Hepatitis E virus (HEV): molecular cloning and sequencing of the full-length viral genome

Hepatitis E virus enters liver cells through a dynamin-2, clathrin and membrane cholesterol-dependent pathway

The hepatitis E virus (HEV) causes large outbreaks and sporadic cases of acute viral hepatitis in developing countries. In the developed world, HEV occurrence has increased as a result of zoonotic transmission from swine. The cellular aspects of HEV infection, especially the determinants of entry, are poorly understood. In the absence of a robust in vitro culture system for HEV, it is not possible to produce high titre infectious virus that can be labeled for tracking its internalization. We have therefore used an Escherichia coli expressed HEV-like particle (HEV-LP) to study HEV entry. Following internalization, the HEV-LP initially trafficks to Rab5-positive compartments en route to acidic lysosomal compartments where it is degraded. Using pharmacological inhibitors, dominant negative and constitutively active mutants, and siRNA-mediated perturbations, we show that HEV entry requires dynamin-2, clathrin, membrane cholesterol and actin, but is independent of factors associated with macropinocytosis. The HEV-LP results were further validated through infection of liver cells with virus from the stool of an infected patient. The comparative analysis also showed involvement of the phosphatidylinositol-3-kinase/Akt pathway in an early post-entry step of viral replication. This report provides a detailed description of endocytic processes associated with HEV infection.

Coinfection of hepatitis E virus and other hepatitis virus in Colombia and its genotypic characterization

INTRODUCTION

Hepatitis E virus has emerged as a public health problem, particularly in developing countries. The four genotypes identified in mammals include the G3 found in indigenous hepatitis in countries and regions with high porcine population, and the G1, associated with maternal deaths. 

OBJECTIVE

To determine coinfection by hepatitis E virus and the circulating genotypes in Colombia in 1,097 samples using serological markers for hepatitis A, B and C. 

MATERIALS AND METHODS

Serum samples of 1,097 patients from different regions of Colombia stored at the Laboratorio de Virología of the Instituto Nacional de Salud were selected to detect IgG and IgM anti-hepatitis E virus antibodies. The viral genomes of positive samples were amplified by RT-PCR, and the products were sequenced and phylogenetically analyzed by comparing ORF2 sequences deposited in the GenBank. 

RESULTS

IgG anti-hepatitis E virus antibodies were found in 278 samples, IgM in 62, and both markers in 64. Hepatitis E virus and hepatitis A virus coinfection determined by IgG anti-hepatitis E virus was 33.6% and 16.1% by IgM; hepatitis E virus and hepatitis B virus coinfection was 23.4% and 8.1%, and hepatitis E virus and hepatitis C virus coinfection was 35.4% and 5.83%, respectively. Among the 52 positive samples by PCR nine were sequenced and grouped within genotype 3A of the American porcine strain. 

CONCLUSIONS

The highest seropositivity was observed for hepatitis A and E. The incidence of hepatitis E virus coinfection with other hepatotropic viruses indicated that this pathogen is more frequent than expected. The circulation of genotype 3A implies that this disease may occur in outbreaks and as zoonosis in Colombia.

Design, Construction and Cloning of Truncated ORF2 and tPAsp-PADRE-Truncated ORF2 Gene Cassette From Hepatitis E Virus in the pVAX1 Expression Vector

BACKGROUND

Hepatitis E Virus (HEV) is the causative agent of enterically transmitted acute hepatitis and has high mortality rate of up to 30% among pregnant women. Therefore, development of a novel vaccine is a desirable goal.

OBJECTIVES

The aim of this study was to construct tPAsp-PADRE-truncated open reading frame 2 (ORF2) and truncated ORF2 DNA plasmid, which can assist future studies with the preparation of an effective vaccine against Hepatitis E Virus.

MATERIALS AND METHODS

A synthetic codon-optimized gene cassette encoding tPAsp-PADRE-truncated ORF2 protein was designed, constructed and analyzed by some bioinformatics software. Furthermore, a codon-optimized truncated ORF2 gene was amplified by the polymerase chain reaction (PCR), with a specific primer from the previous construct. The constructs were sub-cloned in the pVAX1 expression vector and finally expressed in eukaryotic cells.

RESULTS

Sequence analysis and bioinformatics studies of the codon-optimized gene cassette revealed that codon adaptation index (CAI), GC content, and frequency of optimal codon usage (Fop) value were improved, and performance of the secretory signal was confirmed. Cloning and sub-cloning of the tPAsp-PADRE-truncated ORF2 gene cassette and truncated ORF2 gene were confirmed by colony PCR, restriction enzymes digestion and DNA sequencing of the recombinant plasmids pVAX-tPAsp-PADRE-truncated ORF2 (aa 112-660) and pVAX-truncated ORF2 (aa 112-660). The expression of truncated ORF2 protein in eukaryotic cells was approved by an Immunofluorescence assay (IFA) and the reverse transcriptase polymerase chain reaction (RT-PCR) method.

CONCLUSIONS

The results of this study demonstrated that the tPAsp-PADRE-truncated ORF2 gene cassette and the truncated ORF2 gene in recombinant plasmids are successfully expressed in eukaryotic cells. The immunogenicity of the two recombinant plasmids with different formulations will be evaluated as a novel DNA vaccine in future investigations.

Hepatitis E Virus in Domestic Pigs, Wild Boars, Pig Farm Workers, and Hunters in Estonia

While hepatitis E is a growing health concern in Europe, epidemiological data on hepatitis E virus (HEV) in Estonia are scarce. Along with imported HEV infections, autochthonous cases are reported from European countries. Both domestic and wild animals can be a source of human cases of this zoonosis. Here, we investigated the presence of anti-HEV antibodies and HEV RNA in domestic pigs and wild boars, as well as in pig farm workers and hunters in Estonia. Anti-HEV antibodies were detected in 234/380 (61.6%) of sera from domestic pigs and in all investigated herds, and in 81/471 (17.2%) of meat juice samples from wild boars. HEV RNA was detected by real-time PCR in 103/449 (22.9%) of fecal samples from younger domestic pigs and 13/81 (16.0%) of anti-HEV-positive wild boar samples. Analysis of sera from 67 pig farm workers and 144 hunters revealed the presence of HEV-specific IgG in 13.4 and 4.2% of the samples, respectively. No HEV RNA was detected in the human serum samples. Phylogenetic analyses of HEV sequences from domestic pigs and wild boars, based on a 245 bp fragment from the open reading frame 2 showed that all of them belonged to genotype 3. The present study demonstrates the presence of HEV in Estonian domestic pig and wild boar populations, as well as in humans who have direct regular contact with these animals. Our results suggest that HEV infections are present in Estonia and require attention.

Is hepatitis E virus an emerging problem in industrialized countries?

Hepatitis E virus (HEV) is yearly responsible for approximately 20 million infections worldwide. Although most infections occur in developing countries, HEV appears to be an emerging problem in several industrialized countries, where it is mostly associated with either traveling to an HEV endemic area or contact with pigs, which represent a major reservoir of HEV. The major risk groups for HEV infection and its ensuing complications are elderly men, pregnant women, young children, immunocompromised patients, patients with preexisting liver disease, and workers that come into close contact with HEV-infected animals. Whereas HEV mainly causes acute self-limiting infections, chronic infections may occur among immunocompromised patients (e.g., transplant recipients and human immunodeficiency virus [HIV]-infected patients). Accordingly, HEV-HIV coinfection leads to accelerated liver cirrhosis and increased mortality rates compared to HEV infection alone, which is, except during pregnancy, usually associated with only low mortality. In the Western world, the most common genotype (gt) causing HEV infection is gt 3. Ribavirin (RBV) and interferon have been used successfully for treatment of HEV, but this treatment is contraindicated in certain patient groups. Therefore, novel antiviral compounds are highly needed, especially given that viral isolates with RBV resistance have been recently identified. Moreover, eradication of HEV is hampered by long-term environmental persistence of the virus, which represents a continuous source of the virus. In 2011, the first prophylactic HEV vaccine, Hecolin, was approved in China, but it is not yet globally available. In this review, we will discuss the molecular virology of HEV, mode of transmission in industrialized countries, and potential implications for different specific patient populations.

Role of asparagine at position 562 in dimerization and immunogenicity of the hepatitis E virus capsid protein

The hepatitis E virus (HEV) capsid protein, pORF2, contains 2 potential N-glycosylation sites, N137 and N310, located in the S domain, and one site, N562, in the P domain. The last domain located at positions 454-606 aa forms a protruding spike from the shell, with N562 being located in the apical center of the spike, which is also a cell-attachment region and neutralizing antigenic site. Here, we expressed in Pichia pastoris a recombinant polypeptide p179 comprising the region of 439-617 aa of the HEV pORF2 as well as a set of 4 mutant proteins containing substitutions of Q, D, P and Y instead of N at position 562. All proteins were shown to be secreted from yeast. Using SDS-PAGE, Western blot analysis and tunicamycin treatment assay, we showed that the wild-type (wt) protein, p179N562, and 2 mutant variants, p179N562Q and p179N562D, formed homodimers but only the wt protein was shown to be glycosylated. As homodimers, all 3 proteins were immunoreactive with a neutralizing monoclonal antibody (5G5); however, they did not immunoreact with 5G5 after denaturation into monomers. Two other mutant variants, p179N562P and p179N562Y, did not form homodimers but were immunoreactive with the 5G5 antibody. The wt protein was shown to be less immunoreactive with 5G5 than the mutant variants in a double-antibody sandwich ELISA, suggesting a role of glycosylation at N562 in reducing antibody binding. In vitro neutralization experiments showed a more efficient neutralization with mouse antibody against p179N562P and p179N562Y than against the other 3 proteins. These findings indicate that specific substitutions at position 562 have a more measurable effect on the activity of the HEV neutralizing epitope than dimerization or glycosylation of the structural protein. Furthermore, the secretion of monomers fully immunoreactive may call into question the importance of dimerization for an effective presentation of HEV neutralization epitopes.

Hepatitis E virus infection: Epidemiology and treatment implications

Hepatitis E virus (HEV) infection is now established as an emerging enteric viral hepatitis. Standard treatments in acute and chronic hepatitis E remain to be established. This study undertakes a review of the epidemiology, treatment implication and vaccine prevention from published literature. HEV infection is a worldwide public health problem and can cause acute and chronic hepatitis E. HEV genotypes 1 and 2 are primarily found in developing countries due to waterborne transmission, while the zoonotic potential of genotypes 3 and 4 affects mostly industrialized countries. An awareness of HEV transmission through blood donation, especially in the immunocompromised and solid organ transplant patients, merits an effective anti-viral therapy. There are currently no clear indications for the treatment of acute hepatitis E. Despite concerns for side effects, ribavirin monotherapy or in combination with pegylated interferon alpha for at least 3 mo appeared to show significant efficacy in the treatment of chronic hepatitis E. However, there are no available treatment options for specific patient population groups, such as women who are pregnant. Vaccination and screening of HEV in blood donors are currently a global priority in managing infection. New strategies for the treatment and control of hepatitis E are required for both acute and chronic infections, such as prophylactic use of medications, controlling large outbreaks, and finding acceptable antiviral therapy for pregnant women and other patient groups for whom the current options of treatment are not viable.

Establishment of hepatitis E virus infection-permissive and -non-permissive human hepatoma PLC/PRF/5 subclones

PLC/PRF/5 cells show limited permissiveness, meaning that almost all subclones are permissive; however, some subclones do not exhibit permissiveness for hepatitis E virus (HEV) infection. In this study, the single-cell cloning of PLC/PRF/5 was performed and heterogeneous subclones characterized. Notably, the efficiency of intracellular virus replication did not correlate with the permissiveness for HEV infection. However, as well as binding permissive subclones, virus-like particles bound non-permissive subclones on various levels, suggesting that these subclones have some deficiencies in the attachment and entry steps of infection. Our data would be useful for investigating the HEV life cycle.

Case Report Associated with Aspergillosis and Hepatitis E Virus Coinfection in Himalayan Griffons

This study involved a death which occurred in four Himalayan griffons housed in Beijing zoo, China. Based on pathogen identification and the pathological changes observed, we did characterize the fungi and Hepatitis E virus (HEV) in four dead Himalayan griffons. Pathological changes were severe. Membranous-like material was observed on the surface of the internal organs. Spleen was necrotic. Focal lymphocyte infiltration in the liver and many sunflower-like fungi nodules were evident in the tissues, especially in the kidney. PCR was used to identify the pathogen. Based on the 18SrRNA genomic sequence of known fungi, the results confirmed that all four dead Himalayan griffons were infected with Aspergillus. At the same time the detection of HEV also showed positive results. To the best of our knowledge, this work appears to be the first report of concurrent presence of Aspergillosis and Hepatitis E virus in rare avian species.

Epidemiology of Hepatitis E Virus in European Countries

Over the last decade the seroprevalence of immunoglobulin (IgG) anti hepatitis E virus (HEV) has been increasing in European countries and shows significant variability among different geographical areas. In this review, we describe the serological data concerning the general population and risk groups in different European countries. Anti-HEV antibody prevalence ranged from 1.3% (blood donors in Italy) to 52% (blood donors in France). Various studies performed on risk groups in Denmark, Moldova and Sweden revealed that swine farmers have a high seroprevalence of HEV IgG (range 13%-51.1%), confirming that pigs represent an important risk factor in HEV infection in humans. Subtypes 3e,f are the main genotypes detected in the European population. Sporadic cases of autochthonous genotype 4 have been described in Spain, France, and Italy. Although most HEV infections are subclinical, in immune-suppressed and transplant patients they could provoke chronic infection. Fulminant hepatitis has rarely been observed and it was related to genotype 3. Interferon and ribavirin treatment was seen to represent the most promising therapy.

Replacement of the hepatitis E virus ORF3 protein PxxP motif with heterologous late domain motifs affects virus release via interaction with TSG101

The ORF3 protein of hepatitis E virus (HEV) contains a "PSAP" amino acid late domain motif, which allows for interaction with the endosomal sorting complexes required for transport (ESCRT) pathway aiding virion release. Late domain motifs are interchangeable with other viral late domain motifs in several enveloped viruses, however, it remains unknown whether HEV shares this functional interchangeability and what implications this might have on viral replication. In this study, by substituting heterologous late domain motifs (PPPY, YPDL, and PSAA) for the HEV ORF3 late domain (PSAP), we demonstrated that deviation from the PSAP motif reduces virus release as measured by viral RNA in culture media. Virus release could not be restored by insertion of a heterologous late domain motif or by supplying wild-type ORF3 in trans, suggesting that the HEV PSAP motif is required for viral exit which cannot be bypassed by the use of alternative heterologous late domains.

Extended Microbiological Characterization of Göttingen Minipigs in the Context of Xenotransplantation: Detection and Vertical Transmission of Hepatitis E Virus

Xenotransplantation has been proposed as a solution to the shortage of suitable human donors. Pigs are currently favoured as donor animals for xenotransplantation of cells, including islet cells, or organs. To reduce the xenotransplantation-associated risk of infection of the recipient the pig donor should be carefully characterised. Göttingen minipigs from Ellegaard are often used for biomedical research and are regularly tested by their vendor for the presence of numerous bacteria, fungi, viruses and parasites. However, screening for some pathogens transmittable to humans had not been performed.The presence of microorganisms was examined in Göttingen Minipigs by PCR methods. Since zoonotic transmission of porcine hepatitis E virus HEV to humans has been demonstrated, extended search for HEV was considered as a priority. RNA from sera, islet and other cells from 40 minipigs were examined for HEV using different real-time reverse transcription (RT)-PCRs, among them two newly established. In addition, sera were examined by Western blot analysis using two recombinant capsid proteins of HEV as antigens. HEV RNA was not detected in pigs older than one year including gilts, but it was detected in the sera of three of ten animals younger than 1 year. Furthermore, HEV was also detected in the sera of three sows six days after delivery and their offspring, indicating vertical transmission of the virus. PCR amplicons were cloned, sequenced and the viruses were found to belong to the HEV genotype (gt) 3/4. Anti-HEV immunoglobulins G were detected in one sow and maternal antibodies in her six day old piglet. Since Göttingen minipigs were negative for many xenotransplantation-relevant microorganisms, they can now be classified as safe. HEV may be eliminated from the Ellegaard herd by selection of negative animals and/or by treatment of the animals.

Role of TLR gene expression and cytokine profiling in the immunopathogenesis of viral hepatitis E

BACKGROUND

The clinical manifestations of Hepatitis E virus (HEV) range from self-limiting acute viral hepatitis (AVH) to acute liver failure (ALF). The varied clinical course is thought to be immune-mediated. Toll-like receptors (TLRs) play a central role in sensing and initiating innate antiviral-response and downstream signaling of TLRs modulates cytokine production, thereby playing an important role in determining the disease course.

OBJECTIVES

The present study was designed to elucidate the role of TLRs and cytokine production in the immunopathogenesis of HEV.

STUDY DESIGN

Peripheral blood mono-nuclear cells were separated from 50 AVH-HEV, 30 ALF-HEV patients and 50 healthy-controls. One-part of the PBMC was processed for RNA-extraction another pulsed with HEV-ORF2-peptide. Gene-expression levels of TLR (2-4, 7, and 8) were checked using semi-quantitative Real-time-PCR. Cytokine levels were analyzed using Cytokine-Bead-Array. TLR3-silencing experiments were performed and post-silencing cytokine levels were estimated.

RESULTS

TLR3 gene-expression in AVH was significantly higher than ALF (202.4±36.36 Vs 13.71±5.01; p<0.0001). Higher amount of both anti-and pro-inflammatory cytokines; IFNγ, TNF-α, IL10 and TGF-β were detected in the PBMC culture-supernatant of AVH Vs ALF (p<0.0001, p=0.0008, p=0.0002, p<0.0001 respectively). Post-silencing TLR3, significant decrease in IFNγ level was observed in the PBMC culture-supernatant (4.08±1.06 Vs 23.20±12.51; p=N0.0213).

CONCLUSIONS

TLR3 and IFNγ were found to play an important role in HEV disease pathogenesis. Patients capable of expressing high levels of TLR 3 and robust IFNγ response are able to limit the disease and recover uneventfully; while the patients with lower expression of TLR3 and IFNγ progress to ALF.

Mix-breeding with HEV-infected swine induced inapparent HEV infection in SPF rabbits

Studies have shown that swine HEV (sHEV) and rabbit HEV (rHEV) can experimentally infect rabbits and swine, respectively. However, no published data have documented isolating sHEV strains from rabbits in natural environment so far. To clarify the possibility of natural cross-species transmission of sHEV to rabbits, the pigs with HEV infection were farmed along with SPF rabbits in the same enclosed space. Five of 10 rabbits had seroconversion for anti-HEV antibody from the third week after mix-breeding. However, HEV RNA remained undetectable in feces, serum, liver and bile of the ten rabbits; and no obvious elevation of ALT was observed. The results possibly suggested that sHEV might lead to an inapparent infection of SPF rabbits by fecal-oral route.

Hepatitis E virus infection in hematopoietic stem cell transplant recipients

PURPOSE OF REVIEW

Recipients of allogeneic stem cell transplantations are at risk of acquiring acute hepatitis E virus (HEV) infection, leading to chronicity. We review the incidence, sequela, extrahepatic manifestations, and treatment of hepatitis due to HEV infection in allogeneic hematopoietic stem cell transplantation (alloHSCT) recipients.

RECENT FINDINGS

HEV infection and progression to chronic HEV in alloHSCT recipients are recently described. Misdiagnosis of HEV in alloHSCT recipients occurs, with liver enzyme abnormalities often attributed to hepatic graft-versus-host disease or drug-induced liver injury. HEV infection may occur in HSCT donors and emphasizes the need for HEV screening not only after HSCT, but also in donors presenting with liver function disturbances. The discussion about HEV screening of blood products will continue. Extrahepatic manifestations of hepatitis E are described.

SUMMARY

HEV RNA screening in alloHSCT recipients with elevated liver enzymes is advised. Intervention strategies should be considered in cases of acute or chronic HEV infection. The first-line approach includes reduction of immunosuppressive medication. Oral ribavirin is in experienced hands a reasonable well tolerated treatment option, although the optimal dose, duration, and quantitative goals of ribavirin treatment are still unknown. Further studies are needed to improve our understanding of HEV, including extrahepatic manifestations and evaluation of therapeutic options.

Prevalence and clinical consequences of Hepatitis E in patients who underwent liver transplantation for chronic Hepatitis C in the United States

Background

Infection with hepatitis E virus (HEV) in immunocompromised patients can lead to severe liver disease. Treatment options for HEV include peginterferon or ribavirin, routinely also used for the treatment of hepatitis C virus (HCV) infection.

We determined the prevalence and clinical consequences of HEV in United States (US) based patients who underwent liver transplantation (LT) for chronic HCV.

Methods

Seroprevalence of HEV in 145 US LT recipients with a history of chronic HCV was determined pre-LT, 1, 3 and 5 years post-LT. All last available samples and all samples in IgM positive patients and post-LT IgG seroconverters were tested for HEV RNA.

Results

Overall anti-HEV seroprevalence was 42 %. Five patients were HEV IgM positive pre-LT, one patient had IgM seroconversion post-LT and eight patients had IgG seroconversion post-LT. None of the tested samples were positive for HEV RNA. Eight out of nine of the post-LT seroconverters had been treated for HCV recurrence before or at the moment of seroconversion.

Conclusions

LT recipients in the US are at risk of acquiring HEV. Post-LT HCV treatment with interferons and/or ribavirin may have protected patients against chronic HEV. With the arrival of new direct antiviral agents for the treatment of HCV and the elimination of peginterferon and ribavirin from HCV treatment regimens, the prevalence of chronic HEV in this population may rise again.

Distribution and Molecular Characterization of Hepatitis E virus in Domestic Animals and Wildlife in Croatia

Hepatitis E is becoming a growing health concern in European countries as an increase of sporadic human cases of unknown origin has been recorded lately. Its causative agent, Hepatitis E virus (HEV), is known to have zoonotic potential and thus the role of domestic and wild animals in the chain of viral spread should be considered when investigating risk factors and the epidemiology of the disease. A comprehensive survey based on viral RNA detection was carried out in Croatia including blood, spleen and liver samples originating from 1816 different domestic and wild animals and digestive gland samples from 538 molluscs. A high HEV prevalence was detected in domestic pigs (24.5%) and wild boars (12.3%), whereas cattle, molluscs, ruminant and carnivore wildlife samples tested negative. Molecular characterization of both ORF1 and ORF2 genomic regions confirmed the phylogenetic clustering of the obtained sequences into genotype 3, previously reported in Europe. Furthermore, our results proved the presence of identical sequence variants in different samples, regardless of their origin, age or habitat of the host, suggesting transmission events between domestic swine, as well as between domestic swine and wild boars in the country. Moreover, a close genetic relationship of Croatian animal strains and known human HEV strains from GenBank opens the question of possible cross-species HEV transmission in Croatia, especially in the areas with an intensive swine production.

The high prevalence of hepatitis E virus infection in wild boars in Ibaraki Prefecture, Japan

Hepatitis E virus (HEV) is known as a causative agent of zoonosis and food poisoning. Pigs and some species of wild animals, including wild boar, are known to be a reservoir of HEV. In this study, we investigated the situation regarding HEV infection in wild boars in Ibaraki Prefecture, Japan. Serum, liver and feces samples from 68 animals were collected, and the presence or absence of HEV genomic RNA and HEV antibodies were analyzed. The viral genome was detected in samples from 7 (10.3%) animals, with all HEVs classified as genotype 3, subtype 3b. HEV antibodies were detected in samples from 28 (41%) animals. This report demonstrates for the first time the high prevalence of HEV infection in wild boars in Ibaraki Prefecture.

Detection and molecular characterization of zoonotic viruses in swine fecal samples in Italian pig herds

Gastrointestinal disease is frequent in pigs, and among the different etiological agents involved, viruses are considered the leading cause of infection in this animal species. Furthermore, about half of the newly identified swine pathogens are viruses, many of which may be transmitted to humans by direct contact or by indirect transmission pathways. In this study, the prevalence of astrovirus (AstV), group A rotavirus (RVA), norovirus (NoV) and hepatitis E virus (HEV) infections in pigs was investigated. During 2012-2014, 242 fecal samples were collected from pigs at different production stages (5 to 220 days old) on eight swine farms located in northern, central and southern Italy. Seven out of eight farms analyzed were positive for AstV, which was detected in 163 out of 242 (67.4%) samples and was the most prevalent virus; 61 of the 163 AstV-positive animals (37.4%) had diarrhea. HEV was detected on six farms and in 45 (18.6%) of the 242 samples analyzed. Twenty-three HEV-infected pigs had diarrhea (51.1%). A lower prevalence was observed for RVA, which was found in 10 of the 242 samples (4.1%) from three positive farms, and diarrhea was present only in six infected pigs (60.0%). No swine samples were found to be positive for NoV. Genetic diversity and phylogenetic relationships of some strains representative of the different viruses detected were investigated, confirming a wide heterogeneity of viral strains circulating among pigs.

Prevalence of hepatitis viruses in patients with acute hepatitis and characterization of the detected genotype 4 hepatitis E virus sequences in Mongolia

Hepatitis E is considered to be a worldwide public health problem. Although the prevalence of hepatitis E virus (HEV) antibodies in healthy individuals is noted to be 11%, no patients with acute hepatitis E have previously been identified in Mongolia. Three hundred two consecutive patients (183 males and 119 females; median age of 22.0 [Interquartile range: 18.3-25.0] years) who were clinically diagnosed with sporadic acute hepatitis during 2012-2013 in Ulaanbaatar, Mongolia, were studied. By serological and/or molecular approaches, 77 (25.5%), 93 (30.8%), 19 (6.3%), 48 (15.9%), and 12 (4.0%) of the patients were diagnosed with acute hepatitis of types A, B, C, D (superinfection of hepatitis delta virus on a background of chronic hepatitis B virus infection) and E, respectively, while the cause of hepatitis was unknown in the remaining 53 patients (17.5%). The 12 hepatitis E patients had no history of travel abroad in the 3 months before the onset of disease, and lived separately in fixed or movable houses with water supplied via pipe, tank or well, denying transmission from a common water supply. The 12 HEV isolates obtained from the patients showed high nucleotide identities of 99.7-100%, and a representative HEV isolate, MNE13-227, was closest to the Chinese isolates of genotype 4, with the highest identity of 97.3% in the 304-nt ORF2 sequence and 92.1% over the entire genome. The present study revealed the occurrence of autochthonous acute hepatitis E in Mongolia, caused by a monophyletic genotype 4 HEV strain.

The hepatitis E virus ORF1 'X-domain' residues form a putative macrodomain protein/Appr-1″-pase catalytic-site, critical for viral RNA replication

The hepatitis E virus (HEV) ORF1 gene encodes the non-structural polyprotein wherein the 'X-domain' still remains poorly defined. Cellular X-domain associated macrodomain protein/ADP-ribose-1″-monophosphatase (Appr-1″-pase) activities are also reported in coronaviruses (CoV), including identification of its homologs in alpha and rubella viruses. The present study investigated the role(s) of X-domain residues in HEV replication cycle. In silico analysis showed a high degree of evolutionary conservation of X-domain (a.a. 785-942) a.a. positions wherein the N-terminus residues 'Asn806, Asn809, His812, Gly815, Gly816, and Gly817' formed a potential catalytic-site homolog of CoVAppr-1″-pase. To experimentally test this prediction, X-domain 'active-site' residues were subjected to mutational analysis using the HEV-SAR55 replicon (pSK-GFP). FACS analysis of mutant RNA transfected S10-3 cells showed that Gly816Ala and Gly817Ala constructs completely abrogated HEV replication, similar to their Gly816Val and Gly817Val counterparts. However, 'Gly815Ala' mutant replicated very poorly in contrast to 'Gly815Val' that completely abolished GFP synthesis. Furthermore, while 'Asn806Ala' mutant retained RNA replication, the 'Asn809Ala' and His812Leu mutants showed non-viability. Notably, in a sequential-nucleotide mutation analysis, the dispensability of X-domain in HEV replication at transcriptional level has already been demonstrated (Parvez, 2013b). Taken together, the present data strongly argue for an essential role of X-domain residues (Asn809, His812, Gly816 and Gly817) at post-translational level, indicating its involvement in viral replication. In conclusion, the speculated regulatory role of ORF1 X-domain in HEV replication cycle critically depends on the 'Asn, Asn, His, Gly, Gly, Gly' segment/secondary structure. Nevertheless, further biochemical or biophysical characterizations of HEV X-domain associated Appr-1″-pase activity would only confirm its biological significance in virus or host-pathogenesis.

Full genome analysis of a European-type genotype 3 hepatitis E virus variant obtained from a Japanese patient with autochthonous acute hepatitis E

A unique European-type HEV strain (HE-JA12-0725) classifiable into subgenotype 3f was recovered from a 66-year-old Japanese female with autochthonous acute hepatitis E, and its entire genomic sequence was determined and characterized. The HE-JA12-0725 strain shared the highest identity of 92.7% with a Spanish swine isolate (EU723514) over the entire genome and possessed a long hypervariable region sequence of 111 amino acids, identical to the 3f strains of European origin. The patient had consumed pork liver obtained via home delivery in Japan approximately two months before the disease onset. These results suggest the circulation of rare 3f HEV strains in Japan.

Current Knowledge on Hepatitis E

Although only a single serotype of hepatitis E virus (HEV), the causative agent of hepatitis E, has been identified, there is great genetic variation among the different HEV isolates reported. There are at least four major recognized genotypes of HEV: genotypes 1 and 2 are mainly restricted to humans and linked to epidemic outbreaks in nonindustrialized countries, whereas genotypes 3 and 4 are zoonotic in both developing and industrialized countries. Besides human strains, genotype 3 and 4 strains of HEV have been genetically characterized from swine, sika deer, mongooses, sheep, and rabbits. Currently, there are approximately 11,000 human and animal sequences of HEV available at the International Nucleotide Sequence Database Collaboration. HEV is the major cause of waterborne outbreaks of hepatitis in areas of poor sanitation. Additionally, it is responsible for sporadic cases of viral hepatitis in not only endemic but industrialized countries as well. Transmission of HEV occurs predominantly by the fecal-oral route, although parenteral and perinatal routes have been reported. HEV infection develops in most individuals as a self-limiting, acute, icteric hepatitis; with mortality rates around 1%. However, some affected individuals will develop fulminant hepatic failure, a serious condition that is frequently fatal without a liver transplant. This complication is particularly common when the infection occurs in pregnant women, where mortality rates rise dramatically to up to 25%. Among the preventive measures available to avoid HEV infection, two separate subunit vaccines containing recombinant truncated capsid proteins of HEV have been shown to be highly effective in the prevention of disease. One of them, HEV 239, was approved in China, and its commercialization by Innovax began in November 2012 under the name Hecolin(®).

Hepatitis E virus in the countries of the Middle East and North Africa region: an awareness of an infectious threat to blood safety

PURPOSE

Hepatitis E virus (HEV) is mainly transmitted through contaminated water supplies which make the virus endemic in developing countries including countries of the Middle East and North Africa (MENA) region. Recent reports suggest potential risk of HEV transmission via blood transfusion.

METHODS

Related articles on HEV were collected by searching through the 25 countries of the MENA region using Pubmed and Medline within the past 14 years: January 2000-August 2014.

RESULTS

One hundred articles were extracted, of which 25 were not eligible. The articles discussed the seroprevalence of HEV and HEV markers in 12 countries. Eight articles provided data on HEV in blood donors. The seroprevalence of HEV in the general MENA population ranged from 2.0 to 37.5% and was higher in males than in females. Prevalence increased with age, but exposure seems to be in early life.

CONCLUSIONS

In the MENA region, the role of HEV as an infectious threat to blood safety is under-investigated. More data are needed to quantify the risk of transmission and to assess clinical outcomes. This requires, at least, surveillance screening of donors and recipients for HEV markers using sensitive and specific serological tests. At the present time, serious consideration should be given to selective screening for certain groups of patients (e.g., immunocompromised, pregnant women and others) who commonly require blood transfusion and are at high risk of hepatic failure or chronicity from HEV infection.

Effect of swine hepatitis E virus on the livers of experimentally infected Mongolian gerbils by swine hepatitis E virus

Previous studies have shown that hepatitis E virus (HEV) can be transmitted between rats, pigs, cattle, rabbits, chicken, cats, and deer. Because wild and domestic rodents have anti-HEV antibodies, they are considered potential reservoirs of HEV. In the current study, Mongolian gerbils were experimentally infected with swine hepatitis E virus and the effects of this infection were investigated. After inoculation with HEV, the liver-to-body weight ratio increased at 7 dpi. Mongolian gerbils demonstrated significant increase (p<0.05) in Aspartate Transaminase (AST), alanine transaminase (ALT) and total bilirubin (T-BIL) concentrations in the sera, and HEV IgG was detected at 21 days post-inoculation (dpi). Real-time PCR revealed that the copies of HEV RNA in the liver were detected at 7 dpi, and peaked at 28 dpi at a concentration of 7.73 logs g(-1). Using both light and electron microscopy, hepatic lesions were observed in the HEV inoculated animals. In the experimental group, characteristic viral hepatitis lesions were prominent in the liver. HEV antigen was detected in the liver by immunohistochemistry, and HEV ORF3 antigen was detectable in liver by Western blot. These results clearly demonstrate that viral load of HEV in livers was dynamic, and ultrastructural hepatic injury in HEV infected Mongolian gerbils and anti-HEV IgG positive seroconversion were observed during infection.

A Comprehensive Study of Neutralizing Antigenic Sites on the Hepatitis E Virus (HEV) Capsid by Constructing, Clustering, and Characterizing a Tool Box

The hepatitis E virus (HEV) ORF2 encodes a single structural capsid protein. The E2s domain (amino acids 459-606) of the capsid protein has been identified as the major immune target. All identified neutralizing epitopes are located on this domain; however, a comprehensive characterization of antigenic sites on the domain is lacking due to its high degree of conformation dependence. Here, we used the statistical software SPSS to analyze cELISA (competitive ELISA) data to classify monoclonal antibodies (mAbs), which recognized conformational epitopes on E2s domain. Using this novel analysis method, we identified various conformational mAbs that recognized the E2s domain. These mAbs were distributed into 6 independent groups, suggesting the presence of at least 6 epitopes. Twelve representative mAbs covering the six groups were selected as a tool box to further map functional antigenic sites on the E2s domain. By combining functional and location information of the 12 representative mAbs, this study provided a complete picture of potential neutralizing epitope regions and immune-dominant determinants on E2s domain. One epitope region is located on top of the E2s domain close to the monomer interface; the other is located on the monomer side of the E2s dimer around the groove zone. Besides, two non-neutralizing epitopes were also identified on E2s domain that did not stimulate neutralizing antibodies. Our results help further the understanding of protective mechanisms induced by the HEV vaccine. Furthermore, the tool box with 12 representative mAbs will be useful for studying the HEV infection process.

Inhibition of hepatitis E virus replication by peptide-conjugated morpholino oligomers

Hepatitis E virus (HEV) infection is a cause of hepatitis in humans worldwide and has been associated with a case-fatality rate of up to 30% in pregnant women. Recently, persistent and chronic HEV infections have been recognized as a serious clinical problem, especially in immunocompromised individuals. To date, there are no FDA-approved HEV-specific antiviral drugs. In this study, we evaluated antisense peptide-conjugated morpholino oligomers (PPMO) designed against HEV genomic sequences as potential HEV-specific antiviral compounds. Two genetically-distinct strains of human HEV, genotype 1 Sar55 and genotype 3 Kernow-C1, isolated from patients with acute and chronic hepatitis, respectively, were used to evaluate inhibition of viral replication by PPMO in liver cells. The anti-HEV PPMO produced a significant reduction in the levels of HEV RNA and capsid protein, indicating effective inhibition of HEV replication. PPMO HP1, which targets a highly conserved sequence in the start site region of ORF1, was also effective against the genotype 3 Kernow-C1 strain in stably-infected HepG2/C3A liver cells. The antiviral activity observed was specific, dose-responsive and potent, suggesting that further exploration of PPMO HP1 as a potential HEV-specific antiviral agent is warranted.

A novel linear neutralizing epitope of hepatitis E virus

Hepatitis E virus (HEV) is a serious public health problem that causes acute hepatitis in humans and is primarily transmitted through fecal and oral routes. The major anti-HEV antibody responses are against conformational epitopes located in a.a. 459-606 of HEV pORF2. All reported neutralization epitopes are present on the dimer domain constructed by this peptide. While looking for a neutralizing monoclonal antibody (MAb)-recognized linear epitope, we found a novel neutralizing linear epitope (L2) located in a.a. 423-437 of pORF2. Moreover, epitope L2 is proved non-immunodominant in the HEV-infection process. Using the hepatitis B virus core protein (HBc) as a carrier to display this novel linear epitope, we show herein that this epitope could induce a neutralizing antibody response against HEV in mice and could protect rhesus monkeys from HEV infection. Collectively, our results showed a novel non-immunodominant linear neutralizing epitope of hepatitis E virus, which provided additional insight of HEV vaccine.

Hepatitis E virus genotype 3 diversity: phylogenetic analysis and presence of subtype 3b in wild boar in Europe

An increasing number of indigenous cases of hepatitis E caused by genotype 3 viruses (HEV-3) have been diagnosed all around the word, particularly in industrialized countries. Hepatitis E is a zoonotic disease and accumulating evidence indicates that domestic pigs and wild boars are the main reservoirs of HEV-3. A detailed analysis of HEV-3 subtypes could help to determine the interplay of human activity, the role of animals as reservoirs and cross species transmission. Although complete genome sequences are most appropriate for HEV subtype determination, in most cases only partial genomic sequences are available. We therefore carried out a subtype classification analysis, which uses regions from all three open reading frames of the genome. Using this approach, more than 1000 published HEV-3 isolates were subtyped. Newly recovered HEV partial sequences from hunted German wild boars were also included in this study. These sequences were assigned to genotype 3 and clustered within subtype 3a, 3i and, unexpectedly, one of them within the subtype 3b, a first non-human report of this subtype in Europe.

Analysis of complete genome sequences and a V239A substitution in the helicase domain of swine hepatitis E virus strains isolated in Canada

Among Canadian swine HEV strains, only one complete genome sequence has been published so far, and there are no data on the virulence of these strains. A collection of 28 Canadian swine HEV strains was used in this study. After RNA extraction, a portion of ORF2, the 3' end of the helicase domain, and two complete genomes were amplified and sequenced. These two new Canadian complete genomes belonged to two different subtypes and showed 87.5 and 87.7% sequence identity to the Canadian swine HEV strain Arkell. The V239A substitution within the helicase domain, which is associated with increased virulence of genotype 3 HEV, was detected in one Canadian swine HEV strain. However, no human hepatitis E infections have been associated with this strain.

Enhanced mucosal immune responses induced by a combined candidate mucosal vaccine based on Hepatitis A virus and Hepatitis E virus structural proteins linked to tuftsin

Hepatitis A virus (HAV) and Hepatitis E virus (HEV) are the most common causes of infectious hepatitis. These viruses are spread largely by the fecal-oral route and lead to clinically important disease in developing countries. To evaluate the potential of targeting hepatitis A and E infection simultaneously, a combined mucosal candidate vaccine was developed with the partial open reading frame 2 (ORF2) sequence (aa 368–607) of HEV (HE-ORF2) and partial virus protein 1 (VP1) sequence (aa 1–198) of HAV (HA-VP1), which included the viral neutralization epitopes. Tuftsin is an immunostimulatory peptide which can enhance the immunogenicity of a protein by targeting it to macrophages and dendritic cells. Here, we developed a novel combined protein vaccine by conjugating tuftsin to HE-ORF2 and HA-VP1 and used synthetic CpG oligodeoxynucleotides (ODNs) as the adjuvant. Subsequent experiments in BALB/c mice demonstrated that tuftsin enhanced the serum-specific IgG and IgA antibodies against HEV and HAV at the intestinal, vaginal and pulmonary interface when delivered intranasally. Moreover, mice from the intranasally immunized tuftsin group (HE-ORF2-tuftsin + HA-VP1-tuftsin + CpG) showed higher levels of IFN-γ-secreting splenocytes (Th1 response) and ratio of CD4⁺/CD8⁺ T cells than those of the no-tuftsin group (HE-ORF2 + HA-VP1 + CpG). Thus, the tuftsin group generated stronger humoral and cellular immune responses compared with the no-tuftsin group. Moreover, enhanced responses to the combined protein vaccine were obtained by intranasal immunization compared with intramuscular injection. By integrating HE-ORF2, HA-VP1 and tuftsin in a vaccine, this study validated an important concept for further development of a combined mucosal vaccine against hepatitis A and E infection.

The intergenic-junction variant (genotype 2 isolate) of hepatitis E virus restores the CREX 'stem-loop' structural integrity, essential for viral life cycle

Among the known human HEV strains (genotypes 1, 2, 3 and 4), the genotype 2 Mexican isolate has two 'double-base' substitutions (5'U5100G5101→CU/3'C5117U5118→GG) flanking the conserved cis-reactive element (CRE) in the intergenic-junction sequences. While the 'C5100U5101' natural mutations in the upstream ORF1 coding region replace 'alanine' for the conserved 'valine', the 'G5117G5118' doublet resides in the downstream non-coding/promoter region of ORF3 gene. Though a stable 'stem-loop' structure containing CRE, critical for virus replication had been reported, the phenotypic effect of genotype 2 'CU/GG' variations were neither mentioned nor explored. In this study, the evolutionary significance of such tolerable mutations in the conserved regulatory-sequences was investigated. Multiple sequence alignment of intergenic-junction of human HEV strains showed further base conservations flanking the CRE sequences. In silico analysis of the conserved sequences (nts. 5099-5121) of the representative genotypes revealed a stable RNA 'stem-loop' structure (CREX). Of the four genotype-specific CREX, the Mexican mutant bases 'CU/GG' very interestingly, compensated and complemented themselves (5'C5100:3'G5118 and 5'U5101:3'G5117) in the 'lower-stem'. The substitution of 'GG' bases in the ORF3 promoter-region did not affect its 'optimal-context' and therefore, negated its regulatory role at 'nucleotide' level. Virtual mutations introduced to break the two base-pairings in the CREX 'lower-stem', completely destabilized the secondary structure. Further molecular characterization of the CREX mutants in HEV-SAR55 replicon background showed a drastic downregulation of viral RNA replication in S10-3 cells. Though the CREX-mutant RNA were encapsidated into trans-complemented viral capsids (ORF2), and produced virions, they were poorly infectious to naïve HepG2/C3A cells. In conclusion, the compensatory mutations in the intergenic-junction of Mexican isolate suggest strict conservation of the CREX 'stem-loop' structure, essential for HEV genome replication. This could have a greater regulatory role in viral life cycle, including RNA packaging.

New insights into hepatitis E virus virus–host interaction: interplay with host interferon induction

ABSTRACT 

Hepatitis E virus (HEV) is a fecal–oral-transmitted viral pathogen causing several large outbreaks of hepatitis across the world. HEV-mediated hepatitis has a mortality rate from 0.5 to 3% in young adults but is up to 30% in pregnant women. HEV is also a zoonotic pathogen as it has been isolated from different mammalian hosts including the pig, rabbit, rat, ferret, bat and deer. As an invading pathogen, HEV needs to overcome the host innate immune response to establish infection. Notable progress has been recently made in HEV mechanisms of antagonizing the host innate immune responses. In this review, we elaborate on the HEV interplay with host interferon induction while briefly summarizing the major aspects of HEV biology and host interferon induction to assist the understanding of the virus–host interaction.

Structural basis for the neutralization of hepatitis E virus by a cross-genotype antibody

Hepatitis E virus (HEV), a non-enveloped, positive-sense, single-stranded RNA virus, is a major cause of enteric hepatitis. Classified into the family Hepeviridae, HEV comprises four genotypes (genotypes 1-4), which belong to a single serotype. We describe a monoclonal antibody (mAb), 8G12, which equally recognizes all four genotypes of HEV, with ∼ 2.53-3.45 nM binding affinity. The mAb 8G12 has a protective, neutralizing capacity, which can significantly block virus infection in host cells. Animal studies with genotypes 1, 3 and 4 confirmed the cross-genotype neutralizing capacity of 8G12 and its effective prevention of hepatitis E disease. The complex crystal structures of 8G12 with the HEV E2s domain (the most protruded region of the virus capsid) of the abundant genotypes 1 and 4 were determined at 4.0 and 2.3 Å resolution, respectively. These structures revealed that 8G12 recognizes both genotypes through the epitopes in the E2s dimerization region. Structure-based mutagenesis and cell-model assays with virus-like particles identified several conserved residues (Glu549, Lys554 and Gly591) that are essential for 8G12 neutralization. Moreover, the epitope of 8G12 is identified as a key epitope involved in virus-host interactions. These findings will help develop a common strategy for the prevention of the most abundant form of HEV infection.

Characterization of Two Novel Linear B-Cell Epitopes in the Capsid Protein of Avian Hepatitis E Virus (HEV) That Are Common to Avian, Swine, and Human HEVs

Antisera raised against the avian hepatitis E virus (HEV) capsid protein are cross-reactive with human and swine HEV capsid proteins. In this study, two monoclonal antibodies (MAbs) against the avian HEV capsid protein, namely, 3E8 and 1B5, were shown to cross-react with the swine HEV capsid protein. The motifs involved in binding both MAbs were identified and characterized using phage display biopanning, peptide synthesis, and truncated or mutated protein expression, along with indirect enzyme-linked immunosorbent assay (ELISA) and Western blotting. The results showed that the I/VPHD motif is a necessary core sequence and that P and H are two key amino acids for recognition by MAb 3E8. The VKLYM/TS motif is the minimal amino acid sequence necessary for recognition by MAb 1B5. Cross-reactivity between the two epitopes and antibodies against avian, swine, and human HEVs in sera showed that both epitopes are common to avian, swine, and human HEVs. In addition, amino acid sequence alignment of the capsid proteins revealed that the key motifs of both novel epitopes are the same in HEVs from different animal species, predicting that they may be common to HEV isolates from boars, rabbits, rats, ferrets, mongooses, deer, and camels as well. Protein modeling analysis showed that both epitopes are at least partially exposed on the surface of the HEV capsid protein. Protective capacity analysis demonstrated that the two epitopes are nonprotective against avian HEV infection in chickens. Collectively, these studies characterize two novel linear B-cell epitopes common to avian, swine, and human HEVs, which furthers the understanding of HEV capsid protein antigenic structure.

IMPORTANCE

More and more evidence indicates that the host range diversity of hepatitis E virus (HEV) is a global public health concern. A better understanding of the antigenic structure of the HEV capsid protein may improve disease diagnosis and prevention. In this study, binding site mapping and localization as well as the antigenic biology of two novel linear B-cell epitopes common to several different species of HEV were characterized. These findings partially reveal the antigenic structure of the HEV capsid protein and provide potential applications for the development of diagnostics and interventions for HEV infection.

Hepatitis E virus: chronic infection, extra-hepatic manifestations, and treatment

Hepatitis E virus (HEV) infection is a worldwide disease. An improved understanding of the natural history of HEV infection has been achieved within the last decade. Several reservoirs and transmission modes have been identified. It is an underdiagnosed disease because of the use of low-sensitivity serological assays; however, diagnostics tools, including nucleic-acid tests, have improved. HEV infection is usually an acute self-limiting disease, but causes chronic infection with rapidly progressive cirrhosis in adult and pediatric organ-transplant-patients. HEV infection evolves to chronic hepatitis in nearly 60% of HEV-infection solid-organ-transplant patients. HEV can also cause extra-hepatic manifestations, such as neurological symptoms and kidney injury. Reducing immunosuppression in transplant patients can lead to HEV clearance in one-third of patients with chronic hepatitis. The use of anti-viral therapies, such as pegylated-interferon and ribavirin, has been found to efficaciously treat HEV infection.

A valuable antigen detection method for diagnosis of acute hepatitis E

Hepatitis E virus (HEV) is a serious public health problem. The commonly used tests that are specific for current HEV infection diagnosis include the detection of anti-HEV IgM and HEV RNA. Here, we report an improved enzyme-linked immunosorbent assay (ELISA) method for HEV antigen detection with a linear range equivalent to 6.3 × 10(3) to 9.2 × 10(5) RNA copies per ml. The monoclonal antibody (MAb) 12F12, a high-ability MAb that binds HEV virus, was selected as the capture antibody from a panel of 95 MAbs. The positive period of HEV antigenemia in infected monkeys using this test was, on average, 3 weeks longer than previously reported and covered the majority of the acute phase. The positive detection rates of IgM, RNA, and new antigen from the first serum samples collected from 16 confirmed acute hepatitis E patients were 81% (13/16), 81% (13/16), and 100% (16/16), respectively. In three patients, the initial serum specimens that tested negative for IgM, despite the presence of symptoms of acute hepatitis and elevated alanine aminotransferase (ALT) levels, were positive for HEV antigen and HEV RNA. In contrast, the serum samples of the three RNA-negative patients were antigen positive (and IgM positive), possibly due to the degradation of HEV nucleic acids. Our results suggest that this new antigen detection method has acceptable concordance with RNA detection and could serve as an important tool for diagnosing acute hepatitis E.

Natural and experimental hepatitis E virus genotype 3-infection in European wild boar is transmissible to domestic pigs

Hepatitis E virus (HEV) is the causative agent of acute hepatitis E in humans in developing countries, but sporadic and autochthonous cases do also occur in industrialised countries. In Europe, food-borne zoonotic transmission of genotype 3 (gt3) has been associated with domestic pig and wild boar. However, little is known about the course of HEV infection in European wild boar and their role in HEV transmission to domestic pigs. To investigate the transmissibility and pathogenesis of wild boar-derived HEVgt3, we inoculated four wild boar and four miniature pigs intravenously. Using quantitative real-time RT-PCR viral RNA was detected in serum, faeces and in liver, spleen and lymph nodes. The antibody response evolved after fourteen days post inoculation. Histopathological findings included mild to moderate lymphoplasmacytic hepatitis which was more prominent in wild boar than in miniature pigs. By immunohistochemical methods, viral antigens were detected mainly in Kupffer cells and liver sinusoidal endothelial cells, partially associated with hepatic lesions, but also in spleen and lymph nodes. While clinical symptoms were subtle and gross pathology was inconspicuous, increased liver enzyme levels in serum indicated hepatocellular injury. As the faecal-oral route is supposed to be the most likely transmission route, we included four contact animals to prove horizontal transmission. Interestingly, HEVgt3-infection was also detected in wild boar and miniature pigs kept in contact to intravenously inoculated wild boar. Given the high virus loads and long duration of viral shedding, wild boar has to be considered as an important HEV reservoir and transmission host in Europe.

A novel k-word relative measure for sequence comparison

In order to extract phylogenetic information from DNA sequences, the new normalized k-word average relative distance is proposed in this paper. The proposed measure was tested by discriminate analysis and phylogenetic analysis. The phylogenetic trees based on the Manhattan distance measure are reconstructed with k ranging from 1 to 12. At the same time, a new method is suggested to reduce the matrix dimension, can greatly lessen the amount of calculation and operation time. The experimental assessment demonstrated that our measure was efficient. What's more, comparing with other methods' results shows that our method is feasible and powerful for phylogenetic analysis.

Evidence of hepatitis E infection in swine and humans in the East Region of Romania

OBJECTIVE

Swine hepatitis E virus (HEV) is considered to be a new zoonotic agent due to its close genomic resemblance to the human HEV. The aim of this study was to determine human HEV seroprevalence in eastern Romania and to characterize circulating swine HEV sequences.

METHODS

Serological investigations of human serum samples were done using a commercial ELISA kit (MP Biomedicals). Swine faecal samples were tested to detect the HEV ORF2 sequence by nested reverse transcription PCR.

RESULTS

One hundred and forty-eight human serum samples were tested for anti-HEV IgG of which 22 were found to be positive. Fresh swine faeces (pools) were collected from five farms in eastern Romania. Six out of 19 pooled samples were positive for HEV RNA. Phylogenetic analysis based on alignment of the ORF2 sequence indicated that the Romanian swine HEV isolates belonged to genotype 3.

CONCLUSIONS

This is the first study showing HEV to be present in Romanian pig herds and that the human population is exposed.

Serological and virological survey of hepatitis E virus in wild boar populations in northwestern Italy: detection of HEV subtypes 3e and 3f

Although rare in developed countries, most acquired human cases of hepatitis E virus (HEV) infection are associated with travel to developing countries where HEV is endemic. Increasingly, however, sporadic, non-travel-related HEV cases have been reported in developed countries. In Italy, only two studies to date have investigated the presence of HEV in wild boars. Here, we report a serological and virological survey of HEV in wild boar populations in northwestern Italy. During the hunting season, 594 serum and 320 liver samples were collected and screened for antibodies to HEV and HEV RNA. Overall, the seroprevalence was 4.9 %, and HEV RNA was detected in 12 liver samples (p = 3.7 %). No serum samples tested positive for HEV RNA. Phylogenetic analysis of the ORF2 region revealed that the isolates clustered within genotype 3, subtypes 3e and 3f, and were closely related to HEV strains previously detected in domestic pigs farmed in the same geographic area. Although the routes of viral transmission are still poorly understood, our data show that HEV genotypes 3e and 3f circulate in wild boars in northwestern Italy. Also, they provide evidence that autochthonous HEV infections in Italy could also be linked to wild boar populations, suggesting an increased risk for domestically acquired HEV infection in humans through wild animals. The HEV sequences determined in this study may be useful for comparing present and future human isolates to identify transmission events between wild boar, humans, and farmed pigs. Similarly to other more commonly known zoonotic agents, HEV should be included in national or regional disease surveillance programs for wild animals.

Characterization of sporadic acute hepatitis E and comparison of hepatitis E virus genomes in acute hepatitis patients and pig liver sold as food in Mie, Japan

AIM

To characterize hepatitis E in Mie prefecture and to investigate whether raw pig liver sold as food in Mie is contaminated with hepatitis E virus (HEV) strains similar to those recovered from patients.

METHODS

Seventeen patients with sporadic acute hepatitis E treated from 2004 to 2012 were studied. A total of 243 packages of raw pig liver from regional grocery stores were tested for the presence of HEV RNA. The partial genomic sequences of human and swine HEV isolates were determined and subjected to the phylogenetic analyses.

RESULTS

The HEV isolates recovered from the 17 patients segregated into genotype 3 (n = 15) and genotype 4 (n = 2), and 15 genotype 3 isolates further segregated into 3e (n = 11) and 3b (n = 4). Pig liver specimens from 12 (4.9%) of the 243 packages had detectable HEV RNA. All 12 swine HEV isolates were grouped into genotype 3 (3a or 3b). Although no 3e strains were isolated from pig liver specimens, two 3b swine strains were 99.5-100% identical to two HEV strains recovered from hepatitis patients, within 412-nt partial sequences.

CONCLUSION

The 3e HEV was prevalent among hepatitis E patients. HEV RNA was detected in approximately 5% of pig liver sold as food. The presence of identical HEV strains between hepatitis patients and pig liver indicated that pigs play an important role as reservoirs for HEV in humans in Mie. Further studies are needed to clarify the source of 3e HEV in the animal and environmental reservoirs.

Current epidemiology of hepatitis E virus infection in the United States: low seroprevalence in the National Health and Nutrition Evaluation Survey

Analysis of the National Health and Nutrition Evaluation Survey (NHANES) 1988-1994 dataset found a relatively high seroprevalence (21%) of hepatitis E virus (HEV) infection in the U.S. general population. Using data obtained within the NHANES 2009-2010 survey, where a high performance assay for HEV was used, we estimated the weighted seroprevalence of HEV infection among U.S. individuals 6 years and older. We also evaluated factors associated with HEV seropositivity. A total of 8,814 individuals were included in the analysis. The median age of study participants was 37 years (interquartile range [IQR] 17-58 years), with 51.2% being female. The weighted national seroprevalence of HEV was 6% (95% confidence interval [CI] 5.1%-6.9%). About 0.5% of those with HEV had evidence of recent exposure (immunoglobulin M-positive). In the univariate analyses, factors associated with HEV seropositivity were increasing age (P-trend<0.001), birth outside of the U.S., Hispanic race, and "meat" consumption (>10 times/month). No significant association was observed with low socioeconomic status, water source, or level of education. In the multivariate analysis, only older age remained predictive of HEV seropositivity.

CONCLUSION

The weighted national seroprevalence of HEV in the U.S. is much less than previously reported. Using data obtained with a high performance assay, the seroprevalence of HEV was estimated at 6.0% in the U.S. Based on these results, the seroprevalence of HEV is only one-third as high as previously reported.