Rat Hepatitis E Virus as Cause of Persistent Hepatitis after Liver Transplant

Plasmacytoid dendritic cell sensing of hepatitis E virus is shaped by both viral and host factors

Type I and III interferons critically protect the host against viral infection. Previous studies showed that IFN responses are suppressed in cells infected by hepatitis E virus (HEV). Here, we studied the anti-HEV function of IFN secreted by plasmacytoid dendritic cells (pDCs), specialized producers of IFNs. We showed that pDCs co-cultured with HEV-replicating cells secreted IFN in a cell contact-dependent manner. This pDC response required the endosomal nucleic acid sensor TLR7 and adhesion molecules. IFNs secreted by pDCs reduced viral spread. Intriguingly, ORF2, the capsid protein of HEV, can be produced in various forms by the infected cells, and we wanted to study their role in anti-HEV immune response. During infection, a fraction of ORF2 localizes into the nucleus, and glycosylated forms of ORF2 are massively secreted by infected cells. We showed that glycosylated ORF2 potentiates the recognition of infected cells by pDCs, by regulating cell contacts. On the other hand, nuclear ORF2 triggers immune response by IRF3 activation. Together, our results suggest that pDCs may be essential to control HEV replication.

Wastewater and Clinical Based Epidemiology for Viral Surveillance in the Nile Delta of Egypt

The release of inadequately treated wastewater, containing human viruses, into the water environment or agricultural use represent a major problem in public health. In this study, SYBR Green-based real-time polymerase chain (qPCR) was applied to evaluate the prevalence of human polyomavirus (HPyV), papillomavirus (HPV), hepatitis A virus (HAV), and hepatitis E virus (HEV) in urban sewage and among children with acute gastroenteritis. The seasonal distribution in wastewater and viral removal by wastewater treatment process were also evaluated, over the 2 year sampling period. HPyV, HPV, HAV, and HEV were detected in 68%, 39.6% 42.4%, and 33.3% of the raw sewage, respectively, with highest incidence in winter season. In treated sewage samples, HPyV, HPV, HAV, and HEV were detected in 21%, 9.4%, 18.7%, and 0%, respectively. Furthermore, among the 200 diarrheal stool samples, HPyV, HPV, HAV, and HEV were detected in 72.5%, 50%, 13%, and 5%, respectively. HPyV was more prevalent in both environmental and clinical samples. The mean concentration of these viruses in raw sewage, treated sewage, and stool samples was 3.62 × 106 GC/ml, 4.03 × 103 GC/ml, and 4.05 × 106 GC/g, respectively. Examination of wastewater treatment process efficiency based on mean concentration values at entry and exit observed an overall reduction of 49.5%, 47.9%, 41.2%, 100%, for HPyV, HPV, HAV, and HEV, respectively. This study showed the benefit of environmental monitoring as an additional tool to investigate the epidemiology of these viruses circulating in a given community.

Structural basis for hepatitis E virus neutralization by potent human antibodies

Antibodies targeting the hepatitis E virus (HEV) surface capsid protein (CA) are essential for infection control and resolution, yet their molecular and functional attributes remain largely elusive. We characterized 144 human HEV-CA-specific monoclonal antibodies cloned from the memory B cells of HEV-exposed individuals. Most human anti-CA antibodies cross-reacted with all HEV genotype variants, and a subset also recognized the zoonotic rat hepatitis E virus. HEV antibody repertoire was diverse and contained highly potent neutralizing antibodies binding to the CA protruding (P) domain. Structural analyses of CA protein complexed with three potent and broad HEV antibodies uncovered a neutralizing site located on monomeric P domain loops at the apex of the viral spike. These findings provide valuable insights into the protective humoral response to HEV and offer a framework for the rational design of HEV vaccines and immunotherapies.

Prevalence of Rocahepevirus ratti (rat hepatitis E virus) in humans and rats in China

Background & Aims

Rocahepevirus ratti (rat hepatitis E virus; rHEV) is a ubiquitous pathogen of rats that has recently emerged as a cause of hepatitis in humans. Although several rHEV cases have been detected worldwide, the extent of human exposure to this hepatitis agent is still poorly defined. We conducted a multicenter surveillance study in China examining rHEV exposures in demographically diverse human populations from a One Health perspective.

Methods

In this multicenter cross-sectional study, we used fully validated rHEV IgG enzymatic immunoassays and reverse transcription PCR in 1,199 individuals with (n = 655) or without hepatitis (n = 544) recruited from three centers in China (Hainan, Hong Kong, and Shenzhen). The patient population included both urban and rural populations. Characteristics of infected individuals and phylogenetic links with rat epizootics were described.

Results

rHEV IgG seroprevalence was higher in the rural Hainan cohort (15/229, 6.6%) compared with Shenzhen (9/427, 2.1%) and Hong Kong cohorts (2/543, 0.4%) (p <0.0001). This difference persisted on multivariable logistic regression with an adjusted odds ratio of 20.52 (95% CI: 13.86-30.39). rHEV exposure was also associated with increasing age and environmental rodent exposure. We observed rHEV viraemia in two hepatitis patients (2/655; 0.3%) in Hainan and Hong Kong with hepatitis B and renal transplantation, respectively. The latter developed chronic hepatitis E. 19/509 (3.7%) rats captured in Hainan harbored rHEV. Both human rHEV isolates were phylogenetically related to rodent-derived rHEV strains circulating in Hainan and Hong Kong, respectively.

Conclusions

Humans are intermittently exposed to rHEV, especially in rural settings with rodent exposure. Overt hepatitis occurs in individuals with liver disease or immunosuppression. Spillover strains are related to epizootics in rodents offering opportunities for targeted disinfestation.

Impact and implications

Building on our previous work finding that Rocahepevirus ratti (rHEV) is a novel cause of sporadic viral hepatitis in humans, we studied rHEV exposures in humans from various epidemiological settings. We found intermittent exposure to rat hepatitis E in individuals living in both urban and rural settings with a markedly higher seroprevalence in the latter. Spillover viremic infections in individuals with underlying liver disease or immunosuppression were closely linked to epizootic rHEV strains circulating in rodents. Physicians and diagnostic laboratories should incorporate rHEV testing in algorithms for viral hepatitis while policymakers should consider rHEV surveillance in rodents to guide disinfestation efforts.

Updated recommendations for the management of hepatitis B, C, and E virus infections in patients with haematological malignancies and those undergoing haematopoietic cell transplantation: recommendations from the 9th European Conference on Infections in Leukaemia (ECIL-9)

Viral hepatitis remains a global health challenge and immune status affects outcomes. In patients with haematological malignancies, including haematopoietic stem-cell transplantation recipients, viral hepatitis can be life-threatening due to the direct effects of the virus or the need to modify or delay chemotherapy. Additionally, haematopoietic stem-cell donors with past or current viral hepatitis infections might transmit the virus to recipients. The growing recognition of hepatitis E virus (HEV), advances in haematological therapies, and the availability of direct-acting antivirals for hepatitis C virus (HCV), led the 2022 9th European Conference on Infections in Leukaemia (ECIL-9) to update the 2013 ECIL-5 guidelines on viral hepatitis. The ECIL organising committee convened a panel of 13 impartial international experts (all authors of this Review) in viral hepatitis, both within and outside the fields of haematological malignancies and immunosuppression. The ECIL-9 panel conducted a review of the literature on hepatitis B virus (HBV), HCV, and HEV, grading the evidence based on the European Society for Clinical Microbiology and Infectious Diseases system. The panel identified key clinical questions and outcomes and built on the recommendations established during ECIL-5. A consensus conference was held in Sofia Antipolis, France, from Sept 15-17, 2022, bringing together 49 experts from 19 countries. The ECIL-9 panel presented the proposed recommendations, which were revised following expert discussions. A final consensus on updated guidelines was reached in a second plenary session. The updated ECIL-9 guidelines provide evidence-based recommendations on the prevention, screening, treatment, and long-term surveillance of viral hepatitis in patients with haematological malignancies and haematopoietic cell transplantation recipients.

Substantial spillover burden of rat hepatitis E virus in humans

The emergence of Rocahepevirus ratti genotype 1 (rat hepatitis E virus; rat HEV) in humans presents an unprecedented threat; however, the risk of rat HEV transmission to humans is not well understood. Here, we report the "Distinguishing Antibody Response Elicitation (DARE)" method, which distinguishes exposure to rat HEV. We use four study sets from China for large-scale population analysis: set 1 (hospital visit) and set 3 (ALT abnormality) from Yunnan province, a biodiversity hotspot, and set 2 (received physical examination) and set 4 (ALT abnormality) from Jiangsu province, a non-hotspot control region. rat HEV exposure risk is significantly higher in Yunnan, with 21.97% (190 of 865) in set 1 and 13.97% (70 of 501) in set 3, compared to 0.75% (9 of 1196) in Jiangsu's set 2. Six spillover infections for rat HEV are identified in set 1, with one case of abnormal ALT. The rat-1d strains carried by rats are closely related to those human infections. Our study reveals the substantial spillover burden posed by rat HEV in biodiversity hotspots and highlights the utility of DARE method for proactive surveillance of public health emergencies.

Trends and Challenges in the Detection and Environmental Surveillance of the Hepatitis E Virus

The Hepatitis E virus (HEV) is responsible for causing Hepatitis E, a zoonotic disease that has emerged as a significant global health concern, accounting for about 20 million infections and 70,000 deaths annually. Although it is often recognized as a disease that is acute in low-income countries, HEV has also been recognized as a zoonotic disease in high-income countries. The zoonotic transmission requires flexible approaches to effectively monitor the virus, vectors, and reservoirs. However, the environmental monitoring of HEV presents additional challenges due to limitations in current detection methods, making it difficult to accurately assess the global prevalence of the virus. These challenges hinder efforts to fully understand the scope of the disease and to implement effective control measures. This review will explore these and other critical concerns, addressing gaps in HEV research and highlighting the need for improved strategies in the monitoring, prevention, and management of Hepatitis E using a One Health approach.

Diversity of Hepatitis E Viruses in Rats in Yunnan Province and the Inner Mongolia Autonomous Region of China

Hepatitis E virus (HEV) is one of the most common pathogens causing acute hepatitis. Rat HEV, a member of the genus Rocahepevirus, infects mainly rat but can also cause human zoonotic infection. A survey of the virome of rats via next-generation sequencing (NGS) was performed in Yunnan Province and Inner Mongolia in China. Further screening of rat HEV was conducted by nested PCR. The complete genome of six representative strains were obtained by NGS and RT-PCR. The virome analysis revealed that multiple reads were annotated as Hepeviridae. The screening results showed that HEV was detected in 9.6% (34 of 355) of the rat samples and phylogenetically classified into three lineages. The sequences from Yunnan clustered with Rocahepevirus ratti, named the YnRHEV group, and those from Inner Mongolia were separated into two lineages, named the NmRHEV-1 and NmRHEV-2 groups. Complete sequence analysis showed that YnRHEV had very high sequence identity to a human HEV strain identified in immunosuppressed patients (88.7% to 94.3%), a reminder of the risk of cross-species transmission of rodent HEV. Notably, NmRHEV-1 and the most closely related rat HEV, RtCb-HEV/HeB2014, were divergent from other HEV. The phylogenetic analyses and lower sequence identities of the complete genome suggested the NmRHEV-1 to be a novel putative genus of the subfamily Orthohepevirinae. NmRHEV-2 shared the highest sequence identities (70.6% to 72.0%) with the species Rocahepevirus eothenomi, which may represent a putative novel genotype. This study revealed high genetic diversity of Hepeviridae in rats in China and a potentially zoonotic Rocahepevirus ratti strain.

Occurrence and genetic diversity of the zoonotic rat hepatitis E virus in small mammal species, Spain

Rat hepatitis E virus (ratHEV-C1) is a newly zoonotic and globally distributed virus of increasing public health concern. Although rats of the genus Rattus are the main reservoir of this emerging virus, the role of other small mammals in the epidemiology of ratHEV-C1 in Europe is unknown as large-scale survey studies specifically assessing the circulation of ratHEV-C1 in these species have not yet been conducted. In this study, we examined active ratHEV-C1 infection in 514 animals from seven different small mammal species sampled throughout Spain. The presence of viral RNA was evaluated for ratHEV-C1 infection using RT-qPCRs in liver tissue. Sequencing and analysis of ratHEV-C1 shedding in faeces were carried out in positive animals. Viral RNA was detected in 15 individuals (mean Ct value: 34.5), supposing a frequency of 2.9% (95% CI: 1.8-4.8). We confirmed ratHEV infection in house mice (14.5%; 11/76), common voles (0.7%; 2/288) and garden dormice (25.0%; 2/8) and viral shedding in faeces in 36.4% (4/11) of positive house mice. Infected animals were detected in urban areas, small ruminant farms and rural areas throughout Spain. Our sequences showed a considerable genetic diversity, and they were closely related with ratHEV-C1 strains detected in human and rats from Spain, Germany and Hungary. Our study confirms that ratHEV is not limited to Rattus genus, identifying other rodents' species as potential host of ratHEV-C1 in Europe. Our results highlight the importance of continued surveillance in animals to fully understand the dynamics of ratHEV-C1 and its impact on public health.

National survey of the rat hepatitis E virus in rodents in Spain, 2022 to 2023

BackgroundRat hepatitis E virus (ratHEV) is an emerging virus causing acute and chronic hepatitis in humans. Rats are the main natural reservoir of this pathogen. Large-scale studies assessing ratHEV circulation in rodents in Spain are lacking.AimWe aimed to determine the prevalence of ratHEV in rats in Spain and evaluate potential transmission risk to humans.MethodsWe designed a cross-sectional nationwide study where black (Rattus rattus) and Norway (R. norvegicus) rats were collected and analysed between 2022 and 2023 for ratHEV infection using real-time (RT)-qPCR testing of liver tissue. Sequencing and analysis of ratHEV shedding in faeces were carried out in positive animals.ResultsRatHEV was detected in 125 of the 481 rats analysed, supposing a prevalence of 26.0% (95 CI%: 22.3-30.1). Positive rats were found in urban (25.6%), and farm (29.8%) settings. Black rats (31.3%) had 1.5 times higher odds of being infected by the virus than Norway rats (22.5%) (p = 0.049). Significantly higher prevalence of ratHEV was detected in rodents sampled from southern (31.9%) than northern (17.8%) Spain (p = 0.003). Viral RNA was detected in faeces from 45.5% of infected rats. Phylogenetic analysis evidenced a wide genetic diversity of ratHEV sequences, some showing high homology with ratHEV strains found in patients from Spain.ConclusionsCirculation of ratHEV appears to be heterogeneous and the virus appears to be endemic among rat populations in Spain, highlighting the possible risk of zoonotic transmission of this emerging virus in this country.

Rat hepatitis E virus as an aetiological agent of acute hepatitis of unknown origin

BACKGROUND AND AIM

Rat hepatitis E virus (ratHEV) is an emerging cause of acute hepatitis worldwide. The limited number of ratHEV cases may be associated with the lack of a proper molecular diagnosis method; thus, the clinical impact and breadth of ratHEV as a cause of acute hepatitis remain uncertain.

METHODS

The study was carried out in four phases. I) Identification: Molecular assays were identified through a literature search. II) Testing: The methods were evaluated in a rodent testing cohort, and the most suitable molecular diagnosis algorithm was established. III) Derivation: The established algorithm was tested in a larger rodent cohort. IV) Clinical validation: The algorithm was used in a cohort of individuals suffering from acute hepatitis of unknown aetiology, thus establishing the frequency of ratHEV as an aetiological agent of acute hepatitis and its clinical impact.

RESULTS

We detected differences in the frequency of positive results among the assays evaluated. After comparing all available molecular methods, we established a molecular diagnostic algorithm, which revealed that 17.5% of the 103 rodents in the validation cohort were infected with ratHEV. In the clinical validation cohort, of 562 patients with acute hepatitis of unknown origin, 8 cases of ratHEV infection were identified during the three years of the study, representing a frequency of 1.4%. One (37.5%) case had severe acute hepatitis; four (50.0%) patients required hospitalization, one of whom (12.5%) died. The strains detected in these patients revealed a close phylogenetic relationship with those found in rats in Spain.

CONCLUSIONS

Our study demonstrated that ratHEV is an emerging and underdiagnosed cause of acute hepatitis. The results provide evidence that ratHEV should be monitored and included in the differential diagnosis of acute hepatitis.

CLINICAL TRIAL NUMBER

ClinicalTrials.gov Identifier: NCT05062967 IMPACT AND IMPLICATIONS: While rat hepatitis E virus (ratHEV) is a newly emerging zoonotic virus worldwide, the results of the present study indicate that the molecular diagnosis methods for this virus may be inappropriate. After establishing a proper molecular diagnostic algorithm using available assays, we demonstrated that ratHEV is an emerging and underdiagnosed aetiological agent of acute hepatitis of unknown origin. The results also expand the knowledge of the diversity of ratHEV strains capable of infecting humans in Europe. These findings strongly suggest that ratHEV should be monitored and included in the differential diagnosis of acute hepatitis.

Rapid visual detection of hepatitis E virus combining reverse transcription recombinase-aided amplification with lateral flow dipstick and real-time fluorescence

Hepatitis E virus (HEV) is a globally prevalent zoonotic pathogen that is primarily spread through the fecal-oral route, such as by consuming undercooked or contaminated pork. HEV infection leads to an estimated 3.3 million symptomatic cases of viral hepatitis and 70,000 deaths in human populations each year. Therefore, a rapid and accurate method for detecting HEV in serum or stool samples is essential. In this study, we aimed to develop and evaluate two methods for the rapid and convenient detection of HEV RNA: reverse transcription recombinase-aided amplification with lateral flow dipstick (RT-RAA-LFD) and quantitative real-time reverse transcription recombinase-aided amplification (qRT-RAA). We optimized the reaction conditions and assessed their sensitivity and specificity. The RT-RAA-LFD assay completed its reaction at 39°C within 15 minutes, achieving a 95% limit of detection (LOD) of 247 copies/μL. The qRT-RAA assay, completed at 42°C within 20 minutes, had a 95% LOD of 25 copies/μL. Both assays demonstrated no cross-reactivity with other porcine pathogens and exhibited strong specificity. In testing 245 porcine bile and fecal samples, the RT-RAA-LFD assay showed a kappa value of 0.943 (P < 0.001) with a 97.14% (238/245) coincidence rate compared with quantitative reverse transcription PCR. Similarly, the qRT-RAA assay achieved a kappa value of 0.976 (P < 0.001) with a 98.78% (242/245) coincidence rate. In conclusion, these two RT-RAA assays show promising potential as effective diagnostic tools for broad and efficient screening of swine HEV in veterinary clinics.

IMPORTANCE

Hepatitis E virus (HEV) is a globally widespread zoonotic pathogen that poses a significant public health risk. Swine serve as the primary natural host for zoonotic HEV. This study introduces a rapid and precise method for detecting swine HEV RNA, showcasing its potential as an effective diagnostic tool for comprehensive and efficient screening of swine HEV in veterinary clinics.

Burden of rodent-borne viruses in rodents and zoonotic risk in human in Cambodia: a descriptive and observational study

Background

Rodent-borne viruses, including hantaviruses, arenaviruses, and rodent hepatitis virus (HEV-C), pose significant health threats to humans, causing severe diseases such as hepatitis, respiratory illness, and hemorrhagic fevers. In Cambodia, data on these viruses remain limited, and their burdens on human health are unknown. This study investigated the presences of these viruses in rodents and assessed potential human exposure across diverse environmental and socio-economic contexts in Cambodia.

Methods

The study was conducted in urban, semi-urban, and rural areas of Cambodia during the rainy (2020) and dry seasons (2022). Rodents were screened for arenavirus, hantavirus, and HEV-C using RT-PCR. Human serum samples from the same site were tested for IgG antibodies using ELISA. Factors associated with virus spillover into humans were analyzed.

Findings

Among 750 rodents, 9.7% carried at least one virus: 5.2% arenavirus, 3.3% hantavirus, and 1.9% HEV-C. Infection rates were highest in urban (14.5%), followed by semi-urban (11.9%) and rural (2.1%) interfaces. Arenavirus was more prevalent during the rainy season, while hantavirus and HEV-C remained consistent across seasons. Seroprevalence in human was 12.7% for arenavirus, 10.0% for hantavirus, and 24.2% for HEV. Higher arenavirus seroprevalence was associated with urban recidency and lower education level. Hantavirus seroprevalence was associated with urban residency, acute hepatitis history, and flood-prone living areas. HEV seroprevalence increased with urban residency, increasing age, and medical condition history.

Interpretation

Our findings highlighted the need for rodent control, improved market infrastructure, enhanced waste management, and public awareness on hygiene practices and zoonotic risks, especially in urban and high-risk areas.

Identification of novel rodent and shrew orthohepeviruses sheds light on hepatitis E virus evolution

The family Hepeviridae has seen an explosive expansion in its host range in recent years, yet the evolutionary trajectory of this zoonotic pathogen remains largely unknown. The emergence of rat hepatitis E virus (HEV) has introduced a new public health threat due to its potential for zoonotic transmission. This study investigated 2 464 wild small mammals spanning four animal orders, eight families, 21 genera, and 37 species in Yunnan Province, China. Using broadly reactive reverse transcription-polymerase chain reaction (RT-PCR), we systematically screened the presence and prevalence of Orthohepevirus and identified 192 positive specimens from 10 species, corresponding to an overall detection rate of 7.79%. Next-generation sequencing enabled the recovery of 24 full-length genomic sequences from eight host species, including Bandicota bengalensis, Eothenomys eleusis, and Episoriculus caudatus, representing newly reported host species for Orthohepevirus strains. Phylogenetic and sequence analyses revealed extensive genetic diversity within orthohepeviruses infecting rodents and shrews. Notably, among the identified strains, 20 were classified as Rocahepevirus ratti C1, two as C3, and one as Rocahepevirus eothenomi, while the remaining strain exhibited significant divergence, precluding classification. Evolutionary analyses highlighted close associations between orthohepeviruses and their respective host taxa, with distinct phylogenetic clustering patterns observed across different host orders. These findings emphasize the critical roles of co-speciation and cross-species transmission in shaping the evolutionary trajectories of the genera Paslahepevirus and Rocahepevirus.

Effectiveness of Cold Smoking on Inactivating Murine Norovirus in Salami-Like Pork Sausages (Mettwurst), and Hepatitis E Virus and Murine Norovirus in Solution

Hepatitis E virus (HEV) is a zoonotic virus that infects humans when virus-containing pork products are consumed. This study aimed to explore MNV (murine norovirus) and HEV inactivation during cold smoking and ripening/fermentation treatments used for salami-like sausages (mettwurst). MNV inactivation was monitored in culture medium solution and in sausage while being subjected to a salami-like sausage manufacturing process. The inactivation of MNV in the solution was also monitored at room temperature (RT) for four weeks. HEV inactivation was monitored in solution during the cold smoking process and at RT. A TCID50 assay was used to calculate the infectious MNV and HEV titres. MNV survival was modelled using Bayesian inference. MNV load in solution decreased by as much as 4.7 (SD 0.9) log10 TCID50/ml when it was subjected to the cold smoking process. Modelling revealed that 99.999% MNV might be inactivated during the treatment when observed at a level of 95% CI (Bayesian Confidence Interval). On the contrary, MNV load decreased by only 1.8 (0.2) log10 when stored at RT. The low-titre HEV in solution was inactivated (> 1.1 (0.2) log10) when treated, and at RT. However, MNV was resistant in the sausage matrix during the cold smoking process (log10 reduction of 1.9 (0.5) TCID50/ml). Based on modelling, a substantial amount of virus would remain in the product, even when the uncertainty was considered. Hence, viruses, here exemplified by MNV, may not be inactivated from salami-like pork sausages during manufacturing, which poses a risk for consumers in real-life situations.

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.

Endemic maintenance of human-related hepatitis E virus strains in synurbic wild boars, Barcelona Metropolitan Area, Spain

Hepatitis E virus (HEV), shared by humans, domestic animals, and wildlife, is an emerging global public health threat. Because wild boars are a major reservoir of HEV, the new zoonotic interfaces resulting from wild boar population increase and synurbization significantly contribute to increasing the risk of zoonotic transmission of HEV. This study characterizes HEV strains of synurbic wild boars and assesses their relationship with sympatric human and domestic swine HEV strains. We analyzed the faeces of 312 synurbic wild boars collected from 2016 to 2021 in the Barcelona Metropolitan Area (BMA), where there is a high density of wild boars, and found 7 HEV-positive samples among those collected between 2019 and 2020. The molecular analysis of these isolates, along with 6 additional wild boar HEV isolates from a previous study, allowed us to establish a close phylogenetic relationship between these HEV strains and human HEV isolates from sympatric blood donors and domestic pigs from Catalonia. HEV-positive wild boar samples belonged to piglet, juvenile and yearling individuals, but not adults, indicating the endemic maintenance of HEV in the wild boar population of the BMA by naïve young individuals. All wild boar HEV isolates in this study classified within HEV genotype 3. The results show, for the first time, a close molecular similarity between the HEV strains endemically maintained by the synurbic wild boars in the BMA and citizens from the same area and period. The data could also indicate that HEV infection presents a seasonal and interannual variability in wild boars of BMA. Further investigation is required to unveil the HEV transmission routes between synurbic wild boars and sympatric citizens. These findings can serve in other synurbic wildlife-human interfaces throughout the world.

Rat hepatitis E virus (Rocahepevirus ratti) exposure in cats and dogs, Hong Kong

Hepatitis E virus (HEV) variants infecting humans belong to two species: Paslahepevirus balayani (bHEV) and Rocahepevirus ratti (rat hepatitis E virus; rHEV). R. ratti is a ubiquitous rodent pathogen that has recently been recognized to cause hepatitis in humans. Transmission routes of rHEV from rats to humans are currently unknown. In this study, we examined rHEV exposure in cats and dogs to determine if they are potential reservoirs of this emerging human pathogen. Virus-like particle-based IgG enzymatic immunoassays (EIAs) capable of differentiating rHEV & bHEV antibody profiles and rHEV-specific real-time RT-PCR assays were used for this purpose. The EIAs could detect bHEV and rHEV patient-derived IgG spiked in dog and cat sera. Sera from 751 companion dogs and 130 companion cats in Hong Kong were tested with these IgG enzymatic immunoassays (EIAs). Overall, 13/751 (1.7%) dogs and 5/130 (3.8%) cats were sero-reactive to HEV. 9/751 (1.2%) dogs and 2/130 (1.5%) cats tested positive for rHEV IgG, which was further confirmed by rHEV immunoblots. Most rHEV-seropositive animals were from areas in or adjacent to districts reporting human rHEV infection. Neither 881 companion animals nor 652 stray animals carried rHEV RNA in serum or rectal swabs. Therefore, we could not confirm a role for cats and dogs in transmitting rHEV to humans. Further work is required to understand the reasons for low-level seropositivity in these animals.

High prevalence of hepatitis E and rat hepatitis E viruses in wastewater in Gothenburg, Sweden

Hepatitis E virus (HEV) and Rat Hepatitis E virus (RHEV), recognized for their zoonotic potential, pose significant public health concerns. Our previous research identified both viruses in effluent wastewater in Gothenburg, Sweden. However, there are lingering inquiries regarding the prevalence and genetic diversity of these viruses in influent wastewater, as well as the utility of wastewater surveillance in elucidating their community circulation dynamics. To address these knowledge gaps, we conducted weekly collection of wastewater samples at the Rya wastewater treatment plant in Gothenburg throughout 2023. The concentrations of HEV and RHEV were quantified using quantitative polymerase chain reaction (qPCR). Additionally, two semi/nested-PCR were utilized to amplify viral strains. Furthermore, HEV strains from patients within the same region, as well as other regions in Sweden in 2023, were incorporated into the analysis. Remarkably, we observed a high prevalence of HEV (86%) and RHEV (98%) in wastewater samples, with the majority of HEV sequences identified as subtype 3c/i (9/12). In contrast, HEV subtype 3f was the most sequenced among clinical patient samples (6/12). Notably, previously unreported HEV-3b and unclassified strains were detected in wastewater. Almost all RHEV strains (20/21) were clustered into European groups, with none of the RHEV genetically close to strains previously found in human cases. The notable discordance in prevalence and identified subtypes of HEV-3 in wastewater compared to clinical samples suggests either a significant underdiagnosis of HEV infections or differences in viral loads and shedding durations among humans between HEV-3 subtypes. This underscores the urgent need for improved diagnostic techniques and heightened awareness of HEV transmission dynamics. Furthermore, the consistent detection of RHEV in wastewater underscores the necessity for further investigations to assess the potential role of RHEV in hepatitis cases of unknown etiology, given that most currently available clinical diagnostic assays fail to detect RHEV.

The zoonotic LCK-3110 strain of Rocahepevirus ratti leads to mild infection in chickens after experimental inoculation

Rocahepevirus ratti [rat hepatitis E virus (HEV)] was originally isolated from rats and found to be non-infectious to nonhuman primates, suggesting humans were not a susceptible host. However, in 2018, rat HEV infections were identified in human patients. High seroprevalence for rat HEV in rats in many countries necessitates studying this emerging zoonotic outbreak. Lack of a human derived rat HEV infectious clone, cell culture systems, and animal models have hindered this effort. In response to the increase in human infection cases by rat HEV, we utilized an infectious clone of the zoonotic rat HEV LCK-3110 strain originally reported from human cases. Capped RNA transcripts of the rat HEV LCK-3110 strain were synthesized, and replication was assessed in both cell culture via transfection and chickens via intrahepatic inoculation. Naive chickens were cohoused together with inoculated chickens. Our results demonstrated that although chickens were susceptible, virus replication was inefficient with only a few of the chickens inoculated with rat HEV having low levels of viremia and fecal virus shedding. However, LCK-3110 HEV was able to transmit between chickens as several naive cohoused chickens became infected as evidenced by viremia, fecal shedding, and the presence of viral protein upon histopathology of the liver. Rat HEV is an emerging zoonotic virus with an ability to spillover across species. Chickens have potential to serve as intermediary hosts, possibly playing a role in rat HEV spread and exposure to humans.

Human Circovirus in Patients with Hepatitis, Hong Kong

Circovirus human is a new viral species that includes the human circovirus (HCirV), which has been linked to hepatitis in immunocompromised persons. We investigated prevalence of HCirV infection in 278 patients with hepatitis and 184 asymptomatic persons using real-time PCR and sequencing assays. HCirV viremia and sequences were found in 8 (2.9%) hepatitis patients and no asymptomatic patients. Alternate causes of hepatitis (hepatitis E and cholangitis) were clearly identifiable in 2 HCirV-infected patients. HCirV could not be ruled out as a contributor to hepatitis in the remaining 6 patients, 4 of whom were immunocompromised. Persistent infections were documented in 3 patients, but only 1 had relapsing hepatitis. One HCirV patient displayed symptoms of an infectious mononucleosis-like syndrome. Isolates clustered with known HCirV strains from France and China. HCirV-derived virus-like particles bound to PLC/PRF/5 and Hep-G2 human hepatoma cells but not to lung epithelial cells, indicating hepatic tropism.

Rat hepatitis E virus (Rocahepevirus ratti) in people living with HIV

Rat hepatitis E virus (ratHEV; species Rocahepevirus ratti) is considered a newly emerging cause of acute hepatitis of zoonotic origin. ratHEV infection of people living with HIV (PLWH) might portend a worse, as with hepatitis E virus (HEV; species Paslahepevirus balayani), and consequently this group may constitute a high-risk population. We aimed to evaluate the prevalence of ratHEV by measuring viral RNA and specific IgG antibodies in a large Spanish cohort of PLWH. Multicentre study conducted in Spain evaluating PLWHIV included in the Spanish AIDS Research Network (CoRIS). Patients were evaluated for ratHEV infection using PCR at baseline and anti-ratHEV IgG by dot blot analysis to evaluate exposure to ratHEV strains. Patients with detectable ratHEV RNA were followed-up to evaluate persistence of viremia and IgG seroconversion. Eight-hundred and forty-two individuals were tested. A total of 9 individuals showed specific IgG antibodies against ratHEV, supposing a prevalence of 1.1 (95% CI; 0.5%-2.1%). Of these, only one was reactive to HEV IgG antibodies by ELISA. One sample was positive for ratHEV RNA (prevalence of infection: 0.1%; 95% CI: 0.08%-0.7%). The case was a man who had sex with men exhibiting a slightly increased alanine transaminase level (49 IU/L) as only biochemical alteration. In the follow-up, the patients showed undetectable ratHEV RNA and seroconversion to specific ratHEV IgG antibodies. Our study shows that ratHEV is geographical broadly distributed in Spain, representing a potential zoonotic threat.

Serological and molecular survey of rat hepatitis E virus (Rocahepevirus ratti) in drug users

ABSTRACTRat hepatitis E virus (ratHEV) is an emerging cause of acute hepatitis of zoonotic origin. Since seroprevalence studies are scarce, at-risk groups are almost unknown. Because blood-borne infections frequently occur in people with drug use, who are particularly vulnerable to infection due to lack of housing and homelessness, this population constitutes a priority in which ratHEV infection should be evaluated. Therefore, the aim of this study was to evaluate the ratHEV seroprevalence and RNA detection rate in drug users as a potential at-risk population. We designed a retrospective study involving individuals that attended drug rehabilitation centres. Exposure to ratHEV was assessed by specific antibody detection using ELISA and dot blot (DB) assay and the presence of active infection by ratHEV RNA detection using RT-qPCR. Three-hundred and forty-one individuals were included, the most of them being men (67.7%) with an average age of 45 years. A total of 17 individuals showed specific IgG antibodies against ratHEV (4.6%; 95% CI; 3.1%-7.9%). One case of active ratHEV infection was identified (0.3%; 95% CI: 0.1%-1.8%). This was a 57-year-old homeless woman with limited financial resources, who had active cocaine and heroin use via parenteral route. In conclusion, we identified a potential exposure to ratHEV among drug users. Targeted studies in drug users with proper control groups are necessary to evaluate high-risk populations and transmission routes more accurately.

Surveillance of Emerging Rodent-Borne Pathogens in Wastewater in Taiwan: A One Health Approach

Leptospirosis and hantavirus syndrome are two major rodent-borne diseases in Taiwan. Rocahepevirus ratii (RHEV), a virus closely related to hepatitis E virus (HEV, Paslahepevirus balayani), is emerging and has been reported to cause hepatitis in humans. We employed wastewater-based epidemiology to actively monitor rodent-borne pathogens, and the correlations with human cases were evaluated. Wastewater was collected using grab sampling at 11 sites along a sewer system including influents and effluents at a wastewater treatment plant in Tamsui, New Taipei City, Taiwan, monthly during June 2023 to May 2024. The presence of pathogens was examined by reverse transcription-polymerase chain reaction (RT-PCR). The result showed an overall positivity rate of 38.2% (50/131). Leptospira was detected most often (48/131, 36.6%), and RHEV and hantaviruses were found once each during the study period. Sequencing identified Leptospira interrogans close to isolates from rodents and human cases, while sequences of hantavirus and RHEV were most similar to isolates from rodents. No significant correlation was found with human cases or positive samples for rodent DNA. Here, we present an example of a One Health approach applying wastewater to environmental surveillance for the early detection and prevention of emerging diseases.

Cell binding tropism of rat hepatitis E virus is a pivotal determinant of its zoonotic transmission to humans

Classically, all hepatitis E virus (HEV) variants causing human infection belong to the genus Paslahepevirus (HEV-A). However, the increasing cases of rat HEV infection in humans since 2018 challenged this dogma, posing increasing health threats. Herein, we investigated the underlying mechanisms dictating the zoonotic potentials of different HEV species and their possible cross-protection relationships. We found that rat HEV virus-like particles (HEVVLPs) bound to human liver and intestinal cells/tissues with high efficiency. Moreover, rat HEVVLPs and infectious rat HEV particles penetrated the cell membrane and entered human target cells postbinding. In contrast, ferret HEVVLPs showed marginal cell binding and entry ability, bat HEVVLPs and avian HEVVLPs exhibited no binding and entry potency. Structure-based three-dimensional mapping identified that the surface spike domain of rat HEV is crucial for cell binding. Antigenic cartography indicated that rat HEV exhibited partial cross-reaction with HEV-A. Intriguingly, sera of HEV-A infected patients or human HEV vaccine Hecolin® immunized individuals provided partial cross-protection against the binding of rat HEVVLPs to human target cells. In summary, the interactions between the viral capsid and cellular receptor(s) regulate the distinct zoonotic potentials of different HEV species. The systematic characterization of antigenic cartography and serological cross-reactivity of different HEV species provide valuable insights for the development of species-specific diagnosis and protective vaccines against zoonotic HEV infection.

Acute Hepatitis in Children Due to Rat Hepatitis E Virus

Two of 11 children with acute hepatitis of unknown origin were found to have rat hepatitis E virus infection. This infection should be considered in the differential diagnosis of children with acute hepatitis of unknown origin.

Hepatitis E virus immunosuppressed animal models

Hepatitis E virus (HEV) is an important emerging pathogen producing significant morbidity in immunosuppressed patients. HEV has been detrimental to solid organ transplant (SOT) patients, cancer patients, and HIV-positive patients, where chronic HEV infections occur. Blood-borne transfusions and multiple cases of chronic HEV infection in transplant patients have been reported in the past few decades, necessitating research on HEV pathogenesis using immunosuppressed animal models. Numerous animal species with unique naturally occurring HEV strains have been found, several of which have the potential to spread to humans and to serve as pathogenesis models. Host immunosuppression leads to viral persistence and chronic HEV infection allows for genetic adaptation to the human host creating new strains with worse disease outcomes. Procedures necessary for SOT often entail blood transfusions placing immunosuppressive patients into a "high risk group" for HEV infection. This scenario requires an appropriate immunosuppressive animal model to understand disease patterns in these patients. Hence, this article reviews the recent advances in the immunosuppressed animal models for chronic HEV infection with emphasis on pathogenesis, immune correlates, and the liver pathology associated with the chronic HEV infections.

Production and Characterization of Self-Assembled Virus-like Particles Comprising Capsid Proteins from Genotypes 3 and 4 Hepatitis E Virus (HEV) and Rabbit HEV Expressed in Escherichia coli

The zoonotic transmission of hepatitis E virus (HEV) genotypes 3 (HEV-3) and 4 (HEV-4), and rabbit HEV (HEV-3ra) has been documented. Vaccination against HEV infection depends on the capsid (open reading frame 2, ORF2) protein, which is highly immunogenic and elicits effective virus-neutralizing antibodies. Escherichia coli (E. coli) is utilized as an effective system for producing HEV-like particles (VLPs). However, research on the production of ORF2 proteins from these HEV genotypes in E. coli to form VLPs has been modest. In this study, we constructed 21 recombinant plasmids expressing various N-terminally and C-terminally truncated HEV ORF2 proteins for HEV-3, HEV-3ra, and HEV-4 in E. coli. We successfully obtained nine HEV-3, two HEV-3ra, and ten HEV-4 ORF2 proteins, which were primarily localized in inclusion bodies. These proteins were solubilized in 4 M urea, filtered, and subjected to gel filtration. Results revealed that six HEV-3, one HEV-3ra, and two HEV-4 truncated proteins could assemble into VLPs. The purified VLPs displayed molecular weights ranging from 27.1 to 63.4 kDa and demonstrated high purity (74.7-95.3%), as assessed by bioanalyzer, with yields of 13.9-89.6 mg per 100 mL of TB medium. Immunoelectron microscopy confirmed the origin of these VLPs from HEV ORF2. Antigenicity testing indicated that these VLPs possess characteristic HEV antigenicity. Evaluation of immunogenicity in Balb/cAJcl mice revealed robust anti-HEV IgG responses, highlighting the potential of these VLPs as immunogens. These findings suggest that the generated HEV VLPs of different genotypes could serve as valuable tools for HEV research and vaccine development.

Systematic Evaluation of Guidelines for the Diagnosis and Treatment of Hepatitis E Virus Infection

Background and Aims

The hepatitis E virus (HEV) is a zoonotic disease, and infection with HEV in humans primarily causes acute infections and can progress to chronic manifestation in immunocompromised individuals. Over the past decade, guidelines for diagnosing and treating HEV infection have been developed. This study aimed to systematically assess the quality of current guidelines for diagnosing and treating HEV infection, and we analyzed the differences in guideline quality and primary recommendations and explored possible reasons for these differences.

Methods

Guidelines published between 2013 and 2022 were searched, and studies were identified using selection criteria. The study assessed the quality of the included guidelines using the Appraisal of Guidelines for Research and Evaluation tool, extracted the primary recommendations in the guidelines, determined the highest level of evidence supporting the recommendations, and reclassified the evidence using the Oxford Centre for Evidence-Based Medicine grading system.

Results

Seven guidelines were included in the final analysis. The quality of the guidelines varied widely. The discrepancies may have been caused by the lack of external experts, the failure to consider influencing factors in guideline application, and the lack of consideration of the public's opinion. Analysis of the heterogeneity in primary recommendations revealed differences in algorithms for managing chronic HEV infection, the dosage of ribavirin, and a low level of evidence supporting the primary recommendations.

Conclusions

Guideline quality and primary recommendations vary considerably. Refinement by guideline developers and researchers would facilitate updating and applying guidelines for diagnosing and treating HEV infection.

Rocahepevirus ratti: An underrecognised cause of acute hepatitis

Zoonoses are responsible for many of all emerging infectious diseases as well as for those already established. Rocahepevirus ratti is a rat-originated virus related to the hepatitis E virus (Paslahepevirus balayani) but highly divergent genetically from this, with a high cross-species infection potential and zoonotic transmission. It can infect humans, leading to acute hepatitis, and is primarily transmitted through the consumption of contaminated water. Rocahepevirus ratti was first discovered in Germany in 2010. The first human case was described in 2017 in Hong Kong in an immune-compromised patient. The first case of chronic infection with Rocahepevirus ratti was described in 2023. A meta-analysis based on 38 studies published between 2000 and 2023 identified 21 cases in humans described up to this date and 489 infections in different animals. Raising awareness regarding this virus is essential, as there are probably many cases that remain undiagnosed, and the virus even has the ability to produce chronic infections in selected patients.

Investigating the Hepatitis E Virus (HEV) Diversity in Rat Reservoirs from Northern Italy

Hepatitis E virus belonging to the Rocahepevirus ratti species, genotype HEV-C1, has been extensively reported in rats in Europe, Asia and North America. Recently, human cases of hepatitis associated with HEV-C1 infection have been reported, but the zoonotic nature of rat-HEV remains controversial. The transmission route of rat-HEV is unidentified and requires further investigation. The HEV strains of the Paslahepevirus balayani species, belonging to the same Hepeviridae family, and including the zoonotic genotype HEV-3 usually found in pigs, have also sporadically been identified in rats. We sampled 115 rats (liver, lung, feces) between 2020 and 2023 in Northeast Italy and the HEV detection was carried out by using Reverse Transcription PCR. HEV RNA was detected in 3/115 (2.6%) rats who tested positive for HEV-C1 strains in paired lung, intestinal contents and liver samples. Overall, none tested positive for the Paslahepevirus balayani strains. In conclusion, our results confirm the presence of HEV-rat in Italy with a prevalence similar to previous studies but show that there is a wide heterogeneity of strains in circulation. The detection of HEV-C1 genotype of Rocahepevirus ratti species in some human cases of acute hepatitis suggests that HEV-C1 may be an underestimated source of human infections. This finding, with the geographically widespread detection of HEV-C1 in rats, raises questions about the role of rats as hosts for both HEV-C1 and HEV-3 and the possibility of zoonotic transmission.

Rat hepatitis E virus cross-species infection and transmission in pigs

Strains of Rocahepevirus ratti, an emerging hepatitis E virus (HEV), have recently been found to be infectious to humans. Rats are a primary reservoir of the virus; thus, it is referred to as "rat HEV". Rats are often found on swine farms in close contact with pigs. Our goal was to determine whether swine may serve as a transmission host for zoonotic rat HEV by characterizing an infectious cDNA clone of a zoonotic rat HEV, strain LCK-3110, in vitro and in vivo. RNA transcripts of LCK-3110 were constructed and assessed for their replicative capacity in cell culture and in gnotobiotic pigs. Fecal suspension from rat HEV-positive gnotobiotic pigs was inoculated into conventional pigs co-housed with naïve pigs. Our results demonstrated that capped RNA transcripts of LCK-3110 rat HEV replicated in vitro and successfully infected conventional pigs that transmit the virus to co-housed animals. The infectious clone of rat HEV may afford an opportunity to study the genetic mechanisms of rat HEV cross-species infection and tissue tropism.

Prevalence and molecular characterization of hepatitis E virus (HEV) from wild rodents in Hubei Province, China

Hepatitis E, caused by the hepatitis E virus (HEV), is a global public health issue. Low similarity between the gene sequences of mouse and human HEV led to the belief that the risk of human infection was low. Recent reports of chronic and acute hepatitis E caused by murine HEV infection in humans in Hong Kong have raised global concerns. Therefore, it is crucial to investigate the epidemiology and prevalence of HEV in China. We comprehensively analyzed different rodent HEV strains to understand rocahepevirus occurrence in Hubei Province, China. The HEV positivity rate for was 6.43% (73/1136). We identified seven near-full-length rocahepevirus strains and detected rat HEV antigens in tissues from different mouse species. HEV has extensive tissue tropism and a high viral load in the liver. We highlight the genetic diversity of HEVs in rodents and underscore the importance of paying attention to their variation and evolution.

The question of screening organ donors for hepatitis e virus: a case report of transmission by kidney transplantation in France and a review of the literature

BACKGROUND

Hepatitis E is a potentially serious infection in organ recipients, with an estimated two-thirds of cases becoming chronic, and with a subsequent risk of cirrhosis and death. In Europe, transmission occurs most often through the consumption of raw or undercooked pork, more rarely through blood transfusion, but also after solid organ transplantation. Here we describe a case of Hepatitis E virus (HEV) infection transmitted following kidney transplantation and review the literature describing cases of HEV infection transmitted by solid organ transplantation.

CASE PRESENTATION

Three weeks after kidney transplantation, the patient presented with an isolated minimal increase in GGT and hepatic cytolysis 6 months later, leading to the diagnosis of genotype 3c hepatitis E, with a plasma viral load of 6.5 log10IU/mL. In retrospect, HEV RNA was detected in the patient's serum from the onset of hepatitis, and in the donor's serum on the day of donation, with 100% identity between the viral sequences, confirming donor-derived HEV infection. Hepatitis E had a chronic course, was treated by ribavirin, and relapsed 10 months after the end of treatment.

DISCUSSION

Seven cases of transmission of HEV by solid organ transplantation have been described since 2012 without systematic screening for donors, all diagnosed at the chronic infection stage; two patients died. HEV organ donor transmission may be underestimated and there is insufficient focus on immunocompromised patients in whom mild liver function test impairment is potentially related to hepatitis E. However, since HEV infection is potentially severe in these patients, and as evidence accumulates, we believe that systematic screening of organ donors should be implemented for deceased and living donors regardless of liver function abnormalities, as is already the case in the UK and Spain. In January 2024, the French regulatory agency of transplantation has implemented mandatory screening of organ donors for HEV RNA.

Detection of hepatitis E virus genotype 3 in an Algerian mouse (Mus spretus) in Portugal

Virus monitoring in small mammals is central to the design of epidemiological control strategies for rodent-borne zoonotic viruses. Synanthropic small mammals are versatile and may be potential carriers of several microbial agents. In the present work, a total of 330 fecal samples of small mammals were collected at two sites in the North of Portugal and screened for zoonotic hepatitis E virus (HEV, species Paslahepevirus balayani). Synanthropic small mammal samples (n = 40) were collected in a city park of Porto and belonged to the species Algerian mouse (Mus spretus) (n = 26) and to the greater white-toothed shrew (Crocidura russula) (n = 14). Furthermore, additional samples were collected in the Northeast region of Portugal and included Algerian mouse (n = 48), greater white-toothed shrew (n = 47), wood mouse (Apodemus sylvaticus) (n = 43), southwestern water vole (Arvicola sapidus) (n = 52), Cabrera's vole (Microtus cabrerae) (n = 49) and Lusitanian pine vole (Microtus lusitanicus) (n = 51). A nested RT-PCR targeting a part of open reading frame (ORF) 2 region of the HEV genome was used followed by sequencing and phylogenetic analysis. HEV RNA was detected in one fecal sample (0.3%; 95% confidence interval, CI: 0.01-1.68) from a synanthropic Algerian mouse that was genotyped as HEV-3, subgenotype 3e. This is the first study reporting the detection of HEV-3 in a synanthropic rodent, the Algerian mouse. The identified HEV isolate is probably the outcome of either a spill-over infection from domestic pigs or wild boars, or the result of passive viral transit through the intestinal tract. This finding reinforces the importance in the surveillance of novel potential hosts for HEV with a particular emphasis on synanthropic animals.

Immunisation of pigs with recombinant HEV vaccines does not protect from infection with HEV genotype 3

Hepatitis E virus (HEV) is a major cause of acute viral hepatitis worldwide. Up to now, no approved treatment nor a globally licensed vaccine is available. Several recombinant HEV vaccines have been developed to protect against HEV infection in humans, including the commercially available Hecolin vaccine, which are mainly based on HEV genotype 1. However, the efficacy of these vaccines against other HEV genotypes, especially genotype 3 is unknown. In this study, we evaluated the protective efficacy of Hecolin® and a novel genotype 3-based vaccine p239(gt3) against HEV-3 in a pig infection model. Pigs were divided into three groups: one group was vaccinated with Hecolin®, the second group was vaccinated with p239(gt3), and the control group received no vaccine. All pigs were subsequently challenged with HEV genotype 3 to assess the effectiveness of the vaccines. Although all immunised animals developed a high titer of neutralizing antibodies, the results showed that both vaccine applications could not provide complete protection against HEV (gt3) infection: Two out of four animals of the Hecolin® group displayed even virus shedding, and viral RNA could be detected in bile and/or liver of three out of four animals in both vaccination groups. Only one out of four animals in each group was fully protected. Neither Hecolin® nor the novel p239(gt3) vaccine provided sufficient protection against genotype 3 infection. While Hecolin® only partial protected pigs from HEV shedding, the novel p239(gt3) vaccine was at least able to prevent infected pigs from virus shedding. The results highlight the need for further development of HEV vaccines that exhibit broad protection against multiple HEV genotypes and the use of appropriate animal infection models.

Molecularly generated rat hepatitis E virus strains from human and rat show efficient replication in a human hepatoma cell line

The hepatitis E virus (HEV) can cause acute and chronic hepatitis in humans. Whereas HEV genotypes 1-4 of species Paslahepevirus balayani are commonly found in humans, infections with ratHEV (species Rocahepevirus ratti) were previously considered to be restricted to rats. However, several cases of human ratHEV infections have been described recently. To investigate the zoonotic potential of this virus, a genomic clone was constructed here based on sequence data of ratHEV strain pt2, originally identified in a human patient with acute hepatitis from Hongkong. For comparison, genomic clones of ratHEV strain R63 from a rat and of HEV genotype 3 strain 47832mc from a human patient were used. After transfection of in vitro-transcribed RNA from the genomic clones into the human hepatoma cell line HuH-7-Lunet BLR, virus replication was shown for all strains by increasing genome copy numbers in cell culture supernatants. These cells developed persistent virus infections, and virus particles in the culture supernatant as well as viral antigen within the cells were demonstrated. All three generated virus strains successfully infected fresh HuH-7-Lunet BLR cells. In contrast, the human hepatoma cell lines HuH-7 and PLC/PRF/5 could only be infected with the genotype 3 strain and to a lesser extent with ratHEV strain R63. Infection of the rat-derived hepatoma cell lines clone 9, MH1C1 and H-4-II-E did not result in efficient virus replication for either strain. The results indicate that ratHEV strains from rats and humans can infect human hepatoma cells. The replication efficiency is strongly dependent on the cell line and virus strain. The investigated rat hepatoma cell lines could not be infected and other rat-derived cells should be tested in future to identify permissive cell lines from rats. The developed genomic clone can represent a useful tool for future research investigating pathogenicity and zoonotic potential of ratHEV.

Ingrained: Rice farming and the risk of zoonotic spillover, examples from Cambodia

Rice cultivation in Southeast Asia is a One Health interface intersecting human, animal, and environmental health. This complexity creates a potential for zoonotic transmission between diverse reservoirs. Bats harbor viruses like Nipah; mosquitoes transmit arboviruses; rodents spread hantaviruses. Domestic animals- including pigs with influenza and dogs with rabies and aquatic animals can also transmit pathogens. Climate change and urbanization may further disrupt rice agro-ecologies. This paper explores animal viral reservoirs, vectors, and historical practices associated with risk in rice farming. Climate and land use changes could enhance spillover. Solutions are proposed, including surveillance of animals, vectors, water, and air to detect threats before major outbreaks, such as improved biosecurity, hygiene, and livestock vaccinations. Ecological viral surveillance and agricultural interventions together can reduce zoonotic transmission from rice farming.

The Full-Genome Analysis and Generation of an Infectious cDNA Clone of a Genotype 6 Hepatitis E Virus Variant Obtained from a Japanese Wild Boar: In Vitro Cultivation in Human Cell Lines

Hepatitis E virus (HEV) can cause self-limiting acute and chronic hepatitis infections, particularly in immunocompromised individuals. In developing countries, HEV is mainly transmitted via drinking contaminated water, whereas zoonotic transmission dominates the route of infection in developed countries, including Japan. Pigs are an important reservoir for HEV infection. Wild boars, which share the same genus and species as domestic pigs, are also an HEV reservoir. During our nationwide study of HEV infection in wild boar populations in Japan, a genotype 6 (HEV-6) strain, wbJHG_23, was isolated in Hyogo Prefecture in 2023. The genomic length was 7244 nucleotides, excluding the poly(A) tract. The wbJHG_23 strain exhibited the highest nucleotide identity throughout its genome with two previously reported HEV-6 strains (80.3-80.9%). Conversely, it displayed lower similarity (73.3-78.1%) with the HEV-1-5, HEV-7, and HEV-8 strains, indicating that, although closely related, the wbJHG_23 strain differs significantly from the reported HEV-6 strains and might represent a novel subtype. The wbJHG_23 strain successfully infected the human-derived cancer cell lines, PLC/PRF/5 and A549 1-1H8 cells, suggesting that HEV-6 has the potential for zoonotic infection. An infectious cDNA clone was constructed using a reverse genetics system, and a cell culture system supporting the efficient propagation of the HEV-6 strain was established, providing important tools for further studies on this genotype. Using this cell culture system, we evaluated the sensitivity of the wbJHG_23 strain to ribavirin treatment. Its good response to this treatment suggested that it could be used to treat human infections caused by HEV-6.

Isolation and characterization of a novel rodent hepevirus in long-tailed dwarf hamsters (Cricetulus longicaudatus) in China

Hepeviruses have been identified in a broad range of animal hosts, including mammals, birds, and fish. In this study, rodents (n=91) from seven different species and ten pikas (Ochotona curzoniae) were collected in Qinghai Province, China. Using transcriptomic sequencing and confirmatory molecular testing, hepeviruses were detected in 27 of 45 (60 %) long-tailed dwarf hamsters (Cricetulus longicaudatus) and were undetected in other rodents and pika. The complete genome sequences from 14 representative strains were subsequently obtained, and phylogenetic analyses suggested that they represent a novel species within the genus Rocahepevirus, which we tentatively designated as Cl-2018QH. The virus was successfully isolated in human hepatoma (Huh-7) and murine fibroblast (17 Cl-1) cell lines, though both exhibited limited replication as assayed by detection of negative-sense RNA intermediates. A129 immunodeficient mice were inoculated with Cl-2018QH and the virus was consistently detected in multiple organs, despite relatively low viral loads. In summary, this study has described a novel rodent hepevirus, which enhances our knowledge of the genetic diversity of rodent hepeviruses and highlights its potential for cross-species transmission.

Detection of Rat Hepatitis E Virus in Pigs, Spain, 2023

We identified rat hepatitis E virus (HEV) RNA in farmed pigs from Spain. Our results indicate that pigs might be susceptible to rat HEV and could serve as viral intermediaries between rodents and humans. Europe should evaluate the prevalence of rat HEV in farmed pigs to assess the risk to public health.

Molecular epidemiology and phylogeny of the emerging zoonotic virus Rocahepevirus: A global genetic analysis

Human infections with Rocahepevirus ratti genotype C1 (HEV-C1) in Hong Kong of China, Canada, Spain, and France have drawn worldwide concern towards Rocahepevirus. This study conducted a global genetic analysis of Rocahepevirus, aiming to furnish comprehensive molecular insights and promote further research. We retrieved 817 Rocahepevirus sequences from the GenBank database through October 31, 2023, categorizing them according to research, sample collection area and date, genotype, host, and sequence length. Subsequently, we conducted descriptive epidemiological, phylogenetic evolutionary, and protein polymorphism (in length and identity) analyses on these sequences. Rocahepevirus genomes were identified across twenty-eight countries, predominantly in Asia (71.73%, 586/817) and Europe (26.44%, 216/817). The HEV-C1 dominates Rocahepevirus (77.2%, 631/817), while newly discovered Rocahepevirus genotypes (C3/C4/C5 and other unclassified genotypes) were primarily identified in Europe (25/120) and China (91/120). Muridae animals (72.5%, 592/817) serve as the primary hosts for Rocahepevirus, with other hosts encompassing species from the families Soricidae, Hominidae, Mustelidae, and Cricetidae. Additionally, Rocahepevirus genomes (C1 genotype) were identified in sewage samples recently. The phylogenetic evolution of Rocahepevirus exhibits considerable variation. Specifically, HEV-C1 can be classified into at least six genetic groups (G1 to G6), with human HEV-C1 distributed across multiple evolutionary clades. The overall ORF1 and ORF2 amino acid sequence lengths were significantly different (P < 0.001) across Rocahepevirus genotypes. HEV-C1/C2/C3 and HEV-C4/C5 displayed substantial differences in amino acid sequence identity (58.4%-59.6%). The identification of Rocahepevirus genomes has expanded across numerous countries, particularly in European and Asian countries, coinciding with an expanding host range and emergence of new genotypes. The evolutionary path of Rocahepevirus is intricate, where the HEV-C1 dominates globally and internally forms multiple evolutionary groups (G1 to G6), exhibiting diverse genetic variation within human HEV-C1. Significant differences exist in the protein polymorphism (in length and identity) across Rocahepevirus genotypes. Given Rocahepevirus's shift from an animal virus to a zoonotic pathogen, worldwide cooperation in monitoring Rocahepevirus genomes is vital.

Genomic characterization of Rocahepevirus ratti hepatitis E virus genotype C1 in Yunnan province of China

The Rocahepevirus ratti hepatitis E virus genotype C1 (HEV-C1) has been documented to infect humans. However, the understanding of HEV-C1 remains constrained. This study aims to determine the prevalence and genomic characteristics of HEV-C1 in small animals in Yunnan province of southwestern China. A total of 444 liver tissues were collected from animals covering the orders Rodentia, Soricomorpha, Scandentia and Erinaceomorpha in three regions in Yunnan. Then Paslahepevirus balayani and Rocahepevirus were examined using RT-qPCR. The detection rate of Rocahepevirus was 12.95 % (36/278) in animals of order Rodentia, with 14.77 % (35/237) in Rattus tanezumi and 33.33 % (1/3) in Niviventer fulvescens. No Paslahepevirus balayani was detected. Additionally, two full-length Rocahepevirus sequences (MSE-17 and LHK-54) and thirty-three partial ORF1 sequences were amplified and determined to be HEV-C1. MSE-17 and LHK-54 shared moderate nucleotide identity (78.9 %-80.3 %) with HEV-C1 isolated in rats and humans. The HEV-C1 isolated from Niviventer fulvescens demonstrated a 100 % nucleotide identity with that from Rattus tanezumi. The rat HEV-C1 sequences isolated in our study and other Asian HEV-C1 sequences were phylogenetically distant from those isolated in North America and Europe. Furthermore, the two full-length sequences isolated in our study had less amino acid substitutions in the motifs of RNA-dependent RNA polymerase domain (F204L and L238F), compared with other Asian sequences. In summary, HEV-C1 commonly spreads in rats in Yunnan province of China. Our findings suggest a spatially associated phylogeny, and potential cross-species transmission of HEV-C1.

First detection and characterization of hepatitis E virus (Rocahepevirus ratti) from urban Norway rats (Rattus norvegicus) in the Republic of Korea

Hepatitis E virus (HEV), an emerging zoonotic pathogen, poses a significant public health concern worldwide. Recently, rat HEV (Rocahepevirus ratti genotype C1; HEV-C1) has been reported to cause zoonotic infections and hepatitis in humans. Human infections with HEV-C1 are considered to be underestimated worldwide due to limited knowledge of transmission routes, genome epidemiology, and the risk assessment of zoonosis associated with these viruses. A total of 186 wild Norway rats (Rattus norvegicus) were collected from the Republic of Korea (ROK) between 2011 and 2021. The prevalence of HEV-C1 RNA was 8 of 180 (4.4%) by reverse-transcription polymerase chain reaction. We first reported three nearly whole-genome sequences of HEV-C1 newly acquired from urban rats in the ROK. Phylogenetic analysis demonstrated that Korea-indigenous HEV-C1 formed an independent genetic group with those derived from R. norvegicus rats in other countries, indicating geographical and genetic diversity. Our findings provide critical insights into the molecular prevalence, genome epidemiology, and zoonotic potential of Rocahepevirus. This report raises awareness of the presence of Rocahepevirus-related hepatitis E among physicians in the ROK.

Hepatitis E infection: A review

Hepatitis E virus (HEV) is a small non-enveloped virus that is transmitted via the fecal-oral route. It is a highly common cause of acute hepatitis, particularly in low to middle income regions of Asia, Africa, and Central America. Most cases are self-limited, and symptomatic patients usually present with acute icteric hepatitis. A subset of patients including pregnant women, older men, those with pre-existing liver disease and immunocompromised patients however, may develop severe disease and hepatic failure. Immunocompromised patients are also at risk for chronic infection, and their immunosuppression should be decreased in order to facilitate viral clearance. HEV can also present with a variety of extra-intestinal manifestations including neurological, renal, hematological, and pancreatic derangements. The gold standard of diagnosis is HEV ribonucleic acid detection via nucleic acid amplification testing. Currently, there are no approved treatments for Hepatitis E, though ribavirin is the most commonly used agent to reduce viral load. Studies assessing the safety and efficacy of other antiviral agents for HEV are currently underway. HEV vaccination has been approved in China, and is currently being investigated in other regions as well. This review article aims to discuss the epidemiology, pathogenesis, presentation, diagnosis, complications, and treatment of Hepatitis E infection.

Redeveloping antigen detection kits for the diagnosis of rat hepatitis E virus

The emergence of Rocahepevirus ratti [species HEV ratti (r HEV)] as a causative agent of hepatitis E in humans presents a new potential threat to global public health. The R. ratti genotype 1 (r-1 HEV) variant only shares 50%-60% genomic identity with Paslahepevirus balayani [species HEV balayani (b HEV)] variants, which are the main causes of hepatitis E infection in humans. Here, we report antigen diagnoses for r-1 HEV and b HEV using an enzymatic immunoassay (EIA) method. We detected recombinant virus-like particles protein (HEV 239) of r HEV and b HEV using a collection of hepatitis E virus (HEV)-specific monoclonal antibodies. Two optimal candidates, the capture antibody P#1-H4 and the detection antibodies C145 (P#1-H4*/C145#) and C158 (P#1-H4*/C158#), were selected to detect antigen in infected rat samples and r-1 HEV- or b HEV-infected human clinical samples. The two candidates showed similar diagnostic efficacy to the Wantai HEV antigen kit in b HEV-infected clinical samples. Genomic divergence resulted in low diagnostic efficacy of the Wantai HEV antigen kit (0%, 0 of 10) for detecting r-1 HEV infection. Compared with the P#1-H4*/C145# candidate (80%, 8 of 10), the P#1-H4*/C158# candidate had excellent diagnostic efficacy in r-1 HEV-infected clinical samples (100%, 10 of 10). The two candidates bind to a discrete antigenic site that is highly conserved across r HEV and b HEV. P#1-H4*/C145# and P#1-H4*/C158# are efficacious candidate antibody combinations for rat HEV antigen detection.

Rocahepevirus ratti as an Emerging Cause of Acute Hepatitis Worldwide

The hepatitis E virus (HEV) is a widespread human infection that causes mainly acute infection and can evolve to a chronic manifestation in immunocompromised individuals. In addition to the common strains of hepatitis E virus (HEV-A), known as Paslahepevirus balayani, pathogenic to humans, a genetically highly divergent rat origin hepevirus (RHEV) can cause hepatitis possessing a potential risk of cross-species infection and zoonotic transmission. Rocahepevirus ratti, formerly known as Orthohepevirus C, is a single-stranded RNA virus, recently reassigned to Rocahepevirus genus in the Hepeviridae family, including genotypes C1 and C2. RHEV primarily infects rats but has been identified as a rodent zoonotic virus capable of infecting humans through the consumption of contaminated food or water, causing both acute and chronic hepatitis cases in both animals and humans. This review compiles data concluding that 60% (295/489) of RHEV infections are found in Asia, being the continent with the highest zoonotic and transmission potential. Asia not only has the most animal cases but also 16 out of 21 human infections worldwide. Europe follows with 26% (128/489) of RHEV infections in animals, resulting in four human cases out of twenty-one globally. Phylogenetic analysis and genomic sequencing will be employed to gather global data, determine epidemiology, and assess geographical distribution. This information will enhance diagnostic accuracy, pathogenesis understanding, and help prevent cross-species transmission, particularly to humans.

Surveillance for rat hepatitis E in wastewater networks, Italy

IMPORTANCE

Hepatitis E virus (HEV) infection constitutes a significant health problem worldwide. In recent years, in addition to the zoonotic HEV3 and HEV4, emerging highly divergent hepevirus of rat origin (rat HEV [RHEV]) has been associated with human acute and chronic hepatitis. As environmental surveillance can be a complementary tool to explore emerging viruses of human and rodent origin, we investigated the epidemiology and the genetic variability of RHEV targeting 14 wastewater treatment plants in an Italian geographic area considered a hot spot for HEV infection in humans. Our results revealed that RHEV is a significant component of the wastewater microbiota with viral RNA detected in 43.9% of the specimens tested, adding further evidence to the need to investigate more in depth the real burden of RHEV infections in humans.