UK acquired hepatitis E--An emerging problem?

HEV seroprevalence in blood donors in Turkey by two commercial total anti-HEV Ab ELISA kits

Previous hepatitis E virus (HEV) seroprevalence studies in Turkey have shown high variabilities, leading to conflicting results. We aimed to re-evaluate HEV seroprevalence among blood donors in Turkey using the Wantai (Beijing, China) and the Dia.Pro (Milan, Italy) total anti-HEV antibody (Ab) enzyme-linked immunosorbent assay (ELISA) kits and compare their performances and to investigate the presence of HEV RNA in blood donors. Serum total anti-HEV antibodies were determined in a total of 2011 volunteer blood donor samples collected from different regions of Turkey (807 from Ankara, 243 from Kayseri, 284 from İzmir, 200 from Malatya, 200 from Kahramanmaraş, and 277 from Van). HEV RNA was evaluated by a real-time polymerase chain reaction in a total of 272 anti-HEV seropositive samples. The country-wide HEV seroprevalence was calculated as 11.5% (Dia.Pro) and 12.2% (Wantai) with seropositivity rates of 12.0%-12.5% in Ankara, 7.4%-8.2% in Kayseri, 14.5%-15.5% in Malatya, 8.1%-8.8% in İzmir, 15.0%-16.0% in Kahramanmaraş, and 12.6%-13.4% in Van by Dia.Pro and Wantai kits, respectively. The lowest detectable Ab concentrations were 0.16 and 0.14 units/mL WHO, for the Dia.Pro and the Wantai assays, respectively, showing no significant difference between assays. HEV RNA was not detected in any of the anti-HEV seropositive samples. Compared with previous studies, HEV was shown to have a higher overall seroprevalence in Turkey. Despite its limitation, the current study represents the most comprehensive HEV seroprevalence study in Turkey performed with two different commercial ELISA assays with high sensitivities so far. Further investigation is required to determine HEV genotypes in Turkey.

First Detection of Hepatitis E Virus in Shellfish and in Seawater from Production Areas in Southern Italy

Shellfish samples (n = 384) from production areas, water samples from the same areas (n = 39) and from nearby sewage discharge points (n = 29) were analyzed for hepatitis E virus (HEV) by real-time and nested RT-PCR. Ten shellfish samples (2.6%) and five seawater samples (12.8%) tested positive for HEV; all characterized strains were G3 and showed high degree of sequence identity. An integrated surveillance in seafood and waters is relevant to reduce the risk of shellfish-associated illnesses.

Vaccine Development against Zoonotic Hepatitis E Virus: Open Questions and Remaining Challenges

Hepatitis E virus (HEV) is a fecal-orally transmitted foodborne viral pathogen that causes acute hepatitis in humans and is responsible for hepatitis E outbreaks worldwide. Since the discovery of HEV as a zoonotic agent, this virus has been isolated from a variety of hosts with an ever-expanding host range. Recently, a subunit HEV vaccine developed for the prevention of human disease was approved in China, but is not yet available to the rest of the world. Meanwhile, notable progress and knowledge has been made and revealed in recent years to better understand HEV biology and infection, including discoveries of quasi-enveloped HEV virions and of a new function of the HEV-ORF3 product. However, the impact of these new findings on the development of a protective vaccine against zoonotic HEV infection requires further discussion. In this review, hallmark characteristics of HEV zoonosis, the history of HEV vaccine development, and recent discoveries in HEV virology are described. Moreover, special attention is focused on quasi-enveloped HEV virions and the potential role of the HEV-ORF3 product as antibody-neutralization target on the surface of quasi-enveloped HEV virions to provide new insights for the future development of improved vaccines against zoonotic HEV infection.

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.

The emergence of hepatitis E virus in Europe

ABSTRACT 

Hepatitis E virus (HEV) infections appear to be an emerging problem in Europe. Infections are mainly caused by viruses of genotype 3. Pigs and wild boar are the main reservoirs of HEV in Europe and most autochthonous infections are probably caused by the consumption of uncooked or undercooked infected meat. Nevertheless, transfusion-associated transmission has been described in different European countries but the efficiency of this route of transmission need to be further investigated. Most acute infections are asymptomatic or the induced symptoms are rather nonspecific. Although people that are otherwise completely healthy can spontaneously clear an HEV infection, people with underlying liver disease and/or suffering from immune deficiencies may require treatment to avoid chronicity and exacerbation of liver disease. In this review, we give an epidemiological overview of HEV in Europe and the potential complications.

New insights into hepatitis E virus virus–host interaction: interplay with host interferon induction

ABSTRACT 

Hepatitis E virus (HEV) is a fecal–oral-transmitted viral pathogen causing several large outbreaks of hepatitis across the world. HEV-mediated hepatitis has a mortality rate from 0.5 to 3% in young adults but is up to 30% in pregnant women. HEV is also a zoonotic pathogen as it has been isolated from different mammalian hosts including the pig, rabbit, rat, ferret, bat and deer. As an invading pathogen, HEV needs to overcome the host innate immune response to establish infection. Notable progress has been recently made in HEV mechanisms of antagonizing the host innate immune responses. In this review, we elaborate on the HEV interplay with host interferon induction while briefly summarizing the major aspects of HEV biology and host interferon induction to assist the understanding of the virus–host interaction.

Hepatitis E virus in Italy: molecular analysis of travel-related and autochthonous cases

Human hepatitis E virus (HEV) is considered an emerging pathogen in industrialized countries. The aim of the present study was to contribute to the body of knowledge available on the molecular epidemiology of acute hepatitis E in Italy. Three sets of HEV-specific primers targeting the ORF1 and ORF2 were used to examine serum samples collected from acute hepatitis patients positive for anti-HEV IgG and/or IgM, between 2007 and 2010. Seventeen patients (39.5%) tested HEV RNA-positive: 12 infections, due to genotype 1, were associated with travel to endemic areas (Bangladesh, India and Pakistan), while five infections, due to genotype 3, were presumably autochthonous. Risk factors identified in this group included exposure to raw seafood, pork liver sausages and wild boar. Results from the present study confirm that human HEV infection in Italy is caused by different genotypes, depending on whether the infection is travel-related or autochthonous.

Fusion of C3d molecule with neutralization epitope(s) of hepatitis E virus enhances antibody avidity maturation and neutralizing activity following DNA immunization

Previous studies have identified that a hepatits E virus peptide (HEV-p179), spanning amino acids (aa) 439-617 in the 660-aa protein encoded by open reading frame 2(ORF2) of the Chinese epidemic strain (genotype 4), is the minimal size fragment of conformation-dependent neutralization epitope(s). We report here the successful immunization of mice with DNA vaccines expressing the secreted form of HEV-p179 (fused with a human tissue plasminogen activator (tPA) signal sequence) and the tPA-p179-C3d fusion protein (fused with three tandem copies of the murine complement C3d). Analysis of antibody responses in vaccinated mice revealed that immunizations with tPA-p179-C3d3 DNA vaccine dramatically increased both the level and avidity maturation of antibodies against HEV-p179 compared to p179 and tPA-p179 DNA vaccines. In addition, this increased antibody response correlated with neutralizing titers in a PCR-based cell culture neutralization assay. These results indicate that vaccination with C3d conjugated p179 DNA vaccine enhances antibody responses to HEV, and this approach may be applied to overcome the poor immunogenicity of DNA vaccines to generate HEV neutralizing antibodies.

First case of genotype 4 human hepatitis E virus infection acquired in India

This report describes a case of severe hepatitis in an individual returning from India which was found to be the result of infection with HEV genotype 4. HEV was diagnosed using a novel RT-PCR assay (with internal control) for HEV RNA detection/quantitation, described herein. This is the first documented report of zoonotic transmission of HEV genotype 4 infection acquired in India.

Much meat, much malady: changing perceptions of the epidemiology of hepatitis E

Hepatitis E, which is caused by hepatitis E virus (HEV), may now be considered a zoonosis as well as an anthroponosis. Pigs, boars and deer have been identified as reservoirs, and their flesh and entrails--as meat and offal--as vehicles of HEV transmission. Shellfish also act as vehicles. Dietary, gastronomic and culinary preferences influence how extensively HEV conveyed by these vehicles can be inactivated before their ingestion by the host. Another route of infection is paved by HEV that is enterically shed by humans and by live animals into the environment. Although anthroponotic transmission of HEV is primarily environmental, zoonotic transmission may proceed along both foodborne and environmental routes.

Transmission routes and risk factors for autochthonous hepatitis E virus infection in Europe: a systematic review

Increasing numbers of non-travel-associated hepatitis E virus (HEV) infections have been reported in Europe in recent years. Our objective was to review the evidence on risk factors and transmission routes of autochthonous HEV infection and hepatitis E in Europe in order to develop recommendations for future research, prevention and control. A systematic literature review was performed to identify all primary reports and studies published during 1998-2008 on hepatitis E in humans and animals in Europe by searching Pubmed, reference lists of major articles and international conference proceedings. Each of the 106 included studies was categorized into one of three evidence levels (EL) based on study design and diagnostic methodology. The evidence was generally weak (73 were assigned to EL1, two to both EL1 and EL2, and 30 to EL2), further compounded by the use of poorly validated serological assays in some studies. Only one case-control study was assigned to EL3. Persons with autochthonous hepatitis E infection were on average older than the general population and predominantly male. There was no evidence for one main transmission route of HEV infection or risk factor for hepatitis E. However, zoonotic transmission seemed likely and person-to-person transmission too inefficient to cause clinical disease. Multiple routes of transmission probably exist and should be further investigated through analytical studies and reliable diagnostic kits. Based on current evidence that points to zoonotic transmission from pigs, thorough cooking of all porcine products, prevention of cross-contamination in the kitchen and improved education for occupationally exposed people (e.g. pig farmers, veterinarians and sewage workers) may help prevent HEV infection. Although evidence for parenteral transmission is limited, it is recommended that a risk assessment is undertaken.

The course of hepatitis E virus infection in pigs after contact-infection and intravenous inoculation

Background

Worldwide, hepatitis E virus (HEV) genotype 3 is observed in pigs and transmission to humans is implied. To be able to estimate public health risks from e.g. contact with pigs or consumption of pork products, the transmission routes and dynamics of infection should be identified. Hence, the course of HEV-infection in naturally infected pigs should be studied.

Results

To resemble natural transmission, 24 HEV-susceptible pigs were infected either by one-to-one exposure to intravenously inoculated pigs (C1-pigs; n = 10), by one-to-one exposure to contact-infected pigs (C2-pigs: n = 7; C3-pigs: n = 5) or due to an unknown non-intravenous infection route (one C2-pig and one C3-pig). The course of HEV-infection for contact-infected pigs was characterized by: faecal HEV RNA excretion that started at day 7 (95% confidence interval: 5–10) postexposure and lasted 23 (19–28) days; viremia that started after 13 (8–17) days of faecal HEV RNA excretion and lasted 11 (8–13) days; antibody development that was detected after 13 (10–16) days of faecal HEV RNA excretion. The time until onset of faecal HEV RNA excretion and onset of viremia was significantly shorter for iv-pigs compared to contact-infected pigs, whereas the duration of faecal HEV RNA excretion was significantly longer. At 28 days postinfection HEV RNA was detected less frequently in organs of contact-infected pigs compared to iv-pigs. For contact-infected pigs, HEV RNA was detected in 20 of 39 muscle samples that were proxies for pork at retail and in 4 of 7 urine samples.

Conclusion

The course of infection differed between infection routes, suggesting that contact-infection could be a better model for natural transmission than iv inoculation. Urine and meat were identified as possible HEV-sources for pig-to-pig and pig-to-human HEV transmission.

Hepatitis E virus: molecular virology, clinical features, diagnosis, transmission, epidemiology, and prevention

Hepatitis E virus (HEV), the sole member of the genus Hepevirus in the family of Hepeviridae, is the major cause of several outbreaks of waterborne hepatitis in tropical and subtropical countries and of sporadic cases of viral hepatitis in endemic and industrialized countries. Transmission of HEV occurs predominantly by the fecal-oral route although parenteral and perinatal routes have been implicated. The overall death rate among young adults and pregnant women is 0.5-3% and 15-20%, respectively. HEV is a small non-enveloped particle that consists of a polyadenylated single-strand RNA molecule containing three discontinuous and partially overlapping open reading frames. There are four major genotypes of HEV and a single serotype. At present, there are approximately 1,600 sequences of HEV that are already available at INSDC of both human and animal isolates. Diagnostic and molecular assays have been described for the accurate differentiation of ongoing from remote infection of HEV. Identification and characterization of swine HEV in the United States, Japan, and many other countries and their close relationship to locally characterized human HEV found in the same geographic areas prove that HEV is indeed a zoonotic virus and that domestic swine, wild deer, and boars are reservoirs of HEV in nature. A cell culture system for the propagation of the virus has been described, and a very successful phase 2 vaccine trial has been completed. This review summarizes the current knowledge on the molecular biology, clinical features, transmission, diagnosis, epidemiology, and prevention of HEV.

Prevalence of hepatitis E virus infection in children in the northeast of Spain

The prevalence of immunoglobulin G (IgG) anti-hepatitis E virus (anti-HEV) antibodies was studied with a representative sample of 1,249 healthy children aged between 6 and 15 years. IgG anti-HEV antibodies were detected in 57 (4.6%) of the 1,249 samples analyzed, suggesting that some children are exposed to HEV in early childhood.

Prevalence of hepatitis E virus antibodies in patients with chronic hepatitis B and chronic hepatitis C

OBJECTIVES

To investigate the prevalence of hepatitis E virus (HEV) among patients with chronic hepatitis B and chronic hepatitis C, serum samples were collected between January and December 2004 from patients with chronic hepatitis B and chronic hepatitis C.

METHODS

There were 190 adult patients with chronic hepatitis B virus (HBV) and 174 with chronic hepatitis C virus (HCV) infection in the study group. As the control group, a cohort of 178 age- and sex-matched individuals without known liver disease was selected.

RESULTS

Anti-HEV IgG antibodies were positive in 26/190 (13.7%) of chronic HBV and 94/174 (54%) of chronic HCV patients. In the control group anti-HEV positivity was 15.7% (28/178). There was no difference in the percentage of chronic HBV patients and control group who were positive for anti-HEV antibody, but the presence of HEV infection was significantly higher in chronic HCV patients.

CONCLUSIONS

Our findings suggest that HEV and HCV might share a common route of transmission in our region. We recommend that preventive measures against HEV should be undertaken in chronic HCV patients as superinfection with HEV can cause a more severe pattern of disease in chronic hepatitis patients.

Unchanged high prevalence of antibodies to hepatitis E virus (HEV) and HEV RNA among blood donors with an elevated alanine aminotransferase level in Japan during 1991-2006

Hepatitis E is rare in Japan but is occurring more frequently than previously thought. To investigate whether de novo subclinical infection of hepatitis E virus (HEV) has recently increased in Japan, HEV RNA was assayed in serum samples obtained from 4019 Japanese voluntary blood donors with alanine aminotransferase (ALT) of > or =61 IU/l, who are likely to have ongoing HEV infection, during 1991-2006. The overall rates of IgG-class antibody to HEV (anti-HEV IgG), anti-HEV IgM/IgA and HEV RNA among 3185 donors in 2004-2006 were comparable with those among 594 donors in 1998 (5.3 vs. 5.2%, 0.2 vs. 0.5%, and 0.2 vs. 0.3%, respectively). Among blood donors with ALT > or = 201 IU/l in three groups according to the year of blood collection (1991-1995 [n = 156], 1996-1999 [n = 116] and 2004-2006 [n = 61]), there were no appreciable differences in the prevalence of anti-HEV IgG (5.8, 4.3, and 6.6%, respectively), anti-HEV IgM/IgA (1.9, 3.4, and 3.3%, respectively) and HEV RNA (1.3, 3.4, and 3.3%, respectively). The eleven HEV isolates obtained in the present study differed from each other by 1.7-22.8% in the ORF2 sequence and segregated into genotype 3 or 4. The occurrence rate of subclinical infection with divergent HEV strains has essentially remained unchanged during 1991-2006 in Japan.

Egg whites from eggs of chickens infected experimentally with avian hepatitis E virus contain infectious virus, but evidence of complete vertical transmission is lacking

Avian hepatitis E virus (HEV) is genetically and antigenically related to human HEV. Vertical transmission of HEV has been reported in humans, but not in other animals. In this study, we showed that avian HEV could be detected in chicken egg-white samples. Subsequently, avian HEV in egg white was found to be infectious, as evidenced by the appearance of viraemia, faecal virus shedding and seroconversion in chickens inoculated with avian HEV-positive egg white, but not in chickens inoculated with HEV-negative egg white. To further assess the possibility of vertical transmission of avian HEV, batches of embryonated eggs from infected hens were hatched, and hatched chicks were monitored for evidence of avian HEV infection. However, no virus was detected in samples collected from the hatched chicks throughout this study, suggesting that avian HEV could not complete the vertical transmission cycle. The possible implications of our findings are also discussed.

Update on viral hepatitis: 2006

PURPOSE OF REVIEW

This is a concise review of recent developments in the field of viral hepatitis, based on publications between December 2005 and November 2006.

RECENT FINDINGS

Elevated hepatitis B virus DNA levels in patients in their 40s with perinatally acquired hepatitis B virus infection increases the risk for cirrhosis and hepatocellular carcinoma. Six approved therapies are available for chronic hepatitis B. Entecavir is a potent antiviral for nucleoside-naïve patients. For lamivudine resistant hepatitis B virus infection, adefovir should be added to lamivudine to reduce the risk of adefovir-resistant mutations; however, tenofovir may be a more promising alternative to adefovir. A shorter duration of treatment wth pegylated interferon and ribavirin is sufficient for genotype 2 hepatitis C infection but the benefits of extending treatment to 72 weeks for genotype 1 needs to be confirmed. Pegylated interferon monotherapy was shown to be effective in patients with hepatitis D and ribavirin provides no additional benefit.

SUMMARY

New developments in the past year will help us fine tune the treatment of viral hepatitis. Even as new treatments are approved, the potential benefits of treatment should be weighed against the risk of drug-resistant mutations with long-term therapy.

Acute polyarthritis revealing hepatitis E

We report a case of acute hepatitis E occurring in a 51-year-old French woman, revealed by an abrupt onset of polyarthritis involving the ankles and knees followed by the wrists and fingers. Polyarthritis lasted up to 3 months without recurrence. Our case was characterised by a 9-month prolonged viraemia with persistence of specific IgM in the serum. The hepatitis E virus belonged to genotype 3 and may have been contracted in France or during travel to hyperendemic areas. Our case shows that acute polyarthritis could be another systemic manifestation of hepatitis E virus infection.

Ongoing subclinical infection of hepatitis E virus among blood donors with an elevated alanine aminotransferase level in Japan

Ongoing subclinical infection of hepatitis E virus (HEV) has not been fully studied. In the present study, serum samples were collected from 6700 voluntary blood donors with an elevated alanine aminotransferase (ALT) level of 61-476 IU/l at a Japanese Red Cross Blood Center, and were tested for the presence of IgG, IgM and IgA classes of antibodies to HEV (anti-HEV) by in-house ELISA and HEV RNA by nested RT-PCR. Overall, 479 blood donors (7.1%) were positive for anti-HEV IgG, including 8 donors with anti-HEV IgM and 7 donors with anti-HEV IgA. Among the nine donors with anti-HEV IgM and/or anti-HEV IgA, six had detectable HEV RNA. The presence of HEV RNA was further tested in 10-sample minipools of sera from the remaining 6691 donors, and three donors including one without anti-HEV IgG were found to be positive for HEV RNA. When stratified by ALT level, the prevalence of HEV RNA was significantly higher among the 109 donors with ALT > or = 201 IU/l than among the 6591 donors with ALT of 61-200 IU/l (2.8% vs. 0.1%, P < 0.0001). The HEV isolates obtained from the nine viremic donors segregated into genotype 3, shared a wide range of identities of 85.6-98.5% and were 87.3-93.9% similar to the Japan-indigenous HEV strain (JRA1), in the 412-nucleotide sequence of open reading frame 2. This study suggests that approximately 3% of Japanese individuals with ALT > or = 201 IU/l have ongoing subclinical infection with various HEV strains.

Hepatitis E indigenous to economically developed countries: to what extent a zoonosis?

PURPOSE OF REVIEW

Hepatitis E, a disease transmitted by hepatitis E virus, is increasingly recognized as being indigenous to affluent, temperate-zone countries. Issues pertaining to disease acquisition and hepatitis E virus infection, particularly in Western countries, are reviewed and highlighted.

RECENT FINDINGS

Clinical hepatitis E in the West, as in Japan, manifests more commonly in older people (>60 years) and in men, but fulminant hepatitis appears less frequent than in Japan. There, specific gastronomic and culinary risk factors associated with disease are being identified, but in the West, data implicating hepatitis E as being foodborne have yet to emerge. While hepatitis E virus subgenomic sequences in Western case patients are found to be closely related to swine hepatitis E virus, a porcine linkage to their infection remains to be established. Weak associations between occupational contact with pigs and risk of infection have been noted. Findings from earlier studies implicating animals that cohabitate with humans as reservoirs, and sewage as vehicles of infection await confirmation.

SUMMARY

Hepatitis E indigenous to developed countries is a distinct clinico-epidemiological entity. Humans, animals, food and the environment contribute and interact to cause human disease, and to sustain hepatitis E virus endemicity and enzooticity.