Annual risk of hepatitis E virus infection and seroreversion: Insights from a serological cohort in Sitakunda, Bangladesh

Hepatitis E virus (HEV) is a major cause of acute jaundice in South Asia. Gaps in our understanding of transmission are driven by non-specific symptoms and scarcity of diagnostics, impeding rational control strategies. In this context, serological data can provide important proxy measures of infection. We enrolled a population-representative serological cohort of 2,337 individuals in Sitakunda, Bangladesh. We estimated the annual risks of HEV infection and seroreversion both using serostatus changes between paired serum samples collected 9 months apart, and by fitting catalytic models to the age-stratified cross-sectional seroprevalence. At baseline, 15% (95 CI: 14-17%) of people were seropositive, with seroprevalence highest in the relatively urban south. During the study, 27 individuals seroreverted (annual seroreversion risk: 15%, 95 CI: 10-21%), and 38 seroconverted (annual infection risk: 3%, 95CI: 2-5%). Relying on cross-sectional seroprevalence data alone, and ignoring seroreversion, underestimated the annual infection risk five-fold (0.6%, 95 CrI: 0.5-0.6%). When we accounted for the observed seroreversion in a reversible catalytic model, infection risk was more consistent with measured seroincidence. Our results quantify HEV infection risk in Sitakunda and highlight the importance of accounting for seroreversion when estimating infection incidence from cross-sectional seroprevalence data.

Acute Hepatitis E-Associated Guillain-Barré Syndrome

Guillain-Barré syndrome (GBS) is a rare autoimmune disorder of the peripheral nervous system that causes progressive weakness and sensory disturbances, usually following an infection or immunization. It has been associated with multiple causes, including bacterial and viral infections. Hepatitis E virus (HEV) is a common cause of acute viral hepatitis that can rarely develop neurological complications. We report a case of a 72-year-old man who developed GBS secondary to an acute HEV infection. He presented with numbness and weakness of the lower limbs that rapidly evolved into respiratory failure requiring mechanical ventilation and intravenous immunoglobulin therapy (IVIg). This case adds to the literature on the association between HEV infection and GBS and the importance of early detection of this rapidly progressive condition.

Hepatitis E virus: has anything changed?

PURPOSE OF REVIEW

Infection with hepatitis E virus (HEV) is a global health concern, yet a clinically underdiagnosed cause of acute and chronic hepatitis. The WHO estimates that 20 million people are infected with HEV annually, yet the epidemiology, diagnosis and prevention remain elusive in many clinical settings.

RECENT FINDINGS

Orthohepevirus A (HEV-A) genotypes 1 and 2 cause acute, self-limited hepatitis through faecal-oral transmission. In 2022, the first-ever vaccine campaign was implemented as a response to an HEV outbreak in an endemic region. HEV-A genotypes 3 and 4 are zoonotic infections that primarily cause chronic HEV infection in immunosuppressed populations. Pregnant women and immunocompromised persons are at high risk for severe illness in some settings. Another recent advance in our knowledge of HEV is the zoonotic transmission of Orthohepevirus C (HEV-C) to humans, presumably from contact with rodents and/or their excrement. Previously, HEV infection in humans was presumed to be limited to HEV-A only.

SUMMARY

Clinical recognition and accurate diagnosis are essential to the management of HEV infection and understanding the global burden of the disease. Epidemiology affects clinical presentations. Targeted response strategies in HEV outbreaks are needed for the prevention of disease, and vaccine campaigns may prove to be an effective part of these strategies.

Seven years (2015-2021) of blood donor screening for HEV-RNA in France: lessons and perspectives

BACKGROUND

The French health authorities are considering expanding the current selective hepatitis E virus (HEV)-RNA testing procedure to include all donations in order to further reduce transfusion-transmitted HEV infection. Data obtained from blood donors (BDs) tested for HEV-RNA between 2015 and 2021 were used to assess the most efficient nucleic acid testing (NAT) strategy.

MATERIALS AND METHODS

Viral loads (VLs) and the plasma volume of blood components, as well as an HEV-RNA dose of 3.85 log IU as the infectious threshold and an assay with a 95% limit of detection (LOD) at 17 IU/mL, were used to assess the proportion of: (i) HEV-RNA-positive BDs that would remain undetected; and (ii) blood components associated with these undetected BDs with an HEV-RNA dose >3.85 log IU, considering 4 NAT options (Individual testing [ID], MP-6, MP-12, and MP-24).

RESULTS

Of the 510,118 BDs collected during the study period, 510 (0.10%) were HEV-RNA-positive. Based on measurable VLs available in 388 cases, 1%, 15.2%, 21.8%, and 32.6% of BDs would theoretically pass undetected due to a VL below the LOD of ID, MP-6, MP-12, and MP-24 testing, respectively. All BDs associated with a potentially infectious blood component would be detected with ID-NAT while 13% of them would be undetected with MP-6, 19.6% with MP-12, and 30.4% with MP-24 depending on the plasma volume. No red blood cell (RBC) components with an HEV-RNA dose >3.85 log IU would enter the blood supply, regardless of the NAT strategy used.

DISCUSSION

A highly sensitive ID-NAT would ensure maximum safety. However, an MP-based strategy can be considered given that: (i) the risk of transmission is closely related to the plasma volume of blood components; (ii) RBC are the most commonly transfused components and have a low plasma content; and (iii) HEV-RNA doses transmitting infection exceed 4 log IU. To minimise the potential risk associated with apheresis platelet components and fresh frozen plasma, less than 12 donations should be pooled using an NAT assay with a LOD of approximately 20 IU/mL.

Hepatitis E Virus Prevalence and Associated Risk Factors in High-Risk Groups: A Cross-Sectional Study

BACKGROUND

Seroepidemiology, risk factors to hepatitis E virus exposure, and prevalence of hepatitis E virus viremia have not yet been investigated among patients under immunosuppression or with liver disease that are high risk for infection in Turkey.

METHODS

In this cross-sectional study, 292 consecutive serum samples from renal transplant recipients, allogeneic hematopoietic stem cell transplant recipients, patients with acute hepatitis, and patients with chronic hepatitis C were prospectively collected in a ter- tiary university hospital. Sera were tested for hepatitis E virus immunoglobulin G/immunoglobulin M and hepatitis E virus ribonucleic acid using commercial enzyme-linked immunosorbent assay and in-house nested polymerase chain reaction with Sanger sequencing, respectively. Sociodemographic, clinical, laboratory data, and risk factors were collected using a questionnaire and hospital database. Multiple logistic regression analysis was employed to identify independent predictors for anti-hepatitis E virus seropositivity.

RESULTS

Among all patients, only 2 patients (1 renal transplant recipient and 1 patient with acute hepatitis) were identified as having hepatitis E virus genotype 3 viremia. Hepatitis E virus viremia rate was 0.6% in whole group. These patients showed no signs of chronic hepatitis E virus infection for 6 months and were spontaneously seroconverted 6 months after enrollment. Anti-hepatitis E virus IgG was positive in 29 patients yielding a hepatitis E virus seroprevalence of 9.9%. Older age (adjusted odds ratio: 1.03, 95% CI, 1.00-1.06; P = .022) and eating undercooked meat (adjusted odds ratio: 3.11, 95% CI, 1.08-8.92; P = .034) were independent risk factors to anti- hepatitis E virus seropositivity in all patients. Similarly, multiple logistic regression analysis demonstrated that age (adjusted odds ratio: 1.03, 95% CI, 0.99-1.07, P = .058) and eating undercooked meat (adjusted odds ratio: 5.77, 95% CI, 1.49-22.25, P = .011) were indepen- dent risk factors for anti-hepatitis E virus IgG positivity in the liver disease subgroup consisting of acute hepatitis and chronic hepatitis C patients.

CONCLUSION

The hepatitis E virus seroprevalence rate was high (9.9%), despite low viremia rate (0.6%) in high-risk patients. The emer- gence of hepatitis E virus genotype 3 might indicate a serious problem for these patients. Future investigations are needed to elucidate foodborne transmission routes of hepatitis E virus in Turkey.

Hepatitis E Infection in Solid Organ Transplant Recipients in Turkey

BACKGROUND

Hepatitis E virus is a re-emerging pathogen with an increase in human cases that can lead to chronic infection in immunosuppressed patients. Turkey is located between Asia and Europe, 2 regions with distinct epidemiological and clinical features of hepatitis E virus infection. This multicenter cross-sectional study aimed to investigate the prevalence of hepatitis E virus infection in liver and kidney transplant recipients in Turkey and to determine the role of possible transmission factors.

METHODS

A total of 485 plasma samples of solid organ recipients were collected from 7 transplantation centers in Turkey. Samples were tested for anti-hepatitis E virus immunoglobin M, immunoglobin G, and hepatitis E virus ribonucleic acid. Water- and food-related risk factors were evaluated by a questionnaire.

RESULTS

Samples of 300 kidney and 185 liver recipients were collected. Hepatitis E virus ribonucleic acid was tested in 472 samples and none were positive. Anti-hepatitis E virus immunoglobin G and immunoglobin M were detected in 84 (17.3%) and 3 (0.6%) patients, respectively. Seropositivity was associated with older age, male gender, being a liver recipient, and being infected with hepatitis B virus and/or hepatitis C virus. None of the patients under the age of 30 were seropositive. Hepatitis E virus immunoglobin G prevalence was higher in the Central East and Southeast Anatolia. Eating raw meat was the only independent variable associated with hepatitis E virus seropositivity.

CONCLUSION

This is the first prevalence study of hepatitis E virus infection in solid organ recipients in Turkey. Anti-hepatitis E virus immunoglobin G prevalence was 17.3% which was higher than the previously reported rate in blood donors. Seropositivity was significantly higher in liver recipients. Despite the high antibody prevalence, none of the patients were viremic.

The Prevalence of Hepatitis E Virus Infection in the Adult Turkish Population: A Systematic Review of the Literature and Prevalence Study in Blood Donors in Mersin Province

BACKGROUND

The hepatitis E virus (HEV) is an RNA virus that causes acute hepatitis, and can become chronic in immunocompromised patients, though this is rare. The frequency of HEV infection varies, depending on factors such as geographical region, socioeconomic level, and age. Despite limited studies on the adult population in Turkey, there is no current information about HEV frequency in our country. Therefore, we aimed to scrutinize the data found from such studies, in comparison to our own results.

METHODS

A total of 900 volunteers who applied to donate blood to the University Hospital Blood Center and accepted the use of their data were enrolled in the study. Serum anti-HEV IgG antibody (Ab) was examined by the enzyme-linked immunosorbent assays method. The donors' location, occupation, and animal contact status were determined. In addition, we evaluated the full text and conference papers (in Turkish or English) of Turkey-based HEV seroprevalence studies from 1990-2020, investigating the adult population.

RESULTS

The average age of the 900 volunteers in the study was 35.22 ± 9.60 years, of whom 889 (98.7%) were men. Anti-HEV IgG was positive in 12.8% of the serum samples. The average age of the volunteers who were seropositive was 40.40 ± 9.72 years, and 98.2% were men. No association was found between anti-HEV IgG positivity and occupation, place of residence, and contact with animals. An evaluation of the studies conducted in Turkey reveals that the average HEV infection seroprevalence is 9.52% in the healthy population, and the prevalence is increased in the region of Southeastern Anatolia. Patients with acute hepatitis and hemodialysis also had increased rates.

CONCLUSION

The anti-HEV IgG seropositivity rate in healthy blood donors in Mersin province was 12.8%, and was similar to the rates reported earlier in our country. However, this rate, found in a sample of individuals from a healthy society, causes concern about what the frequency may be in sick people. Wide-ranging community screening is needed.

Steroid-Responsive Myositis Associated With Acute Hepatitis E Infection

Acute hepatitis E virus (HEV) infection is usually self-limiting and presents as mild jaundice accompanied by malaise, anorexia, nausea, vomiting, abdominal pain, or fever. Rarely, it can lead to fulminant hepatic failure especially in pregnant women or cause extrahepatic manifestations. We report a case of a young woman already diagnosed with acute HEV infection who presented with a generalized body rash and weakness in all four limbs. She was subsequently diagnosed with inflammatory myositis and treated successfully with steroids. We have reviewed relevant literature for a possible association. Myositis is a rare but known complication of HEV. If timely diagnosed and managed, there is a significant reduction in morbidity.

Hepatitis E Virus Superinfection: an Underrecognized Trigger of Acute Hepatitis B Virus Flare

Hepatitis E virus (HEV) infection is a significant cause of acute hepatitis in endemic areas, such as parts of Asia, Africa, and Mexico, though HEV prevalence in the United States has been estimated between 6% and 20%. Chronic hepatitis B virus (HBV) infection affects about 1 per 1.4 million people in North America. Although well documented in Asia, HBV flare secondary to HEV superinfection is rarely reported in the United States. Here, we present a case of chronic undiagnosed HBV infection with acute flare secondary to HEV superinfection. 

Acute Hepatitis E: A Rare Cause of Acute Liver Failure in a Patient With Acute Myeloid Leukemia

Immunocompromised patients are particularly at risk to develop hepatitis E virus (HEV) infection and its related complications. We present a rare case of HEV infection in a 35-year-old Hispanic female with concomitant acute myeloid leukemia (AML). The patient presented with acute liver failure within a few weeks after receiving a blood transfusion. Our case likely represented an acute de novo HEV infection after chemotherapy in a patient with concurrent AML, evidenced by the presence of anti-HEV IgM antibodies as well as histological findings, and with a previous history of recent transfusions being one of the strongest risk factors for transmission. Liver failure from an acute de novo hepatitis E infection with concurrent AML can be catastrophic in the immunosuppressed patient. Our case is particularly unique due to the uncommon presentation of acute hepatitis E in a non-pregnant reproductive aged Hispanic female with recently diagnosed AML. Clinicians should maintain a low threshold to test serum HEV-RNA if a patient presents with signs and symptoms suggestive of acute hepatitis.

Hepatitis E infection in a patient with rheumatoid arthritis treated with leflunomide: A case report with emphasis on geoepidemiology

RATIONALE

Hepatitis E is an infectious disease due to inflammation of the liver caused by hepatitis E virus (HEV) and represents one of the most common causes of acute hepatitis and jaundice in the world. Although data of hepatitis E infection in patients with rheumatoid arthritis (RA) are accumulating, little is known on the course of HEV infection. We reported, for the 1st time, a case of patient with RA with hepatitis E that developed during leflunomide therapy in combination with low-dose steroids.

PATIENT CONCERNS

We present a 39-year-old woman, affected by RA and treated with leflunomide, reported diffuse itching and persistent fatigue laboratory data revealed elevated liver enzyme levels.

DIAGNOSIS

Positivity for anti-HEV IgM and IgG was observed. HEV-RNA of the genotype 3 was detected, indicating acute E hepatitis.

INTERVENTIONS AND OUTCOMES

Leflunomide was stopped and restarted 5 months after the initial diagnosis at the same dosage, with a close clinical and laboratory follow-up. The virus was eradicated from the serum without chronic transformation. The patient is alive and well 7 months after the initial diagnosis.

LESSONS

To our knowledge, this report is the 1st case of acute E hepatitis in a patient with RA developed during leflunomide therapy in combination with low-dose steroids. Moreover, geoepidemiology of infection is important, due to the fact that Abruzzo, a central region of Italy, has the highest HEV seroprevalence in general population, related to the zoonotic transmission of the infection from domestic and wild animals. Our case highlighted that immunosuppressive therapy, and in particular leflunomide, could be safely reintroduced after the resolution of the infection and the clearance of the virus. Further studies are needed to evaluate potential advantages in serologic testing for HEV infection as a part of the routine workup done to patients with rheumatic diseases and selected for immunosuppressive therapy.

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.

Course of hepatitis E infection in a patient with rheumatoid arthritis and autoimmune hepatitis: A case report

RATIONALE

A 62-year-old male patient was admitted to our clinic in February 2016 with persistently elevated liver enzymes.

PATIENT CONCERNS

Clinical history involved a long time of poly-autoimmunity with a rheumatoid arthritis (in remission under tocilizumab therapy), an autoimmune thyroiditis, an eosinophilia as well as a hyper-immunoglobulin (IgG) 4-syndrome.

DIAGNOSES

Laboratory studies revealed a significant increase in liver enzymes with an alanine aminotransferase (ALT) level of 574 U/L and an aspartate aminotransferase (AST) level of 864 U/L (normal <50 U/L). Furthermore, the patient was positive for anti-nuclear autoantibodies (ANA) with a titer of 1:320 (normal upper limit: 1:80).

INTERVENTIONS

Liver histology, obtained via mini-laparoscopy, demonstrated lobular hepatitis with markedly increased hepatocyte apoptosis, lymphoplasmatic cell infiltration, and 20% microvascular fat without significant fibrosis, which strengthened the diagnosis of autoimmune hepatitis (AIH). Pulse steroid treatment with 100 mg prednisolone for 3 days followed by a tapering down was initiated. Follow-up laboratory analysis demonstrated a decrease in liver enzymes and also of the ANA-titer.

OUTCOMES

At that point, hepatitis E virus (HEV) infection was diagnosed with a positive anti-HEV immunoglobulin M (IgM) antibody and HEV-ribonucleotide acid (RNA) of 6280 copies/mL.

LESSONS

Despite the HEV infection and due to the strength of autoimmunity, we decided to continue immunosuppressive therapy and monitored HEV-PCR regularly. However, HEV-RNA became negative after 2 months and HEV-IgM turned negative after 13 months.

Chronic hepatitis E virus infection in a cirrhotic patient: A case report

RATIONALE

Acute hepatitis E virus (HEV) infections are usually self-limiting in immunocompetent patients. HEV persistence has been described only in immunosuppressed patients such as solid-organ transplant recipients, patients with hematological diseases, or patients with human immunodeficiency virus (HIV) infection.

PATIENT CONCERNS

A 61-year-old patient was admitted in hospital for jaundice and asthenia.

DIAGNOSES

The patient had underlying cirrhosis and developed a chronic HEV infection.

INTERVENTION

Ribavirin therapy was initiated.

OUTCOMES

Ribavirin therapy for 12 months allowed the clearance of the virus and HEV viral load remained undetectable thereafter. This patient had taken no immunosuppressive drugs, was not suffering from any autoimmune disease and was not infected with HIV. We studied the patient's anti-HEV immune response months after the viral clearance. His peripheral blood mononuclear cells (PBMC) were stimulated in vitro by HEV peptides. The patient had a mild T lymphopenia, but polyclonal stimulation of PBMC showed a robust T cell response. The response of his anti-HEV specific interferon-γ producing T cells was low.

LESSONS

Other studies are now needed to identify the population with a chronic evolution of HEV infection despite no apparent immunodepression.

Acute on chronic liver failure because of acute hepatic insults: Etiologies, course, extrahepatic organ failure and predictors of mortality

BACKGROUND AND AIM

Acute on chronic liver failure (ACLF) because of precipitating factors (variceal bleed/infections) identifies cirrhotics at risk for high short-term mortality. Information on ACLF because of acute hepatic insults is lacking. The aim of the study was to evaluate acute hepatic insults in ACLF and their effect on the course and outcome.

METHODS

In a prospective study, 213 consecutive patients of ACLF because of acute hepatic insults were included. Etiology of acute hepatic insult, frequency of silent, and overt chronic liver disease (CLD), organ failure (OF), and outcomes were assessed. Prognostic models such as model for endstage liver disease (MELD), acute physiology and chronic health evaluation (APACHE II), and chronic liver failure-sequential organ failure (CLIF-SOFA) were evaluated.

RESULTS

Etiologies of acute hepatic insult were hepatitis virus(es)- 81 (38%; HBV-42, HEV-39), continuous alcohol consumption-77 (33.3%), antituberculosis drugs-11 (5.2%), autoimmune hepatitis flare-5(2.3%), cryptogenic-44 (20.7%). The common causes of CLD were alcohol (n = 85/40%), HBV(n = 52/24%), and cryptogenic(n = 50/20%). The MELD, APACHE II, and CLIF-SOFA scores were similar among silent and overt CLD and did not influence outcome. Predominant etiologies of ACLF were hepatitis virus(es) reactivation or superinfection in silent CLD(52/112, 46.4%) and alcohol among overt CLD(43/101, 43%). Independent predictors of mortality included hepatic-encephalopathy (early, HR: 4.01; advanced, HR: 6.10), serum creatinine ≥1.5 mg/dl (HR: 4.53), CLIF-SOFA ≥8(HR: 1.69), and etiology of acute hepatic insult (alcohol, HR: 4.08; cryptogenic, HR: 3.18). HEV-ACLF had lower mortality (12.8% vs. 33-54% in other etiologies;P < 0.001). OF was major determinant of mortality. With increasing number of OF, mortality increased linearly(P = 0.001).

CONCLUSIONS

Hepatitis virus(es) and continuous alcohol consumption are important causes of ACLF caused by acute hepatic insults. HEV-ACLF has lower mortality. OF is an important prognostic predictor.

Chronic Hepatitis E Infection in a Persistently Immunosuppressed Patient Unable to Be Eliminated after Ribavirin Therapy

Recent case reports have shown that hepatitis E virus (HEV) infection can cause chronic hepatitis in immunosuppressed or immunocompromised patients. A 37-year-old woman suffered from prolonged elevation of aminotransferases after chemotherapy for Burkitt's lymphoma and was diagnosed with chronic hepatitis E due to a transfusion during chemotherapy. After an 8-month administration of ribavirin, complete HEV clearance was not achieved, likely due to prolonged hypogammaglobulinemia. This case indicates that HEV infection should be ruled out during liver dysfunction in immunosuppressed or immunocompromised patients and suggests that an alternative therapeutic strategy for such patients will be needed.

Molecular detection of hepatitis E virus in sheep from southern Xinjiang, China

Hepatitis E virus (HEV) is a causative agent of infectious hepatitis in animals and humans both in developing and developed countries. Here, we collected 500 sheep sera and 75 raw sheep liver samples from a slaughterhouse in the southern part of the Xinjiang region, China, along with 26 sera of butchers from the same slaughterhouse. All serum samples were tested for anti-HEV antibody by enzyme-linked immunosorbent assay. Both serum and liver samples were evaluated for the presence of HEV RNA by nested polymerase chain reaction targeting partial nucleotide sequences of open reading frame 2 (ORF2). The results indicate that sheep seroprevalence was 35.20 % (176/500) and that four of the 75 (5.3 %) sheep livers showed detectable amounts of HEV RNA. The seroprevalence of the butchers was 57.7 % (15/26). The four amplicons shared 97.8-100 % nucleotide sequence identity and had pairwise sequence identities of 81.6-85.3 %, 84.2-85.3 %, 82.1-85.3 % and 84.7-97.9 % with the corresponding regions of genotypes 1, 2, 3 and 4 of HEV, respectively. A phylogenetic tree was constructed based on alignments of an amplified 186-bp ORF2 sequence and corresponding reference strains. The analysis showed that the four sheep strains detected in our study formed a lineage within a genotype 4 cluster that contains hb-3, bjsw1, T1, swCH189 and swCH25, all of which belong to genotype 4, subtype 4d. The results indicated a high level of seroconversion in sheep and suggested that sheep liver may be a source of foodborne HEV infection in humans.

Antigenic determinants of hepatitis E virus and vaccine-induced immunogenicity and efficacy

There is emerging evidence for an under-recognized hepatitis E virus (HEV) as a human pathogen. Among different reasons for this neglect are the unsatisfactory performance and under-utilization of commercial HEV diagnostic kits; for instance, the number of anti-HEV IgM kits marketed in China is about one-fifth of that of hepatitis A kits. Over the last two decades, substantial progress has been achieved in furthering our knowledge on the HEV-specific immune responses, antigenic features of HEV virions, and development of serological assays and more recently prophylactic vaccines. This review will focus on presenting the evidence of the importance of HEV infection for certain cohorts such as pregnant women, the key antigenic determinants of the virus, and immunogenicity and clinical efficacy conferred by a newly developed prophylactic vaccine. Robust immunogenicity, greater than 195-fold and approximately 50-fold increase of anti-HEV IgG level in seronegative and seropositive vaccinees, respectively, as well as impressive clinical efficacy of this vaccine was demonstrated. The protection rate against the hepatitis E disease and the virus infection was shown to be 100% (95% CI 75-100) and 78% (95% CI 66-86), respectively.

Culture systems for hepatitis E virus

The lack of an efficient cell culture system for hepatitis E virus (HEV) has greatly hampered detailed analyses of this virus. The first efficient cell culture systems for HEV that were developed were capable of secreting infectious HEV progenies in high titers into culture media, using PLC/PRF/5 cells derived from human hepatocellular carcinoma and A549 cells derived from human lung cancer as host cells. The success achieved with the original genotype 3 JE03-1760F strain has now been extended to various HEV strains in fecal and serum samples obtained from hepatitis E patients and to HEV strains in fecal and serum samples and liver tissues obtained from pigs and wild boar across species barriers. In addition, infectious HEV cDNA clones of the wild-type JE03-1760F strain and its variants have been engineered. Cell culture-generated HEV particles and those in circulating blood were found to be associated with lipids and open reading frame 3 (ORF3) protein, thereby likely contributing to the assembly and release of HEV from infected cells both in vivo and in vitro. The ORF3 protein interacts with the tumor susceptibility gene 101, a critical cellular protein required for the budding of enveloped viruses, through the Pro, Ser, Ala, and Pro (PSAP) motif in infected cells; ORF3 is co-localized with multivesicular bodies (MVBs) in the cytoplasm of infected cells, thus suggesting that HEV requires the MVB pathway for the egress of virus particles. This article reviews the development of efficient cell culture systems for a wide variety of infectious HEV strains obtained from humans, pigs, and wild boar, and also provides details of a new model for virion egress.

Hepatitis E virus genotype 3 in wild rats, United States

The role of rodents in the epidemiology of zoonotic hepatitis E virus (HEV) infection has been a subject of considerable debate. Seroprevalence studies suggest widespread HEV infection in commensal Rattus spp. rats, but experimental transmission has been largely unsuccessful and recovery of zoonotic genotype 3 HEV RNA from wild Rattus spp. rats has never been confirmed. We surveyed R. rattus and R. norvegicus rats from across the United States and several international populations by using a hemi-nested reverse transcription PCR approach. We isolated HEV RNA in liver tissues from 35 of 446 rats examined. All but 1 of these isolates was relegated to the zoonotic HEV genotype 3, and the remaining sequence represented the recently discovered rat genotype from the United States and Germany. HEV-positive rats were detected in urban and remote localities. Genetic analyses suggest all HEV genotype 3 isolates obtained from wild Rattus spp. rats were closely related.

HEV infection as an aetiologic factor for acute hepatitis: experience from a tertiary hospital in Bangladesh

Acute hepatitis is seen sporadically round the year in Bangladesh. The incidence of acute viral hepatitis E increases after floods as this allows sewerage contamination of piped and groundwater. The aim of this retrospective study was to assess the burden of hepatitis E virus (HEV infection) in Bangladesh. Patients attending the Hepatology Unit III of the Bangabandhu Sheikh Mujib Medical University, during June 2004-December 2006, were included in the study. All viral markers were tested by enzyme-linked immunosorbent assay. The study population was divided in four groups. Group 1 included 144 patients with acute viral hepatitis. The inclusion criteria were: nausea and/or vomiting, loss of appetite, serum bilirubin >200 micromol/L, raised serum transaminases, and prothrombin time >3 seconds prolonged beyond control value. In Group 2, there were 31 pregnant women with acute viral hepatitis. All the patients had prodrome, icterus, raised serum bilirubin and raised serum transaminase levels. Group 3 included 23 patients presenting with fulminant hepatic failure. In Group 4, 69 patients with cirrhosis of liver were included. They presented with features of decompensation for the first time. The inclusion criteria were: patients with established cirrhosis with jaundice and/or ascites and/or hepatic encephalopathy. In Group 1, 58.33% of the 144 patients had acute viral hepatitis E. In Group 2, 45.16% of the pregnant women also had acute viral hepatitis E. HEV was responsible for 56.52% cases of fulminant hepatic failure in Group 3. In 21.7% cases in Group 4, decompensation of cirrhosis was due to HEV. Acute viral hepatitis E in the third trimester of pregnancy and HEV-induced fulminant hepatic failure were associated with 80% of mortality despite the best possible care. In this clinical context, acute viral hepatitis E is the leading cause of wide spectrum of liver disease ranging from severe acute viral hepatitis, fulminant hepatic failure, to decompensation of liver in cirrhotics in Bangladesh. Sewerage contamination of piped water following floods may contribute to the higher incidence of HEV infection.

Crystallization and preliminary X-ray diffraction analysis of recombinant hepatitis E virus-like particle

Hepatitis E virus (HEV) accounts for the majority of enterically transmitted hepatitis infections worldwide. Currently, there is no specific treatment for or vaccine against HEV. The major structural protein is derived from open reading frame (ORF) 2 of the viral genome. A potential oral vaccine is provided by the virus-like particles formed by a protein construct of partial ORF3 protein (residue 70-123) fused to the N-terminus of the ORF2 protein (residues 112-608). Single crystals obtained by the hanging-drop vapour-diffusion method at 293 K diffract X-rays to 8.3 A resolution. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 337, b = 343, c = 346 A, alpha = beta = gamma = 90 degrees , and contain one particle per asymmetric unit.

A truncated hepatitis E virus ORF2 protein expressed in tobacco plastids is immunogenic in mice

AIM

To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3'-portion of hepatitis E virus (HEV) open reading frame 2 (ORF2) in plastids of tobacco (Nicotiana tabacum cv. SR1), to investigate the transgene expression and pE2 accumulation in plastids, and to evaluate the antigenic effect of the plastid-derived pE2 in mice.

METHODS

Plastid-targeting vector pRB94-E2 containing the E2 fragment driven by rice psbA promoter was constructed. Upon delivery into tobacco plastids, this construct could initiate homologous recombination in psaB-trnfM and trnG-psbC fragments in plastid genome, and result in transgene inserted between the two fragments. The pRB94-E2 was delivered with a biolistic particle bombardment method, and the plastid-transformed plants were obtained following the regeneration of the bombarded leaf tissues on a spectinomycin-supplemented medium. Transplastomic status of the regenerated plants was confirmed by PCR and Southern blot analysis, transgene expression was investigated by Northern blot analysis, and accumulation of pE2 was measured by ELISA. Furthermore, protein extracts were used to immunize mice, and the presence of the pE2-reactive antibodies in serum samples of the immunized mice was studied by ELISA.

RESULTS

Transplastomic lines confirmed by PCR and Southern blot analysis could actively transcribe the E2 mRNA. The pE2 polypeptide was accumulated to a level as high as 13.27 microg/g fresh leaves. The pE2 could stimulate the immunized mice to generate pE2-specific antibodies.

CONCLUSION

HEV-E2 fragment can be inserted into the plastid genome and the recombinant pE2 antigen derived is antigenic in mice. Hence, plastids may be a novel source for cost-effective production of HEV vaccines.