Fetal and neonatal health consequences of vertically transmitted hepatitis E virus infection

A Phase 1, Double-Blinded, Placebo-Controlled Clinical Trial to Evaluate the Safety and Immunogenicity of HEV-239 (Hecolin) Vaccine in Healthy US Adults

BACKGROUND

Establishing the safety and immunogenicity of a hepatitis E virus vaccine in multiple populations could facilitate broader access and prevent maternal and infant mortality.

METHODS

We conducted a phase 1, randomized, double-blinded, placebo-controlled (4:1 vaccine to placebo) trial of 30 µg HEV-239 (Hecolin, Xiamen Innovax Biotech Company Limited, China) administered intramuscularly in healthy US adults aged 18-45 years. Participants were vaccinated on days 1, 29, and 180. Participants reported solicited local and systemic reactions for 7 days following vaccination and were followed through 12 months after enrollment for safety and immunogenicity (IgG, IgM).

RESULTS

Solicited local and systemic reactions between treatment and placebo group were similar and overall mild. No participants experienced serious adverse events related to HEV-239. All participants receiving HEV-239 seroconverted at 1 month following the first dose and remained seropositive throughout the study. HEV-239 elicited a robust hepatitis E IgG response that peaked 1 month following the second dose (geometric mean concentration [GMC], 6.16; 95% confidence interval [CI], 4.40-8.63), was boosted with the third dose (GMC, 11.50; 95% CI, 7.90-16.75) and persisted through 6 months.

CONCLUSIONS

HEV-239 is safe and elicits a durable immune response through at least 6 months after the third dose in healthy US adults.

CLINICAL TRIALS REGISTRATION

NCT03827395.

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

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

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.

A Rare Case of Chronic Liver Disease in a Patient Who Previously Presented With Hepatitis E

Hepatitis E virus (HEV) is among the most common causes of acute viral hepatitis. It typically causes acute infection, but some cases of chronic infection have also been recorded. These cases were particularly seen in developed countries, in patients who were immunocompromised, organ transplant recipients, or those with underlying hematological malignancy. However, we encountered a case of hepatitis E presenting as a chronic liver disease in an immunocompetent patient from a developing country. Therefore, more underlying risk factors need to be studied, which may lead to such a rare presentation of hepatitis E.

Transmission of Hepatitis E Virus

Transmission of hepatitis E virus (HEV) occurs predominantly by the fecal-oral route. Large epidemics of hepatitis E in the developing countries of Asia and Africa are waterborne and spread through contaminated drinking water. The reservoir of HEV in developed countries is believed to be in animals with zoonotic transmission to humans, possibly through direct contact or the consumption of undercooked contaminated meat. And HEV transmission through blood transfusion, organ transplantation, and vertical transmission has been reported.

Ethnic differences in hepatitis A and E virus seroprevalence in patients attending the Emergency Department, Paramaribo, Suriname

BACKGROUND

Hepatitis A virus (HAV) and hepatitis E virus (HEV) have enteric modes of transmission and are common causes of acute hepatitis in low- and middle-income countries. HEV is also characterised as a zoonotic infection and is prevalent in high-income countries. Data on HAV and HEV prevalence in Suriname, a middle-income country in South America, are scarce.

METHODS

Serum samples of 944 and 949 randomly selected patients attending the Emergency Department at the Academic Hospital of Paramaribo, the capital of Suriname, were analysed for anti-HAV antibodies (anti-HAV) and anti-HEV antibodies (anti-HEV), respectively. Determinants of anti-HAV and anti-HEV positive serology were evaluated using multivariable logistic regression.

RESULTS

Anti-HAV prevalence was 58.3% (95% CI 55.4 to 61.4%) and higher prevalence was independently associated with belonging to the Tribal or Indigenous population and older age. Anti-HEV prevalence was 3.7% (95% CI 2.6 to 5.0%) and higher prevalence was associated with Tribal and Creole ethnicity and older age.

CONCLUSIONS

In Suriname, exposure to HAV is consistent with a very low endemic country and exposure to HEV was rare. Both viruses were more prevalent in specific ethnic groups. As anti-HAVantibodies were less frequently found in younger individuals, they could be susceptible to potential HAV outbreaks and might require HAV vaccination.

Seroprevalence of Hepatitis E Virus Infection in Middle Eastern Countries: A Systematic Review and Meta-Analysis

Hepatitis E virus (HEV) is a hepatotropic virus that is a major public health concern worldwide. Autochthonous HEV is spread through oral feces in unsanitary environments, as well as vertical and, occasionally, blood transfusion. HEV is more common in developing countries, but it has recently become more widespread in developed countries as well. The Middle East (ME) has long been an endemic location for HEV infection. Therefore, the aim of this systematic review and meta-analysis was to assess the seroprevalence of anti-HEV antibodies in ME countries. The author systematically searched five databases, namely ScienceDirect, EMBASE, Scopus, PubMed, and Google Scholar, to identify English-language articles published on or before 25 April 2022. Comprehensive meta-analysis software was used for all statistical analyses (CMA, version 3, BioStat, Englewood, CO, USA). After quality control and exclusion of irrelevant studies, 80 studies were included in the qualitative synthesis and meta-analysis. A forest plot showed that the overall pooled seroprevalence of HEV infection in ME countries in the fixed-effect and random-effect models were 21.3% (95% CI: 0.209–0.216) and 11.8% (95% CI: 0.099–0.144), respectively. Furthermore, the findings showed a high level of heterogeneity (I2 = 98.733%) among the included studies. In both fixed-effect and random-effect models, the seroprevalence of HEV infection by country was high in Egypt as compared to other regions, at 35.0% (95% CI: 0.342–0.359), and 34.7% (95% CI: 0.153–0.611), respectively. The seroprevalence of HEV infection by country was high among pregnant women, at 47.9% (95% CI: 0.459–0.499) in the fixed-effect model, and in renal transplant recipients, at 30.8% (95% CI: 0.222–0.410) in the random-effect model. The seroprevalence of HEV infection varies by country and study population in the Middle East. More research is needed to determine the disease’s incidence, morbidity, and mortality in the region, where it is prevalent.

Prospect of acute hepatitis E virus outbreak in the context of the COVID-19 Pandemic in Africa: A contingency plan

Hepatitis E virus (HEV) is the primary cause of acute viral hepatitis in Sub-Saharan Africa (SSA). It is transmitted by oral-faecal route via contaminated water or animal products, which is more pronounced in SSA, where inadequate hygiene measures, low socioeconomic situation, and frail healthcare system increase HEV susceptibility. During the coronavirus disease-19 (COVID-19), numerous initiatives concerning viral hepatitis relief in SSA are implemented. However, national programs do not support most services and are neglected when national and local attention rests on the COVID-19 pandemic. Furthermore, during the COVID-19 pandemic, hepatitis E prevention and control programs were affected in low-income countries due to economic losses. Therefore, an interdisciplinary approach should be adopted to mitigate HEV infections during COVID-19.

Hepatitis E virus infection in high-risk populations in Osun State, Nigeria

Hepatitis E virus (HEV) infection is an emerging infection that is of major public health concern, especially in some vulnerable groups like immunosuppressed individuals, pregnant women and HBV-coinfected individuals. HEV is transmitted faecal/oral or zoonotically depending on the HEV-genotype. This study aimed at investigating HEV infections among different at-risk populations in Osun State, Southwestern Nigeria. A total of 720 serum samples were collected from animal handlers, pregnant women, people living with HIV/AIDS, and Hepatitis B virus (HBV) infected individuals. Commercially available Enzyme-Linked Immunosorbent Assays (ELISA) were used for the detection of anti-HEV total and IgM antibodies. Polymerase chain reaction (PCR) was carried out in the HEV seropositive samples and all the samples from individuals infected with HBV. Descriptive analysis and chi-square test of association were performed. The anti-HEV total antibody seroprevalence in HIV-positive individuals, animal handlers and pregnant women was 11.4% (n = 47/411), 7.9% (n = 7/89), and 6.3% (n = 10/160), respectively. Markers of acute HEV infection (anti-HEV IgM) were detected in 2.2% of HIV-positive individuals (n = 9/411) and 1.8% of animal handlers (n = 2/89), respectively, and in 0.6% of pregnant women (n = 1/160). However, all samples were HEV RNA negative. This study analysed the presence of markers of HEV infection among different at-risk populations without clinical symptoms of HEV infection. Our results showed that HEV is an underestimated threat to public health in Nigeria and underlines the need of an HEV surveillance system to understand the distribution and transmission of HEV infection in animals and/to humans.

Uterine Injury Caused by Genotype 4 Hepatitis E Virus Infection Based on a BALB/c Mice Model

To evaluate whether uterine injury caused by hepatitis E virus (HEV) infection is responsible for adverse pregnancy outcomes. HEV-infected female BALB/c mice were coupled with healthy male BALB/c mice at 0, 7, 14, 21, and 91 dpi to explore the uterine injury caused by HEV infection. Mice were euthanized after 10 days of copulation, and uteruses were collected for HEV RNA and antigen detection and histopathological analysis. Inflammatory responses; apoptosis; and estrogen receptor ɑ (ER-ɑ), endomethal antibody (ERAb), cytokeratin-7 (CK7), vimentin (VIM), and vascular endothelial growth factor (VEGF) expression levels were evaluated. After 10 days of copulation, miscarriage and nonpregnancy, as well as enlarged uteruses filled with inflammatory cytokines, were found in HEV-infected mice. HEV RNA and antigens were detected in the sera and uteruses of HEV-infected mice. Significant endometrial thickness (EMT) thinning, severe inflammatory responses, and aggravated apoptosis in the uteruses of HEV-infected mice that experienced miscarriage might contribute to adverse pregnancy outcomes. Furthermore, significantly suppressed ER-ɑ expression and increased ERAb, CK7, VIM, and VEGF expression levels were found in the uteruses of HEV-infected mice that had miscarried. However, uterine damage recovered after complete HEV clearance, and impaired fertility was improved. EMT injury, severe inflammatory responses, and aggravated apoptosis in the uterus caused by HEV infection are responsible for poor pregnancy outcomes.

Hepatitis E Virus Immunopathogenesis

Hepatitis E virus is an important emerging pathogen producing a lethal impact on the pregnant population and immunocompromised patients. Starting in 1983, it has been described as the cause for acute hepatitis transmitted via the fecal–oral route. However, zoonotic and blood transfusion transmission of HEV have been reported in the past few decades, leading to the detailed research of HEV pathogenesis. The reason behind HEV being highly virulent to the pregnant population particularly during the third trimester, leading to maternal and fetal death, remains unknown. Various host factors (immunological, nutritional, hormonal) and viral factors have been studied to define the key determinants assisting HEV to be virulent in pregnant and immunocompromised patients. Similarly, chronic hepatitis is seen particularly in solid organ transplant patients, resulting in fatal conditions. This review describes recent advances in the immunopathophysiology of HEV infections in general, pregnant, and immunocompromised populations, and further elucidates the in vitro and in vivo models utilized to understand HEV pathogenesis.

Hepatitis E and Pregnancy: An Unholy Alliance Unmasked from Kashmir, India

The adverse relationship between viral hepatitis and pregnancy in developing countries had been interpreted as a reflection of retrospectively biased hospital-based data collection by the West. However, the discovery of hepatitis E virus (HEV) as the etiological agent of an epidemic of non-A, non-B hepatitis in Kashmir, and the documenting of the increased incidence and severity of hepatitis E in pregnancy via a house-to-house survey, unmasked this unholy alliance. In the Hepeviridae family, HEV-genotype (gt)1 from genus Orthohepevirus A has a unique open reading frame (ORF)4-encoded protein which enhances viral polymerase activity and viral replication. The epidemics caused by HEV-gt1, but not any other Orthohepevirus A genotype, show an adverse relationship with pregnancy in humans. The pathogenesis of the association is complex and at present not well understood. Possibly multiple factors play a role in causing severe liver disease in the pregnant women including infection and damage to the maternal-fetal interface by HEV-gt1; vertical transmission of HEV to fetus causing severe fetal/neonatal hepatitis; and combined viral and hormone related immune dysfunction of diverse nature in the pregnant women, promoting viral replication. Management is multidisciplinary and needs a close watch for the development and management of acute liver failure. (ALF). Preliminary data suggest beneficial maternal outcomes by early termination of pregnancy in patients with lower grades of encephalopathy.

Seroprevalence of Hepatitis A and Hepatitis E Viruses among Pregnant Women in Northern Iran

Background

Hepatitis A (HAV) and hepatitis E viruses (HEV) are endemic in Iran and are known major causes of acute viral hepatitis. Also, during pregnancy, they are associated with severe outcomes. Therefore, it is vital to evaluate the antibody levels against HAV and HEV in pregnant women to avoid severe outcomes incidence. Study design and methods. A total of 247 pregnant women were enrolled in this prospective cross-sectional study. In addition to completing the questionnaire and interviewing all participants, the serum samples were tested for anti-HAV and anti-HEV IgG using the enzyme-linked immunosorbent assay (ELISA). The association between anti-HAV and anti-HEV antibodies status and risk factors was evaluated.

Results

The mean age of patients was 28.06 ± 5.29 years. Anti-HAV antibody was found in 111 patients (44.9%), while anti-HEV antibody was detected in only two pregnant women (0.8%). The seroprevalence of HAV was inversely related to the level of education. There was no significant correlation between HAV antibody levels and age, marital status, residence location, and pregnancy trimesters.

Conclusion

Considering many complications of these diseases in pregnancy, the detection of enteroviral hepatitis, especially HAV in pregnant women, is necessary, and therefore, proactive measures, such as promoting education, improving people awareness, and vaccination, are recommended.

Infection dynamics and persistence of hepatitis E virus on pig farms - a review

Background

Hepatitis E virus (HEV) genotype 3 and 4 is a zoonosis that causes hepatitis in humans. Humans can become infected by consumption of pork or contact with pigs. Pigs are the main reservoir of the virus worldwide and the virus is present on most pig farms.

Main body

Though HEV is present on most farms, the proportion of infected pigs at slaughter and thus the level of exposure to consumers differs between farms and countries. Understanding the cause of that difference is necessary to install effective measures to lower HEV in pigs at slaughter. Here, HEV studies are reviewed that include infection dynamics of HEV in pigs and on farms, risk factors for HEV farm prevalence, and that describe mechanisms and sources that could generate persistence on farms. Most pigs become infected after maternal immunity has waned, at the end of the nursing or beginning of the fattening phase. Risk factors increasing the likelihood of a high farm prevalence or proportion of actively infected slaughter pigs comprise of factors such as farm demographics, internal and external biosecurity and immunomodulating coinfections. On-farm persistence of HEV is plausible, because of a high transmission rate and a constant influx of susceptible pigs. Environmental sources of HEV that enhance persistence are contaminated manure storages, water and fomites.

Conclusion

As HEV is persistently present on most pig farms, current risk mitigation should focus on lowering transmission within farms, especially between farm compartments. Yet, one should be aware of the paradox of increasing the proportion of actively infected pigs at slaughter by reducing transmission insufficiently. Vaccination of pigs may aid HEV control in the future.

Towards the Improved Accuracy of Hepatitis E Diagnosis in Vulnerable and Target Groups: A Global Perspective on the Current State of Knowledge and the Implications for Practice

The hepatitis E virus (HEV) is a positive single-stranded, icosahedral, quasi-enveloped RNA virus in the genus Orthohepevirus of the family Hepeviridae. Orthohepevirus A is the most numerous species of the genus Orthohepevirus and consists of eight different HEV genotypes that can cause infection in humans. HEV is a pathogen transmitted via the fecal-oral route, most commonly by consuming fecally contaminated water. A particular danger is the HEV-1 genotype, which poses a very high risk of vertical transmission from the mother to the fetus. Several outbreaks caused by this genotype have been reported, resulting in many premature births, abortions, and also neonatal and maternal deaths. Genotype 3 is more prevalent in Europe; however, due to the openness of the market, i.e., trade-in animals which represent a natural reservoir of HEV (such as pigs), there is a possibility of spreading HEV infections outside endemic areas. This problem is indeed global and requires increased hygiene measures in endemic areas, which entails special care for pregnant women in both endemic and non-endemic regions. As already highlighted, pregnant women could have significant health consequences due to the untimely diagnosis of HEV infection; hence, this is a population that should be targeted with a specific combination of testing approaches to ensure optimal specificity and sensitivity. Until we advance from predominantly supportive treatment in pregnancy and appraise the safety and efficacy of a HEV vaccine in this population, such screening approaches represent the mainstay of our public health endeavors.

Hepatitis E should be a global public health priority: recommendations for improving surveillance and prevention

INTRODUCTION

Hepatitis E virus (HEV) is an important cause of enterically transmitted viral hepatitis and a significant contributor to maternal mortality in endemic regions around the world, yet the global response has been limited. HEV is a disease of poverty, and the populations experiencing the greatest burden of HEV-associated illness are not benefitting from existing interventions, including WASH strategies and immunization.

AREAS COVERED

Though a vaccine exists (HEV 239, Hecolin®, Xiamen Innovax Biotech, China), it is only licensed and available in the private market in China and has yet to be prequalified by the WHO for use in endemic settings and outbreaks. This review of the current state of HEV disease and subsequent recommendations for a coordinated public health response are intended to guide the global health community towards breaking the current 'vicious cycle,' in which a lack of data prevents actions that would improve health outcomes.

EXPERT OPINION

Vaccine implementation in future outbreaks, targeted studies assessing vaccine effectiveness and immunogenicity in endemic regions and populations, improved understanding of the global burden, and improvements in diagnostic and epidemiologic tools are urgently needed. Strategies for implementing routine vaccination programs, improving water, sanitation, and hygiene in endemic regions.

Hepatitis E in Sub Saharan Africa - A significant emerging disease

Hepatitis E is an emerging endemic disease found across the African continent, but there are clear differences in epidemiology between North Africa and countries south of the Sahara. In this systematic review, Google scholar and PubMed databases were searched for peer-reviewed articles on HEV epidemiology. Publications meeting our inclusion criteria were critically reviewed to extract consistent findings and identify knowledge gaps. Hepatitis E has been reported in 25 of the 49 countries in Sub Saharan Africa.

Mortality rates of 1–2% in the general population and ~ 20% in pregnant women. Outbreaks were closely linked to refugees and Internally Displaced Persons in camps which accounted for 50% of reported outbreaks. There was very little research and concrete evidence for sources of contamination and transmission routes. There are indications of zoonotic transmission of Hepatitis E Virus infection but further research in these fields is required.

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No data from 50% of African countries

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Outbreaks closely linked to refugee and IDP camps

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Little data on sources of HEV contamination

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Indications but little evidence of zoonotic transmission

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Low awareness amongst health professionals and general public

A Review of the Diagnosis and Management of Hepatitis E

Purpose of review

We aim to provide the readers an up-to-date knowledge of the structure, epidemiology, and transmission followed by a detailed discussion on testing, diagnostics and management of hepatitis E virus infection. We have also included a comprehensive review of hepatitis E in pregnancy.

Recent findings

European Association for the Study of the Liver established clinical practice guidelines for testing and treatment of suspected hepatitis E virus infections in 2018. Evidence suggests chronic hepatitis E may follow a course similar to hepatitis B/C with progression to cirrhosis and possibly hepatocellular carcinoma in immunocompromised patients.

Summary

Hepatitis E virus is the most common cause of acute viral hepatitis worldwide. A combination of serology and nucleic acid amplification testing is the recommended strategy for suspected patients. Ribavirin therapy for a period of 3 months is the drug of choice for severe acute hepatitis, acute-on chronic liver failure, and chronic infections from hepatitis E virus in immunocompromised patients who are unresponsive to decreased immunosuppression. PEGylated interferon α can be used for ribavirin-resistant liver transplant patients with chronic hepatitis E. Further research in therapeutic options is essential considering the stormy course of hepatitis E infection during pregnancy and teratogenicity of all available options.

Integrated value-chain and risk assessment of Pig-Related Zoonoses in Ghana

The marked increase in the pig-trade in Ghana has raised concerns about increased transmission of related zoonotic diseases. A study on pig-related zoonoses along the pork value-chain was conducted in Greater Accra and Upper East Regions of Ghana. Results showed significant taenia (60%) and trichinella (8%) seroprevalence in pigs in Upper East with little evidence of transmission to humans. Sero-prevalence of HEV was high in both pigs (85%) and humans (37%). Sero-prevalence rates were significantly higher in Upper East than Greater Accra. Pig handlers in Accra had significantly higher sero-prevalence rates (58%) than other community members (18%) but there was no such association in the Upper East. Given the high rates of mortality, miscarriage and stillbirth associated with HEV in pregnancy, it is a cause for concern that 31% women of child-bearing age tested sero-positive for HEV.

Targeted hepatitis E vaccination for women of childbearing age is cost-effective in China

BACKGROUND

Hepatitis E virus (HEV) infection is hyper-endemic in China, it is characterized with a high morbidity of fulminant hepatitis and mortality in pregnant women. The first hepatitis E vaccine, HEV 239, was licensed in China in 2011 which provides an effective preventive measure.

OBJECTIVE

To evaluate the cost-effectiveness of vaccination with HEV 239 in women of childbearing age in China and whether HEV antibody screening should be considered before vaccination.

METHODS

A decision tree-Markov model was constructed to simulate HEV infection in a closed female cohort with an average first-marriage age of 25 years and evaluate health and economic outcomes of two potential vaccination strategies, direct vaccination and combined screening and vaccination, from a societal perspective. An incremental cost-effectiveness ratio (ICER, additional costs per disability-adjusted life-year (DALY) averted) was calculated for each vaccination strategy versus no vaccination and between two vaccination strategies. Univariate and probabilistic sensitivity analyses were conducted to assess the robustness of the model findings.

RESULTS

ICERs of direct vaccination and combined screening and vaccination versus no vaccination were $4040 and $3114 per DALY averted, respectively, much lower than 1-time Chinese per-capita GDP ($8127). Direct vaccination would need additional $45,455 for each DALY averted compared with combined screening and vaccination, far more than the 3-time per-capita GDP. Probabilistic sensitivity analyses confirmed our findings that two vaccination strategies would be cost-effective if the willingness-to-pay reached the 1-time per-capita GDP, and that combined screening and vaccination would be more cost-effective than direct vaccination strategy.

CONCLUSION

Vaccinating women of childbearing age with HEV 239 would cost less than the 1-time per-capita GDP for each DALY averted in China, and the vaccination with a prior screening would be the optimal option.

Natural History, Clinical Manifestations, and Pathogenesis of Hepatitis E Virus Genotype 1 and 2 Infections

Infection with genotype 1 or 2 hepatitis E virus (HEV) results primarily from human-to-human transmission through the fecal-oral route in low-resource countries. It presents primarily as "acute viral hepatitis" syndrome, usually a self-limiting illness. A few cases progress to acute liver failure, a serious illness with high fatality. Clinical disease is infrequent among children. Infection during pregnancy is associated with a higher risk of symptomatic disease, severe liver injury, and mortality. Severe disease is also encountered in persons with preexisting chronic liver disease. Some cases have associated extrahepatic features, particularly acute pancreatitis and neurological manifestations. Chronic infection appears to be extremely infrequent with these HEV genotypes. The exact pathogenesis of liver injury remains unknown, although the host immune response appears to be important for viral clearance as well as for induction of liver injury. Hormonal and immune factors appear to be responsible for the severe disease during pregnancy.

A guide to the management of hepatitis E infection during pregnancy

Hepatitis E virus (HEV) infection has distinct features, depending upon the genotype and geographical area. HEV genotypes 1 and 2 are endemic to various developing countries causing epidemics of acute viral hepatitis with human to human transmission. On the other hand, HEV genotypes 3 and 4 prevalent in developed countries commonly lead to subclinical infection and are transmitted zoonotically. HEV infection typically causes acute self-limiting illness associated with low morbidity and mortality. Infection with HEV genotype 1 or 2 in pregnancy, especially in the third trimester may lead to severe illness and fulminant liver failure. Poor maternal and fetal outcomes have been reported. Areas covered: This review highlights the various aspects of HEV infection in pregnancy including diagnosis, management, and prevention. Expert commentary: Treatment is mainly supportive with diligent monitoring and intensive care. Therapeutic termination of pregnancy cannot be recommended based to the available literature. Early liver transplantation (LT) should be considered in these patients although the indications and timing of LT are still controversial. Prevention of HEV infection or illness by improved sanitation and active/passive immunization needs further research.

Recent Advances Towards the Development of a Potent Antiviral Against the Hepatitis E Virus

Hepatitis E virus (HEV) is one of the leading causes of acute viral hepatitis. It also causes acute liver failure and acute-on-chronic liver failure in many patients, such as those suffering from other infections/liver injuries or organ transplant/chemotherapy recipients. Despite widespread sporadic and epidemic incidents, there is no specific treatment against HEV, justifying an urgent need for developing a potent antiviral against it. This review summarizes the known antiviral candidates and provides an overview of the potential targets for the development of specific antivirals against HEV.

Conservation and variation of the hepatitis E virus ORF2 capsid protein

Hepatitis E virus (HEV) is one of the major pathogens causing acute viral hepatitis. The infectious particle consists of an RNA genome and capsid proteins. The 7.2 kb genome encodes three open reading frames (ORF) and ORF2 is translated into the capsid protein. The knowledge of structure and function of the ORF2 protein is essential for understanding the evolution and life cycle of HEV. However, biophysical research in this respect remains limited due to technical challenges. We have carried out a series of computational analysis on HEV ORF2. We have identified 144 conserved sites among the 660 amino acid (AA) residues. 43 models based on the previously proposed reference sequences and a cell culture adapted infectious clone were successfully built by 3D protein structure prediction and refinement. Structure alignment of domains revealed structural conservation of the S and M domains, but to a lesser extent of the P domain. Moreover, molecular docking has predicted distinct binding affinities of a monoclonal antibody towards ORF2 across different genotypes. Thus, we have expanded the information on ORF2 at both sequence and structure levels. These findings may help to better understand the evolution and life cycle of HEV, but also facilitate the development of genetically engineered vaccines or antibodies.

Pregnancy and infection: using disease pathogenesis to inform vaccine strategy

Vaccination is the mainstay of preventative medicine for many infectious diseases. Pregnant women, unborn fetuses, and neonates represent three at-risk populations that can be simultaneously protected by strategic vaccination protocols. Because the pathogenesis of different infectious microbes varies based on tissue tropism, timing of infection, and host susceptibility, the goals of immunization are not uniform across all vaccines. Mechanistic understanding of infectious disease pathogenesis and immune responses is therefore essential to inform vaccine design and the implementation of appropriate immunization protocols that optimize protection of pregnant women, fetuses, and neonates.

Replication of hepatitis E virus in the ovary and promotion of oocyte apoptosis in rabbits infected with HEV-4

Hepatitis E virus (HEV) infection can induce infertility and miscarriage in pregnant women and infect neonates through vertical transmission. However, the mechanism of infertility and vertical transmission remains unclear. In the present study, we evaluated the replication of HEV in the ovary and structural and molecular changes induced by HEV after intraperitoneal injection of HEV in rabbits. Positive- and negative-strand HEV RNA was detected in the ovaries at 28 and 49 days post-infection. Positive HEV open reading frames 2 and 3 signals were observed in the ovaries by immunohistochemistry staining. Histopathological changes of ovarian tissues were observed, including scattered cell necrosis and lymphocyte infiltration. The ratio of normal follicles decreased, whereas the ratio of atresia follicles increased in the HEV RNA-positive ovaries compared to the control group by counting the number of follicles at all levels. In addition, TUNEL results showed that apoptosis in follicle cells and oocytes was promoted by HEV infection. These results suggest that the ovary is one of the replication sites of HEV and that the expression of HEV RNA and antigen in ovarian tissue caused structural and molecular changes that promoted germ cell apoptosis. HEV can infect and replicate in the ovum at different stages, which is a novel mechanism for HEV vertical transmission.

Acute Hepatitis E Virus Infection in Two Geographical Regions of Nigeria

Hepatitis E virus (HEV) remains a major public health concern in resource limited regions of the world. Yet data reporting is suboptimal and surveillance system is inadequate. In Nigeria, there is dearth of information on prevalence of acute HEV infection. This study was therefore designed to describe acute HEV infection among antenatal clinic attendees and community dwellers from two geographical regions in Nigeria. Seven hundred and fifty plasma samples were tested for HEV IgM by Enzyme Linked Immunosorbent Assay (ELISA) technique. The tested samples were randomly selected from a pool of 1,115 blood specimens previously collected for viral hepatitis studies among selected populations (pregnant women, 272; Oyo community dwellers, 438; Anambra community dwellers, 405) between September 2012 and August 2013. One (0.4%) pregnant woman in her 3rd trimester had detectable HEV IgM, while community dwellers from the two study locations had zero prevalence rates of HEV IgM. Detection of HEV IgM in a pregnant woman, especially in her 3rd trimester, is of clinical and epidemiological significance. The need therefore exists for establishment of a robust HEV surveillance system in Nigeria and especially amidst the pregnant population in a bid to improve maternal and child health.

Risk factors for vertical transmission of hepatitis E virus infection

Hepatitis E virus (HEV) infection can be vertically transmitted, but the factors that transmit the disease to foetuses are still unclear. We studied a total of 144 pregnant women with HEV infection. Cord blood and newborn samples were taken for analysis. Nutritional factors were evaluated on the basis of anthropometric parameters and biochemical factors, and HEV viral load was quantified by real-time PCR. Sequencing of HEV-positive samples was performed. Approximately 14.63% (6/41) of pregnant patients with acute liver failure (ALF) died before delivery. Vertical transmission was observed in 46.09% (59/128) of HEV-IgM-positive mothers. Approximately 23.80% (10/42) of newborns in the acute viral hepatitis group and 29.41% (5/17) in the ALF group were positive for HEV-RNA. No significant difference was observed in the occurrence of vertical transmission in HEV groups. Viral load was found to be a significant predictor for vertical transmission of HEV infection adjusted with haemoglobin and folate in derivation cohort group. Incorporating these variables, a new score predicting vertical transmission of HEV was derived. Using these significant predictors, the probability for vertical transmission of HEV was well stratified in the validation group (P>.05). In conclusion, viral load was associated with vertical transmission of HEV infection. A valid prediction score model was generated that was verified in a validation cohort group.

Hepatitis E: prevention and treatment

PURPOSE OF REVIEW

Infection with the hepatitis E virus (HEV) is very common worldwide. The epidemiology, viral genotypes, and transmission routes differ between low-resource countries and economically developed countries. These differences have resulted in the design of diverse prevention and treatment strategies to combat HEV.

RECENT FINDINGS

The population seroprevalence of HEV immunoglobulin G varies between 5 and 50%. However, the diagnosis of acute hepatitis from HEV has not been common in the United States or Western Europe. Chronic progressive HEV infections have been reported among patients who are immunocompromised. Successful treatment of patients with chronic hepatitis from HEV infection with antiviral agents, such as ribavirin or interferon-α, has been reported. Extrahepatic manifestations of HEV infection are common. Large epidemics of hundreds or thousands of cases continue to be reported among populations in Asia and Africa. A subunit peptide HEV vaccine has been found to be highly efficacious in a large clinical trial. However, the vaccine has not been evaluated in populations of pregnant women or other risk groups and is only available in China.

SUMMARY

Although HEV infections are increasingly recognized as a global public health problem, there are few methods for prevention and treatment that are widely available.

Seroprevalence and incidence of hepatitis E virus among blood donors: A review

Hepatitis E virus (HEV) is an RNA virus with 4 main genotypes. HEV-1 and HEV-2 infect solely humans, while HEV-3 and HEV-4 infect humans and various animals such as pigs, deer, and rabbits. HEV-5 and HEV-6 infect mainly wild boar. Recently, new genotypes, known as HEV-7 and HEV-8, were found to infect camels and humans. HEV is globally distributed into different epidemiological patterns based on socioeconomic factors and ecology. Although HEV is mainly transmitted through the fecal-oral route, it was also recognized as a transfusion-transmitted virus. Transmission through blood donation was documented worldwide with rising annual observations, accounting for more than 2.5% of all transmissions. HEV infection is usually asymptomatic or subclinical in immunocompetent individuals, so it remains questionable whether there is an urgent need to screen for HEV prior to blood transfusion. Moreover, recent studies conducted in the Middle East and North Africa (MENA) region indicate that HEV is highly endemic. Here, we provide a review on HEV epidemiology, transmission, and laboratory diagnosis, giving special emphasis to the newly discovered genotypes, HEV-7 and HEV-8. Furthermore, we underscore the findings of recent HEV seroprevalence and viremia studies among blood donors worldwide. We also shed light on similar studies performed among blood donors in the MENA region.

Hepatitis E: the current state of play

The hepatitis E virus (HEV) is a major cause of acute hepatitis globally. Genotypes 1 and 2 (G1 and G2) are obligate human pathogens transmitted faeco-orally, leading to epidemics in developing countries. In contrast, genotypes 3 and 4 (G3 and G4) have a wider host range, including humans, but are primarily porcine viruses and are transmitted from animals to humans as a food-borne zoonosis when meat from an infected animal is consumed. HEV is increasingly recognised as a problem in developed countries, including countries in Europe. G3 HEV is now the most common cause of acute viral hepatitis in the UK and cases continue to rise. The majority of these infections are acquired within the UK and thought to be from insufficiently cooked meat, predominantly processed pork meat. Previously thought to only cause self-limiting disease, HEV infection can persist in immunosuppressed patients, which may lead to chronic hepatitis and the rapid development of cirrhosis. Of particular interest to the transfusion community has been the possibility of transfusion-transmitted HEV, which has been reported from countries classically considered HEV-endemic but also non-endemic countries in Europe and Japan. This has prompted some countries to introduce screening for HEV in blood donations.

Fetomaternal outcomes in pregnant women with hepatitis E infection; still an important fetomaternal killer with an unresolved mystery of increased virulence in pregnancy

Objective:

Hepatitis is a prevalent infection in developing countries. While hepatitis B and C are deepening their roots in the developed world, hepatitis A and E are common in the developing world. The uniqueness of hepatitis is in its transformation from a relatively self-limiting disease in the non-pregnant state, to a highly virulent disease during pregnancy.

Materials and Methods:

This retrospective observational study was conducted in the Department of Obstetrics and Gynecology, King George’s Medical University, Lucknow, for a period of six months from June 2016 to November 2016 [probably during an endemic peak of hepatitis E virus (HEV)] to observe the clinical outcomes in HEV-infected pregnant women.

Results:

A total of 32 anti-HEV immunoglobulin M-positive pregnant women were included, and fetomaternal outcomes were analyzed. Hepatitis E positivity was significantly associated with maternal mortality, intrauterine demise with prematurity, and premature rupture of membranes was the most common fetal complication noted.

Conclusion:

The difference in extent of virulence of infection and variations in maternal morbidity, mortality, and rates of intrauterine demise, signify the presence of some factors that play a role and need to be further studied and evaluated.

Prolonged Detection of Zika Virus RNA in Pregnant Women

OBJECTIVE

Zika virus infection during pregnancy is a cause of microcephaly and other fetal brain abnormalities. Reports indicate that the duration of detectable viral RNA in serum after symptom onset is brief. In a recent case report involving a severely affected fetus, Zika virus RNA was detected in maternal serum 10 weeks after symptom onset, longer than the duration of RNA detection in serum previously reported. This report summarizes the clinical and laboratory characteristics of pregnant women with prolonged detection of Zika virus RNA in serum that were reported to the U.S. Zika Pregnancy Registry.

METHODS

Data were obtained from the U.S. Zika Pregnancy Registry, an enhanced surveillance system of pregnant women with laboratory evidence of confirmed or possible Zika virus infection. For this case series, we defined prolonged detection of Zika virus RNA as Zika virus RNA detection in serum by real-time reverse transcription-polymerase chain reaction (RT-PCR) 14 or more days after symptom onset or, for women not reporting signs or symptoms consistent with Zika virus disease (asymptomatic), 21 or more days after last possible exposure to Zika virus.

RESULTS

Prolonged Zika virus RNA detection in serum was identified in four symptomatic pregnant women up to 46 days after symptom onset and in one asymptomatic pregnant woman 53 days postexposure. Among the five pregnancies, one pregnancy had evidence of fetal Zika virus infection confirmed by histopathologic examination of fetal tissue, three pregnancies resulted in live births of apparently healthy neonates with no reported abnormalities, and one pregnancy is ongoing.

CONCLUSION

Zika virus RNA was detected in the serum of five pregnant women beyond the previously estimated timeframe. Additional real-time RT-PCR testing of pregnant women might provide more data about prolonged detection of Zika virus RNA and the possible diagnostic, epidemiologic, and clinical implications for pregnant women.

Hepatitis E Virus and the Liver: Clinical Settings and Liver Pathology

Infection with hepatitis E virus (HEV) is a leading cause of acute hepatitis worldwide, now increasingly recognized also in nonendemic regions. Clinical manifestation of hepatitis E includes mostly asymptomatic/subclinical presentations or acute, self-limiting hepatitis, but also potentially fatal liver failure or chronic hepatitis in immunocompromised individuals. Accordingly, hepatitis E histolpathologic patterns range from an unremarkable histology over acute (cholestatic) hepatitis with variable degree of necrosis to chronic hepatitis with fibrosis. Awareness of hepatitis E and its differential diagnoses, knowledge of its clinico-pathologic manifestations and familiarity with its diagnostic tools will enable clinicians and pathologists to competently make this diagnosis.

Hepatitis E and pregnancy: current state

Hepatitis E virus (HEV) is responsible for more than 50% of acute viral hepatitis cases in endemic countries. Approximately 2 billion individuals live in hepatitis E-endemic areas and, therefore, are at risk of infection. According to World Health Organization, HEV causes about 20.1 million infections and 70 000 deaths every year. In developing countries with poor sanitation, this disease is transmitted through contaminated water and is associated with large outbreaks, affecting hundreds or thousands of people. In developed countries, autochthonous cases of HEV have been increasingly recognized in the past several years. Hepatitis E virus typically causes an acute, self-limiting illness similar to other acute viral hepatitis, such as hepatitis A or B, with about 0.2% to 1% mortality rate in the general population. However, the course of hepatitis E in pregnancy is different than the mild self-constraining infection described in other populations. During pregnancy, HEV infection can take a fulminant course, resulting in fulminant hepatic failure, membrane rupture, spontaneous abortions, and stillbirths. Studies from various developing countries have shown a high incidence of HEV infection in pregnancy with a significant proportion of pregnant women progressing to fulminant hepatitis with a fatality rate of up to 30%. The present review will highlight new aspects of the HEV infection and pregnancy.

Incidence and Molecular Characterization of Hepatitis E Virus from Swine in Eastern Cape, South Africa

Hepatitis E virus-mediated infection is a serious public health concern in economically developing nations of the world. Globally, four major genotypes of HEV have been documented. Hepatitis E has been suggested to be zoonotic owing to the increase of evidence through various studies. Thus far, this paper reports on prevalence of hepatitis E virus among swine herd in selected communal and commercial farms in the Eastern Cape Province of South Africa. A total of 160 faecal samples were collected from swine herds in Amathole and Chris Hani District Municipalities of Eastern Cape Province for the presence of HEV. Of the 160 faecal samples screened, only seven were positive (4.4%) for HEV. The nucleotide sequences analyses revealed the isolates as sharing 82% to 99% identities with other strains (KX896664, KX896665, KX896666, KX896667, KX896668, KX896669, and KX896670) from different regions of the world. We conclude that HEV is present among swine in the Eastern Cape Province, albeit in low incidence, and this does have public health implications. There is a need for maintenance of high hygienic standards in order to prevent human infections through swine faecal materials and appropriate cooking of pork is highly advised.

Hepatitis E Virus in Industrialized Countries: The Silent Threat

Hepatitis E virus (HEV) is the main cause of acute viral hepatitis worldwide. Its presence in developing countries has been documented for decades. Developed countries were supposed to be virus-free and initially only imported cases were detected in those areas. However, sporadic and autochthonous cases of HEV infection have been identified and studies reveal that the virus is worldwide spread. Chronic hepatitis and multiple extrahepatic manifestations have also been associated with HEV. We review the data from European countries, where human, animal, and environmental data have been collected since the 90s. In Europe, autochthonous HEV strains were first detected in the late 90s and early 2000s. Since then, serological data have shown that the virus infects quite frequently the European population and that some species, such as pigs, wild boars, and deer, are reservoirs. HEV strains can be isolated from environmental samples and reach the food chain, as shown by the detection of the virus in mussels and in contaminated pork products as sausages or meat. All these data highlight the need of studies directed to control the sources of HEV to protect immunocompromised individuals that seem the weakest link of the HEV epidemiology in industrialized regions.

Viral Hepatitis in Children: A Through E

Hepatitis is defined as inflammation of the liver. This inflammation can be acute and self-limited, chronic (leading to cirrhosis and an increased risk for hepatocellular carcinoma), or fulminant (requiring lifesaving liver transplantation). Although there are many causes of hepatitis, this article focuses on the main childhood viral hepatidities: types A, B, C, D, and E. This review discusses the main characteristics of each virus, including salient epidemiology, clinical characteristics, diagnosis, treatment, and prevention strategies. [Pediatr Ann. 2016;45(12):e420-e426.].

Molecular Biology and Infection of Hepatitis E Virus

Hepatitis E virus (HEV) is a viral pathogen transmitted primarily via fecal-oral route. In humans, HEV mainly causes acute hepatitis and is responsible for large outbreaks of hepatitis across the world. The case fatality rate of HEV-induced hepatitis ranges from 0.5 to 3% in young adults and up to 30% in infected pregnant women. HEV strains infecting humans are classified into four genotypes. HEV strains from genotypes 3 and 4 are zoonotic, whereas those from genotypes 1 and 2 have no known animal reservoirs. Recently, notable progress has been accomplished for better understanding of HEV biology and infection, such as chronic HEV infection, in vitro cell culture system, quasi-enveloped HEV virions, functions of the HEV proteins, mechanism of HEV antagonizing host innate immunity, HEV pathogenesis and vaccine development. However, further investigation on the cross-species HEV infection, host tropism, vaccine efficacy, and HEV-specific antiviral strategy is still needed. This review mainly focuses on molecular biology and infection of HEV and offers perspective new insight of this enigmatic virus.

Hepatitis E in Children: A Position Paper by the ESPGHAN Hepatology Committee

BACKGROUND

Hepatitis E virus (HEV) is endemic in large parts of the developing world. Waterborne transmission of genotypes 1 or 2 commonly causes acute hepatitis, which is usually self-limited in healthy individuals. In addition, acute HEV infections also occur outside endemic areas, mostly related to foodborne transmission of HEV genotype 3. A growing number of publications in the last decade have reported chronic infection progressing to cirrhosis in immunosuppressed patients. It has also been suggested that HEV transmission may occur via contaminated blood products. This publication aims to provide recommendations for diagnosis, prevention, and treatment of HEV infection, particularly in children after solid organ transplantation.

METHODS

A systematic PubMed literature search on HEV infection from 1990 to January 2016 was performed focusing on pediatric studies. The existing body of evidence was reviewed and recommendations were agreed upon following discussion and unanimous agreement by all members of the ESPGHAN Hepatology Committee during a consensus meeting in January 2016. In the absence of randomized controlled studies these recommendations were considered to be expert opinions.

KEY RECOMMENDATIONS

Immunocompetent children with increased transaminases and/or extrahepatic manifestations should be considered for testing for evidence of HEV infection. Immunocompromised children with increased aminotransferases should be repeatedly tested for HEV and may require therapeutic intervention.

Update on hepatitis E virology: Implications for clinical practice

Hepatitis E virus (HEV) is a positive-strand RNA virus transmitted by the fecal-oral route. The 7.2kb genome encodes three open reading frames (ORF) which are translated into (i) the ORF1 polyprotein, representing the viral replicase, (ii) the ORF2 protein, corresponding to the viral capsid, and (iii) the ORF3 protein, a small protein involved in particle secretion. Although HEV is a non-enveloped virus in bile and feces, it circulates in the bloodstream wrapped in cellular membranes. HEV genotypes 1 and 2 infect only humans and cause mainly waterborne outbreaks. HEV genotypes 3 and 4 are widely represented in the animal kingdom and are transmitted as a zoonosis mainly via contaminated meat. HEV infection is usually self-limited but may persist and cause chronic hepatitis in immunocompromised patients. Reduction of immunosuppressive treatment or antiviral therapy with ribavirin have proven effective in most patients with chronic hepatitis E but therapy failures have been reported. Alternative treatment options are needed, therefore. Infection with HEV may also cause a number of extrahepatic manifestations, especially neurologic complications. Progress in the understanding of the biology of HEV should contribute to improved control and treatment of HEV infection.

Hepatitis E virus seroprevalence in pregnant women in Jiangsu, China, and postpartum evolution during six years

Background

China is an endemic area for hepatitis E virus (HEV). The previous surveys of anti-HEV seroprevalence are cross-sectional. This study aimed to investigate the prevalence of infection among pregnant women and their children in Jiangsu, China, and to observe postpartum anti-HEV evolution.

Methods

Sera from 497 women collected during pregnancy and 6-year postpartum and from their 497 children were screened for anti-HEV by ELISA and confirmed by Western blotting. HEV RNA was detected by reverse transcription-nested PCR.

Results

Of the pregnant women, 3 (0.6 %) were anti-HEV IgM positive and 55 (11.1 %) were IgG positive. At 6-year postpartum, 18 anti-HEV IgG positive samples became negative and 18 others became IgG positive; the accumulated prevalence in this cohort of women was at least 14.7 % (73/497). Of the 497 children, the positive rates of anti-HEV IgM and IgG were 0.2 % and 0.4 %, respectively. None of the 18 children from mothers with anti-HEV IgG seroconversion was anti-HEV IgG positive.

Conclusions

Our data indicate that the constant seroprevalence of anti-HEV IgG in adults may be resulted from the balance of negative seroconversion due to waning immunity and positive seroconversion due to novel infections, and the risk of intra-family transmission of HEV was low. The data also imply that cross-sectional seroepidemiological survey may underestimate the prevalence of HEV infection, due to the natural decay of pathogen-specific IgG.

Is hepatitis E virus an emerging problem in industrialized countries?

Hepatitis E virus (HEV) is yearly responsible for approximately 20 million infections worldwide. Although most infections occur in developing countries, HEV appears to be an emerging problem in several industrialized countries, where it is mostly associated with either traveling to an HEV endemic area or contact with pigs, which represent a major reservoir of HEV. The major risk groups for HEV infection and its ensuing complications are elderly men, pregnant women, young children, immunocompromised patients, patients with preexisting liver disease, and workers that come into close contact with HEV-infected animals. Whereas HEV mainly causes acute self-limiting infections, chronic infections may occur among immunocompromised patients (e.g., transplant recipients and human immunodeficiency virus [HIV]-infected patients). Accordingly, HEV-HIV coinfection leads to accelerated liver cirrhosis and increased mortality rates compared to HEV infection alone, which is, except during pregnancy, usually associated with only low mortality. In the Western world, the most common genotype (gt) causing HEV infection is gt 3. Ribavirin (RBV) and interferon have been used successfully for treatment of HEV, but this treatment is contraindicated in certain patient groups. Therefore, novel antiviral compounds are highly needed, especially given that viral isolates with RBV resistance have been recently identified. Moreover, eradication of HEV is hampered by long-term environmental persistence of the virus, which represents a continuous source of the virus. In 2011, the first prophylactic HEV vaccine, Hecolin, was approved in China, but it is not yet globally available. In this review, we will discuss the molecular virology of HEV, mode of transmission in industrialized countries, and potential implications for different specific patient populations.

Experimental infection of pregnant rabbits with hepatitis E virus demonstrating high mortality and vertical transmission

A high mortality rate of approximately 20% in pregnant women with hepatitis E has been reported in previous studies. However, other studies showed no difference between pregnant and nonpregnant women in the severity of hepatitis E. To determine the effects of HEV infection on pregnancy, we successfully established HEV infection in six pregnant rabbits (PR) and six nonpregnant rabbits (NPR) with a rabbit HEV isolate, taking three PR and one NPR without HEV infection as controls. Tests for HEV RNA by RT-PCR, anti-HEV antibodies by ELISA and HEV antigen via immunohistochemistry and histopathology were carried out. Two of six infected PR miscarried and three of the remaining four PR died which may be attributed to severe liver necrosis caused by HEV infection. Moreover, vertical transmission was found to be associated with the replication of HEV in placenta, indicated by the presence of HEV RNA and antigen in placenta from the infected PR. Our findings strongly suggest that HEV infection could lead to adverse outcomes in pregnancy and vertical transmission, suggesting the necessity for pregnant women at risk of HEV infection to be vaccinated.