Rabbit Hepatitis E Virus Infections in Humans, France

Genetic substructure and host-specific natural selection trend across vaccine-candidate ORF-2 capsid protein of hepatitis-E virus

Hepatitis E virus is a primary cause of acute hepatitis worldwide. The present study attempts to assess the genetic variability and evolutionary divergence among HEV genotypes. A vaccine promising capsid-protein coding ORF-2 gene sequences of HEV was evaluated using phylogenetics, model-based population genetic methods and principal component analysis. The analyses unveiled nine distinct clusters as subpopulations for six HEV genotypes. HEV-3 genotype samples stratified into four different subgroups, while HEV-4 stratified into three additional subclusters. Rabbit-infectious HEV-3ra samples constitute a distinct cluster. Pairwise analysis identified marked genetic distinction of HEV-4c and HEV-4i subgenotypes compared to other genotypes. Numerous admixed, inter and intragenotype recombinant strains were detected. The MEME method identified several ORF-2 codon sites under positive selection. Some selection signatures lead to amino acid substitutions within ORF-2, resulting in altered physicochemical features. Moreover, a pattern of host-specific adaptive signatures was identified among HEV genotypes. The analyses conclusively depict that recombination and episodic positive selection events have shaped the observed genetic diversity among different HEV genotypes. The significant genetic diversity and stratification of HEV-3 and HEV-4 genotypes into subgroups, as identified in the current study, are noteworthy and may have implications for the efficacy of anti-HEV vaccines.

Prevalence of Acute Hepatitis E Virus Infections in Swiss Blood Donors 2018-2020

INTRODUCTION

Hepatitis E virus (HEV) genotype 3 is the major cause of acute viral hepatitis in several European countries. It is acquired mainly by ingesting contaminated pork, but has also been reported to be transmitted through blood transfusion. Although most HEV infections, including those via blood products, are usually self-limiting, they may become chronic in immunocompromised persons. It is thus essential to identify HEV-infected blood donations to prevent transmission to vulnerable recipients.

AIMS

Prior to the decision whether to introduce HEV RNA screening for all Swiss blood donations, a 2-year nationwide prevalence study was conducted.

METHODS

All blood donations were screened in pools of 12-24 samples at five regional blood donation services, and HEV RNA-positive pools were subsequently resolved to the individual donation index donation (X). The viral load, HEV IgG and IgM serology, and HEV genotype were determined. Follow-up investigations were conducted on future control donations (X + 1) and previous archived donations of the donor (X - 1) where available.

RESULTS

Between October 2018 and September 2020, 541,349 blood donations were screened and 125 confirmed positive donations were identified (prevalence 1:4331 donations). At the time of blood donation, the HEV RNA-positive individuals were symptom-free. The median viral load was 554 IU/mL (range: 2.01-2,500,000 IU/mL). Men (88; 70%) were more frequently infected than women (37; 30%), as compared with the sex distribution in the Swiss donor population (57% male/43% female, p < 0.01). Of the 106 genotyped cases (85%), all belonged to genotype 3. Two HEV sub-genotypes predominated; 3h3 (formerly 3s) and 3c. The remaining sub-genotypes are all known to circulate in Europe. Five 3ra genotypes were identified, this being a variant associated with rabbits. In total, 85 (68%) X donations were negative for HEV IgM and IgG. The remaining 40 (32%) were positive for HEV IgG and/or IgM, and consistent with an active infection. We found no markers of previous HEV in 87 of the 89 available and analyzed archive samples (X - 1). Two donors were HEV IgG-positive in the X - 1 donation suggesting insufficient immunity to prevent HEV reinfection. Time of collection of the 90 (72%) analyzed X + 1 donations varied between 2.9 and 101.9 weeks (median of 35 weeks) after X donation. As expected, none of those tested were positive for HEV RNA. Most donors (89; 99%) were positive for anti-HEV lgG/lgM (i.e., seroconversion). HEV lgM-positivity (23; 26%) indicates an often-long persistence of lgM antibodies post-HEV infection.

CONCLUSION

The data collected during the first year of the study provided the basis for the decision to establish mandatory HEV RNA universal screening of all Swiss blood donations in minipools, a vital step in providing safer blood for all recipients, especially those who are immunosuppressed.

Cross-species transmission and animal infection model of hepatitis E virus

Zoonotic hepatitis E virus (HEV) infection is an emerging global public health concern, and understanding the dynamics of HEV transmission between animals and humans is crucial for public health. Animal models are critical to advancing the understanding of HEV pathogenesis, drug screening, vaccine development, and other related areas. Here, we provide an overview of recent studies investigating the cross-species transmission of HEV, and also delve into the current research and application of animal HEV infection models including non-human primates, rodents, pigs, and chickens, offering a comprehensive assessment of the advantages and disadvantages of each model. This review highlights the findings related to viral replication, shedding patterns, and immune response in these animal models, and discusses the implications for our understanding of HEV transmission to humans. These advancements in the field enhance our understanding of the biological traits and pathogenic mechanisms of HEV, offering robust support for the development of highly effective and targeted prevention and treatment strategies.

Animal models of hepatitis E infection: Advances and challenges

Hepatitis E virus (HEV) is one of the leading causes of acute viral hepatitis worldwide. Although most of HEV infections are asymptomatic, some patients will develop the symptoms, especially pregnant women, the elderly, and patients with preexisting liver diseases, who often experience anorexia, nausea, vomiting, malaise, abdominal pain, and jaundice. HEV infection may become chronic in immunosuppressed individuals. In addition, HEV infection can also cause several extrahepatic manifestations. HEV exists in a wide range of hosts in nature and can be transmitted across species. Hence, animals susceptible to HEV can be used as models. The establishment of animal models is of great significance for studying HEV transmission, clinical symptoms, extrahepatic manifestations, and therapeutic strategies, which will help us understand the pathogenesis, prevention, and treatment of hepatitis E. This review summarized the animal models of HEV, including pigs, monkeys, rabbits, mice, rats, and other animals. For each animal species, we provided a concise summary of the HEV genotypes that they can be infected with, the cross-species transmission pathways, as well as their role in studying extrahepatic manifestations, prevention, and treatment of HEV infection. The advantages and disadvantages of these animal models were also emphasized. This review offers new perspectives to enhance the current understanding of the research landscape surrounding HEV animal models.

Seroprevalence of hepatitis E virus in patients with chronic liver disease

INTRODUCTION

The seroprevalence of hepatitis E virus (HEV) in patients with chronic liver disease (CLD) is little known in Brazil. Studies have suggested that HEV may harmfully influence the course of CLD, with a higher risk of progression to cirrhosis.

OBJECTIVE

To estimate the prevalence of the anti-HEV antibody (IgG) in patients with CLD and to describe demographic data and risk factors, as well as clinical-laboratory and ultrasound parameters.

PATIENTS AND METHODS

Cross-sectional study that included 227 patients with CLD followed at a referral outpatient clinic from June 2022 to March 2023. The patients were investigated clinically and tested for liver functions, anti-HEV IgG and, in positive cases, for HEV-RNA. Ultrasonography of the upper abdomen was also carried out.

RESULTS

Investigation of 227 patients (50 with hepatitis B, 49 with nonalcoholic fatty liver disease, 33 with hepatitis C, 17 with alcoholic liver disease, 16 with schistosomiasis and 62 with mixed disease), 55.5% were female, with an average age of 57 ± 13 years; 37.9% had liver cirrhosis. Seven patients (3.08%) presented anti-HEV positive and HEV-RNA negative. Ultrasound identified association between anti-HEV and contact with pigs, presence of gynecomastia or palmar erythema, lower platelet count, higher APRI and FIB-4 values, and splenomegaly.

CONCLUSION

Although the prevalence of anti-HEV in patients with CLD was low in this study, the antibody was observed more frequently in cases with a history of contact with pigs and with clinical-laboratory or imaging evidence of more advanced chronic liver disease.

Universal nucleic acid donor screening revealed epidemiological features of hepatitis E and prevented transfusion-transmitted infection in Japan

BACKGROUND

More than 45 cases of transfusion-transmitted hepatitis E virus infection (TT-HEV) have been reported in Japan. Therefore, in 2020, universal individual donation nucleic acid amplification testing (ID-NAT) was implemented for HEV.

STUDY DESIGN AND METHODS

We characterized HEV NAT-positive blood donors. The number of new HEV infections and the asymptomatic infection rate were estimated using the HEV NAT-positive rate. HEV RNA quantitation, phylogenetic analysis, and antibody tests were performed, and the residual risk of TT-HEV was assessed based on the lookback study results.

RESULTS

A total of 5,075,100 blood donations were screened with ID-NAT during the first year of implementation, among which 2804 (0.055%; males: 0.060%, females: 0.043%) were NAT-positive with regional differences. Approximately 270,000 new HEV infection cases were estimated to occur annually in Japan, with an asymptomatic infection rate of 99.9%. The median HEV RNA concentration, excluding cases below the limit of quantification, was 205 IU/mL. Among the 1113 cases where the genotype could be determined, HEV-3 and HEV-4 accounted for 98.8% (1100) and 1.2% (13), respectively. The maximum duration of HEV viremia, including the pre- and post-ID-NAT window periods, was estimated to be 88.2 days. Within the 3 years since ID-NAT implementation, no confirmed cases of breakthrough TT-HEV were observed.

DISCUSSION

Multiple indigenous HEV strains are prevalent in Japan, infecting a significant number of individuals. However, since the implementation of ID-NAT, TT-HEV has been prevented due to the test's high sensitivity.

Detection of Hepatitis E Virus in Rabbits and Rabbit Meat from Slaughterhouses in Hebei Province of China

Background: Hepatitis E virus (HEV) is a zoonotic pathogen. HEV has been found to be widely prevalent in rabbits. Its isolates are classified into HEV-3, rabbit subgenotype (HEV-3ra). The routes of human infection with HEV-3ra remain unclear; however, foodborne transmission is possible when asymptomatically infected animals enter the food chain. The prevalence of HEV infection in slaughtered rabbits and the presence of HEV in rabbit meat were evaluated in this study. Materials and Methods: In three slaughterhouses in Hebei province, China, samples of rabbit blood were collected during the slaughter process, and muscle, liver, and cavity juice were collected from the rabbit carcasses. Anti-HEV antibody in serum samples was detected using enzyme-linked immunosorbent assay. HEV RNA was tested in all samples by reverse transcription nested PCR (RT-nested PCR). The final amplicons of RT-nested PCR were sequenced and phylogenetically analyzed. Results: Of the 459 serum samples, 50 [10.9%, 95% confidence interval (CI): 8.1-13.7] were positive for anti-HEV antibody, and 17 (3.7%, 95% CI: 2.0-5.4) were positive for HEV RNA. HEV RNA was detected in 7 of 60 liver samples (11.7%, 95% CI: 3.3-20) and 2 cavity juice samples from semi-eviscerated carcasses, but was not detected in any muscle sample from either the eviscerated or semi-eviscerated carcasses. All the detected HEV strains belonged to HEV-3ra and related most closely with the rabbit HEV sequence previously reported in China. Conclusion: A portion of rabbits were in the viremia period of HEV infection at the slaughter age, resulting in the possibility of HEV carriage by rabbit carcass, particularly semi-eviscerated carcass containing liver. These findings suggest a potential risk of HEV transmission from raw rabbit products entering the food chain, whereas the presence of HEV appeared to be lower in the eviscerated carcass than in the semi-eviscerated carcass.

Hepatitis E Virus in Livestock-Update on Its Epidemiology and Risk of Infection to Humans

Hepatitis E virus (HEV) is a public health problem worldwide and an important food pathogen known for its zoonotic potential. Increasing numbers of infection cases with human HEV are caused by the zoonotic transmission of genotypes 3 and 4, mainly by consuming contaminated, undercooked or raw porcine meat. Pigs are the main reservoir of HEV. However, it should be noted that other animal species, such as cattle, sheep, goats, and rabbits, may also be a source of infection for humans. Due to the detection of HEV RNA in the milk and tissues of cattle, the consumption of infected uncooked milk and meat or offal from these species also poses a potential risk of zoonotic HEV infections. Poultry infected by avian HEV may also develop symptomatic disease, although avian HEV is not considered a zoonotic pathogen. HEV infection has a worldwide distribution with different prevalence rates depending on the affected animal species, sampling region, or breeding system.

Epidemiology Update of Hepatitis E Virus (HEV) in Uruguay: Subtyping, Environmental Surveillance and Zoonotic Transmission

Hepatitis E Virus (HEV) infection is an emergent zoonotic disease of increasing concern in developed regions. HEV genotype 3 (HEV-3) is mainly transmitted through consumption of contaminated food in high-income countries and is classified into at least 13 subtypes (3a-3n), based on p-distance values from complete genomes. In Latin America, HEV epidemiology studies are very scant. Our group has previously detected HEV3 in clinical cases, swine, wild boars, captive white-collared peccaries, and spotted deer from Uruguay. Herein, we aimed to provide novel insights and an updated overview of the molecular epidemiology of zoonotic HEV in Uruguay, including data from wastewater-based surveillance studies. A thorough analysis of HEV whole genomes and partial ORF2 sequences from Uruguayan human and domestic pig strains showed that they formed a separate monophyletic cluster with high nucleotide identity and exhibited p-distance values over the established cut-off (0.093) compared with reference subtypes' sequences. Furthermore, we found an overall prevalence of 10.87% (10/92) in wastewater, where two samples revealed a close relationship with humans, and animal reservoirs/hosts isolates from Uruguay. In conclusion, a single, new HEV-3 subtype currently circulates in different epidemiological settings in Uruguay, and we propose its designation as 3o along with its reference sequence.

Prevalence of hepatitis E virus in China from 1997 to 2022: a systematic review and meta-analysis

Introduction

Several studies have reported on hepatitis E virus (HEV) prevalence in various regions of China, but the results vary widely. Herein, we conducted a systematic review and meta-analysis to assess the seroprevalence, RNA-positive rate, genotype distribution of HEV in China, and its risk factors.

Methods

We included 208 related studies involving 1,785,569 participants published between 1997 and 2022. Random-effects models were used to pool prevalence, and subgroup analyses were conducted by population, gender, age, study period, regions, and rural-urban distribution. The meta regression models and pooled odds ratios (OR) were performed to identify risk factors for HEV infections.

Results

The pooled anti-HEV IgG, IgM, and Ag seroprevalence, and RNA detection rates in China from 1997 to 2022 were 23.17% [95% confidence interval (CI): 20.23-26.25], 0.73% (95% CI: 0.55-0.93), 0.12% (95% CI: 0.01-0.32), and 6.55% (95% CI: 3.46-12.05), respectively. The anti-HEV IgG seropositivity was higher in the occupational population (48.41%; 95% CI: 40.02-56.85) and older adult aged 50-59 years (40.87%; 95% CI: 31.95-50.11). The dominant genotype (GT) of hepatitis E in China was GT4. Notably, drinking non-tap water (OR = 1.82; 95% CI: 1.50-2.20), consumption of raw or undercooked meat (OR = 1.47; 95% CI: 1.17-1.84), and ethnic minorities (OR = 1.50; 95% CI: 1.29-1.73) were risk factors of anti-HEV IgG seroprevalence.

Discussions

Overall, the prevalence of hepatitis E was relatively high in China, especially among older adults, ethnic minorities, and humans with occupational exposure to pigs. Thus, there is a need for preventive measures, including HEV infection screening and surveillance, health education, and hepatitis E vaccine intervention in high-risk areas and populations.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023397036.

Hepatitis A Virus and Hepatitis E Virus as Food- and Waterborne Pathogens-Transmission Routes and Methods for Detection in Food

Foodborne viruses are an important threat to food safety and public health. Globally, there are approximately 5 million cases of acute viral hepatitis due to hepatitis A virus (HAV) and hepatitis E virus (HEV) every year. HAV is responsible for numerous food-related viral outbreaks worldwide, while HEV is an emerging pathogen with a global health burden. The reported HEV cases in Europe have increased tenfold in the last 20 years due to its zoonotic transmission through the consumption of infected meat or meat products. HEV is considered the most common cause of acute viral hepatitis worldwide currently. This review focuses on the latest findings on the foodborne transmission routes of HAV and HEV and the methods for their detection in different food matrices.

The Re-Emergence of Hepatitis E Virus in Europe and Vaccine Development

Hepatitis E virus (HEV) is one of the leading causes of acute viral hepatitis. Transmission of HEV mainly occurs via the fecal-oral route (ingesting contaminated water or food) or by contact with infected animals and their raw meat products. Some animals, such as pigs, wild boars, sheep, goats, rabbits, camels, rats, etc., are natural reservoirs of HEV, which places people in close contact with them at increased risk of HEV disease. Although hepatitis E is a self-limiting infection, it could also lead to severe illness, particularly among pregnant women, or chronic infection in immunocompromised people. A growing number of studies point out that HEV can be classified as a re-emerging virus in developed countries. Preventative efforts are needed to reduce the incidence of acute and chronic hepatitis E in non-endemic and endemic countries. There is a recombinant HEV vaccine, but it is approved for use and commercially available only in China and Pakistan. However, further studies are needed to demonstrate the necessity of applying a preventive vaccine and to create conditions for reducing the spread of HEV. This review emphasizes the hepatitis E virus and its importance for public health in Europe, the methods of virus transmission and treatment, and summarizes the latest studies on HEV vaccine development.

Preliminary investigation of hepatitis E virus detection by a recombinase polymerase amplification assay combined with a lateral flow strip

Hepatitis E virus (HEV) is a zoonotic pathogen that is a significant public health problem. Detecting HEV relies mainly on conventional PCR, which is time-consuming and requires sophisticated instruments and trained staff. We aimed to establish a reverse-transcription (RT)-recombinase polymerase amplification (RPA) assay (RT-RPA) combined with a lateral flow strip (LFS; RT-RPA-LFS) to rapidly detect HEV RNA in human and rabbit samples. With the optimal reaction conditions (37°C for 30 min), our assay detected as few as 1.0 × 102 copies/mL of HEV and showed no cross-reactivity with other hepatitis viruses. We tested 28 human samples (4 fecal and 24 serum samples) and 360 rabbit samples (180 fecal and 180 serum samples) with our RT-RPA-LFS assay and compared our assay to an RT-qPCR method. There was no significant difference (p > 0.05) in the test results between the 2 assays. Our RT-RPA-LFS assay detected both HEV3 and HEV4 genotypes. Our rapid, sensitive, and specific RT-RPA-LFS assay for the detection of HEV may provide a useful detection tool for limited-resource areas.

Low Replication Efficiency of a Japanese Rabbit Hepatitis E Virus Strain in the Human Hepatocarcinoma Cell Line PLC/PRF/5

A Japanese rabbit hepatitis E virus (HEV) strain, JP-59, has been identified in a feral rabbit. When this virus was transmitted to a Japanese white rabbit, it caused persistent HEV infection. The JP-59 strain shares an <87.5% nucleotide sequence identity with other rabbit HEV strains. Herein, to isolate JP-59 by cell culture, we used a 10% stool suspension recovered from a JP-59-infected Japanese white rabbit and contained 1.1 × 10⁷ copies/mL of the viral RNA and using it to infect a human hepatocarcinoma cell line, PLC/PRF/5. No sign of virus replication was observed. Although long-term virus replication was observed in PLC/PRF/5 cells inoculated with the concentrated and purified JP-59 containing a high titer of viral RNA (5.1 × 10⁸ copies/mL), the viral RNA of JP-59c that was recovered from the cell culture supernatants was <7.1 × 10⁴ copies/mL during the experiment. The JP-59c strain did not infect PLC/PRF/5 cells, but its intravenous inoculation caused persistent infection in rabbits. The nucleotide sequence analyses of the virus genomes demonstrated that a total of 18 nucleotide changes accompanying three amino acid mutations occurred in the strain JP-59c compared to the original strain JP-59. These results indicate that a high viral RNA titer was required for JP-59 to infect PLC/PRF/5 cells, but its replication capability was extremely low. In addition, the ability of rabbit HEVs to multiply in PLC/PRF/5 cells varied depending on the rabbit HEV strains. The investigations of cell lines that are broadly susceptible to rabbit HEV and that allow the efficient propagation of the virus are thus needed.

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.

Fetal Loss in Pregnant Rabbits Infected with Genotype 3 Hepatitis E Virus Is Associated with Altered Inflammatory Responses, Enhanced Virus Replication, and Extrahepatic Virus Dissemination with Positive Correlations with Increased Estradiol Level

Hepatitis E virus (HEV) causes adverse clinical outcomes in pregnant women, but the underlying mechanisms remain poorly understood. To delineate the mechanisms of pregnancy-associated adverse effects during HEV infection, we utilized a genotype 3 HEV from rabbit (HEV-3ra) and its cognate host (rabbits) to systematically investigate the clinical consequences, viral replication dynamics, and host immune and hormonal responses of HEV infection during pregnancy. We found a significant fetal loss of 23% in HEV-infected pregnant rabbits, indicating an early-stage miscarriage. HEV infection in pregnant rabbits was characterized by higher viral loads in feces, intestinal contents, liver, and spleen tissues, as well as a longer and earlier onset of viremia than in infected nonpregnant rabbits. HEV infection altered the pattern of cytokine gene expressions in the liver of pregnant rabbits and caused a transient increase of serum interferon gamma (IFN-γ) shortly after a notable increase in viral replication, which may contribute to early fetal loss. Histological lesions in the spleen were more pronounced in infected pregnant rabbits, although moderate liver lesions were seen in both infected pregnant and nonpregnant rabbits. Total bilirubin was elevated in infected pregnant rabbits. The serum levels of estradiol (E2) in HEV-infected pregnant rabbits were significantly higher than those in mock-infected pregnant rabbits at 14 days postinoculation (dpi) and correlated positively with higher viral loads in feces, liver, and spleen tissues at 28 dpi, suggesting that it may play a role in extrahepatic virus dissemination. The results have important implications for understanding the severe diseases associated with HEV infection during pregnancy. IMPORTANCE HEV causes adverse pregnancy outcomes, with a mortality rate of >30% in pregnant women, but the underlying mechanisms are poorly understood. In this study, we utilized HEV-3ra and its cognate host (pregnant rabbit) to delineate the potential underlying mechanisms of pregnancy-associated adverse outcomes during HEV infection. We found that infected pregnant rabbits had a fetal loss of 23%, which coincided with enhanced viral replication and an elevated systemic IFN-γ response, followed by longer viremia duration and extrahepatic viral dissemination. Estradiol levels were increased in infected pregnant rabbits and correlated positively with higher fecal viral shedding and higher viral loads in liver and spleen tissues. Infected pregnant rabbits had more pronounced splenic lesions, higher serum total bilirubin, and an altered cytokine gene expression profile in the liver. The results will contribute to our understanding of the mechanisms of HEV-associated adverse pregnancy outcomes.

Ribavirin Treatment Failure-Associated Mutation, Y1320H, in the RNA-Dependent RNA Polymerase of Genotype 3 Hepatitis E Virus (HEV) Enhances Virus Replication in a Rabbit HEV Infection Model

Chronic hepatitis E virus (HEV) infection has become a significant clinical problem that requires treatment in immunocompromised individuals. In the absence of an HEV-specific antiviral, ribavirin (RBV) has been used off-label, but treatment failure may occur due to mutations in the viral RNA-dependent RNA polymerase (RdRp), including Y1320H, K1383N, and G1634R. Chronic hepatitis E is mostly caused by zoonotic genotype 3 HEV (HEV-3), and HEV variants from rabbits (HEV-3ra) are closely related to human HEV-3. Here, we explored whether HEV-3ra, along with its cognate host, can serve as a model to study RBV treatment failure-associated mutations observed in human HEV-3-infected patients. By utilizing the HEV-3ra infectious clone and indicator replicon, we generated multiple single mutants (Y1320H, K1383N, K1634G, and K1634R) and a double mutant (Y1320H/K1383N) and assessed the role of mutations on replication and antiviral activity of HEV-3ra in cell culture. Furthermore, we also compared the replication of the Y1320H mutant with the wild-type HEV-3ra in experimentally infected rabbits. Our in vitro analyses revealed that the effects of these mutations on rabbit HEV-3ra are altogether highly consistent with those on human HEV-3. Importantly, we found that the Y1320H enhances virus replication during the acute stage of HEV-3ra infection in rabbits, which corroborated our in vitro results showing an enhanced viral replication of Y1320H. Taken together, our data suggest that HEV-3ra and its cognate host is a useful and relevant naturally occurring homologous animal model to study the clinical relevance of antiviral-resistant mutations observed in human HEV-3 chronically-infected patients. IMPORTANCE HEV-3 causes chronic hepatitis E that requires antiviral therapy in immunosuppressed individuals. RBV is the main therapeutic option for chronic hepatitis E as an off-label use. Several amino acid changes, including Y1320H, K1383N, and G1634R, in the RdRp of human HEV-3 have reportedly been associated with RBV treatment failure in chronic hepatitis E patients. In this study, we utilized an HEV-3ra from rabbit and its cognate host to investigate the effect of these RBV treatment failure-associated HEV-3 RdRp mutations on viral replication efficiency and antiviral susceptibility. The in vitro data using rabbit HEV-3ra was highly comparable to those from human HEV-3. We demonstrated that the Y1320H mutation significantly enhanced HEV-3ra replication in cell culture and enhanced virus replication during the acute stage of HEV-3ra infection in rabbits. The rabbit HEV-3ra infection model should be useful in delineating the role of human HEV-3 RBV treatment failure-associated mutations in antiviral resistance.

Rodent-borne viruses in the region of Middle East

Rodents are one of the most abundant mammal species in the world. They form more than two-fifth of all mammal species and there are approximately 4600 existing rodent species. Rodents are capable of transmitting deadly diseases, especially those that are caused by viruses. Viruses and their consequences have plagued the world for the last two centuries, three pandemics occurred during the last century only. The Middle East is situated at the crossroads of Africa and Asia, along with the Mediterranean Sea and the Indian Ocean, its geographic importance is gained through the diversity of topographies, biosphere, as well as climate aspects that make the region vulnerable to host emerging diseases. Refugee crises also play a major role in expected epidemic outbreaks in the region. Public health has always been the most important priority, and our aim in this review is to raise awareness among public health organisations across the Middle East about the dangers of rodent borne diseases that have been reported or are suspected to be found in the region.

Absence of Hepatitis E Virus (HEV) in Italian Lagomorph Species Sampled between 2019 and 2021

The zoonotic hepatitis E virus genotype 3 (HEV-3) causes most autochthonous human hepatitis E cases in Europe, which are due to the consumption of raw or undercooked food products of animal origin. Pigs and wild boars are considered the main reservoirs of this genotype, while rabbits are the reservoir of a distinct phylogenetic group named HEV-3ra, which is classified within the HEV-3 genotype but in a separate clade. Evidence for the zoonotic potential of HEV-3ra was suggested by its detection in immunocompromised patients in several European countries. HEV-3ra infection was found in farmed and feral rabbit populations worldwide and its circulation was reported in a few European countries, including Italy. Furthermore, Italy is one of the major rabbit meat producers and consumers across Europe, but only a few studies investigated the presence of HEV in this reservoir. The aim of this study was to assess the presence of HEV in 328 Italian hares and 59 farmed rabbits collected in 3 Italian macro-areas (North, North-Central, and South-Central), between 2019 and 2021. For this purpose, liver samples were used to detect HEV RNA using broad-range real-time RT-PCR and nested RT-PCR. Using 28 liver transudates from hares, the ELISA test for anti-HEV IgG detection was also performed. Neither HEV RNA nor anti-HEV antibodies were detected. Further studies will be conducted to assess the HEV presence in Italian lagomorphs to establish the role of this host and the possible risk of transmission for workers with occupational exposure, to pet owners and via food.

Dual Infection of Hepatitis A Virus and Hepatitis E Virus- What Is Known?

Viral hepatitis is an infection of human hepatocytes resulting in liver damage. Dual infection of two hepatotropic viruses affects disease outcomes. The hepatitis A virus (HAV) and hepatitis E virus (HEV) are two enterically transmitted viruses; they are single-stranded RNA viruses and have common modes of transmission. They are transmitted mainly by the fecal-oral route and ingestion of contaminated food, though the HAV has no animal reservoirs. The HAV and HEV cause acute self-limiting disease; however, the HEV, but not HAV, can progress to chronic and extrahepatic infections. The HAV/HEV dual infection was reported among acute hepatitis patients present in developing countries. The impact of the HAV/HEV on the prognosis for acute hepatitis is not completely understood. Studies showed that the HAV/HEV dual infection increased abnormalities in the liver leading to fulminant hepatic failure (FHF) with a higher mortality rate compared to infection with a single virus. On the other hand, other reports showed that the clinical symptoms of the HAV/HEV dual infection were comparable to symptoms associated with the HAV or HEV monoinfection. This review highlights the modes of transmission, the prevalence of the HAV/HEV dual infection in various countries and among several study subjects, the possible outcomes of this dual infection, potential model systems for studying this dual infection, and methods of prevention of this dual infection and its associated complications.

Puzzles for Hepatitis E Virus

Hepatitis E virus (HEV) is an important but understudied virus that has been the major cause of acute viral hepatitis worldwide. In recent decades, our understanding of this neglected virus has changed greatly: novel forms of viral proteins and their functions have been discovered; HEV can transmit via blood transfusion and organ transplantation; HEV can infect many animal species and the number is still increasing; HEV can induce chronic hepatitis and extra-hepatic manifestations. However, we are short of effective treatment measures to counter the virus. In this chapter we tend to briefly introduce the puzzles and major knowledge gaps existed in the field of HEV research.

Hepatitis E as a Zoonosis

Hepatitis E viruses in the family of Hepeviridae have been classified into 2 genus, 5 species, and 13 genotypes, involving different animal hosts of different habitats. Among all these genotypes, four (genotypes 3, 4, 7, and C1) of them are confirmed zoonotic causing sporadic human diseases, two (genotypes 5 and 8) were likely zoonotic showing experimental animal infections, and the other seven were not zoonotic or unconfirmed. These zoonotic HEV carrying hosts include pig, boar, deer, rabbit, camel, and rat. Taxonomically, all the zoonotic HEVs belong to the genus Orthohepevirus, which include genotypes 3, 4, 5, 7, 8 HEV in the species A and genotype C1 HEV in the species C. In the chapter, information of zoonotic HEV such as swine HEV (genotype 3 and 4), wild boar HEV (genotypes 3-6), rabbit HEV (genotype 3), camel HEV (genotype 7 and 8), and rat HEV (HEV-C1) was provided in detail. At the same time, their prevalence characteristics, transmission route, phylogenetic relationship, and detection technology were discussed. Other animal hosts of HEVs were introduced briefly in the chapter. All these information help peer researchers have basic understanding of zoonotic HEV and adopt reasonable strategy of surveillance and prevention.

Animal Models for Hepatitis E Virus

Animal models are one of the most important tools in the study of human hepatitis E virus (HEV) infection. They are particularly important in light of the major limitations of the cell culture system for HEV. Besides nonhuman primates, which are extremely valuable because of their susceptibility to HEV genotypes 1-4, animals like swine, rabbit, and humanized mice are also potential models for studies of pathogenesis, cross-species infection, and the molecular biology of HEV. Identification of a useful animal model for human HEV infection studies is crucial to further investigations into this ubiquitous yet poorly understood virus and facilitate the development of antiviral therapeutics and vaccines.

Is Hepatitis E Virus a Neglected or Emerging Pathogen in Egypt?

Though Egypt ranks among the top countries for viral hepatitis and death-related liver disease, Hepatitis E virus (HEV) is a neglected pathogen. Living in villages and rural communities with low sanitation, use of underground well water and contact with animals are the main risk factors for HEV infection. Domestic animals, especially ruminants and their edible products, are one source of infection. Contamination of water by either human or animal stools is the main route of infection. In addition, HEV either alone or in coinfection with other hepatotropic viruses has been recorded in Egyptian blood donors. HEV seropositivity among Egyptian villagers was 60-80%, especially in the first decade of life. Though HEV seropositivity is the highest among Egyptians, HEV infection is not routinely diagnosed in Egyptian hospitals. The initial manifestations of HEV among Egyptians is a subclinical infection, although progression to fulminant hepatic failure has been recorded. With the improvement in serological and molecular approaches and increasing research on HEV, it is becoming clear that HEV represents a threat for Egyptians and preventive measures should be considered to reduce the infection rate and possible complications.

Hepatitis E virus (HEV) open reading frame 2: Role in pathogenesis and diagnosis in HEV infections

Hepatitis E virus (HEV) infection occurs worldwide. The HEV genome includes three to four open reading frames (ORF1-4). ORF1 proteins are essential for viral replication, while the ORF3 protein is an ion channel involved in the exit of HEV from the infected cells. ORF2 proteins form the viral capsid required for HEV invasion and assembly. They also suppress interferon production and inhibit antibody-mediated neutralisation of HEV, allowing the virus to hijack the host immune response. ORF2 is the only detectable viral protein in the human liver during HEV infection and it is secreted in the plasma, stool, and urine of HEV-infected patients, making it a reliable diagnostic marker. The plasma HEV ORF2 antigen level can predict the outcome of HEV infections. Hence, monitoring HEV ORF2 antigen levels may be useful in assessing the efficacy of anti-HEV therapy. The ORF2 antigen is immunogenic and includes epitopes that can induce neutralising antibodies; therefore, it is a potential HEV vaccine candidate. In this review, we highlighted the different forms of HEV ORF2 protein and their roles in HEV pathogenesis, diagnosis, monitoring the therapeutic efficacy, and vaccine development.

Chronic hepatitis E: Advancing research and patient care

The hepatitis E virus (HEV) was initially thought to exclusively cause acute hepatitis. However, the first diagnosis of chronic hepatitis E in transplant recipients in 2008 profoundly changed our understanding of this pathogen. We have now begun to understand that specific HEV genotypes can cause chronic infection in certain immunocompromised populations. Over the past decade, dedicated clinical and experimental research has substantiated knowledge on the epidemiology, transmission routes, pathophysiological mechanisms, diagnosis, clinical features and treatment of chronic HEV infection. Nevertheless, many gaps and major challenges remain, particularly regarding the translation of knowledge into disease prevention and improvement of clinical outcomes. This article aims to highlight the latest developments in the understanding and management of chronic hepatitis E. More importantly, we attempt to identify major knowledge gaps and discuss strategies for further advancing both research and patient care.

Immunocompromised rabbit model of chronic HEV reveals liver fibrosis and distinct efficacy of different vaccination strategies

BACKGROUND AND AIMS

HEV infection can lead to chronicity and rapid progression to liver fibrosis and cirrhosis in immunocompromised organ transplant recipients. Robust animal models are urgently needed to study the pathogenesis and test the efficacy of vaccines and antiviral drugs in immunosuppressed settings.

APPROACH AND RESULTS

Cyclosporin A was used to induce immunosuppression. Rabbits were challenged with genotype 3 or 4 HEV (i.e., the rabbit-derived HEV3 and human-derived HEV3 or HEV4). We assessed HEV markers within 13 weeks post inoculation (wpi) and pathological changes by hematoxylin and eosin and Masson staining at 4, 8, or 13 wpi. Chronic HEV infection was successfully established in immunocompromised rabbits. HEV RNA and/or antigens were detected in the liver, kidney, intestine, urine, and cerebrospinal fluid samples. Chronically infected animals exhibited typical characteristics of liver fibrosis development. Intrahepatic transcriptomic analysis indicated activation of both innate and adaptive immunity. Establishment of HEV chronicity likely contributed to the inhibited T-cell immune response. Ribavirin is effective in clearing HEV infection in immunocompromised rabbits. Most interestingly, vaccination completed before immunosuppression conferred full protection against both HEV3 and HEV4 infections, but vaccination during immunosuppression was only partially protective, and the efficacy did not improve with increased or additional vaccine doses.

CONCLUSIONS

The immunocompromised rabbit model of both chronic HEV3 and HEV4 infection that was established captured the key features of chronic HEV infection in transplant patients, including liver fibrogenesis, and revealed the distinct effectiveness of vaccination administered before or under immunosuppression. This rabbit model is valuable for understanding the pathogenesis of chronic hepatitis E, as well as for evaluating antiviral agents and vaccines.

Co-Circulation of Different Hepatitis E Virus Genotype 3 Subtypes in Pigs and Wild Boar in North-East Germany, 2019

Hepatitis E is a major cause of acute liver disease in humans worldwide. The infection is caused by hepatitis E virus (HEV) which is transmitted in Europe to humans primarily through zoonotic foodborne transmission from domestic pigs, wild boar, rabbits, and deer. HEV belongs to the family Hepeviridae, and possesses a positive-sense, single stranded RNA genome. This agent usually causes an acute self-limited infection in humans, but in people with low immunity, e.g., immunosuppressive therapy or underlying liver diseases, the infection can evolve to chronicity and is able to induce a variety of extrahepatic manifestations. Pig and wild boar have been identified as the primary animal reservoir in Europe, and consumption of raw and undercooked pork is known to pose a potential risk of foodborne HEV infection. In this study, we analysed pig and wild boar liver, faeces, and muscle samples collected in 2019 in Mecklenburg-Western Pomerania, north-east Germany. A total of 393 animals of both species were investigated using quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR), conventional nested RT-PCR and sequence analysis of amplification products. In 33 animals, HEV RNA was detected in liver and/or faeces. In one individual, viral RNA was detected in muscle tissue. Sequence analysis of a partial open reading frame 1 region demonstrated a broad variety of genotype 3 (HEV-3) subtypes. In conclusion, the study demonstrates a high, but varying prevalence of HEV RNA in swine populations in Mecklenburg-Western Pomerania. The associated risk of foodborne HEV infection needs the establishment of sustainable surveillance and treatment strategies at the interface between humans, animals, and the environment within a One Health framework.

Cross-Species Transmission of Rabbit Hepatitis E Virus to Pigs and Evaluation of the Protection of a Virus-like Particle Vaccine against Rabbit Hepatitis E Virus Infection in Pigs

We investigated the cross-species transmission of rabbit hepatitis E virus (rb HEV) to pigs and evaluated the cross-protection of a swine (sw) HEV-3 virus-like particle (VLP) vaccine against rb HEV infection in pigs. Twelve 4-week-old conventional pigs were divided into negative control (n = 3), positive control (rb HEV-infected, n = 4), and vaccinated (vaccinated and rb HEV-challenged, n = 5) groups. The vaccine was administered at weeks 0 and 2, and viral challenge was conducted at week 4. Serum HEV RNA, anti-HEV antibody, cytokine, and liver enzyme levels were determined. Histopathological lesions were examined in abdominal organs. Viral RNA was detected and increased anti-HEV antibody and alanine aminotransferase (ALT) levels were observed in positive control pigs; liver fibrosis, inflammatory cell infiltration in the lamina propria of the small intestine and shortened small intestine villi were also observed. In vaccinated pigs, anti-HEV antibody and Th1 cytokine level elevations were observed after the second vaccination; viral RNA was not detected, and ALT level elevations were not observed. The results verified the cross-species transmission of rb HEV to pigs and cross-protection of the sw HEV-3 VLP vaccine against rb HEV infection in pigs. This vaccine may be used for cross-protection against HEV infection in other species.

A Less Common Cause of Acute Hepatitis in Kidney Transplant Recipients: A Case Series

BACKGROUND

Hepatitis E virus (HEV) is a cause of significant morbidity and mortality, representing an important global public health problem. Immunocompetent patients with acute hepatitis E can clear the infection spontaneously; however, in approximately two thirds of cases, immunosuppressed patients, such as kidney transplant (KT) recipients, fail to clear the HEV infection and develop chronic hepatitis.

PATIENTS AND METHODS

We report 3 cases of HEV infection in KT patients. Two presented only with laboratory abnormalities and elevated liver enzymes, and 1 presented with symptomatic disease motivating hospital admission. None was able to clear the infection spontaneously, and they were all treated with ribavirin, accompanied with reduction of immunosuppressive drugs. Adverse effects of the treatment were reported in 2 patients, and in 1 case, a dose reduction was necessary. All patients responded to the treatment and have no current evidence of active disease. No alterations of basal kidney function during or related to the treatment were registered.

DISCUSSION

HEV screening in KT patients presenting with abnormal liver function of undetermined cause is fundamental, as it might have poorer outcomes in this specific population. The treatment with ribavirin seems to be safe and effective, although we must always be alert to potential side effects, maintaining a close follow-up of these patients.

Molecular epidemiology and genotype-specific disease severity of hepatitis E virus infections in Germany, 2010-2019

Zoonotic hepatitis E virus (HEV) is endemic in Europe. Genotype 3 (HEV-3) is predominant but information on subtype distribution, trends and clinical implications in Germany is scarce. We analysed 936 HEV RNA positive samples of human origin and corresponding national surveillance data from 2010 to 2019. Samples were referred to the National Consultant Laboratory and sequenced in at least one of four genomic regions. Sequences were analysed using bioinformatics methods and compared to the latest HEV reference set. 1,656 sequences were obtained from 300 female, 611 male and 25 of unknown sex aged 3–92 years (median 55 years). HEV-3c was predominant (67.3%) followed by HEV-3f, HEV-3e and HEV-3i(-like) with 14.3%, 9.7% and 4.0% (other subtypes ≤1.1%). The proportion of HEV-3 group 2 (3abchijklm) strains increased over time. Jaundice, upper abdominal pain, fever, hospitalization, and death due to HEV were significantly more often reported for patients infected with HEV-3 group 1 (3efg) compared to group 2. Larger spatio-temporal clusters of identical sequences were not observed. HEV-3 group 1 infections are more severe as compared to the predominant group 2. Detection of group 2 strains increased over the last years, possibly due to more frequent diagnosis of asymptomatic and mild courses. The diversity of strains and the space–time distribution is compatible with a foodborne zoonosis with supra-regional distribution of the infection vehicle (pork products).

Characterization of Chronic Hepatitis E Virus Infection in Immunocompetent Rabbits

Chronic hepatitis E virus (HEV) infection is frequently reported in immunocompromised patients, but has also been increasingly reported in non-immunocompromised individuals. We characterized the course of chronic HEV infection in immunocompetent rabbits. In two independent experiments, 40 specific-pathogen-free rabbits were infected with a rabbit HEV genotype 3 strain in serial diluted titers (108 to 104 copies/mL). Serum and fecal samples were collected weekly and were tested for HEV RNA, antigen, anti-HEV and liver enzymes. Rabbits that spontaneously cleared the infection before 10 weeks post-inoculation (wpi) were kept to the end of the study as recovery control. Liver tissues were collected from HEV-infected rabbits at 5, 10 and 26 wpi for histopathological analysis. Nineteen rabbits (47.5%) developed chronic HEV infection with persistent viraemia and fecal HEV shedding for >6 months. Seroconversion to anti-HEV was observed in 84.2% (16/19) of the chronically infected rabbits. Serum levels of aminotransferase were persistently elevated in most of the rabbits. Characterizations of chronic HEV infection in immunocompetent settings could be recapitulated in rabbits, which can serve as a valuable tool for future studies on pathogenesis.

Broadly Reactive Real-Time RT-PCR Assay for the Detection of Hepatitis E Virus and Simultaneous Genotyping by Single Nucleotide Polymorphism Analysis

Hepatitis E virus (HEV) infection is a global public health concern. Although HEV infection is usually asymptomatic and self-limiting, extrahepatic manifestations and chronic infections in immunocompromised patients have been described. HEV strains infecting humans have been classified into four main genotypes. In this study we have developed and validated a novel sensitive real-time RT-PCR assay for the detection of all four HEV genotypes. Simultaneous discrimination of genotypes 1, 2, and 4 from genotype 3 by single nucleotide polymorphism (SNP) analysis was possible. In all, 201 serum samples from cases and carriers previously tested for HEV by nested RT-PCR were analyzed. Twenty-seven HEV-positive samples could not be typed by the nested RT-PCR and nucleotide sequencing, but were newly typed by SNP analysis. As polymorphisms were present at the primer or probe binding site, we adopted a degenerate primer and mixed probes. When a mixed probe was added, the fluorescence intensity increased, facilitating genotype determination.

IMPORTANCE The distribution of HEV-3 and HEV-4 has been changing. HEV-4, which had been predominantly found in Asia, is now being detected in other parts of the world, and there are now reports of chronic infections. Additionally, neurological disorders have frequently been reported in patients with acute or chronic HEV infections. HEV-4 has also been shown to lead to a higher severity in terms of acute hepatitis than does HEV-3. Early typing can provide useful information regarding the route of infection and for tailoring treatment to the expected course of the disease. The present method afforded a good detection rate even when polymorphisms were present within the target region for viral gene detection. We believe that this method can be applied to the analysis of mutation-prone viral genes in the future.

The concept of one health applied to the problem of zoonotic diseases

Zoonotic diseases are a burden on healthcare systems globally, particularly underdeveloped nations. Numerous vertebrate animals (e.g., birds, mammals and reptiles) serve as amplifier hosts or reservoirs for viral zoonoses. The spread of zoonotic disease is associated with environmental factors, climate change, animal health as well as other human activities including globalization, urbanization and travel. Diseases at the human-animal environment interface (e.g., zoonotic diseases, vector-borne diseases, food/water borne diseases) continue to pose risk to animals and humans with a great significant mortality and morbidity. It is estimated that of 1400 infectious diseases known to affect humans, 60% of them are of animal origin. In addition, 75% of the emerging infectious diseases have a zoonotic nature, worldwide. The one health concept plays an important role in the control and prevention of zoonoses by integrating animal, human, and environmental health through collaboration and communication among osteopaths, wildlife, physicians, veterinarians professionals, public health and environmental experts, nurses, dentists, physicists, biomedical engineers, plant pathologists, biochemists, and others. No one sector, organization, or person can address issues at the animal-human-ecosystem interface alone.

Identification of hepatitis E virus in wild sika deer in Japan

Hepatitis E virus (HEV) is a zoonotic agent mainly transmitted through the consumption of uncooked or undercooked meat products derived from infected animals. In Japan, domestic pigs and wild boars are the major animal reservoirs, and whether or not deer are an HEV reservoir remains controversial. We analyzed 395 serum and 199 liver samples from 405 sika deer (Cervus nippon) caught in the wild between 1997 and 2020 in 11 prefectures of Japan for markers of HEV infection. Overall, 17 deer had anti-HEV IgG (4.3%), while 1 (0.2%) had HEV RNA (genotype 3b), indicating the occurrence of ongoing HEV infection in wild deer in Japan. An analysis of the complete HEV genome (deJOI_14) recovered from a viremic deer in Oita Prefecture revealed only 88.8% identity with the first HEV strain in sika deer (JDEER-Hyo03L) in Japan, being closest (96.3%) to the HEV obtained from a hepatitis patient living in the same prefecture. Of note, the deJOI_14 strain was 8.7-9.0% different from the wild boar HEV strains obtained in the same habitat and the same year, suggesting that difference in infected HEV strains between boar and deer may be explained by the limited possibility of close contact with each other, although boars are a known source of HEV infection. Increased numbers of hepatitis E cases after consumption of raw or undercooked meat products of wild deer have been reported in Japan. These results suggest a low but nonnegligible zoonotic risk of HEV infection in wild deer in this country.

Risk of transfusion-transmitted hepatitis E virus infection from pool-tested platelets and plasma

BACKGROUND AND AIMS

Immunocompromised patients are at risk of chronic hepatitis E which can be acquired by blood transfusions. Currently, screening of blood donors (BDs) for HEV RNA with a limit of detection (LOD) of 2,000 IU/ml is required in Germany. However, this may result in up to 440,000 IU of HEV RNA in blood products depending on their plasma volume. We studied the residual risk of transfusion-transmitted (tt) HEV infection when an LOD of 2,000 IU/ml is applied.

METHODS

Highly sensitive individual donor testing for HEV RNA on the Grifols Procleix Panther system (LOD 7.89 IU/ml) was performed. HEV loads were quantified by real-time PCR.

RESULTS

Of 16,236 donors, 31 (0.19%) were HEV RNA positive. Three BDs had viral loads between 710 and 2,000 IU/ml, which pose a significant risk of tt hepatitis E with any type of blood product. Eight BDs had viral loads of >32 to 710 IU/ml, which pose a risk of tt hepatitis E with platelet or plasma transfusions because of their higher plasma volume compared to red blood cell concentrates. Eight of these 11 potentially infectious BDs were seronegative for HEV, indicating a recent infection. Only 8 of 31 donors had viral loads >2,000 IU/ml that would also have been detected by the required screening procedure and 12 had very low HEV loads (<32 IU/ml).

CONCLUSIONS

Screening of BDs with an LOD of 2,000 IU/ml reduced the risk of tt HEV infection by about 73% for red blood cell concentrates but by just 42% for platelet and fresh frozen plasma transfusions. Single donor screening (LOD <32 IU/ml) should lead to an almost 100% risk reduction.

LAY SUMMARY

Immunocompromised patients, such as solid organ or hematopoietic stem cell recipients, are at risk of chronic hepatitis E, which can be acquired via blood transfusions. The risk of transfusion-transmitted hepatitis E in these patients may not be sufficiently controlled by (mini-)pool hepatitis E virus RNA screening of blood donors. Single donor screening should be considered to improve the safety of blood products.

Distribution and Genetic Diversity of Hepatitis E Virus in Wild and Domestic Rabbits in Australia

In 2020, Hepatitis E virus (HEV) was detected for the first time in Australian rabbits. To improve our understanding of the genetic diversity and distribution of the virus, 1635 rabbit liver samples from locations across Australia were screened via RT-qPCR for HEV. HEV genomes were amplified and sequenced from 48 positive samples. Furthermore, we tested 380 serum samples from 11 locations across Australia for antibodies against HEV. HEV was detected in rabbits from all states and territories, except the Northern Territory. Seroprevalence varied between locations (from 0% to 22%), demonstrating that HEV is widely distributed in rabbit populations across Australia. Phylogenetic analyses showed that Australian HEV sequences are genetically diverse and that HEV was likely introduced into Australia independently on several occasions. In summary, this study broadens our understanding of the genetic diversity of rabbit HEV globally and shows that the virus is endemic in both domestic and wild rabbit populations in Australia.

Characterization of rabbit hepatitis E virus isolated from a feral rabbit

Rabbit hepatitis E virus (HEV) has been detected among rabbits and recently isolated from immunocompromised patients, suggesting zoonotic transmission. In this study, HEV infection among feral rabbits (Oryctolagus cuniculus) was assessed by detection of anti-HEV antibodies and HEV RNA. The prevalence of anti-HEV antibodies in sera was of 33 % (20/60) and HEV RNA was detected from only one of fecal swabs (1.7 %, 1/58). Furthermore, one naïve rabbit was intravenously inoculated with the suspension of the HEV-positive fecal specimen, exhibiting persistent HEV shedding in feces, intermittent viremia, seroconversion to anti-HEV IgM and IgG, and high alanine aminotransferase (ALT) values, indicating persistent HEV infection. The isolate JP-59 had a length of 7,282 bp excluding a poly (A) tail and possessed the characteristic 93 bp-insertion in ORF1. Phylogenetic analysis indicated that JP-59 formed a cluster with other rabbit HEV isolates from rabbits and human origin. The JP-59 shared the nucleotide sequence identities less than 87 % with other rabbit HEVs, suggesting that a novel rabbit HEV strain was circulating in Japan.

Rat Hepatitis E Virus: Presence in Humans in South-Western France?

Background: Hepatitis E Virus (HEV) is one of the most common causes of hepatitis worldwide, and South-Western France is a high HEV seroprevalence area. While most cases of HEV infection are associated with the species Orthohepevirus-A, several studies have reported a few cases of HEV infections due to Orthohepevirus-C (HEV-C) that usually infects rats. Most of these human cases have occurred in immunocompromised patients. We have screened for the presence of HEV-C in our region. Methods and Results: We tested 224 sera, mostly from immunocompromised patients, for HEV-C RNA using an in-house real time RT-PCR. Liver function tests gave elevated results in 63% of patients: mean ALT was 159 IU/L (normal < 40 IU/L). Anti-HEV IgG (49%) and anti-HEV IgM (9.4%) were frequently present but none of the samples tested positive for HEV-C RNA. Conclusion: HEV-C does not circulate in the human population of South-Western France, despite the high seroprevalence of anti-HEV IgG.

Development and Optimization of an Enzyme Immunoassay to Detect Serum Antibodies against the Hepatitis E Virus in Pigs, Using Plant-Derived ORF2 Recombinant Protein

Hepatitis E is an emerging global disease, mainly transmitted via the fecal-oral route in developing countries, and in a zoonotic manner in the developed world. Pigs and wild boar constitute the primary Hepatitis E virus (HEV) zoonotic reservoir. Consumption of undercooked animal meat or direct contact with infected animals is the most common source of HEV infection in European countries. The purpose of this study is to develop an enzyme immunoassay (EIA) for the detection of anti-hepatitis E virus IgG in pig serum, using plant-produced recombinant HEV-3 ORF2 as an antigenic coating protein, and also to evaluate the sensitivity and specificity of this assay. A recombinant HEV-3 ORF2 110-610_6his capsid protein, transiently expressed by pEff vector in Nicotiana benthamiana plants was used to develop an in-house HEV EIA. The plant-derived HEV-3 ORF2 110-610_6his protein proved to be antigenically similar to the HEV ORF2 capsid protein and it can self-assemble into heterogeneous particulate structures. The optimal conditions for the in-house EIA (iEIA) were determined as follows: HEV-3 ORF2 110-610_6his antigen concentration (4 µg/mL), serum dilution (1:50), 3% BSA as a blocking agent, and secondary antibody dilution (1:20 000). The iEIA developed for this study showed a sensitivity of 97.1% (95% Cl: 89.9-99.65) and a specificity of 98.6% (95% Cl: 92.5-99.96) with a Youden index of 0.9571. A comparison between our iEIA and a commercial assay (PrioCHECK™ Porcine HEV Ab ELISA Kit, ThermoFisher Scientific, MA, USA) showed 97.8% agreement with a kappa index of 0.9399. The plant-based HEV-3 ORF2 iEIA assay was able to detect anti-HEV IgG in pig serum with a very good agreement compared to the commercially available kit.

Global molecular diversity of Hepatitis E virus in wild boar and domestic pig

Our study aim was to describe and characterize the global Hepatitis E virus (HEV) molecular and genotype geographical distribution in domestic pig and wild boar, which could facilitate the traceability of human cases. We performed a systematic sequence search for HEVs identified in domestic pig and wild boar from the available data in GenBank. Only sequences with lengths greater than 300 nt were included. For all sequences, the sequence length, host (i.e., domestic pig or wild boar), country of origin, and HEV genotype/subtype were recorded. Genotypes were assigned by the HEVnet typing tool. The genotype distributions were described by country and host. In countries with sequences available for both species, the genotype coincidences between both animal populations were analyzed. A total of 1404 viral sequences were included: 32.6% from wild boar and 67.4% from domestic pig. Most sequences were consistent with HEV genotype 3 (n = 1165). Genotype 4 was represented by 193 sequences, while genotypes 5 and 6 were represented by only 6 sequences. Sequences were identified in 39 countries, which included all continents except Antarctica. The genotypes with a wide distribution were 3a and 3f. Twenty-five countries had sequences that were found only in domestic pig, three countries only in wild boar, and 11 countries had sequences in both populations. In all countries with available sequences in both populations, the same viral genotype was identified. Our study shows that the number of swine HEV sequences is small, which limits direct comparisons with the sequences identified in humans. The global distribution of genotype 3, together with the wide distribution of genotype 4 in Asia, strongly limits the interpretation of the molecular analysis in the absence of an epidemiological survey of the cases. Increased HEV sequencing in swine should be a priority.

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Our study shows that the number of swine HEV sequences is small.

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The global distribution of genotype 3 strongly limits the interpretation of the molecular analysis.

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Increased HEV sequencing in swine should be a priority.

Immunogenicity and Antigenicity of Rabbit Hepatitis E Virus-Like Particles Produced by Recombinant Baculoviruses

Rabbit hepatitis E virus (HEV) is a novel HEV belonging to genotype 3 (HEV-3) in the Orthohepevirus A species of the genus Hepevirus, family Hepeviridae. Rabbit HEV was originally isolated from rabbits and found to cause zoonotic infection. Although rabbit HEV can be successfully grown in culture with several cell lines, including the human carcinoma cell line PLC/PRF/5, it is difficult to obtain the large amounts of viral antigen required for diagnosis and vaccine development. In this study, we expressed N-terminal 13 and 111 aa-truncated rabbit HEV ORF2 proteins using recombinant baculoviruses and obtained two types of virus-like particles (VLPs), RnVLPs and RsVLPs with ~35 and 24 nm diameter, respectively. Anti-rabbit HEV IgG antibodies were induced in high titer by immunizing rabbits with RnVLPs or RsVLPs. The antibody secretion in the serum persisted more than three years. RsVLPs showed stronger antigenic cross-reactivity against HEV-1, HEV-3 and HEV-4 than rat HEV. Moreover, anti-RsVLPs antibodies neutralized not only the cognate virus but also HEV-1, HEV-3 and HEV-4 ex vivo, indicating that rabbit HEV had the same serotype as human HEVs. In contrast, the antibody did not block rat HEV infection, demonstrating that rat HEV belonged to a different serotype. Animal experiments indicated that immunization with either RnVLPs or RsVLPs completely protected the rabbits from challenge by rabbit HEV, suggesting that the VLPs are candidates for rabbit HEV vaccine development.

Hepatitis E Virus Persistence and/or Replication in the Peripheral Blood Mononuclear Cells of Acute HEV-Infected Patients

BACKGROUND

Hepatitis E virus (HEV) causes about 14 million infections with 300,000 deaths and 5,200 stillbirths worldwide annually. Extrahepatic manifestations are reported with HEV infections, such as renal, neurological, and hematological disorders. Recently, we reported that stool-derived HEV-1 replicates efficiently in human monocytes and macrophages in vitro. However, another study reports the presence of viral RNA but no evidence of replication in the PBMCs of acute hepatitis E (AHE) patients. Therefore, the replication of HEV in PBMCs during AHE infection is not completely understood.

METHODS

PBMCs were isolated from AHE patients (n = 17) enrolled in Assiut University Hospitals, Egypt. The viral load, positive (+) and negative (-) HEV RNA strands and viral protein were assessed. The gene expression profile of PBMCs from AHE patients was assessed. In addition, the level of cytokines was measured in the plasma of the patients.

RESULTS

HEV RNA was detected in the PBMCs of AHE patients. The median HEV load in the PBMCs was 1.34 × 103 IU/ml. A negative HEV RNA strand and HEV open reading frame 2 protein were recorded in 4/17 (23.5%) of the PBMCs. Upregulation of inflammatory transcripts and increased plasma cytokines were recorded in the AHE patients compared with healthy individuals with significantly elevated transcripts and plasma cytokines in the AHE with detectable (+) and (-) RNA strands compared with the AHE with the detectable (+) RNA strand only. There was no significant difference in terms of age, sex, and liver function tests between AHE patients with detectable (+) and (-) RNA strands in the PBMCs and AHE patients with the (+) RNA strand only.

CONCLUSION

Our study shows evidence for in vivo HEV persistence and replication in the PBMCs of AHE patients. The replication of HEV in the PBMCs was associated with an enhanced immune response, which could affect the pathogenesis of HEV.

Hepatitis E: An update on One Health and clinical medicine

The hepatitis E virus (HEV) is one of the main causes of acute hepatitis and the de facto global burden is underestimated. HEV-related clinical complications are often undetected and are not considered in the differential diagnosis. Convincing findings from studies suggest that HEV is clinically relevant not only in developing countries but also in industrialized countries. Eight HEV genotypes (HEV-1 to HEV-8) with different human and animal hosts and other HEV-related viruses are in circulation. Transmission routes vary by genotype and location, with large waterborne outbreaks in developing countries and zoonotic food-borne infections in developed countries. An acute infection can be aggravated in pregnant women, organ transplant recipients, patients with pre-existing liver disease and immunosuppressed patients. HEV during pregnancy affects the fetus and newborn with an increased risk of vertical transmission, preterm and stillbirth, neonatal jaundice and miscarriage. Hepatitis E is associated with extrahepatic manifestations that include neurological disorders such as neuralgic amyotrophy, Guillain-Barré syndrome and encephalitis, renal injury and haematological disorders. The risk of transfusion-transmitted HEV is increasingly recognized in Western countries where the risk may be because of a zoonosis. RNA testing of blood components is essential to determine the risk of transfusion-transmitted HEV. There are currently no approved drugs or vaccines for HEV infections. This review focuses on updating the latest developments in zoonoses, screening and diagnostics, drugs in use and under development, and vaccines.

Variability in molecular characteristics of Hepatitis E virus quasispecies could modify viral surface properties and transmission

Hepatitis E virus (HEV) usually causes self-limited liver diseases but can also result in severe cases. Genotypes 1 (G1) and 2 circulate in developing countries are human-restricted and waterborne, while zoonotic G3 and G4 circulating in industrialized countries preferentially infect human through consumption of contaminated meat. Our aims were to identify amino acid patterns in HEV variants that could be involved in pathogenicity or in transmission modes, related to their impact on antigenicity and viral surface hydrophobicity. HEV sequences from human (n = 37) and environmental origins (wild boar [n = 3], pig slaughterhouse effluent [n = 6] and urban wastewater [n = 2]) were collected for the characterization of quasispecies using ultra-deep sequencing (ORF2/ORF3 overlap). Predictive and functional assays were carried out to investigate viral particle antigenicity and hydrophobicity. Most quasispecies showed a major variant while a mixture was observed in urban wastewater and in one chronically infected patient. Amino acid signatures were identified, as a rabbit-linked HEV pattern in two infected patients, or the S68L (ORF2) / H81C (ORF3) residue mostly identified in wild boars. By comparison with environmental strains, molecular patterns less likely represented in humans were identified. Patterns impacting viral hydrophobicity and/or antigenicity were also observed, and the higher hydrophobicity of HEV naked particles compared with the enveloped forms was demonstrated. HEV variants isolated from human and environment present molecular patterns that could impact their surface properties as well as their transmission. These molecular patterns may concern only one minor variant of a quasispecies and could emerge under selective pressure.

Hepatitis E virus persists in the ejaculate of chronically infected men

BACKGROUND & AIMS

Hepatitis E virus (HEV) infections are prevalent worldwide. Various viruses have been detected in the ejaculate and can outlast the duration of viremia, indicating replication beyond the blood-testis barrier. HEV replication in diverse organs, however, is still widely misunderstood. We aimed to determine the occurrence, features and morphology of HEV in the ejaculate.

METHODS

The presence of HEV in testis was assessed in 12 experimentally HEV-genotype 3-infected pigs. We further tested ejaculate, urine, stool and blood from 3 chronically HEV genotype 3-infected patients and 6 immunocompetent patients with acute HEV infection by HEV-PCR. Morphology and genomic characterization of HEV particles from various human compartments were determined by HEV-PCR, density gradient measurement, immune-electron microscopy and genomic sequencing.

RESULTS

In 2 of the 3 chronically HEV-infected patients, we observed HEV-RNA (genotype 3c) in seminal plasma and semen with viral loads >2 logs higher than in the serum. Genomic sequencing showed significant differences between viral strains in the ejaculate compared to stool. Under ribavirin-treatment, HEV shedding in the ejaculate continued for >9 months following the end of viremia. Density gradient measurement and immune-electron microscopy characterized (enveloped) HEV particles in the ejaculate as intact.

CONCLUSIONS

The male reproductive system was shown to be a niche of HEV persistence in chronic HEV infection. Surprisingly, sequence analysis revealed distinct genetic HEV variants in the stool and serum, originating from the liver, compared to variants in the ejaculate originating from the male reproductive system. Enveloped HEV particles in the ejaculate did not morphologically differ from serum-derived HEV particles.

LAY SUMMARY

Enveloped hepatitis E virus particles could be identified by PCR and electron microscopy in the ejaculate of immunosuppressed chronically infected patients, but not in immunocompetent experimentally infected pigs or in patients with acute self-limiting hepatitis E.

Comparison of Hepatitis E Virus Sequences from Humans and Swine, the Netherlands, 1998-2015

Pigs are suspected to be a major source of zoonotic hepatitis E virus (HEV) infection in industrialized countries, but the transmission route(s) from pigs to humans are ill-defined. Sequence comparison of HEV isolates from pigs with those from blood donors and patients in 372 samples collected in The Netherlands in 1998 and 1999 and between 2008 and 2015 showed that all sequences were genotype 3 except for six patients (with travel history). Subgenotype 3c (gt3c) was the most common subtype. While the proportion of gt3c increased significantly between 1998 and 2008, it remained constant between 2008 and 2015. Among the few circulating HEV subtypes, there was no difference observed between the human and the pig isolates. Hepatitis E viruses in humans are very likely to originate from pigs, but it is unclear why HEV gt3c has become the predominant subtype in The Netherlands.

Infectivity and pathogenicity of different hepatitis E virus genotypes/subtypes in rabbit model

The pathogenicity of each hepatitis E virus (HEV) genotypes/subtypes may be different. This study aimed to investigate the infectivity and pathogenicity of different HEV genotypes/subtypes from different mammalian sources especially human in rabbits, and to assess whether rabbits are an appropriate animal model to study different HEV genotypes/subtypes. Thirty-seven rabbits were randomly divided into nine groups and inoculated with eight different HEV strains, including human-derived HEV3b (hHEV-3b), hHEV-4a, hHEV-4d and hHEV-4h, swine-derived HEV4d (sHEV-4d) and sHEV-4h, rabbit-derived HEV3 (HEV-3ra) and camel-derived HEV8. HEV RNA, antigen, anti-HEV and alanine aminotransferase (ALT) in serum or/and feces were monitored weekly. One rabbit from each group was euthanized at seven weeks post inoculation and the liver specimens were taken for histopathological analysis and immunofluorescence staining of HEV ORF2 proteins. hHEV-4d, sHEV-4d and HEV-3ra infections were successfully established in rabbits and typical acute hepatitis symptoms were observed, including viraemia/antigenemia, fecal virus/antigen shedding, elevated ALT level and liver histopathological changes. One rabbit infected with HEV-3ra showed chronic infection. hHEV-4d and sHEV-4d are less infectious and pathogenic than HEV-3ra in rabbits. hHEV-3b and HEV8 only caused inapparent infection in rabbits as 60% (3/5) and 20% (1/5) of the rabbits seroconverted to anti-HEV, respectively. No obvious signs of HEV infection in rabbits inoculated with hHEV-4a, hHEV-4h and sHEV-4h. The infectivity and pathogenicity of different HEV genotypes/subtypes in rabbits is different, which may be related to the species specificity of HEV. Rabbit can be used as an animal model for the study of HEV-3ra and more importantly human HEV-4d.