An Immunocompetent Mongolian Gerbil Model for Hepatitis E Virus Genotype 1 Infection

Distinct distribution of HEV-3 subtypes across humans, animals, and environmental waters in Sweden

We previously observed a notable discrepancy in the distribution of HEV-3 subtypes between wastewater and clinical samples in Sweden. To confirm this observation and comprehensively elucidate HEV-3 circulation patterns across humans, animals, and environmental waters in Sweden, we analysed the HEV genetic diversity in archived wastewater samples between late 2016 and early 2018, clinical cases between 2012 and 2024, and all available Swedish sequences from the NCBI Virus database. HEV RNA was detected in all archived wastewater samples, with subtype 3c being the only subtype identified. In typed clinical cases, subtypes 3f (45/126) and 3c (44/126) were nearly equally distributed, though regional dominance varied. When incorporating human sequences from other Swedish studies, subtype 3f became dominant (75/168). Analysis of all available sequences revealed that 3f (113/136) was the dominant subtype in Sus scrofa (pigs and wild boars), while 3c (30/33) was dominant in environmental waters. These findings highlight the complex transmission dynamics of HEV-3 in Sweden. The near-absence of 3c in Swedish domestic pigs and wild boars, despite its high proportion in clinical cases, raises the question about the source of human 3c infection. In addition, the near-exclusive detection of 3c in wastewater suggests potential differences in viral shedding, disease severity of HEV-3 subtypes, or alternative host sources. This study emphasizes the importance of integrated One Health surveillance to track HEV circulation across reservoirs.

Molecular characterization of autochthonous Hepatitis E virus detected from a human acute infection in the Calabria Region, Southern Italy

Herein, we reported the molecular characterization of HEV autochthonous strain from an immunocompetent patient. The HEV was classified as subtype 3c and displayed the V1479I ribavirin resistance mutation. The phylogenetic tree analysis showed two statistically supported clusters, including viral strains from symptomatic patients, without severe disease, and meat products.

Burden of acute hepatitis E virus in South Asia: Insights from Global Burden of Disease study 2021

BACKGROUND

Despite global progress, South Asian countries account for a disproportionate burden of Acute hepatitis E (AHE). Understanding the burden of AHE in this region is crucial for targeted interventions.

METHODS

We used Global Burden of Disease (GBD) 2021 data to assess the burden of AHE across eight South Asian countries from 1990 to 2021. Joinpoint regression was used to analyze temporal trends and Estimated Annual Percentage Change (EAPC) was calculated to quantify trends. The relationship between age-standardized disability-adjusted life years rate (ASDR) and socio-demographic index (SDI) was assessed using smoothing spline model and Spearman rank correlation. Rates are expressed per 100,000 population.

RESULTS

Bangladesh had highest age-standardized prevalence rate (ASPR) [33.27 (95 % Uncertainty Interval: 27.64 to 39.95)] and age-standardized incidence rate (ASIR) [433.01 (359.61 to 519.76)], while India had highest ASDR [9.52 (4.33 to 18.42)]. Males had higher ASIR and ASPR than females in most South Asian countries, except Bhutan and India, and higher ASDR except in Nepal and Pakistan. Bhutan had the highest EAPC for both sexes in ASPR and ASIR, while India had the highest EAPC in ASDR, closely followed by Bhutan for both sexes. Age group 5-9 had the highest ASPR and ASIR whereas <1-year age group had the highest ASDR. There was an inverse relationship between ASDR and SDI (R = -0.49, p < 0.01).

CONCLUSION

South Asia bears a high burden of AHE, with variations across countries. Improvements in Water Sanitation and Hygiene (WASH) services are needed to achieve Sustainable Development Goals 3 and 6.

Antiviral resistance and barrier integrity at the maternal-fetal interface restrict hepatitis E virus from crossing the placental barrier

Hepatitis E virus (HEV) genotype 1 (HEV-1) infection in pregnant women is associated with adverse outcomes of pregnancy including fulminant hepatic failure, fetal loss, premature birth, and neonatal mortality, although the underlying mechanisms remain largely unclear. In this study, we first demonstrated that HEV-1 robustly infects pregnant gerbils and causes pregnancy-associated adverse outcomes, which were recorded in 4/6 HEV-1-infected but only 1/5 in PBS-inoculated pregnant gerbils. However, vertical transmission of HEV-1 from mothers to newborns is not evident, as HEV-1 RNA was not detected in uterus tissues or in newborn pups. To further determine whether HEV-1 can cross the placental barrier, we established an in vitro blood-placental barrier by coculturing human placental trophoblast cells (BeWo) and umbilical vein endothelial cells (HUVEC) in Transwell inserts. By using the placental barrier under the conditions in this study, we showed that quasi-enveloped or nonenveloped HEV-1, HEV-3, or HEV-4 virions do not readily cross the barrier prior to 4 d postinoculation when it has high barrier integrity. Importantly, we demonstrated that the placental barrier induces local antiviral resistance at the maternal-fetal interface, that interactions between maternal- and fetal-derived cocultured cells are important for induction of antiviral resistance, and that anti-HEV resistance can be transferred to nonplacental HepG2 liver cells. We also revealed that the main effectors of antiviral resistance at the placental barrier are type III interferons (IFN-λ1, λ2/3) and the chemokine CXCL10. The findings have important implications in understanding the mechanisms leading to HEV-1-associated maternal and fetal adverse outcomes in pregnant women.

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.

One-Pot Assay Based on CRISPR/Cas13a Technology for HEV RNA Point-of-Care Testing

Hepatitis E virus (HEV) poses a serious threat to both public health and animal food safety, thereby highlighting the demands for rapid, sensitive, and easy-to-use detection. This study aimed to develop a One-Pot assay using CRISPR/Cas13a for detecting HEV RNA, suitable for point-of-care testing (POCT) in resource-limited settings. CRISPR/Cas13a combined with reverse transcription polymerase chain reaction (RT-PCR) and reverse transcription recombinase-aided amplification (RT-RAA) was applied to a One-Pot assay device. Additionally, a large cohort of HEV-infected patient (154) and animal (104) specimens was utilized for validation. The RT-PCR/RT-RAA + CRISPR/Cas13a assays for HEV RNA detection (genotypes: HEV-1, HEV-3, and HEV-4) were established, optimized, and validated, achieving a limit of detection (LoD) of 1 copy/μL and 100% specificity. In the application validation for HEV infection, the positive rates of the RT-PCR + CRISPR and RT-RAA + CRISPR assays were 98.6% and 89.6% for patients, and 96.6% and 88.8% for animals, respectively, which were superior to those of RT-qPCR. Furthermore, sample rapid lysis, reagent lyophilization, and the One-Pot device were integrated to construct a One-Pot assay with an LoD of 102 copies/μL. Despite slight decreases in sensitivity, the One-Pot assay significantly reduces the assay time to 35 min, making it easy to perform, minimizing contamination, and meeting the requirements for screening. We developed a One-Pot assay of HEV RNA using the CRISPR/Cas13a which effectively realizes a POCT test and maximizes the impetus for POCT implementation and shows potential as a valuable tool for detecting and monitoring HEV infection.

Epidemiological study of hepatitis E virus infection among students and workers in Hebei Province of China

AIMS

Hepatitis E caused by the hepatitis E virus (HEV) is prevalent worldwide. In China, considerable shifts in the epidemiology of hepatitis E have been observed over the last two decades, with ongoing changes in the prevalence of HEV.

METHODS

This study, in conjunction with the health examinations for students and workers, aims to estimate the seroprevalence and assess the risk factors of HEV infection in general population in Hebei province, China. Epidemiological information was collected using a specific questionnaire and blood samples were collected from each participant during the process of health examination. Anti-HEV IgG and IgM in sera were tested using the Wantai ELISA assay kits. Logistic regression modelling was used to identify associated risk factors.

RESULTS

The average positive rate of anti-HEV IgG in students (6-25 years) was 3.4%. One (0.2%) student was anti-HEV IgM positive, while also testing positive for IgG. The HEV seroprevalence was not related to students' gender, school, or family residence. In occupational populations, the overall seropositivity rate was 13.3% for anti-HEV IgG and 0.67% for IgM. HEV seropositivity increased significantly with age, ranging from 3.8% to 18.6% in age groups, and differed significantly among four occupation groups: farmers (17.6%), food supply workers (18.0%), other non-farm workers (14.7%) and healthcare workers (5.9%) (p = 0.002). Multivariable logistic analysis confirmed the significant correlations of seroprevalence with age and occupation.

CONCLUSIONS

The study found a low seroprevalence of HEV in children and young adults in Hebei Province, China. Advanced age correlates with higher seroprevalence in occupational populations, indicating an accumulation of HEV infection over time. Seroprevalence varied significantly among different occupation groups, suggesting the important role of occupational exposure for HEV infection.

Hepatitis E virus infection during pregnancy: Advances in animal models

Hepatitis E virus (HEV) is one of the major pathogens causing acute viral hepatitis worldwide, which usually causes acute self-limited diseases in general individuals. However, it can lead to high mortality and adverse pregnancy outcomes in pregnant women. Due to the lack of effective and stable cell culture models for HEV, the establishment of suitable animal models for HEV infection during pregnancy is necessary. An electronic search of the relevant database was conducted to identify eligible articles. Main animal models for the study of HEV infection during pregnancy include rabbits, swine, nonhuman primates and Mongolian gerbils. These animal models have been used to study the prevention, treatment and possible mechanisms of HEV infection during pregnancy. Studies using these animal models have investigated the potential pathogenesis of HEV infection during pregnancy. It has been found that immune mechanism (changes in the CD4/CD8 ratio and cytokines), hormonal changes (increase in pregnancy-related hormones) and viral factors (different genotypes and genome structures) can lead to HEV-related adverse pregnancy outcomes in animal models. In this review, we aimed to comprehensively present the characteristics of different animal models and the pathogenesis of HEV-related adverse pregnancy outcomes.

Strain- and Subtype-Specific Replication of Genotype 3 Hepatitis E Viruses in Mongolian Gerbils

Since Mongolian gerbils are broadly susceptible to hepatitis E virus (HEV), including genotypes 1, 4, 5, and 8 (HEV-1, HEV-5, HEV-5, and HEV-8) and rat HEV, they are a useful small animal model for HEV. However, we have observed that the subtypes HEV-3k and HEV-3ra in genotype 3 HEV (HEV-3) were not infected efficiently in the gerbils. A small-animal model for HEV-3 is also needed since HEV-3 is responsible for major zoonotic HEV infections. To investigate whether gerbils can be used as animal models for other subtypes of HEV-3, we injected gerbils with five HEV-3 subtypes (HEV-3b, -3e, -3f, -3k, and -3ra) and compared the infectivity of the subtypes. We detected viral RNA in the gerbils' feces. High titers of anti-HEV IgG antibodies in serum were induced in all HEV-3b/ch-, HEV-3f-, and HEV-3e-injected gerbils. Especially, the HEV-3e-injected animals released high levels of viruses into their feces for an extended period. The virus replication was limited in the HEV-3b/wb-injected and HEV-3k-injected groups. Although viral RNA was detected in HEV-3ra-injected gerbils, the copy numbers in fecal specimens were low; no antibodies were detected in the sera. These results indicate that although HEV-3's infectivity in gerbils depends on the subtype and strain, Mongolian gerbils have potential as a small-animal model for HEV-3. A further comparison of HEV-3e with different genotype strains (HEV-4i and HEV-5) and different genera (rat HEV) revealed different ALT elevations among the strains, and liver damage occurred in HEV-4i- and HEV-5-infected but not HEV-3e- or rat HEV-infected gerbils, demonstrating variable pathogenicity across HEVs from different genera and genotypes in Mongolian gerbils. HEV-4i- and HEV-5-infected Mongolian gerbils might be candidate animal models to examine HEV's pathogenicity.

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.

Optimization of immunosuppression strategies for the establishment of chronic hepatitis E virus infection in rabbits

Chronic hepatitis E mostly occurs in organ transplant recipients and can lead to rapid liver fibrosis and cirrhosis. Previous studies found that the development of chronic hepatitis E virus (HEV) infection is linked to the type of immunosuppressant used. Animal models are crucial for the study of pathogenesis of chronic hepatitis E. We previously established a stable chronic HEV infection rabbit model using cyclosporine A (CsA), a calcineurin inhibitor (CNI)-based immunosuppressant. However, the immunosuppression strategy and timing may be optimized, and how different types of immunosuppressants affect the establishment of chronic HEV infection in this model is still unknown. Here, we showed that chronic HEV infection can be established in 100% of rabbits when CsA treatment was started at HEV challenge or even 4 weeks after. Tacrolimus or prednisolone treatment alone also contributed to chronic HEV infection, resulting in 100% and 77.8% chronicity rates, respectively, while mycophenolate mofetil (MMF) only led to a 28.6% chronicity rate. Chronic HEV infection was accompanied with a persistent activation of innate immune response evidenced by transcriptome analysis. The suppressed adaptive immune response evidenced by low expression of genes related to cytotoxicity (like perforin and FasL) and low anti-HEV seroconversion rates may play important roles in causing chronic HEV infection. By analyzing HEV antigen concentrations with different infection outcomes, we also found that HEV antigen levels could indicate chronic HEV infection development. This study optimized the immunosuppression strategies for establishing chronic HEV infection in rabbits and highlighted the potential association between the development of chronic HEV infection and immunosuppressants.IMPORTANCEOrgan transplant recipients are at high risk of chronic hepatitis E and generally receive a CNI-based immunosuppression regimen containing CNI (tacrolimus or CsA), MMF, and/or corticosteroids. Previously, we established stable chronic HEV infection in a rabbit model by using CsA before HEV challenge. In this study, we further optimized the immunosuppression strategies for establishing chronic HEV infection in rabbits. Chronic HEV infection can also be established when CsA treatment was started at the same time or even 4 weeks after HEV challenge, clearly indicating the risk of progression to chronic infection under these circumstances and the necessity of HEV screening for both the recipient and the donor preoperatively. CsA, tacrolimus, or prednisolone instead of MMF significantly contributed to chronic HEV infection. HEV antigen in acute infection phase indicates the development of chronic infection. Our results have important implications for understanding the potential association between chronic HEV infection and immunosuppressants.

Hepatitis E virus in children and adolescents living in an urban environment in central Argentina: An explorative study

In Argentina, circulation of hepatitis E virus (HEV) genotype 3 has been described, producing sporadic cases of acute and chronic hepatitis. Limited information is available regarding HEV infection in children, so we aimed to investigate this virus in a pediatric population from the country. Serum samples from Argentine children (0-18 years old) (n = 213) were studied for IgG anti-HEV, IgM anti-HEV and RNA-HEV: 202 samples belonged to individuals attending health-care centers for routine check-ups, and 11 samples from patients with acute hepatitis of unknown etiology. Seropositivity for IgG anti-HEV was 1.49 % (3/202). One sample from an 18-years-old female patient with acute hepatitis tested positive for IgM anti-HEV detection, negative for IgG anti-HEV and RNA-HEV, but also positive for IgM anti-EBV. The HEV prevalence was low and showed circulation among children in central Argentina.