Rabbit HEV in immunosuppressed patients with hepatitis E acquired in Switzerland

Inborn errors of type I interferon immunity in patients with symptomatic acute hepatitis E

BACKGROUND AND AIMS

The clinical spectrum of human infection by HEV ranges from asymptomatic to severe acute hepatitis. Furthermore, HEV can cause diverse neurological manifestations, especially Parsonage-Turner syndrome. Here, we used a large-scale human genomic approach to search for genetic determinants of severe clinical presentations of HEV infection.

APPROACH AND RESULTS

We performed whole genome sequencing in 3 groups of study participants with PCR-proven acute HEV infection: (1) 24 patients with symptomatic acute hepatitis E; (2) 12 patients with HEV-associated Parsonage-Turner syndrome; and (3) 16 asymptomatic blood donors (controls). For variant calling and annotation, we used GATK4 best practices followed by Variant Effect Predictor (VEP) and Annovar. For variant classification, we implemented the American College of Medical Genetics and Genomics/Association for Molecular Pathology Bayesian classification framework in R. Variants with a probability of pathogenicity >0.9 were considered damaging. We used all genes with at least 1 damaging variant as input for pathway enrichment analyses.We observed a significant enrichment of type I interferon response pathways in the symptomatic hepatitis group: 10 out of 24 patients carried a damaging variant in one of 9 genes encoding either intracellular viral sensors ( IFIH1 , DDX58 , TLR3 , POLR3B , POLR3C ) or other molecules involved in type I interferon response [interferon regulatory factor 7 ( IRF7 ), MYD88 , OAS3 , GAPDH ]. We did not find any enriched pathway in the Parsonage-Turner syndrome group or in the controls.

CONCLUSIONS

Our results highlight the essential role of type I interferon in preventing symptomatic acute hepatitis E.

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.

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.

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.

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.

Expanding the Hepatitis E Virus Toolbox: Selectable Replicons and Recombinant Reporter Genomes

Hepatitis E virus (HEV) has received relatively little attention for decades although it is now considered as one of the most frequent causes of acute hepatitis worldwide. Our knowledge of this enterically-transmitted, positive-strand RNA virus and its life cycle remains scarce but research on HEV has gained momentum more recently. Indeed, advances in the molecular virology of hepatitis E, including the establishment of subgenomic replicons and infectious molecular clones, now allow study of the entire viral life cycle and to explore host factors required for productive infection. Here, we provide an overview on currently available systems, with an emphasis on selectable replicons and recombinant reporter genomes. Furthermore, we discuss the challenges in developing new systems which should enable to further investigate this widely distributed and important pathogen.

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.

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.

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.

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.

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.

A Modular Hepatitis E Virus Replicon System for Studies on the Role of ORF1-Encoded Polyprotein Domains

Zoonotic hepatitis E virus (HEV) infection is an emerging cause of acute viral hepatitis in developed countries. Known reservoirs of zoonotic genotype 3 (HEV-3) are mainly pigs and wild boar, and to a lesser extent rabbits and deer. Rabbit hepatitis E virus (HEV-3ra) is prevalent in rabbits worldwide and represents a particular risk for zoonotic infection. Current understanding of the molecular mechanisms of HEV pathogenesis is incomplete, particularly due to the limited availability of efficient and reliable cell culture systems. In order to identify genomic regions responsible for HEV propagation in cell culture, we developed a modular chimeric reporter replicon system based on cell culture-adapted (Kernow-C1/p6 and 47832mc) and rabbit-derived HEV strains. Replication in HepG2 cells was monitored on the basis of a Gaussia luciferase reporter gene that was inserted in place of the open reading frame (ORF) 2 of the HEV genome. Luciferase activity of rabbit HEV-derived replicons was significantly lower than that of Kernow-C1/p6 and 47832mc replicons. Serial exchanges of defined ORF1 segments within the Kernow-C1/p6 replicon backbone indicated that HEV replication in HepG2 cells is not determined by a single domain but rather by an interplay of longer segments of the ORF1-derived nonstructural polyprotein. This implies that a specific combination of viral factors is required for efficient HEV propagation in cell culture.

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.

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.

Genetic Diversity of Hepatitis E Virus Type 3 in Switzerland-From Stable to Table

Simple Summary

The main hosts of hepatitis E virus (HEV) genotype 3 are porcine species. Transmission of the virus to humans, for example via undercooked meat, may cause acute or chronic hepatitis. To determine sources and routes of infection, comparing the viruses present in humans to the ones present in main hosts is a helpful tool. However, it requires knowledge of the genetic diversity of the circulating viruses. Therefore, we tested Swiss pigs and wild boars for HEV and determined the virus subtype and part of its genome. In addition, we determined the HEV subtype present in 11 positive meat products. One pig liver from the slaughterhouses (0.3%) and seven livers from a carcass collection (13%) as well as seven wild boar livers (5.8%) were found HEV positive. The same virus subtypes were found in Swiss pigs, wild boars, and meat products. Most of the viruses belonged to a Swiss-specific cluster within the subtype 3h. In addition, one pig liver and one wild boar liver were found positive for 3l and two meat products from Germany for 3c. Our data indicate that Switzerland has its “own” HEV viruses that circulate independent from the rest of Europe.

Abstract

Hepatitis E caused by hepatitis E viruses of the genotype 3 (HEV-3) is a major health concern in industrialized countries and due to its zoonotic character requires a “One Health” approach to unravel routes and sources of transmission. Knowing the viral diversity present in reservoir hosts, i.e., pigs but also wild boars, is an important prerequisite for molecular epidemiology. The aim of this study was to gain primary information on the diversity of HEV-3 subtypes present along the food chain in Switzerland, as well as the diversity within these subtypes. To this end, samples of domestic pigs from slaughterhouses and carcass collection points, as well as from hunted wild boars, were tested for HEV RNA and antibodies. HEV positive meat products were provided by food testing labs. The HEV subtypes were determined using Sanger and next generation sequencing. The genetic analyses confirmed the predominance of a Swiss-specific cluster within subtype HEV-3h in pigs, meat products, and wild boars. This cluster, which may result from local virus evolution due to the isolated Swiss pig industry, supports fast differentiation of domestic and imported infections with HEV.

Screening of Swiss Pig Herds for Hepatitis E Virus: A Pilot Study

Hepatitis E virus (HEV) is an important cause of acute hepatitis in humans worldwide. In industrialised countries, most infections are caused by the zoonotic genotype 3. The main reservoir was found in pigs, with fattening pigs as the main shedders. The aim of this study was to establish a screening tool to detect HEV in pig farms. HEV-positive samples were sequenced using Sanger sequencing. First, different sample materials, including floor swabs, slurry, dust swabs and faeces were tested for HEV. Floor swabs turned out to give the best results and, in the form of sock swabs, were used for the screening of Swiss pig herds. A total of 138 pig farms were tested, with a focus on fattening pigs. Overall, 81 farms (58.8%) were HEV positive. Most sequences belonged to subtype 3h, in which they formed a specific cluster (Swiss cluster). In addition, subtype 3l and two unassigned sequences were detected. As a conclusion, sock swabs were found to be a helpful tool to screen pig herds for HEV and establish a sequence collection that may enable molecular epidemiology and support outbreak investigation and prevention.

Oral Vaccination with Hepatitis E Virus Capsid Protein and Immunobiotic Bacterium-Like Particles Induce Intestinal and Systemic Immunity in Mice

The hepatitis E virus (HEV) genotype 3 (GT3) is an emergent pathogen in industrialized countries. It is transmitted zoonotically and may lead to chronic hepatitis in immunocompromised individuals. We evaluated if the major antigen of HEV, the capsid protein, can be used in combination with immunobiotic bacterium-like particles (IBLP) for oral vaccination in a mouse model. We have cloned and expressed the RGS-His₅-tagged HEV GT3 capsid protein (ORF2) in E. coli and purified it by NiNTA. IBLP were obtained from two immunobiotic Lactobacillus rhamnosus strains acid- and heat-treated. ORF2 and the IBLP were orally administered to Balb/c mice. After three oral immunizations (14-day intervals), blood, intestinal fluid, Peyer´s patches, and spleen samples were drawn. IgA- and IgG-specific antibodies were determined by ELISA. Mononuclear cell populations from Peyer's patches and spleen were analyzed by flow cytometry, and the cytokine profiles were determined by ELISA to study cellular immunity. Orally administered recombinant ORF2 and IBLP from two L. rhamnosus strains (CRL1505 and IBL027) induced both antigen-specific humoral and cellular immune responses in mice. IBLP027 was more effective in inducing specific secretory IgA in the gut. IFN-γ, TNF-α, and IL-4 were produced by Peyer's plaques lymphocytes stimulated with ORF2 ex vivo suggesting a mixed Th1/Th2-type adaptive immune response in immunized mice. Oral vaccines are not invasive, do not need to be administered by specialized personal, and elicit both systemic and local immune responses at the port of entry. Here, we present an experimental oral vaccine for HEV GT3, which could be further developed for human and/or veterinary use.

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.

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.

Prevalence of Hepatitis E Virus Infection among Laboratory Rabbits in China

Hepatitis E virus (HEV) is zoonotic and the leading cause of acute viral hepatitis worldwide. Rabbit HEV can infect humans and is prevalent globally. It is reported that laboratory rabbits are also naturally infected with HEV. Therefore, it is important to investigate in a large scale the prevalence of HEV in laboratory rabbits. Serum samples were collected from 649 laboratory rabbits of 13 different commercial vendors in Beijing, China, from 2017 to 2019, and anti-HEV and HEV antigen (Ag) were tested. Fecal samples were collected from 50 laboratory rabbits from one of the vendors for HEV RNA detection. Six laboratory rabbits with natural HEV infection were euthanized and their liver, kidney, bile and urine samples were collected for HEV RNA quantification. Liver tissues were subjected to histopathology analysis. The overall positive rates of anti-HEV antibodies and HEV-Ag are 2.6% (15/588) and 7.9% (51/649), respectively. HEV RNA was detected in 12.0% (6/50) of the rabbits. High viral load of HEV RNA was detected in liver and bile samples. Liver inflammation was observed. HEV is circulating in laboratory rabbit population in China. Strict screening is crucial to ensure experimental accuracy and prevent zoonotic transmission to research personnel.

A Putative Novel Hepatitis E Virus Genotype 3 Subtype Identified in Rabbit, Germany 2016

Hepatitis E is an emerging viral disease that is the leading cause of viral hepatitis in the world. The vast majority of hepatitis E cases in developed countries are caused by zoonotic genotypes 3 and 4 of hepatitis E virus (HEV) for which pig and wild boar and to lesser extent rabbits are the main reservoir. According to recent reports rabbits are a source of human HEV infection and highlight the risk of zoonotic foodborne transmission. Here we report the molecular analysis of a novel HEV strain identified in a rabbit during a countrywide surveillance of rabbits and hares in Germany, 2016. The analysis of the complete genome reveals characteristics of a putative novel recombinant subtype of the species Orthohepevirus A within the clade of genotype 3 but not closely related to any known subtypes. Importantly, the genome of this strain possesses a nucleotide exchange in the overlapping region of open reading frames ORF2/ORF3 interfering with a broadly applied diagnostic real-time RT-PCR. In conclusion, a new type of HEV strain was identified in a German rabbit with atypical and novel sequence characteristics.

Classification of the Zoonotic Hepatitis E Virus Genotype 3 Into Distinct Subgenotypes

Hepatitis E virus (HEV) genotype 3 is the most common genotype linked to HEV infections in Europe and America. Three major clades (HEV-3.1, HEV-3.2, and HEV-3.3) have been identified but the overlaps between intra-subtype and inter-subtype p-distances make subtype classification inconsistent. Reference sequences have been proposed to facilitate communication between researchers and new putative subtypes have been identified recently. We have used the full or near full-length HEV-3 genome sequences available in the Genbank database (April 2020; n = 503) and distance analyses of clades HEV-3.1 and HEV-3.2 to determine a p-distance cut-off (0.093 nt substitutions/site) in order to define subtypes. This could help to harmonize HEV-3 genotyping, facilitate molecular epidemiology studies and investigations of the biological and clinical differences between HEV-3 subtypes.

Characterization of hepatitis E virus natural infection in farmed rabbits

Rabbit hepatitis E virus (HEV3-ra) is widely distributed in rabbits worldwide and several recent reports found that HEV3-ra can infect humans. Therefore, people exposed to rabbits are at high risk of HEV infection. This study was conducted to investigate the characteristics and outcomes of HEV3-ra natural infection in rabbits. Seventy farmed rabbits (3-month-old) were surveyed in a farm in Beijing, China. Rabbits tested positive for HEV RNA were followed weekly for testing of HEV RNA, antigen, antibody and alanine aminotransferase (ALT) level. Liver and kidney tissue was collected for histopathology. Complete genome sequencing of the isolated HEV3-ra strain was performed (CHN-BJ-r4, GenBank: MT364355). The infectivity of CHN-BJ-r4 was tested in ten naïve rabbits by intravenous injection or gavage. Anti-HEV antibody and HEV RNA were tested positive in 7.14% (5/70) and 11.4% (8/70) of rabbits, respectively. Eight naturally infected rabbits were followed, and 37.5% (3/8) of the observed rabbits were found to have fecal shedding of HEV ranging from 3-22 weeks with high viral load (10⁵ -10⁷ copies/g). Two out of eight rabbits showed temporary viremia. Naturally infected rabbits presented elevated ALT level, seroconversion, and liver histopathology. Complete genome of HEV3-ra isolated in this study shared 84.61%-94.36% nucleotide identity with known HEV3-ra complete genomes. The isolated HEV3-ra strain was infectious and could infect other rabbits through intravenous and fecal-oral route. Naturally infected rabbits showed up to 22-week fecal virus shedding with high viral load. These features increased the risk of rabbit-to-rabbit and rabbit-to-human transmission.

Hepatitis E 3ra Genotype Infection in People Living With HIV in Spain

Background

The objective of our study was to assess the prevalence and incidence of HEV in people living with HIV (PLWH) in a Spanish national cohort.

Methods

Retrospective longitudinal study including PLWH recruited in the cohort of adult HIV-infected patients of the AIDS Research Network in follow-up at 28 Spanish hospitals with available serum samples in 2014 and 2015. All samples were tested for HEV IgG, IgM, and RNA. Samples with detectable HEV viral loads were genotyped. Prevalence and incidence of HEV infection were calculated.

Results

The study sample comprised 845 PLWH. At baseline, 101 patients were positive for HEV IgG antibodies (11.9%), none had HEV IgM antibodies, and 2 presented detectable HEV RNA (0.23%). Forty-two seroconverted for IgG, supposing a cumulative incidence of 5.7%. One subject was positive for IgM (0.13%), and 2 showed detectable HEV RNA (0.27%). One case was infected by the emergent HEV genotype 3ra.

Conclusion

Our study identifies one case of HEV 3ra genotype infection, the main host of which is rabbit, showing a potential zoonotic role of this emerging genotype in Spain.

Recent data on hepatitis E

PURPOSE OF REVIEW

Hepatitis E virus (HEV) has gained increased global recognition in recent years, particularly in developed countries. We summarized here a selection of the literature published since the 1st of June, 2017.

RECENT FINDINGS

Longitudinal studies are increasingly conducted in Europe, to determine trends in HEV prevalence. The spectrum of mammals infected with HEV and potentially capable to transmit it to humans has widened. New virological data on HEV repCon and pathogenicity have been reported and clinical features of HEV infections have been precised or newly described. Finally, there are some new data on the therapeutic management of HEV infections in various clinical settings.

SUMMARY

HEV emergence in developed countries appears to be based on improved diagnosis tools and increased awareness of clinicians that HEV transmission is essentially autochthonous and is a possible cause of life-threatening acute hepatitis, chronic hepatitis, cirrhosis, and extra-hepatic symptoms. In addition, the distribution of HEV strains evolves. Ribavirin remains to date the only specific treatment recommended for HEV infection, being efficient in the majority but not in all cases.

The global epidemiology of hepatitis E virus infection: A systematic review and meta-analysis

BACKGROUND AND AIMS

Hepatitis E virus (HEV), as an emerging zoonotic pathogen, is a leading cause of acute viral hepatitis worldwide, with a high risk of developing chronic infection in immunocompromised patients. However, the global epidemiology of HEV infection has not been comprehensively assessed. This study aims to map the global prevalence and identify the risk factors of HEV infection by performing a systematic review and meta-analysis.

METHODS

A systematic searching of articles published in Medline, Embase, Web of science, Cochrane and Google scholar databases till July 2019 was conducted to identify studies with HEV prevalence data. Pooled prevalence among different countries and continents was estimated. HEV IgG seroprevalence of subgroups was compared and risk factors for HEV infection were evaluated using odd ratios (OR).

RESULTS

We identified 419 related studies which comprised of 1 519 872 individuals. A total of 1 099 717 participants pooled from 287 studies of general population estimated a global anti-HEV IgG seroprevalence of 12.47% (95% CI 10.42-14.67; I²  = 100%). Notably, the use of ELISA kits from different manufacturers has a substantial impact on the global estimation of anti-HEV IgG seroprevalence. The pooled estimate of anti-HEV IgM seroprevalence based on 98 studies is 1.47% (95% CI 1.14-1.85; I²  = 99%). The overall estimate of HEV viral RNA-positive rate in general population is 0.20% (95% CI 0.15-0.25; I²  = 98%). Consumption of raw meat (P = .0001), exposure to soil (P < .0001), blood transfusion (P = .0138), travelling to endemic areas (P = .0244), contacting with dogs (P = .0416), living in rural areas (P = .0349) and receiving education less than elementary school (P < .0001) were identified as risk factors for anti-HEV IgG positivity.

CONCLUSIONS

Globally, approximately 939 million corresponding to 1 in 8 individuals have ever experienced HEV infection. 15-110 million individuals have recent or ongoing HEV infection. Our study highlights the substantial burden of HEV infection and calls for increasing routine screening and preventive measures.

Update: proposed reference sequences for subtypes of hepatitis E virus (species Orthohepevirus A)

In this recommendation, we update our 2016 table of reference sequences of subtypes of hepatitis E virus (HEV; species Orthohepevirus A, family Hepeviridae) for which complete genome sequences are available (Smith et al., 2016). This takes into account subsequent publications describing novel viruses and additional proposals for subtype names; there are now eight genotypes and 36 subtypes. Although it remains difficult to define strict criteria for distinguishing between virus subtypes, and is not within the remit of the International Committee on Taxonomy of Viruses (ICTV), the use of agreed reference sequences will bring clarity and stability to researchers, epidemiologists and clinicians working with HEV.

On the Host Side of the Hepatitis E Virus Life Cycle

Hepatitis E virus (HEV) infection is one of the most common causes of acute hepatitis in the world. HEV is an enterically transmitted positive-strand RNA virus found as a non-enveloped particle in bile as well as stool and as a quasi-enveloped particle in blood. Current understanding of the molecular mechanisms and host factors involved in productive HEV infection is incomplete, but recently developed model systems have facilitated rapid progress in this area. Here, we provide an overview of the HEV life cycle with a focus on the host factors required for viral entry, RNA replication, assembly and release. Further developments of HEV model systems and novel technologies should yield a broader picture in the future.

Clinical Manifestations, Pathogenesis and Treatment of Hepatitis E Virus Infections

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis throughout the world. Most infections are acute but they can become chronic in immunocompromised patients, such as solid organ transplant patients, patients with hematologic malignancy undergoing chemotherapy and those with a human immunodeficiency virus (HIV) infection. Extra-hepatic manifestations, especially neurological and renal diseases, have also been described. To date, four main genotypes of HEV (HEV1-4) were described. HEV1 and HEV2 only infect humans, while HEV3 and HEV4 can infect both humans and animals, like pigs, wild boar, deer and rabbits. The real epidemiology of HEV has been underestimated because most infections are asymptomatic. This review focuses on the recent advances in our understanding of the pathophysiology of acute HEV infections, including severe hepatitis in patients with pre-existing liver disease and pregnant women. It also examines the mechanisms leading to chronic infection in immunocompromised patients and extra-hepatic manifestations. Acute infections are usually self-limiting and do not require antiviral treatment. Conversely, a chronic HEV infection can be cleared by decreasing the dose of immunosuppressive drugs or by treating with ribavirin for 3 months. Nevertheless, new drugs are needed for those cases in which ribavirin treatment fails.

Absence of Hepatitis E virus circulation in wild rabbits (Oryctolagus cuniculus) and Iberian hares (Lepus granatensis) in Mediterranean ecosystems in Spain

In recent decades, cases of autochthonous hepatitis E (HE) have sharply increased in European countries where foodborne transmission is considered the main route of HE virus (HEV) transmission. Although rabbits are considered the main reservoir of the zoonotic HEV-3ra subtype, information on the role of wild lagomorphs in the epidemiology of HEV remains scarce. The aim of this study therefore was to assess the circulation of HEV in European wild rabbits (Oryctolagus cuniculus) and Iberian hares (Lepus granatensis), the most important lagomorph species in Spanish Mediterranean ecosystems. Liver samples from 372 wild rabbits and 78 Iberian hares were analysed using a broad-spectrum RT-PCR that detects HEV genotypes 1-8. None of the 450 lagomorphs tested were positive for HEV infection. To the best of our knowledge, this is the first study to assess HEV circulation in wild rabbits in Spain and the first to evaluate HEV infection in Iberian hares. Our results indicate absence of HEV circulation in wild rabbits and Iberian hares in southern Spain during the study period, which suggests that the risk of transmission of HEV from wild lagomorphs to other species, including humans, is low.

Prophylactic Hepatitis E Vaccines: Antigenic Analysis and Serological Evaluation

Hepatitis E virus (HEV) infection causes sporadic outbreaks of acute hepatitis worldwide. HEV was previously considered to be restricted to resource-limited countries with poor sanitary conditions, but increasing evidence implies that HEV is also a public health problem in developed countries and regions. Fortunately, several vaccine candidates based on virus-like particles (VLPs) have progressed into the clinical development stage, and one of them has been approved in China. This review provides an overview of the current HEV vaccine pipeline and future development with the emphasis on defining the critical quality attributes for the well-characterized vaccines. The presence of clinically relevant epitopes on the VLP surface is critical for eliciting functional antibodies against HEV infection, which is the key to the mechanism of action of the prophylactic vaccines against viral infections. Therefore, the epitope-specific immunochemical assays based on monoclonal antibodies (mAbs) for HEV vaccine antigen are critical methods in the toolbox for epitope characterization and for in vitro potency assessment. Moreover, serological evaluation methods after immunization are also discussed as biomarkers for clinical performance. The vaccine efficacy surrogate assays are critical in the preclinical and clinical stages of VLP-based vaccine development.

Detection of hepatitis E virus (rabbit genotype) in farmed rabbits entering the food chain

Hepatitis E virus (HEV) infects humans and many animal species. The rabbit HEV has been found in farmed, wild and pet rabbits as well as in human patients suggesting zoonotic transmission. Although the routes of human infection with rabbit strains are unclear a foodborne transmission is suggested especially when asymptomatically infected animals could enter the food chain. The aims of the study were an evaluation of the prevalence of HEV infections in slaughtered rabbits, identification of the virus genotype(s) and assessment of their genetic relatedness to other zoonotic HEV strains. A pair of blood and liver samples (n = 482) were collected from meat rabbits of different breeds slaughtered at the age of 2.8 to 6 months. The animals originated from 20 small-scale and 4 large-scale commercial farms operating in Poland. The presence of anti-HEV antibodies in animals was detected by the use of a recomWell HEV IgG (human) ELISA kit (Mikrogen Diagnostik) adapted to rabbit sera. The isolation of HEV and sample process control virus (feline calicivirus) RNA from homogenates of liver destined for food and virus-positive sera was performed using a QIAamp® Viral RNA Mini Kit (Qiagen). A one-step real-time reverse transcription PCR method containing a target-specific internal amplification control was used for detection of HEV. The (sub)genotype of detected rabbit HEV strains was identified based on sequence analysis of the ORF2 and ORF2/3 virus genome fragments. Anti-HEV antibodies were detected in 29 (6%) out of 482 rabbit sera samples collected from animals raised only on the small-scale rabbit farms. Four sera were also positive for HEV RNA. Viral RNA was detected in 72 (14.9%) animal livers. Analysing ELISA and PCR results using Student's t-test, there were significant differences observed in the frequency of HEV infections between rabbits from small-scale and commercial farms (t = 2.675, p = 0.015 < 0.05 for ELISA and t = 2.705, p = 0.014 < 0.05 for PCR). All detected virus strains were identified as HEV gt3 ra subtype. The results of this study provide data on the occurrence of HEV infections in rabbits entering the food chain, suggesting that a risk of foodborne HEV infection due to consumption of contaminated meat and liver exists. In this light, the presence of rabbit HEV in food animals is pertinent as an issue of food safety and the surveillance of these animals for emerging or re-emerging viruses.

Cross-Species Transmission of Swine Hepatitis E Virus Genotype 3 to Rabbits

Hepatitis E virus (HEV) is a quasi-enveloped, positive-sense single stranded RNA virus. HEV continually expands the host ranges across animal species. In this study, the possibility of cross-species infection with swine HEV-3 was investigated using rabbits. A total of fourteen 8-week old, specific pathogen-free rabbits were divided into three experimental groups. Four rabbits were used as negative controls, four rabbits were infected with rabbit HEV as positive controls, and six rabbits were inoculated with swine HEV-3. HEV RNA were detected from serum and fecal samples after viral challenge. The levels of anti-HEV antibodies, pro-inflammatory cytokines (IL-1, IL-6, TNF-α and IFN-α), and liver enzymes (alanine and aspartate aminotransferases) were determined in serum samples. Histopathological lesions were examined in liver tissues. Viral RNA and anti-HEV antibodies were identified in rabbits inoculated with swine HEV-3 demonstrating positive infectivity of the virus. However, pro-inflammatory cytokine and liver enzyme levels in serum were not significantly elevated, and only mild inflammatory lesions were detected in the liver tissues of rabbits infected with swine HEV-3. These results suggest that swine HEV-3 can engage in cross-species transmission to rabbits, but causes only mild inflammation of the liver.

Ribavirin as a First Treatment Approach for Hepatitis E Virus Infection in Transplant Recipient Patients

The hepatitis E virus (HEV) is the major cause of acute hepatitis of viral origin worldwide. Despite its usual course as an asymptomatic self-limited hepatitis, there are highly susceptible populations, such as those with underlying immunosuppression, which could develop chronic hepatitis. In this situation, implementation of therapy is mandatory in the sense to facilitate viral clearance. Currently, there are no specific drugs approved for HEV infection, but ribavirin (RBV), the drug of choice, is used for off-label treatment. Here, we present two cases of chronic HEV infection in transplant patients, reviewing and discussing the therapeutic approach available in the literature. The use of RBV for the treatment of an HEV infection in organ transplant patients seems to be effective. The recommendation of 12 weeks of therapy is adequate in terms of efficacy. Nevertheless, there are important issues that urgently need to be assessed, such as optimal duration of therapy and drug dosage.

Neurologic complications of acute hepatitis E virus infection

Objective

To assess the prevalence and clinical features of neurologic involvement in patients with acute hepatitis E virus (HEV) infection in Southern Switzerland.

Methods

Among 1,940 consecutive patients investigated for acute hepatitis E, we identified 141 cases of acute of HEV infection (anti-HEV immunoglobulin M and immunoglobulin G both reactive and/or HEV RNA positive) between June 2014 and September 2017. Neurologic cases were followed up for 6 months. We compared patients with and without neurologic symptoms.

Results

Neurologic symptoms occurred in 43 acute HEV cases (30.4%) and consisted of neuralgic amyotrophy (NA, n = 15, 10.6%) and myalgia (n = 28, 19.8%). All NA cases were immunocompetent. Men had higher odds (OR = 5.2, CI 1.12–24.0, p = 0.03) of developing NA after infection with HEV, and in 3 couples simultaneously infected with HEV, only men developed NA. Bilateral involvement of NA was predominant (2:1) and occurred only in men. Seven NA cases were viremic (all genotype 3), but HEV was undetectable in their CSF. In the acute phase of NA, 9 patients were treated with intravenous immunoglobulin and 4 with prednisone, reporting no side effects and improvement in pain and strength. Myalgia occurred both without (n = 16) or with (n = 12) concomitant elevated serum creatinine kinase. Seven cases with myalgia in the shoulder girdle did not have muscle weakness (“forme fruste” of NA).

Conclusions

Neurologic symptoms occurred in one-third of acute HEV infections and consisted of NA and myalgia. NA seems to occur more frequently in men infected by HEV and has a predominant (but not exclusive) bilateral involvement.

Mode and tempo of human hepatitis virus evolution

Human viral hepatitis, a major cause of morbidity and mortality worldwide, is caused by highly diverse viruses with different genetic, ecological, and pathogenetic features. Technological advances that allow throughput sequencing of viral genomes, as well as the development of computational tools to analyze such genome data, have largely expanded our knowledge on the host range and evolutionary history of human hepatitis viruses. Thus, with the exclusion of hepatitis D virus, close or distant relatives of these human pathogens were identified in a number of domestic and wild mammals. Also, sequences of human viral strains isolated from different geographic locations and over different time-spans have allowed the application of phylogeographic and molecular dating approaches to large viral phylogenies. In this review, we summarize the most recent insights into our understanding of the evolutionary events and ecological contexts that determined the origin and spread of human hepatitis viruses.

Sofosbuvir add-on to ribavirin for chronic hepatitis E in a cirrhotic liver transplant recipient: a case report

Background

Chronic hepatitis E represents an emerging challenge in organ transplantation, as there are currently no established treatment options for patients who fail to clear hepatitis E virus (HEV) following reduction of immunosuppressive therapy and/or treatment with ribavirin. Sofosbuvir has shown antiviral activity against HEV in vitro but clinical utility in vivo is unknown.

Case presentation

We describe a 57-year-old liver transplant recipient with decompensated graft cirrhosis due to chronic hepatitis E. Reduction of immunosuppressive treatment as well ribavirin alone for 4 months did not result in viral clearance. Add-on of sofosbuvir for 6 months was associated with HEV RNA becoming undetectable in plasma. However, sustained viral clearance could not be achieved.

Conclusions

Sofosbuvir may have some antiviral activity against HEV when added to ribavirin. However, this did not suffice to yield sustained viral clearance. Our well-characterized observation emphasizes the need for new treatment options to cure chronic hepatitis E in the setting of organ transplantation.