Evaluation of assays for antibody to hepatitis E virus by a serum panel. Hepatitis E Virus Antibody Serum Panel Evaluation Group

Epidemiological assessment of hepatitis E virus infection among 1565 pregnant women in Siem Reap, Cambodia using an in-house double antigen sandwich ELISA

AIM

This study investigated hepatitis E virus (HEV) prevalence among pregnant women in Siem Reap, Cambodia, by developing a cost-effective, user-friendly in-house enzyme-linked immunosorbent assay (ELISA) for detecting total anti-HEV immunoglobulins (Ig).

METHODS

The in-house ELISA was designed for large-scale screening in resource-limited settings. Its performance was benchmarked against two commercial tests: the Anti-HEV IgG EIA (Institute of Immunology, Co. Ltd) and the Anti-HEV IgG RecomLine LIA (Mikrogen). The in-house ELISA demonstrated a sensitivity of 76% and 71.4%, and a specificity of 94.1% and 98.6%, against the two commercial tests, respectively, with overall agreement rates of 92.4% and 94.3%.

RESULTS

Among 1565 tested pregnant women, 11.6% were anti-HEV positive. Prevalence increased with age, particularly in women aged 35-40 years and over 40 years. No significant associations were found with education, number of children, family size, or history of blood transfusion and surgery, except for the occupation of the family head as a public officer. Of the total anti-HEV positive women, 22.7% had anti-HEV IgM, indicating recent or ongoing infection.

CONCLUSION

The study concluded that the in-house ELISA is a viable option for HEV screening in regions with limited resources due to its high accuracy and cost-effectiveness. It is particularly suitable for large-scale studies and public health interventions in areas where HEV is endemic and poses a significant risk to pregnant women.

Laboratory Diagnosis of HEV Infection

Serological and nucleic acid tests for detecting hepatitis E virus (HEV) have been developed for both epidemiologic and diagnostic purposes. The laboratory diagnosis of HEV infection depends on the detection of HEV antigen or HEV RNA in the blood, stool, and other body fluids, and serum antibodies against HEV (immunoglobulin [Ig]A, IgM, and IgG). Anti-HEV IgM antibodies and low avidity IgG can be detected during the acute phase of the illness and can last approximately 12 months, representing primary infection, whereas anti-HEV IgG antibodies can last more than several years, representing remote exposure. Thus, the diagnosis of acute infection is based on the presence of anti-HEV IgM, low avidity IgG, HEV antigen, and HEV RNA, while epidemiological investigations are mainly based on anti-HEV IgG. Although significant progress has been made in developing and optimizing different formats of HEV assays, improving their sensitivity and specificity, there are many shortcomings and challenges in inter-assay concordance, validation, and standardization. This article reviews the current knowledge on the diagnosis of HEV infection, including the most common available laboratory diagnostic techniques.

Immunobiology and Host Response to HEV

Hepatitis E virus (HEV) usually causes acute self-limiting hepatitis but sometimes leads to chronic infection in immunocompromised persons. HEV is not directly cytopathic. Immunologically mediated events after HEV infection are believed to play important roles in the pathogenesis and clearance of infection. The anti-HEV antibody responses have been largely clarified since the determination of major antigenic determinant of HEV, which is located in the C-terminal portion of ORF2. This major antigenic determinant also forms the conformational neutralization epitopes. Robust anti-HEV immunoglobulin M (IgM) and IgG responses usually develop 3-4 weeks after infection in experimentally infected nonhuman primates. In humans, potent specific IgM and IgG responses occur in the very early phase of the disease and are critical in eliminating the virus, in concert with the innate and adaptive T-cell immune responses. Testing anti-HEV IgM is valuable in the diagnosis of acute hepatitis E. The long-term persistence and protection of anti-HEV IgG provide the basis for estimating the prevalence of HEV infection and for the development of a hepatitis E vaccine. Although human HEV has four genotypes, all the viral strains are considered to belong to a single serotype. It is becoming increasingly clear that the innate and adaptive T-cell immune responses play critical roles in the clearance of the virus. Potent and multispecific CD4+ and CD8+ T cell responses to the ORF2 protein occur in patients with acute hepatitis E, and weaker HEV-specific CD4+ and CD8+ T cell responses appear to be associated with chronic hepatitis E in immunocompromised individuals.

Application of a truncated ORF2 protein-based ELISA for diagnosis of hepatitis E in an endemic area

Enterically transmitted waterborne hepatitis E (HE) caused due to hepatitis E virus (HEV) prevails as a significant public health problem endemic to India. Due to short-term viremia/fecal excretion and poor in vitro transmissibility of HEV, HE diagnosis depends on detection of specific IgM antibodies in serum. Present study evaluated performances of two in-house and six commercial IgM detection enzyme-linked immunosorbent assays (ELISAs) using sera collected from volunteers/acute hepatitis patients (n = 716). The in-house ELISAs were based on complete and truncated open reading frame 2 (ORF2) proteins containing neutralizing epitope/s region of genotype 1 HEV (ORF2p, 1-660 amino acid (a.a.) and T1NEp, 458-607 a.a., respectively). The commercial ELISAs included Wantai (China), MP Diagnostics (MPD) (Singapore), DIA.PRO Diagnostics (Italy), MBS (Italy), abia (Germany), and ImmunoVision (USA). T1NE ELISA showed 97.0% positive percent agreement (PPA), 99.4% negative percent agreement (NPA), and 98.6% concordance (κ = 0.97, P = 0.0000) with ORF2 ELISA. ORF2, T1NE, Wantai, and MPD ELISAs agreed on results for 88% of sera tested. Two percent sera showed reactivity in each combination of three and two of aforementioned four ELISAs. Remaining 8% sera were single ELISA reactive. PPA and NPA value ranges were 76.3-99.0% and 84.8-99.5%, respectively. Pairwise concordances between all the eight ELISAs ranged from 88.0 to 100% (κ: 0.74-1.00). Both the in-house ELISAs agreed better with Wantai over MPD ELISA. In conclusion, both ORF2 and T1NE ELISAs were equally efficient in diagnosing HEV infections. T1NEp proved to be an excellent tool in HE sero-diagnosis and is worth exploring in development of simple rapid tests. KEY POINTS: • In-house ELISA based on bacterially expressed neutralizing epitope/s region protein • In-house ELISA based on complete ORF2 protein expressed in insect cells • Comparison of two in-house and six commercial anti-HEV IgM antibody detection ELISAs.

Detection of RNA viruses from influenza and HIV to Ebola and SARS-CoV-2: a review

RNA-based viruses likely make up the highest pandemic threat among all known pathogens in about the last 100 years, since the Spanish Flu of 1918 with 50 M deaths up to COVID-19. Nowadays, an efficient and affordable testing strategy for such viruses have become the paramount target for the fields of virology and bioanalytical chemistry. The detection of the viruses (influenza, hepatitis, HIV, Zika, SARS, Ebola, SARS-CoV-2, etc.) and human antibodies to these viruses is described and tabulated in terms of the reported methods of detection, time to results, accuracy and specificity, if they are reported. The review is focused, but not limited to publications in the last decade. Finally, the limits of detection for each representative publication are tabulated by detection methods and discussed. These methods include PCR, lateral flow immunoassays, LAMP-based methods, ELISA, electrochemical methods (e.g., amperometry, voltammetry), fluorescence spectroscopy, AFM, SPR and SERS spectroscopy, silver staining and CRISPR-Cas based methods, bio-barcode detection, and resonance light scattering. The review is likely to be interesting for various scientists, and particularly helpful with information for establishing interdisciplinary research.

Current Paradigm of Hepatitis E Virus Among Pediatric and Adult Patients

Hepatitis E virus (HEV) infection is a polymorphic condition, present throughout the world and involving children and adults. Multiple studies over the last decade have contributed to a better understanding of the natural evolution of this infection in various population groups, several reservoirs and transmission routes being identified. To date, acute or chronic HEV-induced hepatitis has in some cases remained underdiagnosed due to the lower accuracy of serological tests and due to the evolutionary possibility with extrahepatic manifestations. Implementation of diagnostic tests based on nucleic acid analysis has increased the detection rate of this disease. The epidemiological and clinical features of HEV hepatitis differ depending on the geographical areas studied. HEV infection is usually a self-limiting condition in immunocompetent patients, but in certain categories of vulnerable patients it can induce a sudden evolution toward acute liver failure (pregnant women) or chronicity (immunosuppressed patients, post-transplant, hematological, or malignant diseases). In acute HEV infections in most cases supportive treatment is sufficient. In patients who develop chronic hepatitis with HEV, dose reduction of immunosuppressive medication should be the first therapeutic step, especially in patients with transplant. In case of unfavorable response, the initiation of antiviral therapy is recommended. In this review, the authors summarized the essential published data related to the epidemiological, clinical, paraclinical, and therapeutic aspects of HEV infection in adult and pediatric patients.

Role of Hepatitis E Virus Infection in North American Patients With Severe Acute Liver Injury

INTRODUCTION

The aim of this study was to determine the role of hepatitis E virus (HEV) infection in a large cohort of prospectively enrolled patients with severe acute liver injury (ALI).

METHODS

Serum samples from 594 consecutive adults enrolled between 2008 and 2018 in the US Acute Liver Failure Study Group ALI registry were tested for anti-HEV IgM and anti-HEV IgG levels. Those with detectable anti-HEV IgM underwent further testing for HEV RNA using real-time polymerase chain reaction.

RESULTS

The median age of patients was 38 years; 41% were men and 72% Caucasian. Etiologies of ALI included acetaminophen hepatotoxicity (50%), autoimmune hepatitis (8.9%), hepatitis B virus (8.9%), and idiosyncratic drug-induced liver injury (7.9%). Overall, 62 patients (10.4%) were negative for anti-HEV IgM but positive for IgG, whereas only 3 men (0.5%) were positive for both anti-HEV IgM and IgG. These 3 cases were initially diagnosed as having indeterminate, HEV, and hepatitis B virus-related ALI. One of these patients had detectable HEV RNA genotype 3, and another anti-HEV IgM+ patient had detectable HEV antigens by immunohistochemistry on liver biopsy. On multivariate modeling, older (odds ratio: 1.99) and non-Caucasian subjects (odds ratio: 2.92) were significantly more likely to have detectable anti-HEV IgG (P < 0.0001).

DISCUSSION

Acute HEV infection is an infrequent cause of ALI in hospitalized North American adults. The anti-HEV IgG+ patients were significantly older and more likely to be non-Caucasian. These data are consistent with other population-based studies that indicate exposure to HEV in the general US population is declining over time and might reflect a cohort effect.

DEVELOPMENT OF HEPATITIS E 3 GENOTYPE RECOMBINANT PROTEIN CAPSID OF: CLONING, EXPRESSION, PURIFICATION, EVALUATION OF THE ANTIGENIC PROPERTIES

Aim. The development of the hepatitis E virus (HEV) genotype 3 recombinant capsid protein.Materials and methods. E.coli strains, plasmid vectors, serological and clinical samples, ELISA reagent kits, molecular biological, bioinformatic, biotechnological, biochemical and serological methods.Results. Using viruscontaining material from pigs of Belgorod region (Russian Federation) we made E.coli strains producing recombinant capsid protein, containing C-terminal of viral ORF2 protein fragment fused to E.coli β-galactosidase. Recombinant protein ORF2 had been isolated from the bacterial inclusion bodies and purified by size exclusion chromatography. Antigenic specificity of the recombinant polypeptide was confirmed by ELISA and Western blotting with sera of hepatitis E patients and reference groups (healthy donors, patients with hepatitis A, B, C, infectious mononucleosis, cytomegalovirus infection and HIV-infected patients). Conclusion. HEV genotype 3 ORF2 recombinant antigen had been developed, and the possibility to use it in diagnostic tests had been experimentally shown.

Infectious hepatitis: A 3-year retrospective study at a tertiary care hospital in India

Context

Acute viral hepatitis (AVH) is predominantly caused by hepatitis A virus (HAV) and hepatitis E virus (HEV), the prevalence of which varies in different geographical regions.

Aims

This study aimed to determine the prevalence of HAV and HEV infections in patients with AVH, the rate of HAV-HEV co-infection and the prevalence of HEV infection among pregnant women with hepatitis.

Settings and Design

It was a retrospective observational study conducted over 3 years from January 2015 to December 2017, after obtaining clearance from the institutional ethics committee.

Subjects and Methods

A total of 675 serum samples were collected from patients with a clinical diagnosis of AVH, between January 2015 and December 2017. The study population included outdoor and hospitalised patients between 3 and 70 years of age who presented with signs and symptoms of hepatitis. The presence of IgM anti-HAV and IgM anti-HEV antibodies in serum were assessed by enzyme-linked immunosorbent assay.

Statistical Analysis Used

Chi-square test.

Results

The prevalence of HAV, HEV and HAV-HEV co-infection was found to be 6.96%, 9.63% and 2.07%, respectively. Among males, this was 7.3%, 8.8% and 2.6%, respectively and in females 6.7%, 10.2% and 1.7%, respectively. However, these differences in the prevalence rates were of no statistical significance. The prevalence of HEV infection in pregnant women with hepatitis was 9.4%. HAV and HEV infections showed a seasonal trend with predominance during summer and rainy seasons (May to September).

Conclusions

A higher seroprevalence of HEV as compared to HAV together with a co-infection rate of 2.07% mandates screening for HEV in all suspected cases of acute hepatitis, particularly pregnant women in whom the outcomes of HEV infection are poor. Health and civic authorities should make necessary efforts to counter epidemic or outbreak situations, thus reducing morbidity, mortality and economic burden.

Epidemiology and Transmission of Hepatitis A Virus and Hepatitis E Virus Infections in the United States

There are many similarities in the epidemiology and transmission of hepatitis A virus (HAV) and hepatitis E virus (HEV) genotype (gt)3 infections in the United States. Both viruses are enterically transmitted, although specific routes of transmission are more clearly established for HAV than for HEV: HAV is restricted to humans and primarily spread through the fecal-oral route, while HEV is zoonotic with poorly understood modes of transmission in the United States. New cases of HAV infection have decreased dramatically in the United States since infant vaccination was recommended in 1996. In recent years, however, outbreaks have occurred among an increasingly susceptible adult population. Although HEV is the most common cause of acute viral hepatitis in developing countries, it is rarely diagnosed in the United States.

Long-term Antibody Persistence After Hepatitis E Virus Infection and Vaccination in Dongtai, China

Background

Hepatitis E virus (HEV) is of global significance. HEV is a common cause of acute hepatitis in China. One of the major unanswered questions about HEV is the persistence of antibodies after infection and vaccination.

Methods

We examined antibody persistence 6.5 years after HEV exposures through natural infection and vaccination. Ninety-seven vaccine recipients and 70 individuals asymptomatically infected with HEV enrolled in the phase III HEV239 vaccine trial in Dongtai, China, were revisited.

Results

Antibody loss was 23.4% (95% confidence interval [CI], 17.1%-30.5%), with a nonsignificantly higher percentage of loss among those naturally infected (30.0%; 95% CI, 19.6%-42.1%) than those vaccinated (18.6%; 95% CI, 11.4%-27.7%; P = .085). Age and gender were not associated with antibody persistence. Only 2 people (1.2%) self-reported medically diagnosed jaundice or hepatitis-like illness in the last 10 years, both of whom had persistent antibodies. Contact with a jaundice patient and injectable contraceptive use were marginally associated with loss of detectable anti-HEV antibodies (P = .047 and .082, respectively), whereas transfusion was marginally associated with antibody persistence (P = .075).

Conclusions

Antibody loss was more common among those naturally infected compared with those vaccinated. However, none of the characteristics examined were strongly associated with antibody loss, suggesting that factors not yet identified may play a more important role in antibody loss. Long-term postvaccination antibody persistence is currently unknown and will be an important consideration in the development of policies for the use of the highly efficacious HEV vaccine. ClinicalTrials.gov registration.  NCT01014845.

Hepatitis E seroprevalence in the United States: Results for immunoglobulins IGG and IGM

BACKGROUND

Previous research identified a decline in hepatitis E virus (HEV) seroprevalence in US in 1988-1994 and 2009-2010. We investigated most recent HEV epidemiology.

METHOD

Using a nationally representative sample (7656 persons in the National Health and Nutrition Examination Survey [NHANES] 2013-2014 and 7124 persons in NHANES 2015-2016), we compared the weighted seroprevalence of HEV (immunoglobulin G [IgG]/immunoglobulin M [IgM]) among people from the US (aged ≧ 6 years) between these two time periods. Sampling-weighted multivariate logistic regression models were used to identify factors associated with HEV seropositivity.

RESULTS

The median participant age was 37 years (interquartile range = 17-58 years); 51.17% of them were female. Among US-born individuals, HEV seropositivity (IgG/IgM) increased from 4.5% (95% confidence interval [CI] = 3.5%-5.5%) in 2013-2014 to 8.1% (95%CI = 6.5%-9.7%) in 2015-2016. Recent HEV infection (IgM) has nearly doubled in all US-born people. For participants born in and outside of the US, the overall weighted HEV (IgG/IgM) seropositivity increased from 5% (95%CI = 3.9%-6.1%) during 2013-2014 to 7.7% (95%CI = 7.2%-10.5%) during 2015-2016. In "non-Hispanic Asian" females, HEV seropositivity (IgG/IgM) rose from 8.4% (95%CI = 5.6%-11.1%) during 2013-2014 to 20.7% (95%CI = 15.8%-25.7%) during 2015-2016. In "non-Hispanic Asian" males, HEV seropositivity (IgG/IgM) increased from 9.3% (95%CI = 6.9%-11.8%) during 2013-2014 to 16.8% (95%CI = 12.5%-21.2%) during 2015-2016. HEV (IgG/IgM) seropositivity was significantly associated with "non-Hispanic Asian" ethnicity (odds ratio [OR] = 1.69; CI = 1.12-2.56), female (OR = 1.2, CI = 1.06-1.38), and age (OR = 1.058, CI = 1.05-1.06). No clear etiologic agent was found.

CONCLUSION

The combined and strata-specific HEV weighted seroprevalence increased from 2013-2014 to 2015-2016. Although prior studies had found increasing age as the only significant factor associated with HEV, the attribute of "non-Hispanic Asian" had a stronger association with HEV seropositivity than the age factor alone.

A Ten Year Immunopersistence Study of Hepatitis E Antibodies in Rural Bangladesh

Hepatitis E virus (HEV) is a major cause of acute, viral hepatitis in Southeast Asia. Several studies have suggested that antibody persistence after HEV infection may be transient, possibly increasing the risk of re-infection and contributing to the frequency of outbreaks in HEV endemic regions. The specific conditions under which antibodies to HEV are lost, or "sero-reversion" occurs, are poorly understood. Here, one hundred participants from population-based studies in rural Bangladesh were revisited in 2015, ten years after a documented HEV infection to examine long-term antibody persistence. Twenty percent (95% confidence interval: 12.0, 28.0) no longer had detectable antibodies at follow-up, suggesting that antibodies generally persist for at least a decade after infection in rural Bangladesh. Those who were seronegative at follow-up were generally younger at infection than those who remained positive (14.4 years versus 33.6 years, P > 0.0001). This age-dependent antibody loss could partially explain cross-sectional sero-prevalence data from South East Asia where children have reportedly low antibody prevalence. The results of this study provide new insight into the immunological persistence of HEV infection in a micronutrient deficient rural population of South Asia, highlighting the importance of age at infection in the ability to produce long-lasting antibodies against HEV.

Laboratory challenges in the diagnosis of hepatitis E virus

Hepatitis E virus (HEV) is an RNA virus that is an important cause of both acute and chronic hepatitis worldwide. To date, there are eight HEV genotypes that can infect mammals. HEV-1 and HEV-2 infect exclusively humans, while HEV-3 and HEV-4 infect humans and various animals, mainly pigs and deer. Additionally, two new genotypes (HEV-5 and HEV-6) infect mainly wild boar. Recently, newly discovered genotypes HEV-7 and HEV-8 were found to infect camels and possibly humans. Nevertheless, the epidemiological distribution of HEV-7 is not well established. HEV-8 is another newly discovered genotype that was identified in 2016 in Chinese Bactrian camels. Although faecal-oral transmission is the most common route of HEV transmission, HEV can be vertically transmitted from infected mothers to their fetuses. HEV may also spread by zoonotic transmission from infected animals to humans and through person-to-person contact. Nowadays, since the number of reported cases linked to blood donations is increasing annually, HEV is recognized as a transfusion-transmitted virus. Laboratory diagnostic techniques vary in their specificity and sensitivity for HEV detection. Direct techniques allow for detection of the viral proteins, antigens and viral nucleic acid, while HEV-specific IgG and IgM antibodies can help establish a diagnosis in acute and chronic infections. In this review, we will discuss recent technologies in the laboratory diagnosis of HEV, including serological and molecular methods to assess the specificity and sensitivity of currently available HEV commercial assays.

Immunobiology and Host Response to HEV

Hepatitis E virus (HEV) causes acute self-limiting hepatitis in most cases and chronic infection in rare circumstances. It is believed to be noncytopathic, so immunologically mediated events should play important roles in its pathogenesis and infection outcomes. The anti-HEV antibody response was clarified when the major antigenic determinants on the ORF2 polypeptide were determined, which are located in its C-terminal portion. This subregion also forms the conformational neutralization epitopes. Robust anti-HEV immunoglobulin M (IgM) and IgG responses usually develop 3-4 weeks after infection in experimentally infected nonhuman primates. In humans, potent specific IgM and IgG responses occur in the very early phase of the disease and are critical in eliminating the virus, in concert with the innate and adaptive T-cell immune responses. They are also very valuable in the diagnosis of acute hepatitis E, when patients are tested for both anti-HEV IgM and IgG. The long-term persistence and protection of anti-HEV IgG provide the basis for estimating the prevalence of HEV infection and for the development of a hepatitis E vaccine. Although HEV has four genotypes, all the viral strains are considered to belong to a single serotype. It is becoming increasingly clear that the innate and adaptive T-cell immune responses play critical roles in the clearance of the virus. Potent and multispecific CD4⁺ and CD8⁺ T-cell responses to the ORF2 protein occur in patients with acute hepatitis E, and weaker HEV-specific CD4⁺ and CD8⁺ T-cell responses appear to be associated with chronic hepatitis E in immunocompromised individuals.

Laboratory Diagnosis of HEV Infection

Serological and nucleic acid tests for detecting hepatitis E virus (HEV) have been developed for both epidemiologic and diagnostic purposes. The laboratory diagnosis of HEV infection depends on the detection of HEV antigen, HEV RNA, and serum antibodies against HEV (immunoglobulin [Ig]A, IgM, and IgG). Anti-HEV IgM antibodies can be detected during the acute phase of the illness and can last approximately 4 or 5 months, representing recent exposure, whereas anti-HEV IgG antibodies can last more than 10 years, representing remote exposure. Thus, the diagnosis of acute infection is based on the presence of anti-HEV IgM, HEV antigen, and HEV RNA, while epidemiological investigations are mainly based on anti-HEV IgG. Although significant progress has been made in developing and optimizing different formats of HEV assays, improving their sensitivity and specificity, there are many shortcomings and challenges in inter-assay concordance, validation, and standardization. This article reviews the current knowledge on the diagnosis of HEV infection, including the most common available laboratory diagnostic techniques.

The serological markers of acute infection with hepatitis A, B, C, D, E and G viruses revisited

Viral hepatitis is a liver infection caused by one of the six hepatitis viruses: hepatitis A, B, C, D, E, and G virus (HAV to HEV and HGV). These agents differ in their biological, immunological, pathological and epidemiological characteristics. They cause infections that, when symptomatic, lead to clinical manifestations and laboratory findings that are not specific to a particular virus, often making differential diagnosis difficult, especially when no knowledge is available regarding the patient's medical history or the epidemiological background. A number of acute-phase serological markers, such as anti-HAV, anti-HBc, anti-HDV and anti-HEV IgM antibodies, are able to provide a clear indication of an infection caused by HAV, HBV, HDV or HEV. Anti-HCV antibodies and HGV/RNA are used for the diagnosis of HCV and HGV infections. The importance of each of these markers will be reviewed, and different factors that can interfere with the diagnosis of acute infections caused by these viruses will be described.

The role of hepatitis E virus infection in adult Americans with acute liver failure

Acute hepatitis E virus (HEV) infection is a leading cause of acute liver failure (ALF) in many developing countries, yet rarely identified in Western countries. Given that antibody testing for HEV infection is not routinely obtained, we hypothesized that HEV-related ALF might be present and unrecognized in North American ALF patients. Serum samples of 681 adults enrolled in the U.S. Acute Liver Failure Study Group were tested for anti-HEV immunoglobulin (Ig) M and anti-HEV IgG levels. Subjects with a detectable anti-HEV IgM also underwent testing for HEV RNA. Mean patient age was 41.8 years, 32.9% were male, and ALF etiologies included acetaminophen (APAP) hepatotoxicity (29%), indeterminate ALF (23%), idiosyncratic drug-induced liver injury DILI (22%), acute hepatitis B virus infection (12%), autoimmune hepatitis (12%), and pregnancy-related ALF (2%). Three men ages 36, 39, and 70 demonstrated repeatedly detectable anti-HEV IgM, but all were HEV-RNA negative and had other putative diagnoses. The latter 2 subjects died within 3 and 11 days of enrollment whereas the 36-year-old underwent emergency liver transplantation on study day 2. At admission, 294 (43.4%) of the ALF patients were anti-HEV IgG positive with the seroprevalence being highest in those from the Midwest (50%) and lowest in those from the Southeast (28%). Anti-HEV IgG⁺ subjects were significantly older, less likely to have APAP overdose, and had a lower overall 3-week survival compared to anti-HEV IgG^- subjects (63% vs. 70%; P = 0.018).

CONCLUSION

Acute HEV infection is very rare in adult Americans with ALF (i.e., 0.4%) and could not be implicated in any indeterminate, autoimmune, or pregnancy-related ALF cases. Past exposure to HEV with detectable anti-HEV IgG was significantly more common in the ALF patients compared to the general U.S.

POPULATION

(Hepatology 2016;64:1870-1880).

Seroepidemiology of HEV and HAV in two populations with different socio-economic levels and hygienic/sanitary conditions

The epidemiological scenarios of hepatitis E virus (HEV) and hepatitis A virus (HAV) infections have changed in the last few decades, but precise epidemiological data on the prevalence of anti-HEV and anti-HAV, alone or in combination, in the general population are scanty. We investigated HEV and HAV seroprevalence comparing two population samples living in Northern (Abbiategrasso, Milan) and Southern Italy (Cittanova, Reggio Calabria), the latter being characterized by a poorer socio-economic level and hygienic/sanitary conditions. Based on census records, we randomly enrolled and tested 3,365 subjects (Abbiategrasso, n = 2,489; Cittanova, n = 876) aged 18-75 years for anti-HAV and anti-HEV. Anti-HAV (71.3 % vs 52.5 %) and anti-HEV (17.8 % vs 9.0 %) prevalence rates were higher in Southern Italy (both p < 0.001). Most anti-HEV-positive subjects also had anti-HAV. Subjects testing positive for anti-HAV, alone or with anti-HEV, were older (p < 0.001 in both populations) and showed a trend toward declining prevalence in the youngest birth cohorts. The prevalence of subjects with a positive result for anti-HEV alone did not change in birth cohorts in the two towns. Detection of anti-HEV was independently associated with anti-HAV, town, birth cohort, and education level in multivariate analysis. Low socio-economic level and hygienic/sanitary conditions are associated with high HAV and HEV seroprevalence rates in Italy. Recent improvements, especially in the South, have led to a declining prevalence of anti-HAV, alone or with anti-HEV. Seroprevalence of HEV alone is uniformly low and does not change in birth cohorts born between 1938 and 1993.

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.

Incidence and seroprevalence of hepatitis E virus infection in pregnant women infected with hepatitis B virus and antibody placental transfer in infants

BACKGROUND

Hepatitis E has poor outcomes in pregnant women. Superinfection of hepatitis E virus (HEV) in patients infected with hepatitis B virus (HBV) may worsen liver disease.

OBJECTIVES

To estimate the incidence and seroprevalence of HEV infection among HBV-infected pregnant women, to investigate the transplacental transfer of maternal anti-HEV IgG, and to compare the maternal and neonatal outcomes in anti-HEV positive and negative pregnant women.

STUDY DESIGN

Totally 391 HBV-infected pregnant women were recruited from April 2012 to October 2014. Paired mothers and infants were followed up at an average 9.8 months postpartum. Anti-HEV IgG and IgM were tested by ELISA.

RESULTS

Of the pregnant women, none was anti-HEV IgM positive and 42 (10.7%) were IgG positive. At the follow-up, 3 seronegative women converted to anti-HEV IgG positive, with an estimated incidence of 17 per 1000 person-years. No significant differences of gestational age, preterm birth rate, Apgar score and birthweight were observed between newborns of anti-HEV IgG positive and negative mothers. Of the 42 neonates born to anti-HEV IgG positive mothers, 38 (90.5%) had anti-HEV IgG in their cord blood. The neonatal and maternal anti-HEV IgG levels were positively correlated (r=0.827, p<0.05). All infants were negative for both anti-HEV IgM and IgG at the follow-up.

CONCLUSIONS

HBV-infected pregnant women rarely have novel HEV infection during late pregnancy in Jiangsu, China. Maternal anti-HEV IgG efficiently transfers into the fetuses, and disappears in infants before 10 months old.

Differential Immune Responses in Mice Immunized with Recombinant Neutralizing Epitope Protein of Hepatitis E Virus Formulated with Liposome and Alum Adjuvants

In the developing countries, Hepatitis E virus (HEV) is a predominant cause of sporadic acute hepatitis in adults and waterborne epidemics leading to high mortality in pregnant women. Vaccine development mainly focuses on the structural capsid protein open-reading-frame-2 (ORF-2) of the virus. We successfully evaluated liposome-adjuvanted recombinant neutralizing epitope protein (rNEp), a part of ORF-2, 458-607aa, in mice and rhesus macaques. We compared immune response to adjuvants alone, rNEp alone, or adjuvanted with liposome (lipo-rNEp)/alum (al-rNEp) in mice following intramuscular administration of two doses of 5 μg each. IgG anti-HEV titers (enzyme-linked immunosorbent assay), immunophenotyping (flow cytometry, CD3(+)CD4(+), CD3(+)CD8(+), CD11c(+), CD11b(+), CD19(+) cells; costimulatory markers CD80, CD86, MHC-I, MHC-II, and early activation marker CD69), and levels of Th1/Th2 cytokines (IL-2/IFN-γ/IL-4/IL-5 and additionally IL-1β/IL-6/IL-10/TNF for early time points) were determined at early (4/12/24-h postdose-1) and later time points (2 weeks post-both doses). IgG anti-HEV titers were higher in the lipo-rNEp group than al-rNEp post-both doses (p < 0.05). At early time points, cell type proportions were comparable at the site of injection; IL-Iβ levels increased in lipo-rNEp, 24 h, while IL-6 levels rose in lipo-rNEp/al-rNEp/alum-alone groups, 4 h, compared to controls. In the draining lymph nodes (DLNs), CD11c(+)CD86(+) cells increased at 24 h in liposome-alone/lipo-rNEp groups. A rise in the CD11c(+)CD69(+) cells was noted in the lipo-rNEp group compared to other groups (p < 0.05). Cytokine levels in the spleen/sera remained unchanged in all the groups (p > 0.05). At 2 weeks postdose-2, CD11c(+)MHC-II(+)/CD11b(+)MHC-II(+) cells increased in the spleen in the lipo-rNEp and al-rNEp groups, respectively. In the DLNs, CD19(+)MHC-II(+) cells increased in rNEp/al-rNEp/lipo-rNEp groups post-both doses and CD11c(+)CD86(+) cells in the lipo-rNEp group. A balanced Th1/Th2 response was evident in the lipo-rNEp, while a Th2 bias was noted in al-rNEp. Different immune response gene clustering patterns were noted in uncultured spleens from immunized mice and cultured-stimulated splenocytes. In conclusion, lipo-rNEp is a better immunogen, works through dendritic cells, and elicits a balanced Th1/Th2 response, while alum functions through macrophages and induces a Th2 response.

Hepatitis E Virus Does Not Contribute to Hepatic Decompensation Among Patients With Advanced Chronic Hepatitis C

BACKGROUND & AIMS

Hepatitis E (HEV) can cause acute-on-chronic liver failure in persons with pre-existing liver disease. We investigated whether HEV infection contributes to hepatic decompensation in patients with previously stable, advanced chronic hepatitis C.

METHODS

We performed a case-control study using stored serum samples from subjects enrolled in the randomized phase of the Hepatitis C Antiviral Long-Term Treatment Against Cirrhosis Trial (n = 1050; mean age, 51 y; 70% male; 40% with cirrhosis at baseline). Cases were subjects who developed hepatic decompensation within a 24-week period. Controls (3 per case) were subjects without hepatic decompensation matched for fibrosis stage and followed up for a similar period. A serum sample obtained within 6 months after the decompensation event in cases and the same follow-up period in controls were tested for anti-HEV IgG. Subjects with a positive result had a baseline sample similarly tested for anti-HEV IgG. We measured levels of anti-HEV IgM and HEV RNA in blood samples from incident cases.

RESULTS

Of the 1050 subjects analyzed, 314 (30%) experienced a clinical event. Of the 314 subjects who experienced decompensation as defined, 89 (28%) were tested for anti-HEV, along with 267 controls (without decompensation). Similar proportions of cases and controls tested positive for anti-HEV (22.5% and 20.6%, respectively; P = .70). Ten incident HEV infections were identified-4 in cases (4.5%) and 6 in controls (2.2%) (P = .28). HEV RNA was not detected in blood samples from the 10 incident infections. Only 2 of the 4 incident infections among cases were related temporally to the decompensation event.

CONCLUSIONS

HEV does not appear to be a significant cause of hepatic decompensation among persons with previously stable, advanced chronic hepatitis C in the United States.

An outbreak of hepatitis E in an urban area of Bangladesh

We investigated an outbreak of jaundice in urban Bangladesh in 2010 to examine the cause and risk factors and assess the diagnostic utility of commercial assays. We classified municipal residents reporting jaundice during the preceding 4 weeks as probable hepatitis E cases and their neighbours without jaundice in the previous 6 months as probable controls. We tested the sera collected from probable cases and probable controls for IgM anti-hepatitis E virus (HEV), and the IgM-negative sera for IgG anti-HEV using a commercial assay locally. We retested the IgM-positive sera for both IgM and IgG anti-HEV using another assay at the Centre for Disease Control and Prevention (CDC), USA. Probable cases positive for IgM anti-HEV were confirmed cases; probable controls negative for both IgM and IgG anti-HEV were confirmed controls. We explored the local water supply and sanitation infrastructure and tested for bacterial concentration of water samples. Probable cases were more likely than probable controls to drink tap water (adjusted odds ratio: 3.4; 95% CI: 1.2-9.2). Fifty-eight percentage (36/62) of the case sera were IgM anti-HEV positive; and 75% of the IgM-positive samples were confirmed positive on retesting with another assay at CDC. Compared to confirmed controls, cases confirmed using either or both assays also identified drinking tap water as the risk factor. Two tap water samples had detectable thermotolerant coliforms. Research exploring decentralized water treatment technologies for sustainable safe water might prevent HEV transmission in resource-poor cities. Detection of serological markers in a majority of probable cases implied that available diagnostic assays could adequately identify HEV infection during outbreaks.

Arsenic exposure and hepatitis E virus infection during pregnancy

BACKGROUND

Arsenic has immunomodulatory properties and may have the potential to alter susceptibility to infection in humans.

OBJECTIVES

We aimed to assess the relation of arsenic exposure during pregnancy with immune function and hepatitis E virus (HEV) infection, defined as seroconversion during pregnancy and postpartum.

METHODS

We assessed IgG seroconversion to HEV between 1st and 3rd trimester (TM) and 3 months postpartum (PP) among 1100 pregnancies in a multiple micronutrient supplementation trial in rural Bangladesh. Forty women seroconverted to HEV and were matched with 40 non-seroconverting women (controls) by age, parity and intervention. We assessed urinary inorganic arsenic plus methylated species (∑As) (µg/L) at 1st and 3rd TM and plasma cytokines (pg/mL) at 1st and 3rd TM and 3 months PP.

RESULTS

HEV seroconverters' urinary ∑As was elevated throughout pregnancy. Non-seroconverters' urinary ∑As was similar to HEV seroconverters at 1st TM but declined at 3rd TM. The adjusted odds ratio (95% confidence interval) of HEV seroconversion was 2.17 (1.07, 4.39) per interquartile range (IQR) increase in average-pregnancy urinary ∑As. Increased urinary ∑As was associated with increased concentrations of IL-2 during the 1st and 3rd TM and 3 months PP among HEV seroconverters but not non-seroconverters.

CONCLUSIONS

The relation of urinary arsenic during pregnancy with incident HEV seroconversion and with IL-2 levels among HEV-seroconverting pregnant women suggests arsenic exposure during pregnancy may enhance susceptibility to HEV infection.

Antigenic composition and immunoreactivity differences between HEV recombinant capsid proteins generated from different genotypes

Appreciable variability has been observed in hepatitis E virus (HEV) serological diagnostics. Four recombinant proteins (p166s) were generated from position 452 to 617 aa of ORF2 of different HEV genotypes and used in an indirect ELISA to detect anti-HEV IgMs and IgGs in serially diluted sera of patients infected with different HEV genotypes (genotype 1, n=15; genotype 3, n=12; genotype 4, n=17). To evaluate the differences at a conformational level, 3D-structure models of p166s were predicted, and different bioinformatics tools were used to analyze the antigenic composition. With both anti-HEV IgMs and IgGs antibodies, there was a considerable variability between the four antigens immunoreactivities. In silico results revealed the region 483-533 aa with the highest antigenic potential and contains six key aa at positions 488, 489, 512, 533, 483 and 530. This immunoreactivity variation could affect diagnosis results and seroprevalence estimations and the identification in silico of a region highly antigenic would guide the development of efficient serological assays and epitope-based vaccines.

Seroprevalence of hepatitis e among hemodialysis patients: a report from hamadan, iran

BACKGROUND

Previous studies have documented a high prevalence of hepatitis E among patients undergoing maintenance hemodialysis. Available studies reporting on the seroprevalence of hepatitis E in hemodialysis patients in Iran, an endemic region for the disease, are sparse.

OBJECTIVES

The present study aimed to determine the prevalence rate of anti-hepatitis E antibody in hemodialysis patients in Hamadan, Iran.

PATIENTS AND METHODS

In this cross-sectional study, all 153 consecutive patients undergoing hemodialysis in two centers were enrolled. Patients' demographic and clinical data were collected, using a standard questionnaire and from medical records. Serum immunoglobulin G concentrations against hepatitis E were determined using the enzyme linked immunosorbent assay method.

RESULTS

Thirty patients (19.2%), were seropositive. Seropositive patients were not significantly different from seronegative patients, with regard to age, sex, level of education, access to filtered water, and duration and frequency of hemodialysis. The proportions of patients with hepatitis B, C, and HIV infection were comparable between the two groups.

CONCLUSIONS

One in five patients undergoing maintenance dialysis in Hamadan is seropositive for hepatitis E immunoglobulin G antibody. Future studies are needed to investigate the factors contributing to the observed high prevalence rate and the possibility of parenteral transmission of hepatitis E.

Declining prevalence of hepatitis E antibodies among Danish blood donors

BACKGROUND

The increasing incidence of reported hepatitis E cases in Europe has focused attention on hepatitis E virus (HEV) and the risk of transfusion-transmitted hepatitis E. The aim of this study was to investigate the prevalence of antibodies to HEV (anti-HEV) among Danish blood donors in 2013 and to compare it to previous studies in Denmark. In addition we wanted to compare the relative reactivity of two different assays.

STUDY DESIGN AND METHODS

Samples from 504 blood donors were collected and analyzed for anti-HEV with an in-house assay developed at the National Institutes of Health (NIH). In addition the samples were analyzed with the Wantai anti-HEV assay. Demographic information and possible HEV exposure was collected by self-administered questionnaire.

RESULTS

Using the NIH assay the prevalence of anti-HEV among Danish blood donors was 10.7% and with the Wantai assay the prevalence of anti-HEV was 19.8% (p < 0.001). In both cases the presence of anti-HEV was significantly correlated with increasing age. In addition, anti-HEV as measured by the Wantai test was significantly associated with contact with children (p = 0.01), but in multivariate analysis only age was associated with anti-HEV in both assays. By the NIH assay, the prevalence had declined from 20.6% in 2003 to 10.7% in 2013.

CONCLUSIONS

Anti-HEV prevalence had decreased by half among Danish blood donors over 10 years, but was still highly prevalent. The difference in reactivity of the two assays demonstrates the importance of using the same assay when comparing the anti-HEV prevalence in populations over time.

Current epidemiology of hepatitis E virus infection in the United States: low seroprevalence in the National Health and Nutrition Evaluation Survey

Analysis of the National Health and Nutrition Evaluation Survey (NHANES) 1988-1994 dataset found a relatively high seroprevalence (21%) of hepatitis E virus (HEV) infection in the U.S. general population. Using data obtained within the NHANES 2009-2010 survey, where a high performance assay for HEV was used, we estimated the weighted seroprevalence of HEV infection among U.S. individuals 6 years and older. We also evaluated factors associated with HEV seropositivity. A total of 8,814 individuals were included in the analysis. The median age of study participants was 37 years (interquartile range [IQR] 17-58 years), with 51.2% being female. The weighted national seroprevalence of HEV was 6% (95% confidence interval [CI] 5.1%-6.9%). About 0.5% of those with HEV had evidence of recent exposure (immunoglobulin M-positive). In the univariate analyses, factors associated with HEV seropositivity were increasing age (P-trend<0.001), birth outside of the U.S., Hispanic race, and "meat" consumption (>10 times/month). No significant association was observed with low socioeconomic status, water source, or level of education. In the multivariate analysis, only older age remained predictive of HEV seropositivity.

CONCLUSION

The weighted national seroprevalence of HEV in the U.S. is much less than previously reported. Using data obtained with a high performance assay, the seroprevalence of HEV was estimated at 6.0% in the U.S. Based on these results, the seroprevalence of HEV is only one-third as high as previously reported.

Decline in hepatitis E virus antibody prevalence in the United States from 1988-1994 to 2009-2010

BACKGROUND

Previous population-based estimates in the United States have shown a relatively high prevalence of hepatitis E virus (HEV) antibody. We sought to determine whether changes in the prevalence of HEV antibody have occurred over time.

METHODS

We analyzed data from the 2009-2010 National Health and Nutrition Examination Survey (NHANES) and NHANES III (1988-1994). Using the same serologic assay, we compared the estimated anti-HEV immunoglobulin G (IgG) prevalence and risk factors for antibody positivity for the 2 periods.

RESULTS

The prevalence of HEV antibody among those aged ≥6 years declined from 10.2% (95% confidence interval [CI], 9.1%-11.4%) during 1988-1994 to 6.0% (5.2%-6.8%) during 2009-2010, and the prevalence for those of US birth ranged from 9.6% (8.4%-10.9%) to 5.2% (4.4%-6.2%). Among US-born persons, the estimated HEV antibody prevalence declined significantly for all subgroups of age, sex, region of residence, and number of persons per room in the household; significant declines also were observed for persons at or above poverty level and for persons of non-Hispanic white, non-Hispanic black, and Mexican American race/ethnicity. No clear associations with food consumption were found.

CONCLUSIONS

The anti-HEV prevalence is declining in the United States. Although the decline suggests a decrease in exposure to HEV over time, the risks associated with exposure remain unknown.

Hepatitis viruses and liver transplantation: evolving trends in antiviral management

Viral hepatitis is both a leading indication for liver transplant (LT) and an important cause of posttransplant graft loss and mortality. Treatment and prevention of hepatitis B virus in LT recipients, with the observed corresponding improvement in post-LT outcomes, is among the great success stories in transplantation. By comparison, treatment of hepatitis C virus with safe and effective regimens is only just becoming a reality. Chronic hepatitis E virus infection in LT recipients represents a newly described phenomenon that can also lead to graft loss; early diagnosis and treatment may be key in the management of these patients.

Hepatitis E virus infection

Hepatitis E virus (HEV) infection is a worldwide disease. An improved understanding of the natural history of HEV infection has been achieved within the last decade. Several reservoirs and transmission modes have been identified. Hepatitis E is an underdiagnosed disease, in part due to the use of serological assays with low sensitivity. However, diagnostic tools, including nucleic acid-based tests, have been improved. The epidemiology and clinical features of hepatitis E differ between developing and developed countries. HEV infection is usually an acute self-limiting disease, but in developed countries it causes chronic infection with rapidly progressive cirrhosis in organ transplant recipients, patients with hematological malignancy requiring chemotherapy, and individuals with HIV. HEV also causes extrahepatic manifestations, including a number of neurological syndromes and renal injury. Acute infection usually requires no treatment, but chronic infection should be treated by reducing immunosuppression in transplant patients and/or the use of antiviral therapy. In this comprehensive review, we summarize the current knowledge about the virus itself, as well as the epidemiology, diagnostics, natural history, and management of HEV infection in developing and developed countries.

Prevalence of hepatitis E virus infection in West Bengal, India: a hospital-based study

India is an endemic zone for hepatitis E virus (HEV), which is associated with both epidemic and sporadic infections. In West Bengal, only two hepatitis E outbreaks have been studied to date. However, sporadic cases of HEV infection also occur during inter-epidemic periods. The aim of this hospital-based study was to detect the prevalence of HEV infection in patients with acute sporadic hepatitis in West Bengal, India. Blood samples and clinical information were collected from 285 patients of both sexes and different ages with acute viral hepatitis (AVH) at Calcutta Medical College, Kolkata, a tertiary-care centre. Samples were tested for hepatitis B virus (HBV) surface antigen, anti-hepatitis C virus antibodies, anti-hepatitis A virus IgM and anti-HEV antibodies (IgM and IgG) by ELISA. Only those patients with AVH who were in their first week of illness and negative for all hepatotropic viral antibodies were tested for HEV RNA by reverse transcriptase nested PCR. HEV was identified as the most common cause of AVH (41.8% of patients), followed by HBV (21.4%), hepatitis A virus (17.2%) and hepatitis C virus (4.6%). Co-infections with more than one virus were found in 22 patients, with HBV-HEV the most common co-infection (3.8%). Only 14.7% of patients had no viral marker. To the best of our knowledge, this is the first documented epidemiological study of acute sporadic hepatitis with HEV in the state of West Bengal, India, indicating that this state is an endemic zone for HEV infection.

Hepatitis E virus among persons who inject drugs, San Diego, California, USA, 2009-2010

Data about prevalence of hepatitis E virus infection in persons who inject drugs are limited. Among 18–40-year-old persons who inject drugs in California, USA, prevalence of antibodies against hepatitis E virus was 2.7%. This prevalence was associated with age but not with homelessness, incarceration, or high-risk sexual behavior.

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

Hepatitis E virus (HEV) infections lead to tens of thousands of deaths annually, mostly in developing countries. Hepatitis E poses a significant threat to the health of expectant mothers, a well-noted epidemiologic feature of the disease, but the contribution of vertically transmitted HEV infection to fetal and neonatal morbidity and mortality has received limited attention. Evidence assembled to date suggests that mother-to-child HEV transmission may be frequent and deleterious to the fetus and newborn in pregnancies affected by hepatitis E. Additional work is required to resolve key questions. (1) What risks do subclinical maternal HEV infections and infections early in pregnancy pose to fetal health and development? (2) Does vertical transmission occur during labor and/or breastfeeding and contribute appreciably to neonatal morbidity and mortality? (3) How do treatment decisions for severely ill mothers affect fetal and neonatal outcomes? (4) Can maternal vaccination effectively prevent vertical transmission of HEV?

Host immune status and response to hepatitis E virus infection

Hepatitis E virus (HEV), identified over 30 years ago, remains a serious threat to life, health, and productivity in developing countries where access to clean water is limited. Recognition that HEV also circulates as a zoonotic and food-borne pathogen in developed countries is more recent. Even without treatment, most cases of HEV-related acute viral hepatitis (with or without jaundice) resolve within 1 to 2 months. However, HEV sometimes leads to acute liver failure, chronic infection, or extrahepatic symptoms. The mechanisms of pathogenesis appear to be substantially immune mediated. This review covers the epidemiology of HEV infection worldwide, the humoral and cellular immune responses to HEV, and the persistence and protection of antibodies produced in response to both natural infection and vaccines. We focus on the contributions of altered immune states (associated with pregnancy, human immunodeficiency virus [HIV], and immunosuppressive agents used in cancer and transplant medicine) to the elevated risks of chronic infection (in immunosuppressed/immunocompromised patients) and acute liver failure and mortality (among pregnant women). We conclude by discussing outstanding questions about the immune response to HEV and interactions with hormones and comorbid conditions. These questions take on heightened importance now that a vaccine is available.

Antiviral strategies for hepatitis E virus

The hepatitis E virus is a common cause of acute hepatitis. Contrary to hepatitis B and C, hepatitis E is mostly a mild infection, although it has a high mortality in pregnant women and can evolve to chronicity in immunocompromised patients. Ribavirin and pegylated interferon-α are the only available therapies, but both have side effects that are not acceptable for prophylaxis or treatment of mild infections. In addition, these drugs cannot be used for all patient types (e.g. in case of pregnancy, specific organ transplants or co-morbidities) and in resource-poor settings. Hence there is an urgent need for better antiviral treatments that are efficacious and safe, also during pregnancy. In this review, a concise introduction to the virus and disease is provided, followed by a discussion of the available assay systems and potential molecular targets (viral proteins and host factors) for the development of inhibitors of HEV replication. Finally, directions for future research are presented.

Hepatitis E: An emerging infection in high income countries

Hepatitis E virus (HEV) genotype 3 is the most recently characterized hepatotropic virus and is increasingly being recognized as the cause of unexplained liver disease in many western countries. Although asymptomatic in most cases, HEV GT3 may be responsible for a wide range of illnesses, from mild to fulminant acute hepatitis, and also chronic hepatitis in immunocompromised patients. Extrahepatic manifestations have been occasionally described. Anti-HEV antibody detection by immunoassays is hampered by moderate test accuracy particularly in immunocompromised hosts while a WHO international standard for molecular detection of HEV RNA by RT-PCR has recently been introduced. This review describes the basic virology, epidemiology, clinical virology and treatment of HEV GT3 infections in high income countries.

Performance of anti-HEV assays for diagnosing acute hepatitis E in immunocompromised patients

Hepatitis E virus is an emerging concern in immunocompromised patients, who may become chronically infected. This prompted us to assess the performance of two anti-HEV IgG and IgM assays for diagnosing acute HEV infections. The specificities of the assays were estimated by testing samples from 2 to 3 year-old French children and blood donors and their sensitivities by testing 40 immunocompromised patients acutely infected. Both anti-HEV IgM assays were highly specific (99.6% and 100%). The sensitivity of the Adaltis was 87.5%, and that of Wantai was 85%. The specificities of anti-HEV IgG Wantai (97.8%) and Adaltis tests (89.5%, p=0.1) were similar but the Wantai test was more sensitive (45%) than the Adaltis test (15%, p<0.001). None of the samples was anti-HEV IgM negative and IgG positive. We conclude that these anti-HEV IgM assays performed well in immunosuppressed subjects with acute hepatitis E and can be used as first line virological tools. Testing for anti-HEV IgG and IgM simultaneously at the acute phase did not improve the diagnostic performance. In contrast, molecular detection of HEV RNA appears essential to exclude an HEV infection in patients who are negative for anti-HEV IgM and to assess the evolution of hepatitis E 3 months thereafter.

An exploratory case control study of risk factors for hepatitis E in rural Bangladesh

Hepatitis E virus (HEV) is the major cause of epidemic and sporadic hepatitis globally. Outbreaks are associated with fecal contamination of drinking water, yet the environmental reservoir of HEV between epidemics remains unclear. In contrast to neighboring countries, where epidemics and sporadic disease co-occur, HEV-endemic communities in rural Bangladesh seldom report outbreaks; sporadic hepatitis E is reported from urban and rural areas of the country. Besides typical enteric risk factors, other routes for HEV infection and disease are unclear. We conducted monthly household surveillance of a southern Bangladeshi community of 23,500 people to find incident cases of acute hepatitis E over a 22 month period. An algorithm was used to capture 279 candidate cases, of which 46 were confirmed acute HEV infections. An exploratory case-control study was conducted to identify putative risk factors for disease. Nearly 70% of cases were over 15 years old. Female gender seemed protective (OR:0.34) against hepatitis E in this conservative setting, as was the use of sanitary latrines (OR:0.28). Socioeconomic status or animal exposures were not significant predictors of disease, although outdoor employment and recent urban travel were. Unexpectedly, recent contact with a “jaundiced” patient and a history of injection exposure in the 3 months prior to disease (OR:15.50) were significant. Susceptible individuals from “endemic” communities share similar enteric exposure risks to those commonly associated with tourists from non-endemic countries. This study also raises the novel possibility of parenteral and person-to-person transmission of HEV in non-epidemic, sporadic disease settings.

An analysis of the benefit of using HEV genotype 3 antigens in detecting anti-HEV IgG in a European population

Background

The benefit of using serological assays based on HEV genotype 3 in industrialised settings is unclear. We compared the performance of serological kits based on antigens from different HEV genotypes.

Methods

Taking 20 serum samples from patients in southwest France with acute HEV infection (positive PCR for HEV genotype 3) and 550 anonymised samples from blood donors in southwest Switzerland, we tested for anti-HEV IgG using three enzyme immunoassays (EIAs) (MP Diagnostics, Dia.Pro and Fortress) based on genotype 1 and 2 antigens, and one immunodot assay (Mikrogen Diagnostik recomLine HEV IgG/IgM) based on genotype 1 and 3 antigens.

Results

All acute HEV samples and 124/550 blood donor samples were positive with ≥1 assay. Of PCR-confirmed patient samples, 45%, 65%, 95% and 55% were positive with MP Diagnostics, Dia.Pro, Fortress and recomLine, respectively. Of blood donor samples positive with ≥1 assay, 120/124 (97%), were positive with Fortress, 19/124 (15%) were positive with all EIAs and 51/124 (41%) were positive with recomLine. Of 11/20 patient samples positive with recomLine, stronger reactivity for HEV genotype 3 was observed in 1/11(9%), and equal reactivity for both genotypes in 5/11 (45.5%).

Conclusions

Although recomLine contains HEV genotype 3, it has lower sensitivity than Fortress in acute HEV infection and fails to identify infection as being due to this genotype in approximately 45% of patients. In our single blood donor population, we observe wide variations in measured seroprevalence, from 4.2% to 21.8%, depending on the assay used.