Hepatitis E Virus Genome Research Articles

Establishment of enterically transmitted hepatitis virus animal models using lipid nanoparticle-based full-length viral genome RNA delivery system

BackgroundEnterically transmitted hepatitis viruses, such as hepatitis A virus (HAV) and hepatitis E virus (HEV), remain notable threats to public health. However, stable and reliable animal models of HAV and...

The 2023 South Sudanese outbreak of Hepatitis E emphasizes ongoing circulation of genotype 1 in North, Central, and East Africa

In April 2023, an outbreak of acute hepatitis was reported amongst internally displaced persons in the Nazareth community of South Sudan. IgM serology-based screening suggested the likely etiologic agent to be Hepatitis E virus (HEV). In this study, plasma specimens collected from anti-HEV IgM-positive cases were subjected to additional RT-qPCR testing and sequencing of extracted nucleic acids, resulting in the recovery of five full and eight partial HEV genomes. Maximum likelihood phylogenetic reconstruction confirmed the genomes belong to HEV genotype 1. Using distance-based methods, we show that genotype 1 is best split into three sub-genotypes instead of the previously proposed seven, and that these sub-genotypes are geographically restricted. The South Sudanese sequences confidently cluster within sub-genotype 1e, endemic to northeast, central, and east Africa. Bayesian Inference of phylogeny incorporating sampling dates shows that this new outbreak is not directly descended from other recent local outbreaks for which sequence data is available. However, the analysis suggests that sub-genotype 1e has been consistently and cryptically circulating locally for at least the past half century and that the known outbreaks are often not directly descended from one another. The ongoing presence of HEV, combined with poor sanitation and hygiene in the conflict-affected areas in the region, place vulnerable populations at risk for infection and its more serious effects, including progression to fulminant hepatitis.

Combining RNA Interference and RIG-I Activation to Inhibit Hepatitis E Virus Replication.

Hepatitis E virus (HEV) poses a significant global health threat, with an estimated 20 million infections occurring annually. Despite being a self-limiting illness, in most cases, HEV infection can lead to severe outcomes, particularly in pregnant women and individuals with pre-existing liver disease. In the absence of specific antiviral treatments, the exploration of RNAi interference (RNAi) as a targeted strategy provides valuable insights for urgently needed therapeutic interventions against Hepatitis E. We designed small interfering RNAs (siRNAs) against HEV, which target the helicase domain and the open reading frame 3 (ORF3). These target regions will reduce the risk of viral escape through mutations, as they belong to the most conserved regions in the HEV genome. The siRNAs targeting the ORF3 efficiently inhibited viral replication in A549 cells after HEV infection. Importantly, the siRNA was also highly effective at inhibiting HEV in the persistently infected A549 cell line, which provides a suitable model for chronic infection in patients. Furthermore, we showed that a 5' triphosphate modification on the siRNA sense strand activates the RIG-I receptor, a cytoplasmic pattern recognition receptor that recognizes viral RNA. Upon activation, RIG-I triggers a signaling cascade, effectively suppressing HEV replication. This dual-action strategy, combining the activation of the adaptive immune response and the inherent RNAi pathway, inhibits HEV replication successfully and may lead to the development of new therapies.

The AP-1 adaptor complex is essential for intracellular trafficking of the ORF2 capsid protein and assembly of Hepatitis E virus

Although the Hepatitis E virus (HEV) is an emerging global health burden, little is known about its interaction with the host cell. HEV genome encodes three proteins including the ORF2 capsid protein that is produced in different forms, the ORF2i protein which is the structural component of viral particles, and the ORF2g/c proteins which are massively secreted but are not associated with infectious material. We recently demonstrated that the endocytic recycling compartment (ERC) is hijacked by HEV to serve as a viral factory. However, host determinants involved in the subcellular shuttling of viral proteins to viral factories are unknown. Here, we demonstrate that the AP-1 adaptor complex plays a pivotal role in the targeting of ORF2i protein to viral factories. This complex belongs to the family of adaptor proteins that are involved in vesicular transport between the trans-Golgi network and early/recycling endosomes. An interplay between the AP-1 complex and viral protein(s) has been described for several viral lifecycles. In the present study, we demonstrated that the ORF2i protein colocalizes and interacts with the AP-1 adaptor complex in HEV-producing or infected cells. We showed that silencing or drug-inhibition of the AP-1 complex prevents ORF2i protein localization in viral factories and reduces viral production in hepatocytes. Modeling of the ORF2i/AP-1 complex also revealed that the S domain of ORF2i likely interacts with the σ1 subunit of AP-1 complex. Hence, our study identified for the first time a host factor involved in addressing HEV proteins (i.e. ORF2i protein) to viral factories.

Oxysterol binding protein (OSBP) contributes to hepatitis E virus replication

Hepatitis E virus (HEV) is a positive-sense, single-stranded RNA virus and causes primarily acute self-limiting infections. The ORF1 of the HEV genome encodes a polyprotein around 190 kDa, which contains several putative domains, including helicase and RNA-dependent RNA polymerase. The HEV-encoded helicase is a member of the superfamily 1 helicase family and possesses multiple enzymatic functions, such as RNA 5′-triphosphatase, RNA unwinding, and NTPase, which are thought to contribute to viral RNA synthesis. However, the helicase interaction with cellular proteins remains less known. Oxysterol binding protein (OSBP) is a lipid regulator that shuffles between the Golgi apparatus and the endoplasmic reticulum for cholesterol and phosphatidylinositol-4-phosphate exchange and controls the efflux of cholesterol from cells. In this study, the RNAi-mediated silencing of OSBP significantly reduced HEV replication. Further studies indicate that the HEV helicase interacted with OSBP, shown by co-immunoprecipitation and co-localization in co-transfected cells. The presence of helicase blocked OSBP preferential translocation to the Golgi apparatus. These results demonstrate that OSBP contributes to HEV replication and enrich our understanding of the HEV-cell interactions.

Hepatitis E Virus Genotype 3 among Hemodialysis Patients in Mexico: First Identification of Chronic Infection.

The global distribution of hepatitis E virus (HEV) is attributed to its capacity to spread through several routes of transmission; hemodialysis has gained increased amounts of attention in recent years. Although Mexico is considered a hyperendemic region for hepatitis E, no HEV surveillance is performed in the country. The frequency of HEV in hemodialysis (HD) patients has not been determined. Herein, we conducted a cross-sectional single-center analytical study including 67 serum samples from HD patients. Anti-HEV IgG and IgM antibodies and the viral genome were determined; partial regions within the HEV genome were sequenced for further phylogenetic analysis. Globally, 14.9% of the tested patients exhibited reactivity for IgG antibodies against HEV, and none showed reactivity to IgM. A total of 5.9% of the samples showed HEV genome amplification, and sequencing confirmed the identity of genotype 3; subsequent analysis of positive cases revealed two acute cases and chronic hepatitis E infection in one patient. Notably, the chronic patient was negative for anti-HEV IgG antibodies. Our findings highlight the importance of viral genome testing in HD patients and the need to establish guidelines for HEV detection in Mexico.

Multifunctional ORF3 protein of hepatitis E virus.

Hepatitis E virus (HEV) is an emerging zoonotic pathogen that is transmitted primarily through the fecal-oral route and can cause acute hepatitis in humans. Since HEV was identified as a zoonotic pathogen, different species of HEV strains have been globally identified from various hosts, leading to an expanding range of hosts. The HEV genome consists of a 5' noncoding region, three open reading frames (ORFs), and a 3' noncoding region. The ORF3 protein is the smallest but has many functions in HEV release and pathogenesis. In this review, we systematically summarize recent progress in understanding the functions of the HEV ORF3 protein in virion release, biogenesis of quasi-enveloped viruses, antigenicity, and host environmental regulation. This review will help us to understand HEV replication and pathogenesis mechanisms better.

Seroprevalence and Phylogenetic Characterization of Hepatitis E Virus (Paslahepevirus balayani) in Guinean Pig Population.

Background: Hepatitis E virus (HEV) is transmitted by the fecal route, usually through contaminated water in humans and/or infected animals, especially pigs. The objective of this study was to evaluate the level of anti-HEV antibodies in a panel of pig sera and to identify HEV in pig feces in farms. Methodology: The presence of HEV antibodies was tested by an in-house ELISA and a commercial ELISA IDvet. HEV genome was assessed by nested RT-PCR, and then, genotype was identified by sequencing (MinION Nanopore technology). Results: In 2017-2019, the 43% seroprevalence found in Forest Guinea was significantly higher than the 7% found in the Lower region (p < 0.01). Presence of HEV genotype 3c was demonstrated during a secondary study in the Lower region (Conakry) in 2022. Conclusion: The presence of HEV-3c in pigs calls for an evaluation of seroprevalence in human populations and for a HEV genotype human circulation check. Contribution Heading: This study is the first report, to our knowledge, of seroprevalence and characterization of HEV infection in pigs in Guinea.

Quantification of Hepatitis E Virus ORF2 Protein by a Novel Sandwich ELISA.

Hepatitis E virus (HEV) causes acute hepatitis in humans, which can progress to chronicity in immunosuppressed individuals. Almost all reported HEV infections are caused by Paslahepevirus balayani genotypes 1-4. The structural ORF2 protein is the major antigen detected in the blood of HEV-infected individuals. ELISA assays to detect IgM antibodies to HEV are the first-line diagnostic tests; however, they showed variable performance with frequently discordant results. A qualitative HEV antigen (ORF2) ELISA is currently available for research use. Here, we report a novel quantitative sandwich ELISA to measure HEV ORF2 protein in 3 matrix types. An optimal pair of capture and detection antibodies was selected among 12 unique combinations tested. A sandwich ELISA protocol was developed using these mAbs and biotin-streptavidin technology. The protocol was further optimized to quantify ORF2 antigen in different matrices by interpolating from a standard curve with a linear range of 3.17 to 50.8 femtomoles/mL. Using this method, ORF2 protein was detected in the cell culture medium of Huh7 cells as early as 2-3 days after transfection with HEV genome RNA and in a medium of human hepatocytes infected with HEV. ORF2 antigen was readily detected in the first 2 weeks post-HEV infection in gerbil sera. In immunosuppressed gerbils, ORF2 was detected up to 6 weeks, and the levels were significantly higher between 3 and 6 weeks post-infection. HEV ORF2 antigen levels showed a strong positive correlation with HEV RNA levels in both cell culture medium and gerbil sera. Our novel sandwich ELISA detected at least 7.3 femtomoles/mL ORF2 protein in human plasma spiked with cell culture propagated HEV and detected ORF2 protein in human plasma samples that tested positive for HEV RNA but negative for anti-HEV antibodies. Further, the assay was nonreactive, with negative human plasma, and HBV or HCV-positive human plasma demonstrating specificity. Overall, our ORF2 antigen ELISA will be useful for quantifying ORF2 antigen in cell culture medium, gerbil serum, and human plasma. Further studies are warranted to evaluate its utility in HEV clinical diagnosis.

Development of a Sensitive and Specific Quantitative RT-qPCR Method for the Detection of Hepatitis E Virus Genotype 3 in Porcine Liver and Foodstuff

As an international and zoonotic cause of hepatitis, hepatitis E virus (HEV) poses a significant risk to public health. However, the frequency of occurrence and the degree of contamination of food of animal origin require further research. The aim of this study was to develop and validate a highly sensitive quantitative RT-qPCR assay for the detection and quantification of HEV contamination in porcine liver and food. The focus was on genotype 3, which is most common as a food contaminant in developed countries and Europe. The selected assay has its target sequence in the open reading frame 1 (ORF1) of the HEV genome and showed good results in inclusivity testing, especially for HEV genotype 3. The developed assay seems to show high efficiency and a low intercept when compared to other assays, while having a comparable limit of detection (LOD). In addition, a standard curve was generated using artificially spiked liver to provide more accurate quantitative results for contamination assessment and tracking in this matrix. Application of the assay to test 67 pig livers from different origins resulted in a positivity rate of 7.5%, which is consistent with the results of numerous other prevalence studies. Quantitative detection of the viral genome in the food chain, particularly in pig livers, is essential for understanding the presence and evolution of HEV contamination and thus ensures consumer safety.

The hepatitis E virus ORF1 hypervariable region confers partial cyclophilin dependency.

Hepatitis E virus (HEV) is an emerging pathogen responsible for more than 20 million cases of acute hepatitis globally per annum. Healthy individuals typically have a self-limiting infection, but mortality rates in some populations such as pregnant women can reach 30 %. A detailed understanding of the virus lifecycle is lacking, mainly due to limitations in experimental systems. In this regard, the cyclophilins are an important family of proteins that have peptidyl-prolyl isomerase activity and play roles in the replication of a number of positive-sense RNA viruses, including hepatotropic viruses such as hepatitis C virus (HCV). Cyclophilins A and B (CypA/B) are the two most abundant Cyps in hepatocytes and are therefore potential targets for pan-viral therapeutics. Here, we investigated the importance of CypA and CypB for HEV genome replication using sub-genomic replicons. Using a combination of pharmacological inhibition by cyclosporine A (CsA), and silencing by small hairpin RNA we find that CypA and CypB are not essential for HEV replication. However, we find that silencing of CypB reduces replication of some HEV isolates in some cells. Furthermore, sensitivity to Cyp silencing appears to be partly conferred by the sequence within the hypervariable region of the viral polyprotein. These data suggest HEV is atypical in its requirements for cyclophilin for viral genome replication and that this phenomenon could be genotype- and sequence-specific.

A pig model of chronic hepatitis E displaying persistent viremia and a downregulation of innate immune responses in the liver.

Hepatitis E virus (HEV) is a zoonotic virus transmitted by pig meat and responsible for chronic hepatitis E in immunocompromised patients. It has proved challenging to reproduce this disease in its natural reservoir. We therefore aimed to develop a pig model of chronic hepatitis E to improve the characterization of this disease. Ten pigs were treated with a tacrolimus-based regimen and intravenously inoculated with HEV. Tacrolimus trough concentration, HEV viremia, viral diversity, innate immune responses, liver histology, clinical disease and biochemical markers were monitored for 11 weeks post-infection (p.i.). HEV viremia persisted for 11 weeks p.i. HEV RNA was detected in the liver, small intestine, and colon at necropsy. Histological analysis revealed liver inflammation and fibrosis. Several mutations selected in the HEV genome were associated with compartmentalization in the feces and intestinal tissues, consistent with the hypothesis of extrahepatic replication in the digestive tract. Antiviral responses were characterized by a downregulation of IFN pathways in the liver, despite an upregulation of RIG-I and ISGs in the blood and liver. We developed a pig model of chronic hepatitis E that reproduced the major hallmarks of this disease. This model revealed a compartmentalization of HEV genomes in the digestive tract and a downregulation of innate immune responses in the liver. These original features highlight the relevance of our model for studies of the pathogenesis of chronic hepatitis E and for validating future treatments.

Prevalence of hepatitis E virus genotype 4 of probable human origin in Tibetan pigs from the Qinghai-Tibetan Plateau, China.

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis worldwide. In 2018-2022, we investigated the presence of HEV RNA in 1233 stool samples collected in the Qinghai-Tibetan Plateau, including humans (16), Tibetan pigs (624), yaks (312), sheep (267), and dogs (14). HEV RNA was only detected in Tibetan pig faecal samples (18.27%, 114/624). To perform molecular characterization of HEV strains in Tibetan pigs, we obtained 21 complete HEV genome sequences between 2018 and 2022. Sequence comparisons showed that 21 HEV strains from Tibetan pigs shared the mean nucleotide identities with the reference HEV strains ranging between 82.9% and 94.9% and 89.3% and 92.1% similarities with human HEV strains. Phylogenetic analysis confirmed that all HEV strains were genotype 4, closely related to human HEV strains. Sequence recombinant analysis showed five potential recombinant strains identified in this study, of which SWU/D18/2018 (GenBank No. MK410044) was recombinant with human and swine HEV strains, located 6509-6878 nt from the recombination point. Based on the Bayesian evolutionary trees, we found that most HEV strains diverged later than human HEV (16 Tibetan pig HEV strains diverged later than 1979, and seven human HEV strains diverged earlier than 1979). Therefore, we speculated that the prevalence of HEV 4 in Tibetan pigs possibly originated from humans in the Qinghai-Tibetan Plateau.

Molecular characterisation of a rabbit Hepatitis E Virus strain detected in a chronically HEV-infected individual from Germany

In immunocompromised individuals persisting viremia frequently leads to a chronic hepatitis E virus (HEV) infection. Zoonotic transmission of HEV from pigs and wild boar to humans is proven and sporadic infections with rabbit HEV (raHEV) have recently been reported. Here, the molecular characterisation of a raHEV strain isolated from an immunocompromised, chronically HEV-infected, heart-transplanted patient is described. After successful ribavirin (RBV) treatment of a HEV infection in 2019, the patient was again tested HEV positive in 2021 and received a second RBV therapy cycle. Full-length HEV genome amplification and next generation sequencing was performed on a plasma sample taken between first and second cycle of RBV therapy and a stool sample taken two months after starting the second cycle. The sequence of plasma (raHEV-83) and stool (raHEV-99) derived virus showed the highest nucleotide sequence identity to a Chinese raHEV and a phylogenetic relationship to a raHEV strain isolated from a French patient. Furthermore, sequence analysis revealed the presence of RBV-associated substitutions V1479I and G1634K in the HEV sequences from plasma and additionally K1398R from stool. The results underline the role of rabbits as putative sources of HEV infection and emphasize the need of a one health concept for a better understanding of HEV epidemiology and to develop tools for prevention and control of HEV infection.

Higher Risk of Chronic Hepatitis E Virus Infection in Patients with Human Immunodeficiency Virus-1: An Iranian Cross-sectional Study.

Occurrence of Hepatitis E Virus (HEV) infection may be common in Human Immunodeficiency Virus (HIV-1) patients and may lead to chronic infection as well as cirrhosis. We intended to determine the incidence of HEV infection among HIV-1 patients compared to individuals without HIV-1 infection. In our cross-sectional study, 87 HIV-1-positive patients were compared to 93 healthy individuals in Kerman, Iran. Plasma and peripheral blood mononuclear cells (PBMCs) were obtained from all the participants. Plasma samples were evaluated for HEV IgM and IgG using the ELISA kit. Then, reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) was used in RNA extractions from PBMCs to check for the presence of HEV RNA. Among the subjects examined in our study, 61 (70.1%) and 71 (77.4%) out of patients with HIV-1 infection and healthy individuals were male, respectively. The average ages of patients with HIV-1 and the control group were 40.2 years and 39.9 years, respectively. No discernible differences were found between the two groups based on IgM and IgG seropositivity against the HEV. However, HEV-RNA was found in 8% of patients with HIV-1 and 1.1% of HIV-1-negative individuals (P=0.03). There was also an association between the HEV genome and anti-HEV and anti-HCV antibodies in HIV-1-positive patients (P=0.02 and P=0.014, respectively). HEV infection may be more common in HIV-1 patients and may develop a chronic infection in immunocompromised individuals. Molecular-based HEV diagnostic tests, including RT-PCR assays, should be performed in HIV-1 patients with unknown impaired liver function tests.

ИСПОЛЬЗОВАНИЕ СИНОНИМИЧНЫХ КОДОНОВ В ГЕНОМЕ ВИРУСА ГЕПАТИТА Е

Hepatitis E virus (HEV) is a poorly understood pathogen that is widespread in humans and animals. In the genomes of all organisms, there is a bias in the use of synonymous codons. Mutations, genetic drift and natural selection are the main factors that determine codon usage bias in the genomes of viruses. The aim of this study was to study the systematic error in the use of synonymous codons in whole genome sequences of HEV RNA genotypes 1 and 3 isolated from different hosts. We studied 309 complete HEV genomes deposited in the GenBank NCBI database (in silico). In the sequences of open reading frames ORF1, ORF2, and ORF3, the nucleotide composition, the composition of dinucleotides, the relative use of synonymous codons were studied, ENC-Plot analysis and parity rule analysis was performed, the dN/dS ratio was calculated. Found: GC composition of HEV sequences is 59.3±0.52%; in ORF1 and ORF2 in the third codon position, 3T(U) or 3C is more preferred, and in ORF3 – 3C or 3G; in ORF1 and ORF2, CpG and TpC dinucleotides are underrepresented, while TpG are overrepresented; in the synonymous codons of ORF2, a U/A terminal shift was detected, in ORF1 and ORF2 – 3G or 3C; the effect of translational selection on HEV-1 is more pronounced than HEV-3; preference for the use of synonymous codons in ORF3 does not depend on the action of translational selection; the leading factor in the evolution of ORF1 and ORF2 HEV is negative (purifying) selection; neutrally selected sites predominate in ORF3 of HEV-1, which is a consequence of the established relationship between the virus and the host.

Search for the putative RNA thermometers in the genome of Hepatitis E virus

Currently, some temperature-sensitive elements in bacteria are known. Structurally and functionally different RNA thermometers control a variety of cellular processes in bacteria including virulence. Up-to-date experimental confirmation of RNA thermometers functioning in viruses was obtained only for West Nile virus. But other, unknown yet, types of RNA thermometers may exist in nature. The goal of this study was the determination of conservative stem-loop structures in the swine, wild boars’ hepatitis E virus (HEV) genome which may act as RNA thermometers. The search for putative RNA thermometers in the swine HEV which is a common pathogen in the pig population worldwide was executed. Bioinformatics analysis was used to predict the secondary structure of the linear RNA fragments and to determine the melting temperature of the potential hairpins in the HEV genome. 108 swine, wild boars genotype 3 and genotype 4 HEV isolates with complete genomes from the GenBank database were analyzed for the availability of stem-loop structures. Conservative hairpin with the putative thermoregulating function was found in genotype 3 HEV isolates from pig and wild boar for 64 HEV isolates from 108 analyzed ones. The stem of the hairpin with a length of 37 nt contains two AUG start codons of translation initiation and the melting temperature of the hairpin is equal to 38–42 °С for ionic strength of 0.165 M Na+. These hairpins contain a metastable element (one or two bulges) in the stem. Conservative secondary stem-loop structures with putative thermoregulating function for genomic RNA of 64 HEV isolates with complete genome were found by bioinformatics analysis. These hairpins contain a metastable element (one or two bulges) in the stem like an RNA thermometer of West Nile virus and satisfy the necessary and sufficient conditions of RNA thermometer formation. Determined stem-loop structures are proposed as putative thermoregulator elements because they are highly conservative uncanonical structures that are present in the genomes of 64 HEV isolates from 108 analyzed ones

КЛИНИКО-ЭПИДЕМИОЛОГИЧЕСКАЯ И МОЛЕКУЛЯРНО-ГЕНЕТИЧЕСКАЯ ХАРАКТЕРИСТИКА ПЕРВОГО СЛУЧАЯ ОСТРОГО ГЕПАТИТА Е В ГРОДНЕНСКОМ РЕГИОНЕ

Background. The emergence of hepatitis E virus (HEV) in developed countries is driven by improved diagnostic tools, increased clinician awareness of the autochthonous nature of transmission and the potential for life-threatening acute and chronic liver damage. Objective. To present the first confirmed case of acute hepatitis E (AHE) caused by the E virus of the first genotype (HEV-1) in the Grodno region, registered in 2022. Material and methods. The patient is a native of Pakistan, who has been living and working in Grodno for recent years. He visited Italy and Pakistan several times within last six months, returned to Grodno 2 weeks before the onset of clinical manifestations of the disease. The patient was hospitalized in the Regional infectious diseases hospital. The methods for laboratory and etiological diagnosis of hepatitis included: general clinical methods, serological and molecular genetic ones (ELISA - IgM, IgG HEV; PCR - RNA HEV, genotyping and sequencing of the HEV genome). Results. Epidemiological, clinical and laboratory methods made it possible to exclude viral hepatitis A, B, C, D and establish the diagnosis of AHE of icteric (bilirubin at the height of the disease - 209.1 μmol/l, ALT - 1795 U/l), moderate form with a favorable outcome. IgM and IgG to HEV were detected in the patient's blood. HEV RNA was isolated from the patient's biological material. The isolated sequence in 100% bootstrap replications was assigned to HEV genotype 1. The insignificant value of the evolutionary distance between the "Grodno" sequence and the sequence isolated from a patient's body in Pakistan indicated a high degree of their homology, which made it possible to conclude that this case of AHE was imported. Conclusions. For the first time in the Grodno region, there was registered an imported case of AHE acquired during travel to HEV hyperendemic territory. The identified sequence is 100% HEV-1 genotype and 94.3% homologous to the sequence obtained from a patient in Pakistan. Under favourable conditions, HEV-1, which has a significant epidemic potential, can cause the development of HEV outbreaks.

The endocytic recycling compartment serves as a viral factory for hepatitis E virus

Although hepatitis E virus (HEV) is the major leading cause of enterically transmitted viral hepatitis worldwide, many gaps remain in the understanding of the HEV lifecycle. Notably, viral factories induced by HEV have not been documented yet, and it is currently unknown whether HEV infection leads to cellular membrane modeling as many positive-strand RNA viruses. HEV genome encodes the ORF1 replicase, the ORF2 capsid protein and the ORF3 protein involved in virion egress. Previously, we demonstrated that HEV produces different ORF2 isoforms including the virion-associated ORF2i form. Here, we generated monoclonal antibodies that specifically recognize the ORF2i form and antibodies that recognize the different ORF2 isoforms. One antibody, named P1H1 and targeting the ORF2i N-terminus, recognized delipidated HEV particles from cell culture and patient sera. Importantly, AlphaFold2 modeling demonstrated that the P1H1 epitope is exposed on HEV particles. Next, antibodies were used to probe viral factories in HEV-producing/infected cells. By confocal microscopy, we identified subcellular nugget-like structures enriched in ORF1, ORF2 and ORF3 proteins and viral RNA. Electron microscopy analyses revealed an unprecedented HEV-induced membrane network containing tubular and vesicular structures. We showed that these structures are dependent on ORF2i capsid protein assembly and ORF3 expression. An extensive colocalization study of viral proteins with subcellular markers, and silencing experiments demonstrated that these structures are derived from the endocytic recycling compartment (ERC) for which Rab11 is a central player. Hence, HEV hijacks the ERC and forms a membrane network of vesicular and tubular structures that might be the hallmark of HEV infection.

Isolation and Genome Sequencing of Hepatitis E Virus Genotype 1 Imported from India to Japan.

Hepatitis E virus (HEV) is the causative agent of viral hepatitis E. In Japan, HEV genotype 3 (G3) and G4 are predominantly detected, while G1, mainly imported from countries in continental Asia, is rare. In the present study, we detected a G1 HEV strain in a patient who visited Japan from India. When PLC/PRF/5 cells (subclone 4-21) were inoculated with a stool suspension from this patient, accumulation of HEV RNA was observed in the spent culture medium, indicating that HEV had been successfully isolated from this specimen. A nearly complete HEV genome was obtained by RT-PCR amplification. Phylogenetic analyses revealed that the newly isolated HEV strain, designated 9HE36c, belongs to subtype 1g of HEV G1.