Genetic variability and the classification of hepatitis E virus. J Virol. 2013;87:4161-4169. [PMID: 23388713 DOI: 10.1128/jvi.02762-12]

Relevance of Tacrolimus Trough Concentration and Hepatitis E virus Genetic Changes in Kidney Transplant Recipients With Chronic Hepatitis E

Introduction

Hepatitis E virus (HEV) can cause chronic infection (≥3 months) and cirrhosis in immunocompromised patients, especially kidney transplant recipients. Low alanine aminotransferase (ALT) levels and high HEV intrahost diversity have previously been associated with evolution toward chronicity in these patients. We hypothesized that additional clinical and viral factors could be associated with the risk of chronic HEV infection.

Methods

We investigated a series of 27 kidney transplant recipients with HEV infection, including 20 patients with chronic hepatitis E.

Results

High tacrolimus trough concentration at diagnosis was the most relevant marker associated with chronic hepatitis E (9.2 vs. 6.4 ng/ml, P = 0.04). Most HEV genetic changes selected during HEV infection were compartmentalized between plasma and feces.

Conclusion

This compartmentalization highlights the diversity and complexity of HEV replication compartments. Tacrolimus trough concentration at diagnosis of HEV infection could allow an early identification of patients at high risk of chronic hepatitis E and guide treatment initiation.

First Seroepidemiological Investigation of Hepatitis E Virus Infection in Backyard Pigs from Northeastern India: Prevalence and Associated Risk Factors

Hepatitis E virus (HEV) is the leading cause of acute viral hepatitis globally, with zoonotic potential, and pigs are considered the major reservoir. To determine the seroprevalence of HEV infection in pigs reared in backyard conditions in the northeastern region of India, blood samples were collected from 400 pigs from five northeastern states (80 samples from each state) and tested for IgG antibodies against HEV using an ELISA assay. Questionnaires on farm characteristics and management practices were completed, and risk factors associated with HEV were studied using univariate and multivariate analysis. The apparent seroprevalence of HEV infection was 51% (46.1-55.9, 95% CI), with a true prevalence of 52.98% (47.22-58.75, 95% CI). The risk factors significantly associated with higher HEV seropositivity were as follows: lack of disinfection (OR 4.65), feeding swill (restaurant and bakery waste) (OR 2.55), failure to follow the all-in-all-out production system (OR 3.47), and medium holding size (OR 9.83), which refers to mixed rearing of younger and older age groups. This study demonstrates that HEV is widespread among pigs reared in northeastern India. The risk factor analysis conducted in this study provides valuable insights into the prevalence of HEV in the region.

Hepatitis E Virus Seroprevalence and Associated Risk Factors in Pregnant Women Attending Antenatal Consultations in Senegal

In West Africa, research on the hepatitis E virus (HEV) is barely covered, despite the recorded outbreaks. The low level of access to safe water and adequate sanitation is still one of the main factors of HEV spread in developing countries. HEV infection induces acute or sub-clinical liver diseases with a mortality rate ranging from 0.5 to 4%. The mortality rate is more alarming (15 to 25%) among pregnant women, especially in the last trimester of pregnancy. Herein, we conducted a multicentric socio-demographic and seroepidemiological survey of HEV in Senegal among pregnant women. A consecutive and non-redundant recruitment of participants was carried out over the period of 5 months, from March to July 2021. A total of 1227 consenting participants attending antenatal clinics responded to a standard questionnaire. Plasma samples were collected and tested for anti-HEV IgM and IgG by using the WANTAI HEV-IgM and IgG ELISA assay. The overall HEV seroprevalence was 7.8% (n = 96), with 0.5% (n = 6) and 7.4% (n = 91) for HEV IgM and HEV IgG, respectively. One of the participant samples was IgM/IgG-positive, while four were declared indeterminate to anti-HEV IgM as per the manufacturer’s instructions. From one locality to another, the seroprevalence of HEV antibodies varied from 0 to 1% for HEV IgM and from 1.5 to 10.5% for HEV IgG. The data also showed that seroprevalence varied significantly by marital status (p < 0.0001), by the regularity of income (p = 0.0043), and by access to sanitation services (p = 0.0006). These data could serve as a basis to setup national prevention strategies focused on socio-cultural, environmental, and behavioral aspects for a better management of HEV infection in Senegal.

Hepatitis E: Genotypes, strategies to prevent and manage, and the existing knowledge gaps

Hepatitis E virus (HEV) is considered an emergent source of viral hepatitis worldwide, with an increasing burden of jaundice, liver failure, extrahepatic illnesses, and deaths in developed countries. With the scarcity of data from efficient animal models, there are still open-ended questions about designing new models to study pathogenesis, types, virology, and evolution of these viruses. With an emphasis on available data and updates, there is still enough information to understand the HEV life cycle, pathogen interaction with the host, and the valuation of the role of vaccine and new anti-HEV therapies. However, the World Health Organization (WHO) and the European Association for the Study of the Liver (EASL) preferred to stress prevention and control measures of HEV infections in animals, zoonotic transmission, and foodborne transmission. It is being reviewed that with current knowledge on HEV and existing prevention tools, there is an excellent room for in-depth information about the virus strains, their replication, pathogenicity, and virulence. The current knowledge set also has gaps regarding standardized and validated diagnostic tools, efficacy and safety of the vaccine, and extrahepatic manifestations specifically in pregnant females, immunocompromised patients, and others. This review highlights the areas for more research exploration, focusing on enlisted research questions based on HEV infection to endorse the need for significant improvement in the current set of knowledge for this public health problem.

First molecular detection of hepatitis E virus genome in camel and pig faecal samples in Ethiopia

BACKGROUND

Hepatitis E is an enteric and zoonotic disease caused by hepatitis E virus (HEV) that is mainly transmitted via the faecal-oral route through contaminated food or the environment. The virus is an emerging infectious agent causing acute human infection worldwide. A high seroprevalence of the disease was reported in pregnant women in Addis Ababa, Ethiopia, raising significant public health concern. The presence of HEV specific antibodies were also reported in dromedary camels in the country; however, the infectious virus and/or the viral genome have not been demonstrated to date in animal samples.

METHODS

To address this gap, a total of 95 faecal samples collected from both apparently healthy pigs of uncharacterised types (50 samples) in Burayu and Addis Ababa areas and camels (Camelus dromedarius, 45 samples) in west Hararghe were screened for the presence of HEV genome using universal primers in a fully nested reverse transcription polymerase chain reaction (nRT-PCR). The protocol is capable of detecting HEV in faecal samples from both pigs and camels.

RESULTS

The nRT-PCR detected HEV genes in six (12%) pig faecal samples and one camel sample (2.2%). Therefore, the results indicate that HEV is circulating in both pigs and camels in Ethiopia and these animals and their products could serve as a potential source of infection for humans.

CONCLUSION

The detection of HEV in both animals could raise another concern regarding its public health importance as both animals' meat and camel milk are consumed in the country. Further studies to determine the prevalence and distribution of the virus in different animals and their products, water bodies, food chain, and vegetables are warranted, along with viral gene sequencing for detailed genetic characterisation of the isolates circulating in the country. This information is critically important to design and institute appropriate control and/or preventive measures.

A tightly clustered hepatitis E virus genotype 1a is associated with endemic and outbreak infections in Bangladesh

BACKGROUND

Hepatitis E virus (HEV) infection is endemic in Bangladesh and there are occasional outbreaks. The molecular characteristics and pathogenesis of endemic and outbreak HEV strains are poorly understood. We compared the genetic relatedness and virulence associated mutations of endemic HEV strains with outbreak strains.

METHODS

We analyzed systematically collected serum samples from HEV immunoglobulin M (IgM) positive patients attended at Bangabandhu Sheikh Mujib Medical University, Dhaka from August 2013 to June 2015. HEV RNA positive samples were subjected to whole genome sequencing. Genotype and subtype of the strains were determined by phylogenetic analysis. Virulence associated mutations e.g. acute viral hepatitis (AVH), fulminant hepatic failure (FHF), chronic hepatitis, ribavirin treatment failure (RTF), B and T cell neutralization epitopes were determined.

RESULTS

92 HEV immunoglobulin M (IgM) antibody positive plasma samples (43 in 2013-2014 and 49 in 2014-2015) were studied. 77.1% (70/92) of the samples were HEV RNA positive. A 279 bp open reading frame (ORF) 2 and ORF 3 sequence was obtained from 54.2% (38/70) of the strains. Of these 38 strains, whole genome sequence (WGS) was obtained from 21 strains. In phylogenetic analysis of 38 (279 bp) sequence all HEV sequences belonged to genotype 1 and subtype 1a. Further phylogenetic analysis of 21 HEV WGS, Bangladeshi HEV sequences clustered with genotype 1a sequences from neighboring countries. Within genotype 1a cluster, Bangladesh HEV strains formed a separate cluster with the 2010 HEV outbreak strains from northern Bangladesh. 80.9 to 100% of the strains had A317T, T735I, L1120I, L1110F, P259S, V1479I, G1634K mutations associates AVH, FHF and RTF. Mutations in T cell recognition epitope T3, T5, T7 was observed in 76.1%, 100% and 100% of the strains respectively.

CONCLUSION

Strains of HEV genotype 1a are dominant in Bangladesh and are associated with endemic and outbreak of HEV infection. HEV isolates in Bangladesh have high prevalence of virulence associated mutations and mutation which alters antigenicity to B and T cell epitopes.

Identification and genetic diversity of hepatitis E virus in domestic swine from Slovakia

Background

Hepatitis E virus (HEV) is agent causing hepatitis worldwide. Originally considered to be limited to developing countries, this virus was also detected in developed countries. In recent years an increasing number of reports indicate that farmed domestic pigs are widely infected with HEV in several European countries. The HEV status in Slovakia is still missing.

Results

In this study, the circulation of HEV among domestic swine in Slovakia and genetic diversity of the virus was studied. Overall HEV RNA was detected in 53/388 (13.7, 95% CI: 10.40–17.48%) pig rectal swabs in five production stages (age categories) with statistically significant differences among all the stages. The highest HEV prevalence was observed in weaners 24/81 (29.6, 95% CI: 19.99–40.81%) and then significantly declined in growers and fatteners. No HEV was detected in suckling piglets and sows. Twenty-eight partial sequences of ORF1 (242 bp) and seventeen of ORF2 (304 bp) were analysed. Phylogenetic analysis and p-distance comparisons confirmed in both ORFs that all Slovak HEV sequences belong to the genotype HEV-3, major clade 3abchij with higher identity to 3a and 3i subtypes. Three sequences were outside of all lastly updated HEV-3 subtypes.

Conclusion

This is the first report to fill the information gap about HEV infection in pigs in Slovakia. The results suggested a lower prevalence of HEV in Slovak pig farms than observed in other European countries. While most HEV isolates were typed as HEV-3 clade 3abchij, three sequences were unclassified.

Harmless or Threatening? Interpreting the Results of Molecular Diagnosis in the Context of Virus-Host Relationships

Molecular methods, established in the 1980s, expanded and delivered tools for the detection of vestigial quantities of nucleic acids in biological samples. Nucleotide sequencing of these molecules reveals the identity of the organism it belongs to. However, the implications of such detection are often misinterpreted as pathogenic, even in the absence of corroborating clinical evidence. This is particularly significant in the field of virology where the concepts of commensalism, and other benign or neutral relationships, are still very new. In this manuscript, we review some fundamental microbiological concepts including commensalism, mutualism, pathogenicity, and infection, giving special emphasis to their application in virology, in order to clarify the difference between detection and infection. We also propose a system for the correct attribution of terminology in this context.

Hepatitis E virus: Whole genome sequencing as a new tool for understanding HEV epidemiology and phenotypes

Hepatitis E Virus (HEV) is emerging as a public health concern across Europe and tools for complete genome data to aid epidemiological and virulence analysis are needed. The high sequence heterogeneity observed amongst HEV genotypes has restricted most analyses to subgenomic regions using PCR-based methods, which can be unreliable due to poor primer homology. We designed a panel of custom-designed RNA probes complementary to all published HEV full genome NCBI sequences. A target enrichment protocol was performed according to the NimbleGen® standard protocol for Illumina® library preparation. Optimisation of this protocol was performed using 40 HEV RNA-positive serum samples and the World Health Organization International Reference Panel for Hepatitis E Virus RNA Genotypes for Nucleic Acid Amplification Technique (NAT)-Based Assays and related reference materials. Deep sequencing using this target enrichment protocol resulted in whole genome consensus sequences from samples with a viral load range of 1.25 × 10⁴-1.17 × 10⁷ IU/mL. Phylogenetic analysis of these sequences recapitulated and extended the partial genome results obtained from genotyping by Sanger sequencing (genotype 1, ten samples and genotype 3, 30 samples). The protocol is highly adaptable to automation and could be used to sequence full genomes of large sample numbers. A more comprehensive understanding of hepatitis E virus transmission, epidemiology and viral phenotype prediction supported by an efficient method of sequencing the whole viral genome will facilitate public health initiatives to reduce the prevalence and mitigate the harm of HEV infection in Europe.

Serological prevalence and molecular characterization of hepatitis E virus in imported pigs in Singapore (2000-2019)

Hepatitis E is a significant liver disease caused by infection with hepatitis E virus (HEV). The risk factors for hepatitis E in developed countries include blood transfusion and ingestion of undercooked meat or meat products derived from HEV-infected animals. Since 2000, there has been increased human hepatitis E incidence reported in Singapore. Although the causes of this increase have not been established, several studies have linked zoonotic HEV infections in humans to pork consumption. It is therefore important to closely monitor the presence of HEV in food sources for the prevalence and virulence. In this study, we demonstrated the presence of HEV in pigs imported into Singapore for consumption through serological and molecular investigation of live pig and post-slaughter samples collected between 2000 and 2019. Among imported pigs, anti-HEV antibody prevalence remained at a level around 35% until 2017, with a statistically significant increase in 2018. HEV RNA was detected in 8.40% (34/405) of the faecal samples, indicative of an active infection in the pigs. HEV RNA was also detected in 6.67% (4/60) of liver samples obtained post-slaughter. We also report the development of an RT-PCR-based next-generation sequencing (NGS) method that enabled full sequencing of the HEV genome in HEV RNA-positive samples in a relatively short span of time. Phylogenetic analysis identified the HEV in one of the imported pigs (HEV-S28) as genotype 3a, which clustered together with the human HEV strains previously identified in Singapore. We found that the HEV-S28 strain exhibited amino acid substitutions that are associated with reduced HEV replication efficiency. The increase in anti-HEV seroprevalence in the pig population from 2018 is worth further exploration. We will continue to monitor the prevalent HEV strains and assess the genetic diversity of HEV in the imported pigs to confirm the potential association with human infections.

Increased risk of hepatitis E virus infection in workers occupationally exposed to sheep

Hepatitis E virus (HEV) is an enteric RNA virus from the family Hepeviridae with five genotypes (genotypes 1-4 and 7) known to infect humans. HEV infection is known to have a zoonotic swine origin in industrialized countries. The role of pigs and wild boars as major reservoirs for human infection is today well-established; however, the list of new animal reservoirs is ever-expanding as new HEV strains are continuously being found in a broad host range. The recent detection of HEV in sheep stools brings concerns on the possibility of HEV transmission from these animals to humans, particularly in those occupationally exposed. The present work investigated the potential occupational risk of HEV infection in shepherds and sheep milk cheesemakers-workers occupationally exposed to ovine (WOEOs; N = 96)-from a region of the Centre of Portugal ('Serra da Estrela') based on the differences of anti-HEV IgG seroprevalence rates between these professionals and the general population (N = 192). The presence of HEV-specific antibodies in sheep (N = 90) from the same region was also evaluated. The HEV seroprevalence in WOEOs (29.3%) was found to be significantly higher (p = .0198) when compared with population controls (16.1%) which suggests an increased risk for HEV infection in these workers. HEV-specific antibodies were also found in 16.6% of the studied sheep showing that HEV circulates in these animals. Further studies are needed to confirm the zoonotic potential of sheep HEV.

Virological analyses in collective catering outbreaks in France between 2012 and 2017

Enteric viruses cause the majority of foodborne illnesses and common symptoms of many foodborne illnesses include vomiting, diarrhea, abdominal pain, and fever. Among the enteric viruses, human Norovirus (NoV) and hepatitis virus (HAV and HEV) are the main viruses suspected to cause foodborne outbreaks and represent a serious public health. The study presents survey tools of viruses in a wide variety of foodstuffs and results obtained during 56 foodborne outbreaks investigation in France between 2012 and 2017. 246 suspected foods were examined for the presence of four human enteric viruses (NoV GI and NoV GII, HAV or HEV) either using methods described in the EN ISO 15216-1 or in house methods. All viral analysis of food samples were performed with the implementation of process control and an external amplification controls. Eighteen of 56 foodborne outbreaks investigated included at least one positive food sample (16/18 NoV, 1/18 HAV and 1/18 HEV). The genomic levels of four viruses detected ranged from < 10² to 10⁷ genome copies per g or per L. This study showed the interest to develop methods for the extraction of viruses in different foodstuffs to increase the possibility to identify the association between viral illness and food consumption.

A Novel Hepe-Like Virus from Farmed Giant Freshwater Prawn Macrobrachium rosenbergii

The family Hepeviridae includes several positive-stranded RNA viruses, which infect a wide range of mammalian species, chicken, and trout. However, few hepatitis E viruses (HEVs) have been characterized from invertebrates. In this study, a hepevirus, tentatively named Crustacea hepe-like virus 1 (CHEV1), from the economically important crustacean, the giant freshwater prawn Macrobrachium rosenbergii, was characterized. The complete genome consisted of 7750 nucleotides and had a similar structure to known hepatitis E virus genomes. Phylogenetic analyses suggested it might be a novel hepe-like virus within the family Hepeviridae. To our knowledge, this is the first hepe-like virus characterized from crustaceans.

HEV Occurrence in Waste and Drinking Water Treatment Plants

Hepatitis E virus (HEV), particularly zoonotic genotype 3, is present in environmental waters worldwide, especially in industrialized countries. Thus, monitoring the presence of HEV in wastewater treatment plants (WWTPs) is an emerging topic due to the importance of reusing water on a global level. Given the limited data, this study aimed to monitor the occurrence of HEV in influent and effluent water in waste- and drinking-water treatment plants (WWTPs and DWTPs). To this end, different procedures to concentrate HEV in influent and effluent water from WWTPs and DWTPs were initially evaluated. The evaluated procedures resulted in average HEV recoveries of 15.2, 19.9, and 16.9% in influent, effluent, and drinking water samples, respectively, with detection limits ranging from 103 to 104 international units (IU)/L. Then, a one-year pilot study was performed to evaluate the performance of the selected concentration method coupled with three RT-qPCR assays in influent and effluent water samples from four different WWTPs. HEV prevalence in influent water varied based on both the RT-qPCR assay and WWTP, while HEV was not detected in effluent water samples. In addition, HEV prevalence using only RT-qPCR3 was evaluated in influent (n = 62) and effluent samples (n = 52) from four WWTPs as well as influent (n = 28) and effluent (n = 28) waters from two DWTPs. The present study demonstrated that HEV circulated in the Valencian region at around 30.65% with average concentrations of 6.3 × 103 IU/L. HEV was only detected in influent wastewater samples, effluent samples from WWTPs and influent and effluent samples from DWTPs were negative. However, given that the infective dose in waterborne epidemics settings is not yet known and the low sensibility of the assay, unfortunately, no direct conclusion could be achieved on the risk assessment of environmental contamination.

Hepatitis E virus genotype 3 in echinoderms: First report of sea urchin (Paracentrotus lividus) contamination

Hepatitis E virus (HEV) deriving from manure application runoffs and faecal waste spill over of swine and human origin bypass wastewater treatment plants and contaminate coastal waters. Shellfish bioaccumulate enteric viruses such as HEV from fecally contaminated coastal waters and under current European Regulations, shellfish sanitary status surveillance is mandatory but only by means of bacterial faecal indicators. The sea urchins are under the same regulations and their vulnerability to fecal contamination has been pointed out. Since they are consumed raw and with no steps to control/reduce hazards, sea urchin contamination with enteric viruses can represent a food safety risk. Hence, the aim of the present study was to screen sea urchin gonads destined for human consumption for the presence of HEV. HEV was detected and quantified in gonads of sea urchins collected in north Portugal by a reverse transcription-quantitative PCR (RT-qPCR) assay targeting the ORF3 region, followed by genotyping by a nested RT-PCR targeting the ORF2 region. Sequencing and phylogenetic analysis clustered the HEV sequence within genotype 3, subgenotype e. This the first study reporting HEV contamination of sea urchins. We hypothesize that like shellfish, sea urchins can also be a food vehicle for HEV transmission to humans.

Waterborne Transmission of Enteric Viruses and Their Impact on Public Health

Viruses of human or animal origin can spread in the environment and infect people via water and food. These viruses are released into the environment by various routes including water runoffs and aerosols. Furthermore, zoonotic viruses may infect humans exposed to contaminated surface waters.

Viruses are emerging pathogens and are able to adapt by mutation, recombination, and reassortment and can thus become able to infect new hosts and to adjust to new environments. Enteric viruses are among the commonest and most hazardous waterborne pathogens, causing both sporadic and outbreak-related illness.

While considerable research has documented the risk of enteric viruses to human health from contact with contaminated water, the current bacterial indicator-based methods for the evaluation of water quality are often ineffectual proxies for pathogenic viruses, but no correlation was established between the enteric bacteria and viruses studied.

The present chapter will focus on viral pathogens shown to be transmitted through water. It will also provide an overview of viruses that had not been a concern for waterborne transmission in the past, but that may represent potentially emerging waterborne pathogens due to their occurrence and persistence in water environments.

Monitoring effluents from wastewater treatment plants is important to preventing both environmental contamination and the spread of disease.

Detection of Hepatitis E Virus in Shellfish Harvesting Areas from Galicia (Northwestern Spain)

The hepatitis E virus (HEV) affects almost 20 million individuals annually, causing approximately 3.3 million acute liver injuries, 56,600 deaths, and huge healthcare-associated economic losses. Shellfish produced close to urban and livestock areas can bioaccumulate this virus and transmit it to the human population. The aim of this study was to evaluate the presence of HEV in molluscan shellfish, in order to deepen the knowledge about HEV prevalence in Galicia (northwestern Spain), and to investigate this as a possible route of HEV transmission to humans. A total of 168 shellfish samples was obtained from two different Galician rías (Ría de Ares-Betanzos and Ría de Vigo). The samples were analyzed by reverse transcription-quantitative PCR (RT-qPCR). RT-nested PCR and sequencing were used for further genotyping and phylogenetic analysis of positive samples. HEV was detected in 41 (24.4%) samples, at quantification levels ranging from non-quantifiable (<102 copies of the RNA genome (RNAc)/g tissue) to 1.1 × 105 RNAc/g tissue. Phylogenetic analysis based on the open reading frame (ORF)2 region showed that all sequenced isolates belonged to genotype 3, and were closely related to strains of sub-genotype e, which is of swine origin. The obtained results demonstrate a significant prevalence of HEV in bivalve molluscs from Galician rías, reinforcing the hypothesis that shellfish may be a potential route for HEV transmission to humans.

Transmission of hepatitis E virus by water: An issue still pending in industrialized countries

Hepatitis E virus (HEV) is an enteric virus divided into eight genotypes. Genotype 1 (G1) and G2 are specific to humans; G3, G4 and G7 are zoonotic genotypes infecting humans and animals. Transmission to humans through water has been demonstrated for G1 and G2, mainly in developing countries, but is only suspected for the zoonotic genotypes. Thus, the water-related HEV hazard may be due to human and animal faeces. The high HEV genetic variability allows considering the presence in wastewater of not only different genotypes, but also quasispecies adding even greater diversity. Moreover, recent studies have demonstrated that HEV particles may be either quasi-enveloped or non-enveloped, potentially implying differential viral behaviours in the environment. The presence of HEV has been demonstrated at the different stages of the water cycle all over the world, especially for HEV G3 in Europe and the USA. Concerning HEV survival in water, the virus does not have higher resistance to inactivating factors (heat, UV, chlorine, physical removal), compared to viral indicators (MS2 phage) or other highly resistant enteric viruses (Hepatitis A virus). But the studies did not take into account genetic (genogroups, quasispecies) or structural (quasi- or non-enveloped forms) HEV variability. Viral variability could indeed modify HEV persistence in water by influencing its interaction with the environment, its infectivity and its pathogenicity, and subsequently its transmission by water. The cell culture methods used to study HEV survival still have drawbacks (challenging virus cultivation, time consuming, lack of sensitivity). As explained in the present review, the issue of HEV transmission to humans through water is similar to that of other enteric viruses because of their similar or lower survival. HEV transmission to animals through water and how the virus variability affects its survival and transmission remain to be investigated.

Cell culture systems for the study of hepatitis E virus

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans and is the leading cause of enterically-transmitted viral hepatitis worldwide. Increasing numbers of HEV infections, together with no available specific anti-HEV treatment, contributes to the pathogen's major health burden. A robust cell culture system is required for virologic studies and the development of new antiviral drugs. Unfortunately, like other hepatitis viruses, HEV is difficult to propagate in conventional cell lines. Many different cell culture systems have been tested using various HEV strains, but viral replication usually progresses very slowly, and infection with low virion counts results in non-productive HEV replication. However, recent progress involving generation of cDNA clones and passaging primary patient isolates in distinct cell lines has improved in vitro HEV propagation. This review describes various approaches to cultivate HEV in cellular and animal models and how these systems are used to study HEV infections and evaluate anti-HEV drug candidates.

Hepatitis E Virus Genome Structure and Replication Strategy

Hepatitis E virus (HEV) possesses many of the features of other positive-stranded RNA viruses but also adds HEV-specific nuances, making its virus-host interactions unique. Slow virus replication kinetics and fastidious growth conditions, coupled with the historical lack of an efficient cell culture system to propagate the virus, have left many gaps in our understanding of its structure and replication cycle. Recent advances in culturing selected strains of HEV and resolving the 3D structure of the viral capsid are filling in knowledge gaps, but HEV remains an extremely understudied pathogen. Many steps in the HEV life cycle and many aspects of HEV pathogenesis remain unknown, such as the host and viral factors that determine cross-species infection, the HEV-specific receptor(s) on host cells, what determines HEV chronicity and the ability to replicate in extrahepatic sites, and what regulates processing of the open reading frame 1 (ORF1) nonstructural polyprotein.

Classification and Genomic Diversity of Enterically Transmitted Hepatitis Viruses

Hepatitis A virus (HAV) and hepatitis E virus (HEV) are significant human pathogens and are responsible for a substantial proportion of cases of severe acute hepatitis worldwide. Genetically, both viruses are heterogeneous and are classified into several genotypes that differ in their geographical distribution and risk group association. There is, however, little evidence that variants of HAV or HEV differ antigenically or in their propensity to cause severe disease. Genetically more divergent but primarily hepatotropic variants of both HAV and HEV have been found in several mammalian species, those of HAV being classified into eight species within the genus Hepatovirus in the virus family Picornaviridae. HEV is classified as a member of the species Orthohepevirus A in the virus family Hepeviridae, a species that additionally contains viruses infecting pigs, rabbits, and a variety of other mammalian species. Other species (Orthohepevirus B-D) infect a wide range of other mammalian species including rodents and bats.

Detection of a novel RNA virus with hepatitis E virus-like non-structural genome organization in amphibian, agile frog (Rana dalmatina) tadpoles

In recent years, relatives (bastrovirus, hepelivirus) of hepeviruses (family Hepeviridae) have been reported in a variety of vertebrate hosts. Preliminary studies indicated that inter-viral family recombination events at the junction of the genomes that encodes non-structural (ORF1) and structural protein (ORF2) were implicated in the genesis of hepeviruses. Using viral metagenomics, next generation sequencing and RT-PCR techniques a genetically divergent hepevirus-like RNA virus was identified and characterized from agile frog (Rana dalmatina) tadpoles living in aquatic environment in three natural ponds (Mélymocsár, Lake Ilona and Lake Katlan) in the Pilis Mountains, in Hungary. The complete genome of the viral strain agile frog/RD6/2015/HUN (MH330682) is 7188 nt long including a 48-nt 5' and a 122-nt 3' non-coding region. Sequence analysis indicated that the agile frog/RD6/2015/HUN genome has potentially three non-overlapping ORFs. ORF1 (4740 nt/1579aa) has a hepevirus-like non-structural genome organization and encodes several hepevirus-like amino acid sequence motifs. The ORF2 is a potential capsid protein. The functions of the ORF3 were not predictable. The study virus was present in 18 (46%) of the 39 faecal specimen pools from agile frog tadpoles. The taxonomic position of this novel virus is presently unknown.

Diversity of hepatitis E virus genotype 3

Hepatitis E virus genotype 3 (HEV-3) can lead to chronic infection in immunocompromised patients, and ribavirin is the treatment of choice. Recently, mutations in the polymerase gene have been associated with ribavirin failure but their frequency before treatment according to HEV-3 subtypes has not been studied on a large data set. We used single-molecule real-time sequencing technology to sequence 115 new complete genomes of HEV-3 infecting French patients. We analyzed phylogenetic relationships, the length of the polyproline region, and mutations in the HEV polymerase gene. Eighty-five (74%) were in the clade HEV-3efg, 28 (24%) in HEV-3chi clade, and 2 (2%) in HEV-3ra clade. Using automated partitioning of maximum likelihood phylogenetic trees, complete genomes were classified into subtypes. Polyproline region length differs within HEV-3 clades (from 189 to 315 nt). Investigating mutations in the polymerase gene, distinct polymorphisms between HEV-3 subtypes were found (G1634R in 95% of HEV-3e, G1634K in 56% of HEV-3ra, and V1479I in all HEV-3efg, clade HEV-3ra, and HEV-3k strains). Subtype-specific polymorphisms in the HEV-3 polymerase have been identified. Our study provides new complete genome sequences of HEV-3 that could be useful for comparing strains circulating in humans and the animal reservoir.

Evaluation of Heating Conditions for Inactivation of Hepatitis E Virus Genotypes 3 and 4

Hepatitis E virus (HEV) is a causative agent of acute hepatitis throughout the world. HEV genotypes 1 through 4 infect humans, whereas genotypes 3 and 4 (Gt3 and Gt4) also infect other animals. In developed countries, the main HEV infection route is by foodborne transmission, resulting from the consumption of undercooked meat. It is important to know the criteria for HEV control in daily cooking. In this study, we assessed the heat conditions required to inactivate HEV Gt3 and Gt4 in culture supernatants and spiked minced pork meat. HEV inactivation was determined by measuring viral RNA amplification in PLC/PRF/5 cell culture. In our cell culture assay, an inoculum containing HEV titer that is equivalent to >10⁵ genome RNA copies can be determined as infectious. The internal temperature of pork during heating was measured to represent that achieved during cooking. Both HEV Gt3 and Gt4 were inactivated in culture supernatants heated at >65°C for 5 min and at >80°C for 1 min and in minced meat at 70°C for 5 min. Inoculated culture supernatant contained 10⁸ HEV genome RNA copies (10³ infectious units [IU]); therefore, it was indicated that HEV titer decreased >3 log IU after heating. In a comparison of Gt3 and Gt4, Gt4 showed slightly greater heat stability than Gt3. Boiling showed superior heating efficacy compared with roasting, and pork liver was slightly easier to heat than pork loin. Heating for 5 min by both boiling and roasting increased the internal temperature of pork products to more than 70°C. Although our data revealed that HEV Gt4 was slightly more heat stable than Gt3, both genotypes were inactivated by the appropriate heating conditions. Therefore, the risk of HEV foodborne infection could be mitigated by the appropriate cooking of pork meat. It is also important that both the supplier and the consumer are cognizant of the risk of HEV foodborne infection from livestock products.

Hepatitis E Virus: A New Foodborne Zoonotic Concern

Hepatitis E virus (HEV) is an enteric nonenveloped single-stranded RNA virus. Among the mammalian lineages, four genotypes are associated to human infection: genogroups 1 and 2 infect only humans and are mainly found in developing countries, while genogroups 3 and 4 are zoonotic, being found in a variety of animal species including pigs, and are autochthonous in developed countries. HEV infection can result in liver damage and with genotypes 1 and 2 symptoms can be particularly severe in pregnant women, with a high lethality ratio. Several cases of foodborne transmission of hepatitis E have been reported, often involving consumption of meat, especially raw or undercooked. Information is lacking on the exact extent of foodborne transmission of HEV.

Sogatella furcifera hepe-like virus: First member of a novel Hepeviridae clade identified in an insect

A novel virus was identified in the white-backed planthopper (Sogatella furcifera, Hemiptera: Delphacidae) and tentatively named Sogatella furcifera hepe-like virus (SfHeV). Its genome is a linear, single-stranded monopartite RNA, 7,312 nucleotides (nt) long with a 66-nt 5' UTR, 54-nt 3' UTR, and 28-nt polyA, showing typical genomic features of viruses in the family Hepeviridae, but highly divergent from known members in the family, with amino acid sequence identities of only 18.9-23% (ORF1), 13.1-18.8% (ORF2) and 1.9-11% (ORF3). Phylogenetic analysis revealed that SfHeV was closer to cutthroat trout virus (CTV), but did not cluster with any members of the family. SfHeV is the first hepe-like virus identified in a hemipteran insect and was detected in all developmental stages suggesting the presence of some level of vertical transmission. On the basis of these data, we propose that SfHeV represents a novel clade in the family Hepeviridae and tentatively name the genus Insecthepevirus.

Chevrier's Field Mouse (Apodemus chevrieri) and Père David's Vole (Eothenomys melanogaster) in China Carry Orthohepeviruses that form Two Putative Novel Genotypes Within the Species Orthohepevirus C

Hepatitis E virus (HEV) is the prototype of the family Hepeviridae and the causative agent of common acute viral hepatitis. Genetically diverse HEV-related viruses have been detected in a variety of mammals and some of them may have zoonotic potential. In this study, we tested 278 specimens collected from seven wild small mammal species in Yunnan province, China, for the presence and prevalence of orthohepevirus by broad-spectrum reverse transcription (RT)-PCR. HEV-related sequences were detected in two rodent species, including Chevrier's field mouse (Apodemus chevrieri, family Muridae) and Père David's vole (Eothenomys melanogaster, family Cricetidae), with the infection rates of 29.20% (59/202) and 7.27% (4/55), respectively. Further four representative full-length genomes were generated: two each from Chevrier's field mouse (named RdHEVAc14 and RdHEVAc86) and Père David's vole (RdHEVEm40 and RdHEVEm67). Phylogenetic analyses and pairwise distance comparisons of whole genome sequences and amino acid sequences of the gene coding regions showed that orthohepeviruses identified in Chinese Chevrier's field mouse and Père David's vole belonged to the species Orthohepevirus C but were highly divergent from the two assigned genotypes: HEV-C1 derived from rat and shrew, and HEV-C2 derived from ferret and possibly mink. Quantitative real-time RT-PCR demonstrated that these newly discovered orthohepeviruses had hepatic tropism. In summary, our work discovered two putative novel genotypes orthohepeviruses preliminarily named HEV-C3 and HEV-C4 within the species Orthohepevirus C, which expands our understanding of orthohepevirus infection in the order Rodentia and gives new insights into the origin, evolution, and host range of orthohepevirus.

Vaccine Development against Zoonotic Hepatitis E Virus: Open Questions and Remaining Challenges

Hepatitis E virus (HEV) is a fecal-orally transmitted foodborne viral pathogen that causes acute hepatitis in humans and is responsible for hepatitis E outbreaks worldwide. Since the discovery of HEV as a zoonotic agent, this virus has been isolated from a variety of hosts with an ever-expanding host range. Recently, a subunit HEV vaccine developed for the prevention of human disease was approved in China, but is not yet available to the rest of the world. Meanwhile, notable progress and knowledge has been made and revealed in recent years to better understand HEV biology and infection, including discoveries of quasi-enveloped HEV virions and of a new function of the HEV-ORF3 product. However, the impact of these new findings on the development of a protective vaccine against zoonotic HEV infection requires further discussion. In this review, hallmark characteristics of HEV zoonosis, the history of HEV vaccine development, and recent discoveries in HEV virology are described. Moreover, special attention is focused on quasi-enveloped HEV virions and the potential role of the HEV-ORF3 product as antibody-neutralization target on the surface of quasi-enveloped HEV virions to provide new insights for the future development of improved vaccines against zoonotic HEV infection.

Knowledge gaps and research priorities in the prevention and control of hepatitis E virus infection

Hepatitis E virus (HEV), family Hepeviridae, is a main cause of epidemic hepatitis in developing countries and sporadic and cluster cases of hepatitis in industrialized countries. There are an increasing number of reported cases in humans especially in industrialized countries, and there is a high potential for transboundary spread of zoonotic genotypes of the virus through the transport of pigs, pig products and by-products. Bloodborne transmission of the virus has been reported with a significant medical concern. To better coordinate HEV research and design better control measures of HEV infections in animals, a group of HEV experts reviewed the current knowledge on the disease and considered the existing disease control tools. It was concluded that there is a lack of in-depth information about the spread of the virus from pigs to humans. The role of animals other than pigs in the zoonotic transmission of the virus to humans and the extent of foodborne transmission are poorly understood. Factors involved in development of clinical disease such as infectious dose, susceptibility and virulence of virus strains need to be studied more extensively. However, such studies are greatly hindered by the absence of a broadly applicable, efficient and sensitive in vitro cell culture system for HEV. Diagnostic tools for HEV are available but need to be further validated, harmonized and standardized. Commercially available HEV vaccines for the control of HEV infection in animal populations are needed as such vaccines can minimize the zoonotic risk for humans. Anti-HEV drugs for treatment of HEV-infected patients need to be studied more extensively. The detailed expert review can be downloaded from the project website at http://www.discontools.eu/.

Zoonotic Hepatitis E Virus: An Ignored Risk for Public Health

Hepatitis E virus (HEV) is a quasi-enveloped, single-stranded positive-sense RNA virus. HEV belongs to the family Hepeviridae, a family comprised of highly diverse viruses originating from various species. Since confirmation of HEV's zoonosis, HEV-induced hepatitis has been a public health concern both for developing and developed countries. Meanwhile, the demonstration of a broad host range for zoonotic HEV suggests the existence of a variety of transmission routes that could lead to human infection. Moreover, anti-HEV antibody serosurveillance worldwide demonstrates a higher than expected HEV prevalence rate that conflicts with the rarity and sporadic nature of reported acute hepatitis E cases. In recent years, chronic HEV infection, HEV-related acute hepatic failure, and extrahepatic manifestations caused by HEV infection have been frequently reported. These observations suggest a significant underestimation of the number and complexity of transmission routes previously predicted to cause HEV-related disease, with special emphasis on zoonotic HEV as a public health concern. Significant research has revealed details regarding the virology and infectivity of zoonotic HEV in both humans and animals. In this review, the discovery of HEV zoonosis, recent progress in our understanding of the zoonotic HEV host range, and classification of diverse HEV or HEV-like isolates from various hosts are reviewed in a historic context. Ultimately, this review focuses on current understanding of viral pathogenesis and cross-species transmission of zoonotic HEV. Moreover, host factors and viral determinants influencing HEV host tropism are discussed to provide new insights into HEV transmission and prevalence mechanisms.

Classification of human and zoonotic group hepatitis E virus (HEV) using antigen detection

Hepatitis E virus (HEV) is one of the major pathogens that cause acute viral hepatitis. The human (genotypes 1 and 2) and zoonotic (genotypes 3 and 4) groups of HEV present different epidemiology and clinical features. In this study, we developed a classification method for rapidly classifying HEV into human or zoonotic groups that combines a general antigen test with a zoonotic group-specific antigen test. Evaluation of serial samples from HEV-infected rhesus monkeys indicated that HEV antigen-positive samples can be classified using the antigen-based classification method. The antigen-based classification method was evaluated further on 55 genotyped samples from acute hepatitis E patients, including 9 human and 46 zoonotic groups. The novel method was completely consistent with the sequencing results: 9/9 for the human groups (100%, 95% confidence interval [CI] 66.4-100%) and 46/46 for the zoonotic groups (100%, 95% CI 92.3-100%). This method was also successfully used for the clustering of some samples that could not be clustered by sequencing. Compared with the sequencing-based method, this method is less time-consuming, less expensive, and less technically complex and is therefore ideal for large numbers of samples. In conclusion, this study provides a convenient and sensitive method for classifying different groups of HEV, and it has potentially important public health applications, especially in underdeveloped areas that cannot afford the high cost of nucleic acid testing.

Hepatitis E in Italy: A silent presence

Hepatitis E virus (HEV) was discovered in the 1980s and has been considered as being confined to developing countries. The purpose of this critical review was to determine the reported HEV seroprevalence rates in Italy, to identify predisposing factors and individuals at risk and to assess possible importation of HEV by immigrants. A critical review of 159 articles published in PubMed from 1994 to date was done. Only 27 original reports of 50 or more subjects, written in the English or Italian language, were included. Over three decades, the HEV seroprevalence varied from 0.12% to 49%, with the highest rates being reported from the central region of Italy. Risk factors included ingestion of raw pork or potentially contaminated food. The seroprevalence among immigrants ranged from 15.3% to 19.7% in Apulia. Italy has a population of 60656000; the total number of individuals surveyed was only 21.882 (0.036%). A national epidemiological survey program is needed to capture more comprehensive seroprevalence data.

Detection of Serum Antibodies to Hepatitis E Virus Based on HEV Genotype 3 ORF2 Capsid Protein Expressed in Nicotiana benthamiana

BACKGROUND

Hepatitis E virus (HEV) causes epidemics in developing countries and is primarily transmitted through the fecal-oral route. There have been recent reports on the zoonotic spread of the virus, and several animal species, primarily pigs, have been recognized as reservoirs of HEV. Because of its possible spread, there is an urgent need of a method for the cost-effective production of HEV proteins that can be used as diagnostic antigens for the serological detection of anti-HEV antibodies.

METHODS

The HEV open reading frame (ORF)2 protein was purified from plant tissue by using immobilized metal-anion chromatography (IMAC). The recombinant protein was used to develop an in-house ELISA for testing anti-HEV antibodies in both human and swine sera. Thirty-six serum samples collected from patients with serologically proven HEV infection with commercial kits were tested for anti-HEV IgG antibodies by using the plant-expressed protein. Forty-five serum samples collected from apparently healthy pigs in Bulgarian farms were also tested.

RESULTS

We confirmed the transient expression and purification of a truncated version of the HEV genotype 3 capsid protein in Nicotiana benthamiana and its usefulness as a diagnostic antigen. ELISA showed the presence of anti-HEV IgG antibodies in 29 of the 36 human samples. The in-house ELISA showed anti-HEV IgG antibodies in 34 of the 45 pigs.

CONCLUSIONS

We describe a method for the production of HEV ORF2 protein in N. benthamiana and the usefulness of this protein for the serological detection of anti-HEV antibodies in both humans and swine.

Public health risks associated with hepatitis E virus (HEV) as a food-borne pathogen

Hepatitis E virus (HEV) is an important infection in humans in EU/EEA countries, and over the last 10 years more than 21,000 acute clinical cases with 28 fatalities have been notified with an overall 10-fold increase in reported HEV cases; the majority (80%) of cases were reported from France, Germany and the UK. However, as infection in humans is not notifiable in all Member States, and surveillance differs between countries, the number of reported cases is not comparable and the true number of cases would probably be higher. Food-borne transmission of HEV appears to be a major route in Europe; pigs and wild boars are the main source of HEV. Outbreaks and sporadic cases have been identified in immune-competent persons as well as in recognised risk groups such as those with pre-existing liver damage, immunosuppressive illness or receiving immunosuppressive treatments. The opinion reviews current methods for the detection, identification, characterisation and tracing of HEV in food-producing animals and foods, reviews literature on HEV reservoirs and food-borne pathways, examines information on the epidemiology of HEV and its occurrence and persistence in foods, and investigates possible control measures along the food chain. Presently, the only efficient control option for HEV infection from consumption of meat, liver and products derived from animal reservoirs is sufficient heat treatment. The development of validated quantitative and qualitative detection methods, including infectivity assays and consensus molecular typing protocols, is required for the development of quantitative microbial risk assessments and efficient control measures. More research on the epidemiology and control of HEV in pig herds is required in order to minimise the proportion of pigs that remain viraemic or carry high levels of virus in intestinal contents at the time of slaughter. Consumption of raw pig, wild boar and deer meat products should be avoided.

Hepatitis E Virus Genotypes and Evolution: Emergence of Camel Hepatitis E Variants

Hepatitis E virus (HEV) is a major cause of viral hepatitis globally. Zoonotic HEV is an important cause of chronic hepatitis in immunocompromised patients. The rapid identification of novel HEV variants and accumulating sequence information has prompted significant changes in taxonomy of the family Hepeviridae. This family includes two genera: Orthohepevirus, which infects terrestrial vertebrates, and Piscihepevirus, which infects fish. Within Orthohepevirus, there are four species, A–D, with widely differing host range. Orthohepevirus A contains the HEV variants infecting humans and its significance continues to expand with new clinical information. We now recognize eight genotypes within Orthohepevirus A: HEV1 and HEV2, restricted to humans; HEV3, which circulates among humans, swine, rabbits, deer and mongooses; HEV4, which circulates between humans and swine; HEV5 and HEV6, which are found in wild boars; and HEV7 and HEV8, which were recently identified in dromedary and Bactrian camels, respectively. HEV7 is an example of a novel genotype that was found to have significance to human health shortly after discovery. In this review, we summarize recent developments in HEV molecular taxonomy, epidemiology and evolution and describe the discovery of novel camel HEV genotypes as an illustrative example of the changes in this field.

Hepatitis E virus: A potential threat for patients with liver disease and liver transplantation

Immunocompromised patients are at risk of acquiring acute hepatitis E virus infection (HEV), leading to chronicity. Chronic HEV infection is associated with persistent viraemia, raised transaminase activity, histological features associated with chronic hepatitis and evidence of rapid development of cirrhosis. Extrahepatic manifestations have been associated with HEV. Most frequently reported are neurological disorders with predominantly involvement of the peripheral nervous system. In patients using immunosuppressive drugs antibody production is often delayed and HEV RNA detection is superior to serology to detect infection. Therapeutic options for chronic HEV includes tapering immunosuppressive and secondly ribavirin, pegylated interferon alpha (PEG-IFN). Present recommendation is to treat chronic HEV patients for 3 months, asses serum HEV RNA and stool HEV RNA and stop therapy if both are undetectable. Studies are required to determine which other antiviral agents than ribavirin and (PEG-)IFN are of clinical utility in treating HEV in the minority of patients who do not respond to ribavirin.

The Viruses of the Gut Microbiota

The gut virome is the viral component of the gut microbiome. Knowledge regarding its composition, interindividual and temporal variability is increasing, and the significance of its impact on human health, both in homeostasis and disease is being recognized. Here we review the recent advances in this field, and the questions that arise in the context of the rapidly increasing information regarding its composition and function. With the extending collection of human data, the power of next generation sequencing, and functional studies, the factors that influence the composition of the gut virome and its impact on human health will be further refined in the coming years.

Taxonomic Changes and Additions for Human and Animal Viruses, 2012 to 2015

Taxonomical classification of newly discovered viruses and reclassification of previously discovered viruses provide an important foundation for detailing biological differences of scientific and clinical interest. The development of molecular analytical methods has enabled finer levels and more precise levels of classification. Periodically, there is need to refresh the literature and common understanding of current taxonomic classification, which we attempt to do here in addressing changes in human and animal viruses of medical significance between 2012 and 2015.

A Comparative Study of Assay Performance of Commercial Hepatitis E Virus Enzyme-Linked Immunosorbent Assay Kits in Australian Blood Donor Samples

Hepatitis E virus (HEV) is transfusion-transmissible and therefore poses a risk to blood transfusion safety. Seroprevalence studies are useful for estimating disease burden and determining risk factors. Considerable variability in the sensitivity of HEV antibody detection assays exists. This study aimed to compare the performances of commercially available HEV enzyme-linked immunosorbent assays (ELISA) in Australian blood donor samples. Plasma samples that tested positive (n = 194) or negative (n = 200) for HEV IgG (Wantai HEV IgG ELISA) were selected. Of the 194 HEV IgG positive samples, 4 were positive for HEV IgM (Wantai HEV IgM ELISA). All samples were tested with the MP Diagnostics: HEV IgG ELISA, total (IgG, IgM, and IgA) HEV antibody ELISA, and HEV IgM ELISA. Of the 194 Wantai HEV IgG positive samples, 92 (47%) tested positive with the MP Diagnostics HEV IgG ELISA (κ = 0.47) and 126 (65%) with MP Diagnostics total HEV antibody assay (κ = 0.65). There was poor agreement between Wantai and MP Diagnostics HEV IgM assays. This study demonstrated poor agreement between the assays tested. These observations are consistent with previous reports demonstrating significant variability between HEV ELISAs, highlighting that results of HEV serology should be interpreted with caution.

The effect of phylogenetic signal reduction on genotyping of hepatitis E viruses of the species Orthohepevirus A

Commonly, hepatitis E virus (HEV) sequences are genotyped phylogenetically using subgenomic sequences. This paper examines this practice with sequences from members of the species Orthohepevirus A. As the length of sequences becomes progressively shorter, the number of identical sequences in an alignment tends to increase; however, these sequences retain their genotypic identity down to 100 nucleotides in length. The best substitution models tend to become less parameterized, bootstrap support decreases, and trees created from short subgenomic fragments are less likely to be isomorphic with trees from longer subgenomic fragments or complete genome sequences. However, it is still possible to correctly genotype sequences using fragments as small as 200 nucleotides. While it is possible to correctly genotype sequences with short subgenomic sequences, the estimates of evolutionary relationships between genotypes degrade to such an extent that sequences below 1600 nucleotides long cannot be used reliably to study these relationships, and comparisons of trees from different subgenomic regions with little or no sequence overlap can be problematic. Subtyping may be done, but it requires a careful examination of the region to be used to ensure that it correctly resolves the subtypes.

A novel avian-like hepatitis E virus in wild aquatic bird, little egret (Egretta garzetta), in Hungary

Hepatitis E virus (HEV), family Hepeviridae, has public health concerns because of its zoonotic potential; however, the host species spectrum, animal to animal transmissions, the natural chain of hepevirus infections and the genetic diversity of HEV in wildlife especially in birds are less known. Using random amplification and next generation sequencing technology a genetically divergent avian HEV was serendipitously identified in wild bird in Hungary. HEV RNA was detected with high faecal viral load (1.33×10⁸genomiccopies/ml) measured by real-time PCR in faecal sample from a little egret (Egretta garzetta). The complete genome of HEV strain little egret/kocsag02/2014/HUN (KX589065) is 6660-nt long including a 18-nt 5' end and a 103-nt 3' end (excluding the poly(A)-tail). Sequence analyses indicated that the ORF1 (4554nt/1517aa), ORF2 (1728nt/593aa) and ORF3 (339nt/112aa) encoded proteins of little egret/kocsag02/2014/HUN shared the highest identity (62.8%, 71% and 61.5%) to the corresponding proteins of genotype 1 avian (chicken) HEV in species Orthohepevirus B, respectively. This study reports the identification and complete genome characterization of a novel orthohepevirus distantly related to avian (chicken) HEVs at the first time in wild bird. It is important to recognize all potential hosts, reservoirs and spreaders in nature and to reconstruct the phylogenetic history of hepeviruses. Birds could be an important reservoir of HEV generally and could be infected with genetically highly divergent strains of HEV.

Molecular Biology and Infection of Hepatitis E Virus

Hepatitis E virus (HEV) is a viral pathogen transmitted primarily via fecal-oral route. In humans, HEV mainly causes acute hepatitis and is responsible for large outbreaks of hepatitis across the world. The case fatality rate of HEV-induced hepatitis ranges from 0.5 to 3% in young adults and up to 30% in infected pregnant women. HEV strains infecting humans are classified into four genotypes. HEV strains from genotypes 3 and 4 are zoonotic, whereas those from genotypes 1 and 2 have no known animal reservoirs. Recently, notable progress has been accomplished for better understanding of HEV biology and infection, such as chronic HEV infection, in vitro cell culture system, quasi-enveloped HEV virions, functions of the HEV proteins, mechanism of HEV antagonizing host innate immunity, HEV pathogenesis and vaccine development. However, further investigation on the cross-species HEV infection, host tropism, vaccine efficacy, and HEV-specific antiviral strategy is still needed. This review mainly focuses on molecular biology and infection of HEV and offers perspective new insight of this enigmatic virus.

Hepatitis E virus derived from different sources exhibits different behaviour in virus inactivation and/or removal studies with plasma derivatives

Hepatitis E virus (HEV) causes viral hepatitis, and is considered a risk factor for blood products. Although some HEV inactivation/removal studies have been reported, detailed investigations of different manufacturing steps as heat treatment, partitioning during cold ethanol fractionation, low pH treatment, and virus filtration have yet to be reported for plasma-derived medicinal products. In this study, human serum- and swine faeces-derived HEVs, with and without detergent treatment, were used. The kinetic patterns of inactivation, log reduction value, or partitioning during the process were evaluated. In addition, the mouse encephalomyocarditis virus (EMCV) and canine and porcine parvoviruses (CPV/PPV) were also evaluated as model viruses for HEV. Small pore size (19 or 15 nm) virus filtration demonstrated effective removal of HEV. Middle pore size (35 nm) virus filtration and 60 °C liquid heating demonstrated moderate inactivation/removal. Ethanol fractionation steps demonstrated limited removal of HEV. Unpurified HEV exhibited different properties than the detergent-treated HEV, and both forms displayed differences when compared with EMCV, CPV, and PPV. Limited or no inactivation of HEV was observed during low pH treatment. Untreated plasma-derived HEV from humans showed different properties compared to that of HEV treated with detergent or derived from swine faeces. Therefore, HEV spike preparation requires more attention.