Hepatitis E virus-induced primary cutaneous CD30(+) T cell lymphoproliferative disorder

Hepatitis E virus infects human testicular tissue and Sertoli cells

Globally, hepatitis E virus (HEV) infections are prevalent. The finding of high viral loads and persistent viral shedding in ejaculate suggests that HEV replicates within the human male genital tract, but its target organ is unknown and appropriate models are lacking. We aimed to determine the HEV tropism in the human testis and its potential influence on male reproductive health. We conducted an ex vivo culture of human testis explants and in vitro culture of primary human Sertoli cells. Clinically derived HEV genotype 1 (HEV1) and HEV3 virions, as well as rat-derived HEV-C1, were used for inoculation. Transcriptomic analysis was performed on testis tissues collected from tacrolimus-treated rabbits with chronic HEV3 infection. Our findings reveal that HEV3, but not HEV1 or HEV-C1, can replicate in human testis explants and primary human Sertoli cells. Tacrolimus treatment significantly enhanced the replication efficiency of HEV3 in testis explants and enabled successful HEV1 infection in Sertoli cells. HEV3 infection disrupted the secretion of several soluble factors and altered the cytokine microenvironment within primary human Sertoli cells. Finally, intratesticular transcriptomic analysis of immunocompromised rabbits with chronic HEV infection indicated downregulation of genes associated with spermatogenesis. HEV can infect the human testicular tissues and Sertoli cells, with increased replication efficiency when exposed to tacrolimus treatment. These findings shed light on how HEV may persist in the ejaculate of patients with chronic hepatitis E and provide valuable ex vivo tools for studying countermeasures.

Primary Cutaneous CD30-Positive Lymphoproliferative Disorders-Current Therapeutic Approaches with a Focus on Brentuximab Vedotin

One of the most common subgroups of cutaneous T-cell lymphomas is that of primary cutaneous CD30-positive lymphoproliferative disorders. The group includes lymphomatoid papulosis (LyP) and primary cutaneous anaplastic large cell lymphoma (pcALCL), as well as some borderline cases. Recently, significant progress has been made in understanding the genetics and treatment of these disorders. This review article summarises the clinical evidence supporting the current treatment options for these diseases. Recent years have seen the introduction of novel agents into clinical practice; most of these target CD30, such as anti-CD30 monoclonal antibodies and conjugated antibodies (brentuximab vedotin), bispecific antibodies and cellular therapies, particularly anti-CD30 CAR-T cells. This paper briefly reviews the biology of CD30 that makes it a good therapeutic target and describes the anti-CD30 therapies that have emerged to date.

Viral Biology and Immune Privilege in the Development of Extrahepatic Manifestations During Hepatitis E Virus Infection

Hepatitis E virus (HEV) exhibits tropism toward hepatocytes and thus affects the liver; however, HEV may also affect other tissues, including the heart, kidneys, intestines, testicles, and central nervous system. To date, the pathophysiological links between HEV infection and extrahepatic manifestations have not yet been established. Considering that HEV infects multiple types of cells, the direct effects of virus replication in peripheral tissues represent a plausible explanation for extrahepatic manifestations. In addition, since the immune response is crucial in the development of the disease, the immune characteristics of affected tissues should be revisited to identify commonalities explaining the effects of the virus. This review summarizes the most recent advances in understanding the virus biology and immune-privileged status of specific tissues as major elements for HEV replication in diverse organs. These discoveries may open avenues to explain the multiple extrahepatic manifestations associated with HEV infection and ultimately to design effective strategies for infection control.

CD30 in Cutaneous Pathology

ABSTRACT

The discovery of CD30 as a diagnostic marker was essential in the identification of not only some lymphomas but also many other solid tumors and benign reactive conditions. Many CD30+ cutaneous disorders and tumors have been categorized since the identification of the marker. With the design of targeted therapies against CD30+ tumoral cells, the interest in CD30 determination was not only diagnostic but also mainly therapeutic. In this article, we explore the historical aspects of the discovery of CD30 and examine the main CD30-related cutaneous pathology, susceptible of anti-CD30 modern treatments.

Hepatitis E Virus Infections: Epidemiology, Genetic Diversity, and Clinical Considerations

According to the World Health Organization, approximately 20 million people worldwide are infected annually with the hepatitis E virus (HEV). There are four main genotypes of HEV. Genotype 1 and genotype 2 are common in developing countries and are transmitted by contaminated water from a fecal-oral route. Genotype 3 and genotype 4 are common in developed countries and can lead to occasional transmission to humans via undercooked meat. Hepatitis E virus 1 and HEV3 can lead to fulminant hepatitis, and HEV3 can lead to chronic hepatitis and cirrhosis in immunocompromised patients. The majority of patients with HEV infection are asymptomatic and usually have spontaneous viral clearance without treatment. However, infection in immunocompromised individuals can lead to chronic HEV infection. Both acute and chronic HEV infections can have extrahepatic manifestations. No specific treatment is required for acute HEV infection, no treatment has been approved in chronic infection, and no HEV vaccine has been approved by the (United States) Food and Drug Administration. This review focuses on the molecular virology (HEV life cycle, genotypes, model systems, zoonosis), pathogenesis, clinical manifestation, and treatment of chronic HEV infection, especially in immunocompromised patients, to provide clinicians a better understanding of the global distribution of these infections and the significant effect they can have on immunocompromised patients.

Puzzles for Hepatitis E Virus

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

Chronic hepatitis E: Advancing research and patient care

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

Clinical features of hepatitis E infections in patients with hematologic disorders

Hepatitis E virus is increasingly being reported to cause chronic infection in immunocompromised patients. However, less is known about patients with an underlying hematologic disease. In particular, the impact of hepatitis E infection on oncological therapy has been poorly described. In this retrospective single-center study, we analyzed 35 hematologic patients with hepatitis E, including 20 patients under active oncological treatment and 15 patients who were in the posttreatment follow-up or under active surveillance. The primary aim was to describe the clinical courses with particular focus on any hepatitis E-related therapy modifications of cancer-directed therapy. In the majority (60%) of patients who were under active oncological treatment, hepatitis E-related therapy modifications were made, and 25% of deaths were due to progression of the hematologic disease. In patients receiving concomitant oncological treatment, no hepatitis Erelated deaths occurred. In contrast, two patients in the follow-up group died from hepatitis E-associated acute-onchronic liver failure. Chronic hepatitis E was observed in 34% of all cases and 43% received ribavirin therapy; of those, 27% achieved a sustained virological response. CD20-directed therapy was the only independent risk factor for developing chronic hepatitis E. We conclude that CD20-directed treatment at any time point is a risk factor for developing chronic hepatitis E. Nevertheless, since mortality from the progression of hematologic disease was higher than hepatitis E-related mortality, we suggest careful case-by-case decisions on modifications of cancer treatment. Patients in the posttreatment follow-up phase may also suffer from severe courses and hepatitis E chronicity occurs as frequently as in patients undergoing active therapy.

Characterization of Chronic Hepatitis E Virus Infection in Immunocompetent Rabbits

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

Treatment for chronic hepatitis E virus infection: A systematic review and meta-analysis

Hepatitis E virus infection can cause chronic hepatitis in immunocompromised patients with significant chance of progressive fibrosis and possibly cirrhosis. The aim of this systematic review was to summarize the efficacy and safety of the various treatment options for chronic hepatitis E. We performed a systematic literature search. The primary outcome measure was a sustained virological response (SVR). Secondary end points were rapid virological response (RVR), relapse rates, side effects and adverse events. Forty-four articles were included with a total of 582 patients. Reduction of immunosuppressive medication induced viral clearance in 55/174 (32%) of the patients. Meta-analysis of 395 patients showed a pooled SVR rate of 78% (95-CI 72%-84%) after ribavirin treatment. Twenty-five per cent of the patients obtained a RVR, whereas a relapse occurred in 18% of the patients. Anaemia during treatment led to dose reduction, use of erythropoietin and/or blood transfusion in 37% of the patients. A second treatment attempt with ribavirin led to a SVR in 39/51 (76%) of the patients. Pegylated interferon-alpha was administered to 13 patients and SVR was obtained in 85%. Two patients (15%) suffered from acute transplant rejection during treatment with interferon. In conclusion, reduction of immunosuppressive medication and treatment with ribavirin is safe, generally well tolerated and induced viral clearance in 32% and 78% of patients, respectively. Therefore, ribavirin should be considered as first treatment step for chronic hepatitis E. Treatment with pegylated interferon-alpha increases the risk of transplant rejection and should therefore be administered with great caution.

Mobilization of γδ T Cells and IL-10 Production at the Acute Phase of Hepatitis E Virus Infection in Cytomegalovirus Carriers

Alterations in the γδ T cell compartment have been reported in immunocompromised individuals infected with hepatitis E virus (HEV)-g3. We now report the analysis of blood γδ T cells from acutely HEV-infected individuals in the absence of immunosuppression. In these patients, non-Vδ2 (ND2) γδ T cells outnumbered otherwise predominant Vδ2 cells selectively in human CMV (HCMV)-seropositive patients and were higher than in HCMV^pos controls, mimicking HCMV reactivation, whereas their serum was PCR-negative for HCMV. Stimulation of their lymphocytes with HEV-infected hepatocarcinoma cells led to an HEV-specific response in γδ subsets of HCMV^pos individuals. HEV infection was associated with a lowered expression of TIGIT, LAG-3, and CD160 immune checkpoint markers on ND2 effector memory cells in HCMV^neg but not in HCMV^pos HEV patients. γδ cell lines, predominantly ND2, were generated from patients after coculture with hepatocarcinoma cells permissive to HEV and IL-2/12/18. Upon restimulation with HEV-infected or uninfected cells and selected cytokines, these cell lines produced IFN-γ and IL-10, the latter being induced by IL-12 in IFN-γ-producing cells and upregulated by HEV and IL-18. They were also capable of suppressing the proliferation of CD3/CD28-activated CD4 cells in transwell experiments. Importantly, IL-10 was detected in the plasma of 10 of 10 HCMV^pos HEV patients but rarely in controls or HCMV^neg HEV patients, implying that γδ cells are probably involved in IL-10 production at the acute phase of infection. Our data indicate that HEV mobilizes a pool of ND2 memory cells in HCMV carriers, promoting the development of an immunoregulatory environment.

Presence and persistence of hepatitis E virus RNA and proteins in human bone marrow

Hepatitis E virus (HEV) infection is primarily manifesting as acute hepatitis, but extra-hepatic replication and injury are frequently reported. During the study period, we discovered two acute myeloid leukaemia (AML) patients infected with HEV genotype 3 and 4, respectively, and HEV RNA and/or viral proteins were persistently detected in the bone marrow of both patients. The finding suggests that HEV can replicate in human bone marrow as it may serve as a new target site and reservoir of HEV persistence.

Recent data on hepatitis E

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

A Systematic Review of the Extra-Hepatic Manifestations of Hepatitis E Virus Infection

Hepatitis E virus (HEV) is a non-enveloped, positive-sense, single-stranded RNA icosahedral virus belongs to the genus Orthohepevirus within the Hepeviridae family. HEV infection can be asymptomatic, or it can cause icteric or fulminant hepatitis. Off late, there have been a number of publications reporting the extra-hepatic manifestations of HEV infection, and this systematic review is aimed at summarizing the available evidence in this regard. Two independent investigators searched PubMed, PubMed Central and Embase databases using the search string "(((hepatitis E) AND (Extrahepatic OR Extra-Hepatic))) OR ((Hepatitis E) AND (Neurology OR Cardiology OR Respiratory OR Lung OR Gastrointestinal OR musculoskeletal OR immunology OR pulmonary)) Filters: Abstract availability, English language, and Human studies". The extra-hepatic manifestations reported in each of the selected articles were classified and reported as neurological, cardiovascular, and hematological and miscellaneous manifestations. The total number of various manifestations reported in our study were n = 324. These include neurological manifestations (n = 178/324 (54.94%)), cardiovascular and hematological manifestations (n = 113/324 (34.88%)), gastro-intestinal/pancreaticobiliary manifestations (n = 24/324 (7.41%)) and other rarer manifestations involving systems such as renal (n = 4/324; 1.24%), endocrine (n = 1/324; 0.31%), dermatology (n = 1/324; 0.31%), respiratory (n = 1/324; 0.31%), muscular (n = 1/324; 0.31%) and immune system (n = 1/324; 0.31%). Thus, HEV can have extra-hepatic manifestations affecting any system of the human body. Further research is needed to elucidate the underlying pathophysiological manifestations of these extra-hepatic manifestations and to prove causal association with HEV.

Extrahepatic manifestations of hepatitis E virus: An overview

Hepatitis E virus (HEV) is a significant health problem with approximately 20 million individuals infected annually. HEV infection has been associated with a wide spectrum of extrahepatic manifestations, including neurological, hematological and renal disorders. Guillain-Barré syndrome and neuralgic amyotrophy are the most frequent neurological manifestations. In addition, HEV infection has been observed with other neurological diseases, such as encephalitis, myelitis and Bell’s palsy. Hematologic manifestations include anemia due to glucose-6-phospate dehydrogonase deficiency, autoimmune hemolytic anemia and severe thrombocytopenia. Membranoproliferative glomerulonephritis and relapse IgA nephropathy with or without coexisting cryoglobulinemia appear to be the most common renal injuries related with HEV infection. Also, HEV infection has been associated with acute pancreatitis and other immune-mediated manifestations, such as arthritis and myocarditis. However, the pathophysiologic mechanisms of HEV-related extrahepatic manifestations are still largely unclear.

Locally Acquired Chronic Hepatitis E Followed by Epstein-Barr Virus Reactivation and Burkitt Lymphoma as a Suspected Extrahepatic Manifestation in a Liver Transplant Recipient

BACKGROUND Hepatitis E virus (HEV) is a common cause of acute hepatitis in developing regions. In high-income countries, hepatitis E is an emergent zoonotic disease of increasing concern. Clinically, the infection is usually acute and self-limited in immunocompetent individuals, although rare chronic cases in immunocompromised patients have been reported. Both acute and chronic infections have been recently associated with several extrahepatic manifestations, including neurological and hematological disorders. CASE REPORT A case of autochthonous chronic HEV infection in a liver-transplanted man from a non-endemic country is presented. Phylogenetic analysis revealed a swine origin of the HEV human infection. Chronic hepatitis E was treated with a 9-week course of ribavirin, after which viral clearance was achieved. Subsequently, the patient developed a post-transplant lymphoproliferative disorder (PTLD) in the form of Burkitt lymphoma. At the time of lymphoma diagnosis, the patient had shown a strong reactivation of Epstein-Barr virus (EBV) infection. After additional antiviral ganciclovir therapy and chemotherapy, the patient had a complete recovery with no sequelae. CONCLUSIONS The differential diagnosis of persistently elevated transaminases in transplanted and/or immunocompromised patients should include testing for HEV by appropriate nucleic acid techniques (NATs). Cases of HEV infection with an atypical clinical outcome, such as the one presented herein, highlights the need for increased awareness of chronic hepatitis E and its association with a wide range of extrahepatic manifestations.

The Clinical Perspective on Hepatitis E

Every year, there are an estimated 20 million hepatitis E virus (HEV) infections worldwide, leading to an estimated 3.3 million symptomatic cases of hepatitis E. HEV is largely circulating in the west and is associated with several hepatic and extrahepatic diseases. HEV Genotype 1 and 2 infections are waterborne and causative for epidemics in the tropics, while genotype 3 and 4 infections are zoonotic diseases and are mainly transmitted by ingestion of undercooked pork in industrialized nations. The clinical course of these infections differs: genotype 1 and 2 infection can cause acute illness and can lead to acute liver failure (ALF) or acute on chronic liver failure (ACLF) with a high mortality rate of 20% in pregnant women. In contrast, the majority of HEV GT-3 and -4 infections have a clinically asymptomatic course and only rarely lead to acute on chronic liver failure in elderly or patients with underlying liver disease. Immunosuppressed individuals infected with genotype 3 or 4 may develop chronic hepatitis E, which then can lead to life-threatening cirrhosis. Furthermore, several extra-hepatic manifestations affecting various organs have been associated with ongoing or previous HEV infections but the causal link for many of them still needs to be proven. There is no approved specific therapy for the treatment of acute or chronic HEV GT-3 or -4 infections but off-label use of ribavirin has been demonstrated to be safe and effective in the majority of patients. However, in approximately 15% of chronically HEV infected patients, cure is not possible.

Early changes in gene expression of the entire pathological process in Cutaneous T-cell lymphoma

In this study, we aimed to explore the time-course relating to the pathological progression of Cutaneous T-cell lymphoma (CTCL) and to identify the early changes in gene expression. The raw microarray data of CTCL was downloaded from the Gene Expression Omnibus database and a weighted gene coexpression network analysis was performed. A total of 2183 genes that positively correlated with the time course of CTCL development were identified in as part of the turquoise module as well as 1096 genes negatively correlated with the time course of CTCL development, which was identified in the blue module. To better understand the effects of these genes on prognosis, we further performed the Spearman correlation analysis, univariate Cox regression analysis, and Kaplan-Meier survival analysis. We identified 10 differentially expressed genes whose expression was significantly associated with prognosis in patients with CTCL. Our findings can help our understanding of the underlying mechanisms of CTCL as well as the development of novel drugs.

Evaluation of an antigen assay for diagnosing acute and chronic hepatitis E genotype 4 infection

BACKGROUND AND AIM

Results obtained from different hepatitis E virus (HEV) tests are usually inconsistent. The detection of serum HEV antigen (Ag) has been suggested to be more sensitive for the diagnosis of genotypes 1 and 3 HEV.

METHODS

We compared the diagnostic accuracies of serum HEV Ag and HEV RNA by using 202 serum samples from patients suspected acute viral hepatitis.

RESULTS

The HEV Ag assay was 100% specific. The lower detected levels of viremia ranged from 10² to 10³  copies/mL. The sensitivity of the HEV Ag test was 90.5%. One of the 42 cases was negative for anti-HEV IgM, but HEV Ag was still detectable. The detectable period of HEV Ag was in concordance with the detectable period of HEV RNA. Serum HEV Ag was persistently detected in two cases of chronic hepatitis E, confirmed by the persistent presence of HEV RNA despite being negative for anti-HEV IgM. HEV Ag demonstrated good consistency with positive HEV RNA (k = 0.938, P < 0.001). Receiver operating characteristic analysis of HEV Ag suggested a second cut-off value of >0.095 to predict HEV patients with 95.24% sensitivity and 98.75% specificity, and the area under the curve was 0.9887, which was higher than that of three commercial anti-HEV IgM ELISA tests.

CONCLUSIONS

The presence of HEV Ag has good consistency with HEV RNA in both acute and chronic genotype 4 hepatitis E. HEV Ag is a more promising serum marker to identify active genotype 4 HEV infection than anti-HEV IgM and HEV RNA.

Multiple remissions of extracavitary primary effusion lymphoma treated with a single cycle of liposomal doxorubicin in a patient infected with HIV

Primary effusion lymphoma (pel) is a rare human herpesvirus 8 (hhv8)-related large B cell lymphoma with plasmablastic, immunoblastic, or anaplastic features that often carries a poor prognosis. This lymphoma occurs mainly in patients with hiv infection, most often with Epstein-Barr virus (ebv) co-infection, and usually presents as body cavity effusions or, less commonly, as extracavitary lesions without effusion (ec-pel). Chemotherapeutic treatment options are limited and require concurrent antiretroviral therapy (art). Here, we report the case of an adult patient with hiv infection and chronic hepatitis E virus (hev) co-infection who had low CD4 T cell recovery after years of art. The patient then developed a cutaneous ec-pel which rapidly regressed after 1 cycle of liposomal doxorubicin (ld) for his Kaposi sarcoma (ks) before treatment with chop chemotherapy. He had previously received numerous cycles of ld for cutaneous ks over 2 years. Because of the patient's low CD4 T cell count, hev co-infection, and earlier unexpected remission of ec-pel before chop, the patient opted for a single trial of ld before other options. Surprisingly, he experienced a complete remission lasting 18 months. Subsequently, his ec-pel relapsed twice at 31 and at 41 months after the initial diagnosis. Upon recurrence, a similar single cycle of ld was given, which again induced remission. The patient today is in complete remission after a total of 4 ld infusions over 54 months. This patient represents a unique case of hiv-with-hhv8-related, ebv-negative ec-pel with chronic hev coinfection, in which rapid remission was achieved after a single cycle of ld, suggesting an antiviral response in addition to the chemotherapeutic effect.

Hepatitis E virus - key points for the clinical haematologist

In recent years there has been a paradigm shift in our understanding of the epidemiology and clinical features of hepatitis E virus (HEV) infection. Once classically described as an acute hepatitis associated with waterborne outbreaks in areas of poor sanitation, HEV is now recognised to be endemic in Europe and is probably zoonotic in origin. Evidence for transfusion-transmitted HEV has prompted the introduction of blood donor screening in a number of countries, but the risk to the haematology patient from food sources remains. The aim of this review therefore, is to equip the clinical haematologist with the knowledge required to diagnose HEV infection and to aid decision-making in patient management. The article also provides information on addressing patient concerns about their risk of acquiring hepatitis E and how this risk can be mitigated.

Hepatitis E virus: advances and challenges

At least 20 million hepatitis E virus (HEV) infections occur annually, with >3 million symptomatic cases and ∼60,000 fatalities. Hepatitis E is generally self-limiting, with a case fatality rate of 0.5-3% in young adults. However, it can cause up to 30% mortality in pregnant women in the third trimester and can become chronic in immunocompromised individuals, such as those receiving organ transplants or chemotherapy and individuals with HIV infection. HEV is transmitted primarily via the faecal-oral route and was previously thought to be a public health concern only in developing countries. It is now also being frequently reported in industrialized countries, where it is transmitted zoonotically or through organ transplantation or blood transfusions. Although a vaccine for HEV has been developed, it is only licensed in China. Additionally, no effective, non-teratogenic and specific treatments against HEV infections are currently available. Although progress has been made in characterizing HEV biology, the scarcity of adequate experimental platforms has hampered further research. In this Review, we focus on providing an update on the HEV life cycle. We will further discuss existing cell culture and animal models and highlight platforms that have proven to be useful and/or are emerging for studying other hepatotropic (viral) pathogens.