Identification of novel human hepatitis E virus (HEV) isolates and determination of the seroprevalence of HEV in Korea

Cross-Species Transmission of Rabbit Hepatitis E Virus to Pigs and Evaluation of the Protection of a Virus-like Particle Vaccine against Rabbit Hepatitis E Virus Infection in Pigs

We investigated the cross-species transmission of rabbit hepatitis E virus (rb HEV) to pigs and evaluated the cross-protection of a swine (sw) HEV-3 virus-like particle (VLP) vaccine against rb HEV infection in pigs. Twelve 4-week-old conventional pigs were divided into negative control (n = 3), positive control (rb HEV-infected, n = 4), and vaccinated (vaccinated and rb HEV-challenged, n = 5) groups. The vaccine was administered at weeks 0 and 2, and viral challenge was conducted at week 4. Serum HEV RNA, anti-HEV antibody, cytokine, and liver enzyme levels were determined. Histopathological lesions were examined in abdominal organs. Viral RNA was detected and increased anti-HEV antibody and alanine aminotransferase (ALT) levels were observed in positive control pigs; liver fibrosis, inflammatory cell infiltration in the lamina propria of the small intestine and shortened small intestine villi were also observed. In vaccinated pigs, anti-HEV antibody and Th1 cytokine level elevations were observed after the second vaccination; viral RNA was not detected, and ALT level elevations were not observed. The results verified the cross-species transmission of rb HEV to pigs and cross-protection of the sw HEV-3 VLP vaccine against rb HEV infection in pigs. This vaccine may be used for cross-protection against HEV infection in other species.

Implications of Hepatitis E Virus in Blood Transfusions, Hemodialysis, and Solid Organ Transplants

Hepatitis E Virus (HEV) is emerging as the primary cause of acute viral hepatitis in humans. The virus is commonly transmitted by the fecal-oral route via contaminated water in endemic regions or through the consumption of inadequately cooked swine products or game meats in industrialized regions. HEV genotypes 1 and 2 are predominantly associated with waterborne transmission in developing countries, whereas HEV3 and HEV4 are mainly zoonotically transmitted in industrialized countries. Seroprevalence in populations determined by detecting anti-HEV antibodies and serum HEV RNA is commonly used to analyze the presence of HEV. Although HEV RNA-based detection is now standardized, there is a lack of agreement between the assaying methods used for gathering seroprevalence data. Since 2004, HEV has been considered as a transmissible infectious agent through blood transfusion. Recent seroprevalence studies in European countries indicate an underestimated risk for blood transfusion and hence warrant testing the blood supply. HEV infection is usually self-limiting and spontaneously cleared. However, in about 60% of recipients of solid organ transplants, HEV progresses to chronic hepatitis. Immunosuppressive drugs such as tacrolimus are a major cause of chronic hepatitis and reducing its dosage results in viral clearance in about 30% of patients. In hemodialysis patients, the parenteral route is implicated as an important mechanism of transmission. In this review, we explore the clinical and epidemiological characteristics of various HEV genotypes in blood donors, hemodialysis patients, and transplant recipients.

[Hepatitis E Virus: Epidemiology, Diagnosis, and Management]

The HEV is a known cause of water-borne outbreaks of acute non-A non-B hepatitis in developing countries, which affects young people and may result in high mortality in pregnant women. In recent decades, however, HEV genotypes 3 and 4 have been known as a cause of sporadic zoonotic infections in older males from swine HEV worldwide. Most acute HEV infections are self-limited. On the other hand, in immunosuppressed patients, including solid organ transplant recipients, chronic HEV infections may exist and progress to liver cirrhosis or decompensation. Therefore, physicians need to recognize HEV as a major pathogen for acute and chronic hepatitis of unknown causes and investigate this disease.

Systematic review and meta-analysis of the seroprevalence of hepatitis E virus in the general population across non-endemic countries

BACKGROUND

Hepatitis E virus (HEV) has commonly been associated with large waterborne outbreaks of human jaundice in endemic areas but it has been increasingly recognised as a cause of sporadic human cases of jaundice in non-endemic areas, in individuals with no history of travel. Zoonotic exposure is widely hypothesized to be an important potential transmission route in these sporadic human cases. Serosurveys conducted to determine the frequency of HEV human exposure report wide ranges in prevalence across studies and locations. Our study objective was to compute meta-analysis summary estimates of human seroprevalence of HEV IgG within countries considered HEV non-endemic, where possible, and to determine whether this varied significantly across these countries, as well as investigating the role of potential HEV seroprevalence predictors such as population age structure.

MATERIALS AND METHODS

A broad literature search was conducted in six electronic databases. Citations were appraised, and relevant data extracted using forms designed and pre-tested a priori. Meta-analysis and meta-regression were conducted in R, with HEV IgG seroprevalence in blood donors or the general population being the outcome of interest, and country, assay, population age and sex structure, and chronological time investigated as predictors of the outcome.

RESULTS

From 4163 unique citations initially captured, data were extracted from 135 studies investigating HEV serology in blood donors or the general population, of 31 countries among those categorised as 'very high human development' by the United Nations. Country of sampling and assay employed were consistently significant predictors of HEV IgG seroprevalence with chronological time being a non-significant predictor in the dataset of captured studies.

CONCLUSIONS

While country of sampling and assay employed were significant predictors of HEV seroprevalence, comparison of HEV seroprevalence across non-endemic countries is hampered by the lack of a gold standard assay and uncertainty regarding residual bias across studies, as well as regional differences within some countries.

Detection of hepatitis E virus genotypes 3 and 4 in pig farms in Korea

Zoonotic transmission of hepatitis E virus (HEV) is mostly mediated by HEV-3 and HEV-4 genotypes, and domestic pigs are an important reservoir of these genotypes. A survey of 14 pig farms in Korea revealed HEV RNA in 30 of 148 (20.3%) fecal samples. HEV-3a and HEV-4c subtypes were identified in five pig farms (35.7%) and two pig farms (14.3%), respectively. Phylogenetic analysis indicated that the isolated HEV strains were closely related to previously reported zoonotic strains in Korea. The results of the genetic analysis partially explain the possible source of the zoonotic transmission of HEV to humans in Korea.

Prevalence of hepatitis E infection in the general population of Iran: a systematic review and meta-analysis

Aim: Hepatitis E is a form of acute viral hepatitis, which is caused by hepatitis E virus (HEV). The study objective was to evaluate the prevalence of HEV to provide an overall relative frequency in Iran. Methods: In this study, databases such as PubMed and Scopus were searched using the following keywords according to MeSH, “Hepatitis E virus”, “Epidemiology”, “Enzyme-linked immunosorbent assay (ELISA)” and “Iran”. Then studies which had reported prevalence of HEV were selected. Results: We selected 36 researches out of 9246 for our study. From all the samples, the pooled estimated prevalence of HEV positive was 9.7%. It should be noted that HEV infection's relative frequency varied from 1.1% in Tehran to 46.1% in Ahvaz. Conclusion: HEV is common in Iran, although comparing to some neighboring countries, its prevalence is lower.

Isolation of hepatitis E virus genotype 4 from patients with acute cryptogenic hepatitis in Korea

BACKGROUND

Autochthonous hepatitis E occurs sporadically in developed countries. The consumption of undercooked pork containing hepatitis E virus genotype 3 (HEV-3) or 4 (HEV-4) is the major risk factor for infection. The serological diagnostic kits currently used in hospitals sometimes produce false-negative or -positive results. Therefore, detection of both HEV RNA and antibodies to the virus is required for confirmative diagnosis of hepatitis E.

OBJECTIVES

We aimed to detect HEV in serum samples from patients with cryptogenic hepatitis and to determine the origin of HEV.

STUDY DESIGN

A nested polymerase chain reaction (PCR) method was developed for detection of HEV-3 and HEV-4 in patients with hepatitis. A total of 23 serum samples, deposited in 2006-2012, from patients with acute cryptogenic hepatitis who were serologically negative for hepatitis A, B, C, and E were examined using this method. The amplified PCR products were genetically analyzed.

RESULTS

Four HEV-4 isolates were detected from the 23 serum samples. Phylogenetic analysis indicated that three of the four isolates were closely related to HEV-4 isolates found in pigs in Korea and in patients with hepatitis E in Japan.

CONCLUSIONS

The newly developed nested PCR method was useful for detection of HEV in patients with cryptogenic hepatitis. The close relationship between the human HEV-4 isolates identified in this study and swine isolates implied that zoonotic transmission of HEV might be a source of infection in patients with hepatitis.

Hepatitis E virus as an emerging zoonotic pathogen

Hepatitis E outbreaks are a serious public health concern in developing countries. The disease causes acute infections, primarily in young adults. The mortality rate is approximately 2%; however, it can exceed 20% in pregnant women in some regions in India. The causative agent, hepatitis E virus (HEV), has been isolated from several animal species, including pigs. HEV genotypes 3 and 4 have been isolated from both humans and animals, and are recognized as zoonotic pathogens. Seroprevalence studies in animals and humans indirectly suggest that HEV infections occur worldwide. The virus is primarily transmitted to humans via undercooked animal meats in developed countries. Moreover, transfusion- and transplantation-mediated HEV infections have recently been reported. This review summarizes the general characteristics of hepatitis E, HEV infection status in animals and humans, the zoonotic transmission modes of HEV, and HEV vaccine development status.

Epidemiology of Hepatitis E Virus in European Countries

Over the last decade the seroprevalence of immunoglobulin (IgG) anti hepatitis E virus (HEV) has been increasing in European countries and shows significant variability among different geographical areas. In this review, we describe the serological data concerning the general population and risk groups in different European countries. Anti-HEV antibody prevalence ranged from 1.3% (blood donors in Italy) to 52% (blood donors in France). Various studies performed on risk groups in Denmark, Moldova and Sweden revealed that swine farmers have a high seroprevalence of HEV IgG (range 13%-51.1%), confirming that pigs represent an important risk factor in HEV infection in humans. Subtypes 3e,f are the main genotypes detected in the European population. Sporadic cases of autochthonous genotype 4 have been described in Spain, France, and Italy. Although most HEV infections are subclinical, in immune-suppressed and transplant patients they could provoke chronic infection. Fulminant hepatitis has rarely been observed and it was related to genotype 3. Interferon and ribavirin treatment was seen to represent the most promising therapy.

Current Knowledge on Hepatitis E

Although only a single serotype of hepatitis E virus (HEV), the causative agent of hepatitis E, has been identified, there is great genetic variation among the different HEV isolates reported. There are at least four major recognized genotypes of HEV: genotypes 1 and 2 are mainly restricted to humans and linked to epidemic outbreaks in nonindustrialized countries, whereas genotypes 3 and 4 are zoonotic in both developing and industrialized countries. Besides human strains, genotype 3 and 4 strains of HEV have been genetically characterized from swine, sika deer, mongooses, sheep, and rabbits. Currently, there are approximately 11,000 human and animal sequences of HEV available at the International Nucleotide Sequence Database Collaboration. HEV is the major cause of waterborne outbreaks of hepatitis in areas of poor sanitation. Additionally, it is responsible for sporadic cases of viral hepatitis in not only endemic but industrialized countries as well. Transmission of HEV occurs predominantly by the fecal-oral route, although parenteral and perinatal routes have been reported. HEV infection develops in most individuals as a self-limiting, acute, icteric hepatitis; with mortality rates around 1%. However, some affected individuals will develop fulminant hepatic failure, a serious condition that is frequently fatal without a liver transplant. This complication is particularly common when the infection occurs in pregnant women, where mortality rates rise dramatically to up to 25%. Among the preventive measures available to avoid HEV infection, two separate subunit vaccines containing recombinant truncated capsid proteins of HEV have been shown to be highly effective in the prevention of disease. One of them, HEV 239, was approved in China, and its commercialization by Innovax began in November 2012 under the name Hecolin(®).

A survey on the status of hepatitis e virus infection among slaughterhouse workers in South Korea

Objectives:

The seroprevalence of hepatitis E virus (HEV) among high-risk groups overseas is high, but studies in these groups are rare in South Korea. We conducted the present study from April to November 2012 to obtain data on the seroprevalence and associated risk factors for HEV among slaughterhouse workers in South Korea.

Methods:

Slaughterhouse workers from 80 workplaces nationwide were surveyed in South Korea in 2012. The subjects comprised 1848 cases: 1434 slaughter workers and 414 residual products handlers. By visiting 80 slaughterhouses, which were mixed with 75 of which also performed residual products handling, we conducted a questionnaire survey for risk factors and obtained blood samples in order to determine the seropositivity and seroprevalence of HEV. Anti-HEV IgG and IgM were measured using HEV IgG and IgM enzyme-linked immunospecific assay kits and HEV antigen was measured by reverse transcription polymerase chain reaction (RT-PCR).

Results:

The seropositivity of anti-HEV IgG was 33.5% (slaughter workers 32.8% and residual products handlers 36.2%), and among the seropositive individuals the seroprevalence of anti-HEV IgM was 0.5% (slaughter workers 0.5%, residual products handlers 0.7%). The response rate of HEV-antigen as measured by RT-PCR was 0.2%. Risk factors significantly related to anti-HEV IgG seropositivity were age, sex , and working duration (slaughter workers only).

Conclusions:

There were significant risk factors (sex, age, and working duration) for HEV identified in our study. All three positive cases for HEV-antigen by RT-PCR were related to pig slaughter but without statistical significance. To prevent HEV, an educational program and working guidelines may be needed for high risk groups.

Hepatitis E Virus (HEV) seroprevalence in the general population of the Republic of Korea in 2007-2009: a nationwide cross-sectional study

Background

Hepatitis E virus (HEV) is an emerging pathogen associated with endemic and acute viral hepatitis. In this study, we investigate the HEV seroprevalence and putative risk factors by a nationwide cross-sectional study in the Republic of Korea.

Methods

The prevalence of anti-HEV antibody was investigated in 2,450 serum samples collected in fourth Korea National Health and Nutrition Examination Survey. In addition, epidemiological information on possible risk factors including gender, age, education, occupation, and residence location for exposure to HEV was obtained.

Results

The frequency of anti-EIA reactive sample was 5.9% (144/2450). The individuals in groups with male, older age, low education level and living in rural or coastal regions had high seroprevalence estimates (P ≤ 0.001). In addition, seroprevalence was significantly higher among individuals with self-identified skilled agricultural, forestry, and fishery workers (31.3%, P < 0.001).

Conclusions

This study provides valuable data that could be used to investigate associations of HEV seroprevalence and putative risk factors by a nationwide cross-sectional study. The high HEV seroprevalence of skilled agricultural, forestry, and fishery workers and individuals lived in coastal and rural area indicated that zoonotic transmission is an important risk factor for HEV infection in the republic of Korea. Further studies that include detailed and continuous nationwide surveys are required to identify unrecognized risk factors and to monitor the HEV infection prevalence.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-517) contains supplementary material, which is available to authorized users.

Hepatitis E: an emerging disease

Currently, the infection with the hepatitis E virus represents the most frequent cause for acute hepatitis and jaundice in the world. According to WHO estimations, around two billion people, representing one third of the world's population, live in endemic areas for HEV and, therefore, are at risk of infection. In developed countries, the circulation of the virus in both human and animal (swine, boar, deer) sewage has been confirmed; however, the incidence rate is low compared to that of developing countries where outbreaks of acute hepatitis transmitted via the fecal-oral route are originated, more frequently in the flooding season or after natural disasters, combined with deficient sanitary conditions. There are currently 4 known genotypes of HEV. Genotypes 1 and 2 are isolated in all human epidemic outbreaks in developing countries, while genotypes 3 and 4 are isolated not only in humans but also in animals, in both developing and industrialized countries. These data support genotypes 3 and 4 having zoonotic nature. The diagnosis of this disease is based in the detection of anti-HEV IgG and IgM in blood serum using enzyme-linked immunosorbent methods. However, the method that best confirms the diagnosis is the RT-PCR, which detects HEV RNA in blood serum and also provides the genotype. The clinical course is generally that of an acute hepatitis which in some cases may require hospitalization and that, in transplant patients or HIV infected individuals can become a chronic hepatitis. Furthermore, the virus constitutes an important risk for pregnant women. The hepatitis E can present a wide range of symptoms, from a subclinical case to chronic liver disease with extrahepatic manifestations. For this reason, the diagnostic is challenging if no differential diagnosis is included. There is no specific antiviral drug for hepatitis E, but satisfactory results have been observed in some patients treated with pegylated interferon alfa2a and/or ribavirin. This revision is an update of all the molecular, epidemiological, clinic and preventive knowledge on this emergent disease up to date.

Development of a novel enzyme-linked immunosorbent assay to detect anti-IgG against swine hepatitis E virus

Swine hepatitis E virus (HEV) is widespread throughout pigs in both developing and industrialized countries. This virus is an important zoonotic agent and a public concern worldwide. Infected pigs are asymptomatic, so diagnosing swine HEV relies on detection of the virus or antibodies against the virus. However, several obstacles need to be overcome for effective and practical serological diagnosis. In this study, we developed an enzyme-linked immunosorbent assay (ELISA) that used a purified recombinant capsid protein of swine HEV. The potential clinical use of this assay was evaluated by comparing it with a commercial kit (Genelabs Technologies, Diagnostics, Singapore). Results of the ELISA were highly correlated with those of the commercial kit with a sensitivity of 97% and specificity of 95%. ROC (receiving operator characteristic) analysis of the ELISA data produced a value of 0.987 (95% CI, 0.977~0.998, p < 0.01). The cut-off value for the ELISA was also determined using negative pig sera. In summary, the HEV-specific ELISA developed in the present study appears to be both practical and economical.

Detection of hepatitis E virus (HEV) through the different stages of pig manure composting plants

Hepatitis E virus (HEV) is an increasing cause of acute hepatitis in industrialized countries. The aim of this study was to evaluate the presence of HEV in pig manure composting plants located in Spain. For this purpose, a total of 594 samples were taken in 54 sampling sessions from the different stages of composting treatment in these plants as follows: slurry reception ponds, anaerobic ponds, aerobic ponds, fermentation zone and composting final products. HEV was detected by reverse transcription polymerase chain reaction (RT-nested PCR) in four (80%) of five plants studied, mainly in the first stages of the process. HEV was not detected in any final product (compost) sample, destined to be commercialized as a soil fertilizer, suggesting that composting is a suitable method to eliminate HEV and thus, to reduce the transmission of HEV from pigs to humans.

Seroprevalence of Hepatitis E Virus infection among volunteer blood donors in central province of Iran in 2012

BACKGROUND AND OBJECTIVES

Hepatitis E virus (HEV) is a major public health concern in developing countries. HEV transmission occurs primarily by the fecal-oral route. It has also been reported that blood donors are potentially able to cause transfusion-associated hepatitis E in endemic areas. This study aimed to determine the seroprevalence of HEV infection among volunteer blood donors in Central province of Iran in 2012.

MATERIAL AND METHODS

A total of 530 consecutive blood donor samples collected from Blood Transfusion Organization, Central Province of Iran. All samples were tested for the presence of IgG Hepatitis E antibody (anti-HEV) using enzyme-linked immunosorbent assay (ELISA).

RESULTS

From 530 blood donors, 91.9% were male and 8.1% were female. Overall, anti-HEV was found in 76 of 530 samples (14.3%). There was no significant difference in HEV seropositivity between the subjects regarding gender and area of residence (urban vs. rural). Anti-HEV was distributed among all age groups. Although people aged 31-50 years had the highest prevalence, but there was no statistical difference between the age groups.

CONCLUSION

This study shows a relatively high prevalence of anti-HEV in the blood donors of Central province of Iran. More investigations are needed to assess the potential benefit of adding HEV screening of blood products to the current blood donor selection criteria.

New approaches in microbial pathogen detection

Viruses are common causes of foodborne outbreaks. Viral diseases have low fatality rates but transmission to humans via food is important due to the high probability of consuming fecally contaminated food or water because of poor food handling. Because of the low infectious doses of some foodborne viruses, there is a need for standardization and the development of new sensitive methods for detecting viruses. The focus is on molecular and non-molecular approaches, and emerging methods for the detection of foodborne viruses. The detection of noroviruses, hepatitis A and E viruses, rotaviruses and adenoviruses will be discussed. The chapter will conclude with insights into future research directions.

Seroprevalence of anti-hepatitis E virus (HEV) in a Korean population: comparison of two commercial anti-HEV assays

Background

Hepatitis E virus (HEV) has emerged as an important cause of epidemic and sporadic acute viral hepatitis worldwide. This study investigated the seroprevalence of anti-HEV in a Korean population and compared the performance of two commercially available anti-HEV assays.

Methods

A total 147 health-check examinees were randomly sampled as matched to the age- and sex- adjusted standard population based on the Korean National Census of 2007. Serum immunoglobulin G anti-HEV was determined by using the Genelabs assay (Genelabs, Singapore) and the Wantai assay (Wantai, Beijing, China).

Results

The overall anti-HEV seroprevalence was 23.1% (95% CI, 16.1-30.1%) using the Wantai assay and 14.3% (95% CI, 8.3-20.3%) using the Genelabs assay. Only 12 samples (8.1%) were positive for anti-HEV as measured by both assays; agreement between the two assays was poor (kappa value of 0.315). The anti-HEV seroprevalence increased with age from 2% and 3% in the people younger than 20-years-of-age to 34.6% and 42.3% in those over 59-years-of-age by the Genelabs and Wantai assay, respectively.

Conclusions

The HEV seroprevalence in Korean population is about 20% overall, with seroprevalence increasing in this population with increasing age. There was poor concordance in the results of the Genelabs and Wantai assays, which warrants further study concerning a reliable diagnostic test for the diagnosis of hepatitis E.

Current status of hepatitis e virus infection in Korea

Hepatitis E virus (HEV) is an emerging pathogen associated with acute viral hepatitis, and HEV is becoming increasingly recognized. Approximately 2% of acute viral hepatitis is caused by HEV, and 18 cases of hepatitis E have been reported in Korea. Of these cases, only two have involved a history of travel from India, which suggests that they were imported cases. The remaining reported cases include a sporadic case of acute hepatitis E with genotype 4 HEV isolates and identification of the full genome sequence, as well as another case of genotype 4 HEV hepatitis that developed after ingestion of the raw bile juice of a wild bear living on a mountain in southern Korea. Moreover, genotype 3 HEV, which shows close genetic homology with swine HEV in Korea, has been detected in collected human serum samples. Therefore, genotypes 3 and 4 HEV are currently circulating in the Korean community and may be related to zoonotic transmission and food-borne infection. The reported anti-HEV seroprevalence of 17% to 27% in the Korean population suggests that HEV infection has been autochthonously circulating, thereby resulting in subclinical infection in Korea. Given the discrepancies among anti-HEV assays, the diagnosis of hepatitis E should be made with caution using adequate antibody assays, and HEV RNA should be preferably detected from the stool. Further virological characterization and epidemiological study of the virus are warranted.

Seroprevalence of hepatitis a and e viruses based on the third Korea national health and nutrition survey in Korea

Objectives

The purpose of this study was to investigate the seroprevalence of hepatitis A virus (HAV) and hepatitis E virus (HEV) in Korea during 2005.

Methods

Study subjects were selected from across Korea using a stratified multistage probability sampling design, and HAV and HEV seroprevalence was compared on the basis of sex, age, and residency. A total of 497 rural and urban people aged 10–99 years of age (mean ± SD age = 28.87 ± 17.63 years) were selected by two-stage cluster sampling and tested serologically for anti-HAV and anti-HEV IgG using an enzyme-linked immunosorbent assay.

Results

Among this population, the overall seroprevalence of HAV was 63.80% (55.21% aged in their 20s and 95.92% in their 30s, p < 0.01) and that of HEV was 9.40% (5.21% aged in their 20s and 7.14% in their 30s, p < 0.01). Seroprevalence also varied according to area of residence. HEV prevalence in rural areas was higher than that of urban regions based on the anti-HEV antibody, odds ratio 3.22 (95% confidence interval: 1.46–7.10, p < 0.01). There were no significant differences between male and female against anti-HAV/HEV antibodies.

Conclusion

Our study suggested that the seropositive rates of HAV and HEV might be related to age and environmental conditions.

A systematic review/meta-analysis of primary research investigating swine, pork or pork products as a source of zoonotic hepatitis E virus

The objectives of our study were to identify and categorize primary research investigating swine/pork as a source of zoonotic hepatitis E virus (HEV) using the relatively new technique of scoping study, and to investigate the potential association between human exposure to swine/pork and HEV infection quantitatively using systematic review/meta-analysis methodology. From 1890 initially identified abstracts, 327 were considered for the review. Five study design types (cross-sectional, prevalence, genotyping, case-report and experimental transmission studies) were identified. A significant association between occupational exposure to swine and human HEV IgG seropositivity was reported in 10/13 cross-sectional studies. The association reported between pork consumption and HEV IgG seropositivity was inconsistent. The quantification of viral load in swine and retail pork, viral load required for infection in primates, cohort and case-control studies in humans, and formal risk assessment are recommended before specific public-health policy actions are taken.

The complete genome sequence and molecular analysis of human hepatitis E virus genotype IV identified from a Korean patient

Hepatitis E virus (HEV) was originally identified as the etiological agent of non-HAV enterically transmitted hepatitis. One HEV strain (FJ763142) was identified from an acute viral hepatitis E patient with IgM anti-HEV in Korea. The complete genome sequence consisted of 7,238 nucleotides (nt) plus a 22-nt poly(A) tail. The strain belongs to genotype IV, with 91% homology compared with AB197674, which was found in a Japanese patient who had traveled to China. This finding suggests that HEV genotype IV already circulates in Korea, and this HEV might be the first example of an indigenous strain.

Molecular detection of genotype 3 porcine hepatitis E virus in aborted fetuses and their sows

By reverse transcription (RT)-nested polymerase chain reaction (PCR), hepatitis E virus (HEV) RNA was simultaneously detected in the livers of aborted fetuses and in fecal and serum samples from their sows, obtained from two of 14 farms tested. Sequence and phylogenetic analyses showed that these HEVs belonged to genotype 3 HEV. HEV RNA was detected by real-time RT-PCR at 2.0 x 10(3)-2.8 x 10(4) viral copies/microl in the HEV-positive samples. All HEV-positive fetuses tested positive for porcine circovirus type 2 (PCV2). These results indicate that transplacental infection of HEV with PCV2 coinfection may occur in sows with reproductive failure, which is suggestive of similarities to HEV infection in women.

Analysis of complete genome sequences of swine hepatitis E virus and possible risk factors for transmission of HEV to humans in Korea

The hepatitis E virus (HEV) is an emerging zoonotic agent, for which pigs are the most important reservoir. Complete genome sequences of two swine HEV strains, designated swKOR-1 and swKOR-2, were determined via RT-PCR and RACE-PCR. The strains contained genomes composed of 7,222- and 7,221-bp excluding the poly(A) tails, respectively. The swKOR-1 and swKOR-2 strains were classified into subtype 3a of genotype 3 via phylogenetic analysis. These strains formed a distinctive cluster in the phylogenetic tree with human and swine HEVs isolated in the USA and human HEVs isolated in Japan. Anti-HEV antibodies were identified via ELISA in 8 of 99 (8.1%) cats, whereas, among 115 cattle and 213 dogs, no HEV-specific antibodies were detected. The conserved RNA-dependent RNA polymerase (RdRp) gene of HEV could be detected via RT-PCR in 8.7% of raw oysters collected from coastal regions in Korea. The HEV RNAs detected in oysters were identified as belonging to subtype 3a. The HEV RNAs in oysters most closely resembled that of the swKOR-2 strain. They also showed a close genetic relationship with the swKOR-1 strain and the swine and human HEVs isolated in the USA. This is the first report describing the detection in oysters of HEV that may have originated from genotype 3 swine HEV in Korea. Pigs and cats infected with HEV, as well as oysters contaminated with HEV, are potential risk factors for HEV transmission to humans.

[Recent etiology and clinical features of acute viral hepatitis in a single center of Korea]

BACKGROUND AND AIMS

The etiology of acute viral hepatitis in Korea has been dynamically changing during the recent years. The aim of this study was to investigate the recent etiology and the clinical features of acute viral hepatitis in a single center of Korea.

METHODS

We performed a retrospective analysis of a prospective cohort of 55 patients who were diagnosed with acute viral hepatitis A to E during the period from May 2005 to August 2006. In addition to the clinically acute manifestations, the confirmatory serological tests were performed for the diagnosis of acute hepatitis A, B, C and E.

RESULTS

The proportion of patients with acute viral hepatitis A, B, C, E and others were 56.4% (n=31), 12.7% (n=7), 18.2% (n=10), 9.1% (n=5) and 3.6% (n=2), respectively. The mean age of the patients with acute hepatitis A, B, C and E were 29.1+/-4.38, 38.7+/-11.72, 45.3+/-17.62 and 32.4+/-6.58 years, respectively. There was no fatal case. All cases of acute hepatitis B and six out of ten cases of acute hepatitis C recovered spontaneously. Four out of the five patients with acute hepatitis E had no history of travel to endemic area.

CONCLUSIONS

The most common etiology of acute viral hepatitis in Korea is hepatitis A virus, and hepatitis C and B virus were the next most common causes. The sporadic cases of acute hepatitis E were not rare, and coinfection of HAV and HEV was observed. A multicenter, prospective study is warranted in the future.

Hepatitis E: a complex and global disease

Thirty years after its discovery, the hepatitis E virus (HEV) continues to represent a major public health problem in developing countries. In developed countries, it has emerged as a significant cause of non-travel-associated acute hepatitis. HEV infects a wide range of mammalian species and a key reservoir worldwide appears to be swine. Genomic sequence similarity between some human HEV genotypes and swine HEV strains has been identified and we know that humans can acquire HEV infection from animals. Although for the most part the clinical course of HEV infection is asymptomatic or mild, significant risk of serious disease exists in pregnant women and those with chronic liver disease. In addition, there are data on the threat of chronic infections in immunocompromised patients. Beyond management of exposure by public health measures, recent data support that active immunisation can prevent hepatitis E, highlighting the need for vaccination programmes. Here we review the current knowledge on HEV, its epidemiology, and the management and prevention of human disease.

Hepatitis E virus in Isfahan Province: a population-based study

INTRODUCTION

Hepatitis E virus (HEV) is an enterically transmitted acute viral hepatitis with the highest incidence in Asia, Africa, the Middle East, and Central America. There are few published data on the epidemiology of the infection in Iran. Hence, this study was carried out to evaluate anti-HEV seroprevalence in Isfahan Province, Iran.

METHODS

In 2005, a cross-sectional study of 816 subjects over 6 years of age from urban and rural areas of Isfahan Province, selected using the multistage cluster sampling method, was undertaken. Demographic data and blood samples were collected, and anti-HEV antibodies were measured by ELISA method. The Chi-square test was used for statistical analysis and p<0.05 was considered significant.

RESULTS

Of the study subjects, 428 were female (52.5%) and 388 were male (47.5%). The overall anti-HEV seroprevalence rate was 3.8%. There was no significant difference in HEV seropositivity between the subjects grouped according to gender (4.2% in females and 3.4% in males, p=0.78), household number (p=0.95), and area of residence (2.7% in rural and 4.1% in urban areas, p=0.09). HEV seroprevalence increased with age from 0.9% in children aged 6-9 years to 8.1% in persons over 50 years old, without statistical differences (p=0.08). There were statistical differences in HEV seropositivity in the different regions of Isfahan Province, with the highest prevalence seen in Khomeini Shahr (13.3%; p<0.001).

CONCLUSION

HEV seroprevalence in Isfahan Province is lower than that previously reported in other parts of Iran and the Middle East area. More studies in other parts of Iran are needed to obtain a prevalence map for creating preventional strategies.

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.

[Seroprevalences of hepatitis A and E infections in Tunisia]

OBJECTIVE

Viral hepatitis A (HAV) and E (HEV) infections are still frequent in many regions of the world, particularly in developing countries where sanitary conditions and socioeconomic level are frequently low. In this work, we have studied seroprevalences of these two infections in Tunisian children, teenagers and young adults.

MATERIAL AND METHODS

The studied population included 3357 individuals from different regions of Tunisia and distributed in three groups 1 (n=1145), 2 (n=707) and 3 (n=1505) with a mean of age of 6.94, 12.84 and 20.71 years, respectively.

RESULTS

Rates of HAV infection prevalence of 84.0, 90.5 and 91.7% were found within groups 1, 2 and 3, respectively. These rates are lower than those previously found in the country; thus, primary infection with HAV in Tunisia is progressively shifting to older ages, which is probably due to the improvement of sanitary conditions. Lower anti-HAV prevalences were found in costal regions as compared to the rest of the country. This difference may be due to the higher socioeconomic level of the population living in costal regions. Antibodies against HEV were assessed in individuals of group 3. A seroprevalence of 4.3% was found which indicates that, despite the absence of epidemics, the virus is circulating among the Tunisian population as sporadic cases.

CONCLUSION

The present work contributes to a better knowledge of HAV and HEV infections in Tunisia and highlights the need of the establishment of a national program for virological surveillance of hepatitis cases and of further studies to monitor changes in the epidemiology of these infections.

Prevalence of hepatitis E virus and sapovirus in post-weaning pigs and identification of their genetic diversity

Hepatitis E virus (HEV) and sapovirus (SaV) induce acute hepatitis and gastroenteritis, respectively, in humans. As pigs have been recognized as an important reservoir for these viruses, we evaluated the infection rates of both viruses using fecal samples collected from post-weaning pigs via RT-PCR methods. In the five swine farms assessed in this study, 3 farms were found to be HEV-positive and 4 farms were SaV-positive. The overall prevalence of HEV and SaV in the pigs was 17.0 and 23.1%, respectively. Phylogenetic tree analysis revealed that the isolated swine HEVs belonged to genotype 3 and the porcine SaVs belonged to genogroup III. This study proved that both HEV and SaV are prevailing in post-weaning pigs in Korea.

Molecular characterization of hepatitis E virus detected in swine farms in the province of Quebec

Swine Hepatitis E virus (HEV) could be a zoonotic agent for HEV infection in humans. In Canada, approximately 60% of 6-mo-old commercial pigs are seropositive for HEV; the prevalence is higher in the provinces of Quebec and Ontario. A study was set up to evaluate the presence of swine HEV in Quebec farms and to compare the strains detected in fecal samples with human and swine HEV strains reported worldwide. Fecal samples were collected randomly from May 2003 to January 2004 from 70 swine farms in Quebec. In 24 specimens, representing 34% of the visited farms, HEV RNA was extracted and detected by nested reverse-transcription polymerase chain reaction (RT-PCR). All amplified nested RT-PCR products were purified, cloned, and sequenced. The nucleotide sequences of a 304 base pair fragment at the 5' end of the open reading frame 2 gene were determined. Phylogenetic analysis revealed that the 24 amplified fragments clustered in genotype 3 and had 85% to 99% nucleotide-sequence similarity with HEV strains identified in Japan, the United States, and Canada. Three strains identified in the study (swSTHY1, swSTHY31, and swSTHY47) showed 95% homology with 2 Japanese (swJ1-1 and HE-JA10) and 1 American (US1) HEV human strains.

Detection of swine hepatitis E virus in the porcine hepatic lesion in Jeju Island

Swine hepatitis E virus (HEV) is an emerging zoonotic pathogen due to its close genomic similarity to human HEV. The prevalence of swine HEV in the hepatic lesion of pigs from the Jeju Island was investigated by reverse transcriptase polymerase chain reaction (RT-PCR). In total, 40 pigs with hepatitis lesions were selected from 19 different farms, based on examination by microscopy. RT-PCR findings revealed swine HEV in 22 cases (55%), including 18 suckling pigs and 4 growing pigs. Several histopathological lesions, including multifocal lymphoplasmacytic hepatitis, portal inflammation, and focal hepatocellular necrosis, were observed in liver sections of swine HEV PCR-positive pigs. The present study suggests that the prevalence of swine HEV is very high in the pig population in Jeju Island, and that pigs are infected at early stages of growth (under 2 months of age). The high prevalence of swine HEV in pigs in Jeju Island and the ability of this virus to infect across species puts people with swine-associated occupations at possible risk of zoonotic infection.

Increased hepatitis E virus prevalence on Dutch pig farms from 33 to 55% by using appropriate internal quality controls for RT-PCR

Pigs have been suggested to be a potential reservoir for locally acquired human hepatitis E virus (HEV) infections in the Netherlands. To study possible trends in HEV prevalence in the Dutch pig population, 97 pig farms have been screened for the presence of HEV in stools. The prevalence rate of HEV was estimated at 55% (53/97) in 2005, indicating a significant increase as compared to the prevalence rate of 22% (25/115) as was reported in 1999. The current data suggest that this increase is due to the inclusion of appropriate quality assurance controls such as internal amplification controls for RT-PCR. The abundant presence of pigs excreting HEV raises concerns on potential zoonotic transmission of the virus, either by exposure through the environment or by consumption of contaminated pork products. Moreover, one of the detected strains belonged to a European cluster which was not detected in the Netherlands before, suggesting that HEV strains spread through European countries. These data demonstrate the need to include appropriate controls in diagnostic assays, especially in complex matrices such as feces which are known to contain PCR inhibitory substances.

Transmission dynamics of hepatitis E among swine: potential impact upon human infection

BACKGROUND

Hepatitis E virus (HEV) infection is a zoonosis for which pigs play a role as a reservoir. In Japan, the infection has been enzootic in swine. Clarifying the detailed mechanisms of transmission within farms is required in order to facilitate an understanding of the age-specific patterns of infection, especially just prior to slaughter.

RESULTS

Here we reanalyze a large-scale seroprevalence survey dataset from Japanese pig farms to estimate the force of infection. The forces of infection of swine HEV were estimated to be 3.45 (95% confidence interval: 3.17, 3.75), 2.68 (2.28, 3.14) and 3.11 (2.76, 3.50) [x10-2 per day] in Hokkaido, Honshu and Kyushu, respectively. The estimates with our model assumptions indicated that the average ages at infection ranged from 59.0-67.3 days and that the basic reproduction number, R0, was in the order of 4.02-5.17. Sensitivity analyses of age-specific incidence at different forces of infection revealed that a decline in the force of infection would elevate the age at infection and could increase the number of virus-excreting pigs at the age of 180 days.

CONCLUSION

Although our estimates imply that more than 95% of pigs are infected before the age of 150 days, the model shows that a decline in the force of infection could increase the risk of pig-to-human transmission. If the force of infection started to decline, it might be necessary to implement radical countermeasures (e.g. separation of uninfected pigs from infected herds beginning from the end of the suckling stage) to minimize the number of virus-positive pigs at the finishing stage.

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.

Comparison of real-time reverse transcriptase-polymerase chain reaction and nested or commercial reverse transcriptase-polymerase chain reaction for the detection of hepatitis E virus particle in human serum

Hepatitis E virus (HEV) was originally identified as the causative agent of enterically transmitted non-A, non-B hepatitis. The virus is the 7.5-kb single-stranded positive RNA virus and has been classified in the genus Herpevirus [corrected] of the [corrected] Herpeviridae [corrected] Recently, HEVs were identified from several countries worldwide from human and animals including swine. Studies on the genomic analysis of HEV isolates and seroprevalence of anti-HEV antibodies suggested that HEV has been considered as a potent zoonotic agent. The HEV infection has been diagnosed by detection of anti-HEV antibodies or virus by using reverse transcriptase-polymerase chain reaction (RT-PCR) methods in the blood or feces. However, these diagnostic methods were not quantitative and not enough to diagnose small amounts of target molecules. Moreover, these methods were not adequate during the incubation period or early acute phase. To overcome these problems, real-time RT-PCR method was developed with a cloned viral DNA and in vitro transcribed cRNA in this study. The sensitivity of the reaction was 1.68 x 10(1) copies per reaction. Correlation coefficient values of the reactions in the repeated experiments were over 0.99. Ranges of slopes and coefficient variation values were from 3.341 to 3.435 and from 1.20 to 5.98, respectively. In comparison of the real-time PCR with nested or commercial RT-PCR, HEV particles could be detected in the negative samples, which were determined by conventional nested RT-PCR.

Prevalence and genotyping of hepatitis E virus in swine population in Korea between 1995 and 2004: a retrospective study

Hepatitis E virus (HEV) infections have been reported in pigs throughout the world but have only recently been recorded in Korean pigs. The aim of this study was to investigate whether HEV was present in archived porcine hepatic tissues collected between 1995 and 2004 using RT-PCR and immunohistochemistry and, if so, to determine the genotype of the isolates. Swine HEV was identified in the liver tissue of 42 pigs of 388 submissions (four pigs every year on average). The isolates showed genetic homology with swine and human HEV isolates identified in the United States and Japan (92.5-97%) and phylogenetic tree analysis indicated they belonged to genotype III. The study indicates that HEV is not a newly emerging virus in Korean pigs, but a pathogen that has existed in the country since at least 1995.