were used to study samples from 277 patients with acute hepatitis of unknown aetiology received during a six-year period. Samples were sent by 52 hospitals from almost all regions of Spain.

RESULTS

Evidence of acute infection by HEV was obtained for 30 patients in total (10.8%), and 16 cases were unrelated to recent international travel. On samples from 158 patients tested for both anti-HEV IgM and HEV RNA at admission, the yield of IgM antibody testing (11.4%) was higher than the yield of HEV RNA testing (9.5%).

CONCLUSIONS

HEV could be responsible in Spain of about 11% of cases of acute hepatitis of unknown origin overall, and of about 8% of cases unrelated to international travel or immigration. India and neighbour countries represent the highest risk for import of epidemic HEV strains into Spain. Both antibody assays and molecular tests are required to optimise the final yield of laboratory diagnosis.

Molecular epidemiology of hepatitis E virus in humans, pigs and wild boars in Sweden

Hepatitis E infections in humans are usually acquired in endemic countries in Asia or Africa. In Sweden 17 cases infected in Europe, between 1993 and 2009, were identified. All had clinical hepatitis E with unknown source of infection. Hepatitis E virus (HEV) was identified in faecal samples from 63 piglets in 12 pig farms in Sweden. HEV was also identified in blood from 13 out of 159 investigated Swedish wild boars from nine counties. Partial HEV genomes from humans, pigs and wild boars were sequenced and compared by phylogeny. The results showed close relatedness between HEV strains from piglets from the same farm and from wild boars from the same county. HEV strains from humans showed relatedness with strains from pigs and wild boars from the same county. This study showed that HEV strains form geographical clusters in the phylogenetic tree. The methods used in this study may thus be used for tracing the origin of an infecting strain. Furthermore, this study indicated that there are endemic sources of human HEV infections in Sweden.

Seroprevalence and molecular detection of hepatitis E virus in wild boar and red deer in The Netherlands

To date, sources of hepatitis E virus (HEV) in the Netherlands, including swine and wild boar, have been identified, but no direct attribution to Dutch hepatitis E cases have been demonstrated. Other animal sources may exist. To identify these species, HEV RNA detection by RT-PCR is required, but complicated. A preselection based on serology may be useful. Therefore, wildlife species were studied by serology and molecular methods. Using a species-independent double-antigen sandwich ELISA, HEV-specific antibodies were detected in sera from 12% of 1029 wild boar (Sus scrofa scrofa), in 5% of 38 red deer (Cervus elaphus) and in none of 8 studied roe deer (Capreolus capreolus). Differences in background signals were observed between species and accounted for by fitting finite mixture distributions. HEV RNA was detected in 8% of 106 wild boars, in 15% of 39 red deer and in none of 8 roe deer. In conclusion, HEV was shown to be present in European red deer for the first time. This preselection based on species-independent serological assays may be beneficial to identify new potential animal reservoirs of HEV. The consumption of Dutch undercooked wild boar and red deer meat may lead to human exposure to HEV.

Analysis of complete genome sequences of swine hepatitis E virus and possible risk factors for transmission of HEV to humans in Korea

The hepatitis E virus (HEV) is an emerging zoonotic agent, for which pigs are the most important reservoir. Complete genome sequences of two swine HEV strains, designated swKOR-1 and swKOR-2, were determined via RT-PCR and RACE-PCR. The strains contained genomes composed of 7,222- and 7,221-bp excluding the poly(A) tails, respectively. The swKOR-1 and swKOR-2 strains were classified into subtype 3a of genotype 3 via phylogenetic analysis. These strains formed a distinctive cluster in the phylogenetic tree with human and swine HEVs isolated in the USA and human HEVs isolated in Japan. Anti-HEV antibodies were identified via ELISA in 8 of 99 (8.1%) cats, whereas, among 115 cattle and 213 dogs, no HEV-specific antibodies were detected. The conserved RNA-dependent RNA polymerase (RdRp) gene of HEV could be detected via RT-PCR in 8.7% of raw oysters collected from coastal regions in Korea. The HEV RNAs detected in oysters were identified as belonging to subtype 3a. The HEV RNAs in oysters most closely resembled that of the swKOR-2 strain. They also showed a close genetic relationship with the swKOR-1 strain and the swine and human HEVs isolated in the USA. This is the first report describing the detection in oysters of HEV that may have originated from genotype 3 swine HEV in Korea. Pigs and cats infected with HEV, as well as oysters contaminated with HEV, are potential risk factors for HEV transmission to humans.

Hepatitis E virus is highly prevalent in the Danish pig population

The objective of this study was to examine the prevalence of Hepatitis E virus (HEV) in the Danish pig population. Faecal samples from 97 pigs, 1-5 months of age were analysed for HEV RNA by a new PriProET real time RT-PCR assay. In addition, serum samples from 71 sow herds were screened for the presence of anti-HEV IgG antibodies by ELISA. The genotype of the detected HEV positive samples was estimated based on the melting temperature obtained by the PriProET real time RT-PCR assay. The HEV prevalence of faecal samples was 55.0% and 49.5% for herds and animals, respectively. A HEV IgG prevalence of 91.5% was found for the sow herds which correspond to 73.2% of the sows. The PriProET assay indicated that all HEV positive samples belonged to genotype 3 or 4, which is consistent with the observation of genotype 3 as dominant in European pigs. This is the first study showing that HEV is highly prevalent in the Danish pig population. The abundant presence of HEV in Danish pigs and the known high similarity between HEV isolates from pigs and humans support previous reports indicating possible zoonotic transmission of HEV.

Zoonotic hepatitis E: animal reservoirs and emerging risks

Hepatitis E virus (HEV) is responsible for enterically-transmitted acute hepatitis in humans with two distinct epidemiological patterns. In endemic regions, large waterborne epidemics with thousands of people affected have been observed, and, in contrast, in non-endemic regions, sporadic cases have been described. Although contaminated water has been well documented as the source of infection in endemic regions, the modes of transmission in non-endemic regions are much less known. HEV is a single-strand, positive-sense RNA virus which is classified in the Hepeviridae family with at least four known main genotypes (1–4) of mammalian HEV and one avian HEV. HEV is unique among the known hepatitis viruses, in which it has an animal reservoir. In contrast to humans, swine and other mammalian animal species infected by HEV generally remain asymptomatic, whereas chickens infected by avian HEV may develop a disease known as Hepatitis-Splenomegaly syndrome. HEV genotypes 1 and 2 are found exclusively in humans while genotypes 3 and 4 are found both in humans and other mammals. Several lines of evidence indicate that, in some cases involving HEV genotypes 3 and 4, animal to human transmissions occur. Furthermore, individuals with direct contact with animals are at higher risk of HEV infection. Cross-species infections with HEV genotypes 3 and 4 have been demonstrated experimentally. However, not all sources of human infections have been identified thus far and in many cases, the origin of HEV infection in humans remains unknown.

Much meat, much malady: changing perceptions of the epidemiology of hepatitis E

Hepatitis E, which is caused by hepatitis E virus (HEV), may now be considered a zoonosis as well as an anthroponosis. Pigs, boars and deer have been identified as reservoirs, and their flesh and entrails--as meat and offal--as vehicles of HEV transmission. Shellfish also act as vehicles. Dietary, gastronomic and culinary preferences influence how extensively HEV conveyed by these vehicles can be inactivated before their ingestion by the host. Another route of infection is paved by HEV that is enterically shed by humans and by live animals into the environment. Although anthroponotic transmission of HEV is primarily environmental, zoonotic transmission may proceed along both foodborne and environmental routes.

A nationwide survey of hepatitis E virus infection in the general population of Japan

To investigate nationwide the prevalence of hepatitis E virus (HEV) infection in the general population of Japan, serum samples were collected from 22,027 individuals (9,686 males and 12,341 females; age, mean +/- standard deviation: 56.8 +/- 16.7 years; range: 20-108 years) who lived in 30 prefectures located in Hokkaido, mainland Honshu, Shikoku, and Kyushu of Japan and underwent health check-ups during 2002-2007, and were tested for the presence of IgG, IgM, and IgA classes of antibodies to HEV (anti-HEV) by in-house ELISA and HEV RNA by nested RT-PCR. Overall, 1,167 individuals (5.3%) were positive for anti-HEV IgG, including 753 males (7.8%) and 414 females (3.4%), the difference being statistically significant (P < 0.0001). The prevalence of anti-HEV IgG generally increased with age and was significantly higher among individuals aged >or=50 years than among those aged <50 years (6.6% vs. 2.7%, P < 0.0001). Although 13 individuals with anti-HEV IgG also had anti-HEV IgM and/or anti-HEV IgA, none of them had detectable HEV RNA. The presence of HEV RNA was further tested in 50 or 49-sample minipools of sera from the remaining 22,014 individuals, and three individuals without anti-HEV antibodies tested positive for HEV RNA. The HEV isolates obtained from the three viremic individuals segregated into genotype 3 and were closest to Japan-indigenous HEV strains. When stratified by geographic region, the prevalence of anti-HEV IgG as well as the prevalence of HEV RNA or anti-HEV IgM and/or anti-HEV IgA was significantly higher in northern Japan than in southern Japan (6.7% vs. 3.2%, P < 0.0001; 0.11% vs. 0.01%, P = 0.0056; respectively).

Detection of hepatitis E virus in samples of animal origin collected in Hungary

Hepatitis E virus (HEV) is an enterically transmitted human pathogen. HEV infections are mainly associated with acute, self-limited, icteric hepatitis with an average mortality rate of 1%. Animal reservoirs are considered to play an important role in the maintenance of the virus and in the spread of HEV to humans. HEV-induced seroconversion was described in several species, however clinical hepatitis in animals has not been observed to date. HEV strains from animals are genetically closely related to human HEV isolates, which supports the opinions on the zoonotic transmission of the virus. In this expansive study the occurrence of HEV was investigated in Hungarian wild and domesticated animal samples. HEV RNA was detected by reverse transcription-polymerase chain reaction in liver samples of wild boars, roe deer, and deer. The investigations of domestic swine samples detected HEV in 39% of the investigated Hungarian pig farms. Simultaneous investigation revealed no definite difference between liver and faeces samples of domestic pigs in the frequency of HEV positivity. The highest (36%) incidence of HEV infection was found among the 11-16-week-old pigs. Samples from domestic cattle and rodents collected in pig farms, forests and meadows were tested negative for HEV RNA. Phylogenetic analysis of partial sequences amplified within the ORF1 and ORF2 regions of selected strains revealed that the detected viruses belong to three subgroups of the third genogroup of HEV, and are closely related to human and swine HEV strains detected in different countries. The investigations revealed widespread distribution of HEV in Hungarian wild ungulate and domesticated swine populations, with considerable genetic diversity among the strains.

High HEV presence in four different wild boar populations in East and West Germany

Swine Hepatitis E virus (HEV) can be transmitted from pigs to humans causing hepatitis. A high prevalence of HEV in wild boar populations is reported for several European countries, but actual data for Germany are missing. During the hunting season from October to December 2007 liver, bile and blood samples were collected from wild boars in four different German regions. The samples were tested for HEV RNA by quantitative PCR (qPCR) and anti-HEV IgG antibodies by two different ELISAs and a Line immunoassay. A seroprevalence of 29.9% using ELISA and 26.2% in the Line immunoassay was determined. The seroprevalence rate varied greatly within the analyzed regions. However, qPCR analysis revealed a higher prevalence of 68.2% positive animals with regional differences. Surprisingly, also adult wild sows and wild boars were highly HEV positive by qPCR. Compared to liver and serum samples, bile samples showed a higher rate of positive qPCR results. Sequencing and phylogenetic analysis of a 969nt fragment within ORF 2 revealed that all isolates clustered within genotype 3 but differed in the subtype depending on the hunting spot. Isolates clustered within genotypes 3i, 3h, 3f and 3e. Within one population HEV isolates were closely related, but social groups of animals in close proximity might be infected with different subtypes. Two full-length genomes of subtypes 3i and 3e from two different geographic regions were generated. The wild boar is discussed as one of the main sources of human autochthonous infections in Germany.