Hepatitis E virus infection in central China reveals no evidence of cross-species transmission between human and swine in this area. PLoS One. 2009;4:e8156. [PMID: 19997619 PMCID: PMC2785466 DOI: 10.1371/journal.pone.0008156]

Hepatitis E virus infection in buffaloes in South China

ABSTRACT Hepatitis E virus (HEV) infection is an important global public health issue. HEV infections are recognized as a zoonotic disease. Swine are believed to be the main reservoir of HEV. Recently, yaks, cows, and yellow cattle have been reported as new reservoirs of HEV. However, whether other species of cattle and buffaloes are sensitive to HEV infection is unknown. To investigate the prevalence of HEV infection in buffaloes, enzyme-linked immunosorbent assay (ELISA) and reverse transcription-nested polymerase chain reaction (RT-nPCR) were performed. Only one buffalo was positive to anti-HEV IgM antibody (1/106, 0.94%), and none were positive for anti-HEV IgG antibody. To our surprise, five serum (5/106, 4.72%) and three milk samples (3/40, 7.50%) from buffaloes were positive to HEV RNA. All strains of HEV isolated from buffaloes belong to genotype 4. Results indicate that buffaloes may be a new reservoir of HEV.

Prevalence of hepatitis E virus infection among people and swine in mainland China: A systematic review and meta-analysis

Hepatitis E virus (HEV) infection remains an important public health problem, and it is endemic primarily in developing countries. This study aimed to evaluate the seroprevalence of HEV among the general population, occupational population and swine in mainland China and its risk factors based on a systematic review and meta-analysis. Systematic search from EMBASE, PubMed, Web of Science, Cochrane Library and several Chinese databases, such as Wanfang (WF) Data, China National Knowledge Infrastructure (CNKI), Chinese Science and Technology Periodical Database (VIP) and SINOMED, was searched from inception up to 25 April 2018. The overall seroprevalence of HEV and its corresponding 95% confidence interval (CI) as well as the correlation coefficients between different groups were estimated using stata 12.0 and r-3.4.1 software. Potential sources of heterogeneity were explored using subgroup and sensitivity analyses. Twenty-eight studies with 57,274 participants (including human and swine) were included. The seroprevalence of anti-HEV immunoglobulin G (IgG) among the general population, occupational population and swine was 27.3% (95% CI: 22.4-32.2), 47.4% (95% CI: 40.1-54.8) and 66.4% (95% CI: 61.7-71.1), respectively. The overall prevalence of IgM among the general population was 1.8% (95% CI: 0.7-2.9). The odds ratio for the occupational population, as compared to the general population, was 2.63. The highest anti-HEV IgG prevalence (59%) was observed in East China, whereas the lowest (34.8%) was noted in Northeast and North China. In the occupational population, the highest prevalence (77.0%) was observed among swine vendors. Seven studies included 30,392 participants (humans and swine); the correlation coefficient for the prevalence of anti-HEV IgG between the professional population and adult pigs was 0.88. Sensitivity analyses showed that the stability of results was not considered significant. This research found that HEV is common in China, and contact with pork or other pig products may be an important mode of HEV transmission.

Serological evidence of hepatitis E virus infection in pigs and jaundice among pig handlers in Bangladesh

Hepatitis E virus (HEV) is the most common cause of viral hepatitis in humans. Pigs may act as a reservoir of HEV, and pig handlers were frequently identified with a higher prevalence of antibodies to HEV. The objectives of this study were to identify evidence of HEV infection in pigs and compare the history of jaundice between pig handlers and people not exposed to pigs and pork. Blood and faecal samples were collected from 100 pigs derived from three slaughterhouses in the Gazipur district of Bangladesh from January to June, 2011. We also interviewed 200 pig handlers and 250 non-exposed people who did not eat pork or handled pigs in the past 2 years. We tested the pig sera for HEV-specific antibodies using a competitive ELISA and pig faecal samples for HEV RNA using real-time RT-PCR. Of 100 pig sera, 82% (n = 82) had detectable antibody against HEV. Of the 200 pig handlers, 28% (56/200) demonstrated jaundice within the past 2 years, whereas only 17% (43/250) of controls had a history of jaundice (p < .05). Compared to non-exposed people, those who slaughtered pigs (31% versus 15%, p < .001), reared pigs (37% versus 20%, p < .001), butchered pigs (35% versus 19%, p < .001) or involved in pork transportation (28% versus 13%, p < .001) were more likely to be affected with jaundice in the preceding 2 years. In multivariate logistic regression analysis, exposure to pigs (odds ratio [OR]: 2.2, 95% CI: 1.2-3.9) and age (OR: 0.97, 95% CI: 0.95-0.99) was significantly associated with jaundice in the past 2 years. Pigs in Bangladesh demonstrated evidence of HEV infection, and a history of jaundice was significantly more frequent in pig handlers. Identifying and genotyping HEV in pigs and pig handlers may provide further evidence of the pig's role in zoonotic HEV transmission in Bangladesh.

From the epidemiology of hepatitis E virus (HEV) within the swine reservoir to public health risk mitigation strategies: a comprehensive review

Hepatitis E virus (HEV) is the causative agent of hepatitis E in humans, an emerging zoonosis mainly transmitted via food in developed countries and for which domestic pigs are recognised as the main reservoir. It therefore appears important to understand the features and drivers of HEV infection dynamics on pig farms in order to implement HEV surveillance programmes and to assess and manage public health risks. The authors have reviewed the international scientific literature on the epidemiological characteristics of HEV in swine populations. Although prevalence estimates differed greatly from one study to another, all consistently reported high variability between farms, suggesting the existence of multifactorial conditions related to infection and within-farm transmission of the virus. Longitudinal studies and experimental trials have provided estimates of epidemiological parameters governing the transmission process (e.g. age at infection, transmission parameters, shedding period duration or lag time before the onset of an immune response). Farming practices, passive immunity and co-infection with immunosuppressive agents were identified as the main factors influencing HEV infection dynamics, but further investigations are needed to clarify the different HEV infection patterns observed in pig herds as well as HEV transmission between farms. Relevant surveillance programmes and control measures from farm to fork also have to be fostered to reduce the prevalence of contaminated pork products entering the food chain.

Genotype 4 Hepatitis E Virus Prevalent in Eastern China Shows Diverse Subtypes

BACKGROUND

Hepatitis E Virus (HEV), a zoonotic pathogen, uses several species of animal as reservoirs. Swine is considered as the major reservoir for HEV infection in humans. Genotype 4 HEV is the dominant cause of hepatitis E disease in humans in China.

OBJECTIVES

Although many researches revealed that genotype 4 HEV is the main genotype that prevalent in eastern China, few researches have done to study the subtype of HEV in this area. Thus, this study aimed to investigate the subtype of HEV prevalent in eastern China.

MATERIALS AND METHODS

A total of 125 anti-HEV IgM positive human serum and 290 swine fecal samples were subjected to reverse transcription polymerase chain reaction (RT-PCR) screening of HEV RNA. Positive PCR products were sequenced and phylogenetically analyzed.

RESULTS

From a total of 125 human serum samples, 19.2% (24.125) were positive, while 9.66% (28.290) of the 290 swine fecal samples were positive for HEV RNA. Phylogenetic analysis based on partial capsid gene showed that the 51 HEV strains in the current study all belonged to genotype 4, clustering into 6 different subtypes. Our results also revealed that some of HEV isolates prevalent in the human and swine populations were classified into the same clusters.

CONCLUSIONS

Genotype 4 HEV in eastern China shows subtype diversity and some HEV isolates are involved in cross-species transmission.

Seroprevalence and evolutionary dynamics of genotype 4 hepatitis E virus in Shandong Province, China

AIM: To investigate the seroprevalence and evolutionary dynamics of hepatitis E virus (HEV) and assess the ancestor of HEVs in China’s Shandong Province.

METHODS: A total of 2028 serum, 60 fecal and 82 bile samples were collected from the general human population, patients and swine, respectively. This seroepidemiological study was conducted using an immunnosorbent assay and HEV RNA was detected by the reverse transcription-nested polymerase chain reaction (RT-nPCR) method. Complete genome sequences of the prevalent strains (CH-YT-HEV01, CH-YT-HEV02 and CH-YT-sHEV01) were determined, and the sequences were analyzed phylogenetically. In addition, the evolutionary dynamics of three HEV isolates were determined using the framework of coalescent analysis in the program package BEAST, and the time of the most recent common ancestors (TMRCAs) of China-indigenous genotype 4 HEV isolates was calculated.

RESULTS: The overall viral burden in the general human population was 0.1%, and the positive rates of anti-HEV IgG and IgM in the serum specimens were 25.1% (509/2028) and 2.3% (51/2028), respectively. In addition, IgG positivity increased with age. The phylogenetic analysis based on the full-length nucleotide sequences showed that the strain CH-YT-HEV02 was directly related to CH-YT-sHEV01 with a 94% identity, suggesting that they were involved in cross-species transmission. The isolate CH-YT-HEV01 was close to HB-3 and CHN-SD-sHEV with a bootstrap value of 100%, sharing a 96.1%-96.4% identity with each other. Surprisingly, the HB-3 strain was a representative strain prevalent in swine in Hubei, and the isolate CHN-SD-sHEV was obtained from swine in Shandong in a previous report. TMRCA for the clade of CH-YT-HEV01 and HB-3 was 2003, which was consistent with the TMRCA for the clade of CHN-SD-sHEV and HB-3, and they were both earlier than the TMRCA for the clade of CH-YT-HEV01 and CHN-SD-sHEV (2004).

CONCLUSION: The strains CH-YT-HEV01, CHN-SD-sHEV and HB-3 are involved in trans-regional transmission, and the ancestors of HEVs in Shandong come from Hubei Province.

Hepatitis E virus infection

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

Epidemiology and associated risk factors of hepatitis e virus infection in plateau state, Nigeria

A cross-sectional study in Nigeria was undertaken to determine the epidemiology, seroprevalence, and associated risk factors, of hepatitis E virus (HEV). A total of 462 subjects were used for the study, categorized into four groups: apparently healthy persons, pregnant women, HIV positive subjects, and animal handlers. Information was obtained from subjects using interviewer-administered questionnaire. Blood samples were collected and analyzed for HEV antibodies (IgG and IgM) using enzyme-linked immunosorbent assay (ELISA) technique. Results obtained were analyzed using Statistical Package for Social Sciences (SPSS) version 17.0 statistical software. The overall seroprevalence of IgG and IgM was 42.7 and 0.9%, respectively. Animal handlers had the highest seroprevalence (66.7%). The associated risk factors for IgM seroprevalence were rural dwelling (P = 0.039, odds ratio (OR) 3.3, 95% confidence interval (CI) 0.7–15.4), blood transfusion (P < 0.001, OR 9.6, 95% CI 2.6–35.6), attending to animals (P = 0.032, OR 4.9, 95% CI 0.9–26.6), and waste disposal (P < 0.001). Factors associated with IgG were age (P = 0.044), location (P < 0.001), marital status (P < 0.001), formal education (P < 0.001), farming as occupation (P < 0.001), rural dwelling (P = 0.001), waste disposal (P < 0.001), alcohol consumption (P = 0.001, OR 2.4, 95% CI 1.4–4.0), open defecation (P < 0.001, OR 2.9, 95% CI 1.4–5.7), attending to animals (P < 0.001, OR 2.3, 95% CI 1.6–3.4), consuming unwashed fruits/vegetables (P < 0.001, OR 4.2, 95% CI 0.3–54.1), and stream/river as a source of drinking water (P < 0.001, OR 3.6, 95% CI 1.6–7.8). Preventive public health measures should be reinforced among all communities, particularly domestic animal handlers and pregnant women. Potable water should be provided for all communities. Data suggest that HEV remains an under-recognized and significant public health problem, warranting further attention and research.

HEV-ORF3 Encoding Phosphoprotein Interacts With Hepsin

BACKGROUND

Hepatitis E virus (HEV) is a major causative agent of acute clinical hepatitis in adults through much of Asia, the Middle East and Africa. Open reading frame 3 (ORF3) encodes around 120 amino acids of phosphorylation protein that associates with the cytoskeleton, while its precise biological function is still unknown.

OBJECTIVES

In order to understand the function of ORF3 protein (pORF3) in depth, HEV ORF3 interacting proteins were screened in human hepatocytes cDNA library using two-hybrid system techniques and further verification of the interactions were carried out through co-immunoprecipitation (Co-IP).

MATERIALS AND METHODS

The Cyto-Trap two-hybrid system technology, a classical method for analyzing protein interactions, was used to screen the pORF3 interacting proteins from human hepatocytes cDNA library.

RESULTS

Through the Cyto-Trap two-hybrid system, eight proteins interacting with pORF3 were winnowed. The Co-IP results confirmed that hepsin which is reported to function as the inhibitor of several tumors reacted with pORF3.

CONCLUSIONS

Out of eight screened proteins interacting with pORF3, hepsin was confirmed to have specific interactions with pORF3.

Host immune status and response to hepatitis E virus infection

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

Genotype analysis of hepatitis E virus from sporadic hepatitis E cases in northern China

Hepatitis E is an important public health problem in many countries. However, there is no definite conclusion about the zoonotic reservoir, transmission patterns and risk factors of hepatitis E in the human population. The aim of this study was to analyze the epidemiological and viral genotype characteristics of hepatitis E cases in northern China. Surveillance was conducted in two hospitals in Liaoning and Hebei province from July 2010 to June 2012. Out of a total of 116 diagnosed patients, 88 (75.9%) were male and 28 (24.1%) were female and most (73%) were in the age group 40-70 years. In both hospitals, cases were diagnosed more frequently in March than in other months. HEV RNA was amplified from 41 patients and characterized by nucleotide sequencing and phylogenetic analysis. Most of the isolates (37 strains, 90.3%) were genotype 4, including subgenotypes 4a, 4b, 4d, 4h, 4i and a new subgenotype. One subgenotype 3a strain was isolated from Baoding, Hebei province. Three genotype 1b strains were found from patients in Jinzhou, Liaoning province. Most of the genotype 4 strains and the genotype 3 strains were phylogenetically related to known swine isolates. In conclusion, the finding that HEV infects mostly middle-aged and elderly men and that the incidence spiked in March may reflect the zoonotic transmission characteristics of HEV infection. Pigs, but not rabbits, were the important reservoirs in this area, because genotype 4 HEV was found to be responsible for the majority hepatitis E cases. However, genotype 1 is still present in northern China. Also, the first isolation of genotype 3 HEV in this area indicates that alternative routes of HEV transmission might exist.

Analysis of the complete genome sequences of one swine and two human hepatitis E virus genotype 4 strains isolated in Beijing, China

Full-length sequences were determined and analyzed for two human (MO and W3) and one swine (W2-5) hepatitis E virus (HEV) isolates from Beijing, China. The genomes of the three strains were composed of 7242, 7239, 7239 nucleotides, respectively, excluding the poly (A) tails, and were 84% identical to each other. All were classified into genotype 4. Sequence analysis shows that the 2 human isolates have up to 91-94% nucleotide identity in full length genome with swine strains isolated in China, while the swine isolate share 92% identity with the human strain T1 from Beijing. At the amino acid level, the three strains share 94%, 97% and 89-92% identity in the ORF1, ORF2 and ORF3, proteins respectively. The human strains MO and W3 have the highest identity, 97%, 98-99% and 96-98% in ORFs 1-3, respectively, to swine strains CHN-XJ-SW13 and CHN-XJ-SW33 from Xinjiang, China, while swine strain W2-5 has highest identity with the human strain HE-JA2, 96%, 99% and 91% in ORFs 1-3, respectively. Genotype specific amino acid substitutions were found at a single site in all three ORFs by sequences alignment, and genotype specific short sequences (5-10aa in length) were found in ORF1 and the C-terminus of ORF3. However, no difference was found at any amino acid position that discriminates between human and swine HEVs within genotype 4 for any of the three ORFs. These results indicated that the genotype 4 HEV strains from humans and pigs in China may evolve from the common ancestor.

Seasonal pattern of hepatitis E virus prevalence in swine in two different geographical areas of China

We studied seasonal patterns of swine hepatitis E virus (HEV) infection in China. From 2008 to 2011, 4200 swine bile specimens were collected for the detection of HEV RNA. A total of 92/2400 (3·83%) specimens in eastern China and 47/1800 (2·61%) specimens in southwestern China were positive for HEV. Seasonal patterns differing by geographical area were suggested. In eastern China, the major peak of HEV RNA prevalence was during March-April, with a minor peak during September-October, and a dip during July-August. In southwestern China, the peak was during September-October and the dip during March-April. The majority of subtype 4a cases (63/82, 76·83%) were detected in the first half of the year, while the majority of subtype 4b cases (26/29, 89·66%) were concentrated in the second half of the year, suggesting that different subtypes contribute to different peaks. Our results indicate that the distribution of HEV subtypes is associated with seasonal patterns.

High prevalence of hepatitis E in humans and pigs and evidence of genotype-3 virus in swine, Madagascar

Hepatitis E virus (HEV) causes an orofecal disease transmitted through poor hygiene environments, contaminated food (mainly pork products), or by contacts with infected animals. Very little data are currently available regarding the disease in the Southwestern Indian Ocean Islands. We report the first sero- and viro-survey for HEV in human and swine in Madagascar. A seroprevalence rate of 14.1% (60 of 427) was measured in slaughterhouse workers. Seroprevalence to HEV in pigs was estimated to 71.2% (178 of 250), strongly suggesting the existence of a zoonotic cycle. Three out of 250 pig livers (1.2%) tested HEV RNA-positive by quantitative polymerase chain reaction. Phylogenetic analyses based on 1-kb sequences of the ORF 2-3 identified these viruses as HEV genotype 3. Sequences clustered in a distinct Malagasy sub-clade, possibly representative of a new sub-genotype, for which the date of emergence was estimated around 1989. Further studies are needed to confirm other transmission routes of HEV to humans, especially through non-zoonotic cycles.

[Hepatitis E: molecular virology, epidemiology and pathogenesis]

Hepatitis E represents a significant proportion of enteric transmitted liver diseases and poses a major public health problem, mainly associated with epidemics due to contamination of water supplies, especially in developing countries. Hepatitis E virus (HEV) is responsible for self-limiting acute liver oral-faecal infections. In industrialised countries, acute hepatitis E is sporadic, detected in travellers from endemic areas but also in sporadic cases with no risk factors. HEV is a non-enveloped virus with a single-stranded RNA genome classified into 4 genotypes and a single serotype. Genotypes 1 and 2 only infect humans, and are predominant in the developing countries, while 3 and 4 are predominant in industrialised countries, and also infect other species of mammals, especially pigs, and multiple evidence classifies HEV as a zoonotic agent. Some HEV chronic infections have recently been reported in kidney and liver transplant patients. The mortality rate of HEV infection is greater than hepatitis A. In addition to faecal-oral transmission, parenteral transmission of HEV has also been reported. Several vaccines are currently in development. The severity of this infection in some groups of patients, especially pregnant women, and the occurrence of chronic hepatitis, even with progression to cirrhosis, have raised interest in the application of interferon and/or ribavirin therapy.

The epidemiology of hepatitis E virus infections in developed countries and among immunocompromised patients

Hepatitis E virus (HEV) is an important cause of acute hepatitis in humans worldwide, both as epidemic and sporadic disease. Since the virus was identified in 1983, epidemics have occurred regularly in many countries across South and Southeast Asia when seasonal floods have contaminated drinking water supplies and in Africa during humanitarian crises among refugee populations without access to clean water. In addition, sporadic cases and small clusters of HEV infections have been recognized throughout the world in developed countries over the past couple of decades. This review will focus on emerging evidence of HEV infection as an under-recognized pathogen in Europe, the USA and other industrialized countries. We will discuss some of the issues associated with the recognition, diagnosis and treatment of these sporadic cases. We will also summarize the recent literature on autochthonous HEV infection among populations in developed countries in industrialized Europe, the USA, Japan and other industrialized Asian countries. We will review recent reports of acute and chronic HEV infections among transplant recipients and other immunocompromised individuals including HIV/AIDS patients.

Phylogenetic analysis of 626 hepatitis E virus (HEV) isolates from humans and animals in China (1986-2011) showing genotype diversity and zoonotic transmission

Hepatitis E is considered as a public health problem in China. To determine the overall molecular epidemiology of hepatitis E virus (HEV) and analyze the situation of cross-species transmission between humans and swine in China over the last 25 years (1986-2011), 626 HEV complete and partial sequences (89 isolates identified by our group) isolated from humans and animals in China were retrieved from GenBank and subjected to phylogenetic analysis. There were three genotypes and 11 sub-genotypes of HEV prevailing in China. Furthermore, rabbit HEVs, of which the genotype is controversial, are also widespread in China. Genotype 1 was the most isolated genotype prior to 2000 and mainly detected in Xinjiang, Beijing and East China. However, genotype 4, which was identified in most regions of China during the last 10 years, has overtaken genotype 1 in frequency of isolation nationwide. Genotype 3 HEV strains have been found only in eastern China and were thought to be imported from Japan. Both genotypes 3 and 4 were found in humans and swine and cross-species transmission from pigs to humans of the two genotypes may have occurred in Northeast, Northwest, North, East and South China. These results indicate that HEV strains with considerable genetic diversity are widespread and the zoonotic transmission between swine and humans appears ubiquitous in China.

Identification of genotype 4 Hepatitis E virus binding proteins on swine liver cells

Hepatitis E virus (HEV) is a zoonotic pathogen of which several species of animal were reported as reservoirs. Swine stands out as the major reservoir for HEV infection in humans, as suggested by the close genetic relationship of swine and human virus and cross-species infection of HEV. Up to now, the mechanism of cross-species infection of HEV from swine to humans is still unclear. This study sought to identify receptor element for genotype 4 HEV on swine liver cells using the viral overlay protein binding assay (VOPBA) technique and Mass Spectrometry fingerprinting. A single virus binding band with natural molecular weight about 55 kDa was observed, and mass spectrometry revealed that this virus binding band contained 31 different proteins. Infection inhibition assay suggested that this 55 kDa protein could prevent HEV from infecting its susceptible A549 cell line, which was further confirmed by the HEV genome detecting in the inoculated cells. Further research should be performed to elucidate the accurate receptor of HEV on the swine liver cells.

Potential risk of zoonotic transmission from young swine to human: seroepidemiological and genetic characterization of hepatitis E virus in human and various animals in Beijing, China

The aim of this study was to further investigate the prevalence of infection and genotype of hepatitis E virus (HEV) among different species of animals, people whose works are related to pigs and the general population in the suburb of Beijing, China. Serum and faecal samples were collected from 10 animal species and humans. Anti-HEV was detected by enzyme immunoassays (EIA); HEV RNA was amplified by reverse transcription-nested polymerase chain reaction (RT-nPCR) method. PCR products were cloned and sequenced. The isolated swine HEV sequences were analysed phylogenetically. The positive rates of serum anti-HEV in swine, cattle, milk cow, horse, sheep, donkey, dog, duck, chicken, pig farm workers and slaughterhouse workers, and general population were 81.17% (802/988), 25.29% (66/261), 14.87% (40/269), 14.29% (40/280), 9.30% (53/514), 0 (0/25), 0 (0/20), 2.53% (8/316), 3.03% (7/231), 58.73% (37/63), 35.87% (66/184) and 20.06% (538/2682), respectively. The anti-HEV prevalence in adult swine (≥ 6 months) and younger swine (≤ 3 months) was 91.49% (591/646) and 61.7% (211/342), respectively. The positive rate of HEV RNA in young swine faeces was 47.94% (93/194). All 93 isolates from the younger swine shared 87.8-100% nucleotide homology with each other and had identities of 75.6-78.9%, 73.9-76.1%, 76.4-80.6% and 83.1-95.0% with the corresponding regions of genotypes 1-4 HEV, respectively. Phylogenetic analysis showed that all HEV isolates belong to genotype 4, subgenotype 4d. These results suggest a potential risk of zoonotic transmission of HEV from younger swine to farmers who rear pigs.

Seroepidemiology and molecular characterization of hepatitis E Virus in Macaca mulatta from a village in Yunnan, China, where infection with this virus is endemic

BACKGROUND

Hepatitis E virus (HEV) infection is a significant public health concern and has been identified as a zoonotic infection.

OBJECTIVES

Since no reports have characterized the epidemiological and genotypic features of HEV infections in Macaca mulatta (rhesus macaques) from Yunnan, China, where swine HEV infections are endemic, we aimed to investigate these characteristics.

MATERIALS AND METHODS

Seroepidemiological and molecular characterization of HEV in both Macaca mulatta and pigs from the Yunnan province of China were conducted using enzyme-linked immunosorbent assay (ELISA) and reverse transcription-nested PCR (RT-nPCR). Four hundred and eighty-two stool samples (320 from Macaca mulatta and 162 from pigs) and 92 serum samples (all from Macaca mulatta) were collected for the detection of HEV RNA and anti-HEV antibodies (IgG/IgM).

RESULTS

Thirty-three rhesus macaques (35.87%) were positive for HEV IgG. Of these, 3 were also positive for HEV IgM. Four different strains of swine HEV RNA were detected in pigs; however, we failed to detect any in Macaca mulatta.

CONCLUSIONS

Results indicate that Macaca mulatta may not be a natural reservoir of HEV.

Seroprevalence and molecular detection of hepatitis E virus in Yunnan Province, China

In this study, the prevalence and characteristics of hepatitis E virus (HEV) in pigs and the general population in the Yunnan province, China, were evaluated. Nine hundred sixty sera, 95 liver and 60 feces samples were randomly collected from pig farms and abattoirs, in addition 173 human sera were sampled in the provincial capital city for a serological survey and an RT-nPCR assay. The screening results showed that among 621 samples collected from five pig farms, the HEV-specific IgG positive rate ranged from 73.2% to 83.5%, and the overall seroprevalence was 78.9% (490/621). A further analysis revealed that the seroprevalence increased with age. The positive rate of human serum samples was 39.9% (69/173). HEV RNA was detected in five swine feces, six swine liver and one anti-HEV-IgM-positive human serum sample by RT-nPCR. Sequence and alignment of the 348-nt PCR-amplified products of 12 HEV strains identified nine distinct nucleotide sequences. Phylogenetic and molecular evolutionary analysis revealed that these nine sequences shared 84.2% to 100.0% nucleotide sequence identity with each other, with all isolates belonging to genotype 4 HEV and clustering with other Chinese swine and human HEV sequences determined earlier. This study results suggest that the prevalence of genotype 4 HEV is serious, both in pig herds and in the human population, and authorities should pay more attention to the prevalence of HEV in southwest China.

Prevalence of hepatitis E virus and porcine caliciviruses in pig farms of Guizhou province, China

BACKGROUND

Hepatitis E virus (HEV) and caliciviruses are enteric pathogens of humans and animals, and pigs have been considered an important reservoir of these viruses.

OBJECTIVES

The aim of this study is to determine the infection rates of HEV and caliciviruses (sapovirus [SaV] and norovirus [NoV]) in different age groups of pigs in Guizhou province, China, and characterize the strains that are prevalent in this mountainous area.

MATERIALS AND METHODS

A total of 209 stool samples from healthy pigs of different ages were collected from 6 pig farms in Guizhou province from May to June 2009 and tested for HEV, SaV, and NoV by reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

The overall prevalence of porcine HEV and porcine SaV was 6.7% (15/209) and 1.0% (2/209), respectively. No NoV was detected. The prevalence rates of porcine HEV infection were 15.4% in piglets aged < 1 mon (4/26), 6.8% in piglets aged between 1 and 4 mon (3/44), 12.5% in piglets aged ≈ 4 mon (6/48), and 1.1% in sows aged between 6 and 14 mon (2/91). Porcine SaV was detected only in piglets (7.7%, 2/26). All 10 HEV isolates belonged to genotype 4, clustering with a human HEV strain (AF103940) from an adjacent province.

CONCLUSIONS

This is the first report on the existence of porcine SaV in swine in Guizhou province, China. The clustering of the porcine HEV isolates with a human strain suggests cross-species transmission between swine and humans in this area.

The molecular epidemiology of hepatitis E virus infection

Molecular characterization of various hepatitis E virus (HEV) strains circulating among humans and animals (particularly swine, deer and boars) in different countries has revealed substantial genetic heterogeneity. The distinctive four-genotype distribution worldwide of mammalian HEV and varying degrees of genetic relatedness among local strains suggest a long and complex evolution of HEV in different geographic regions. The population expansion likely experienced by mammalian HEV in the second half of the 20th century is consistent with an extensive genetic divergence of HEV strains and high prevalence of HEV infections in many parts of the world, including developed countries. The rate and mechanisms of human-to-human transmission and zoonotic transmission to humans vary geographically, thus contributing to the complexity of HEV molecular evolution.

Design and evaluation of a recombinant multi-epitope-based ELISA for the serological surveillance of HEV infection in northern China

In this study, seven recombinant epitope peptides from within the ORF2 protein of the local genotype 4 swine hepatitis E virus (HEV) DQ strain were designed and analyzed. Then, a new multi-epitope-based ELISA was established. In comparison with a commercial kit, this test exhibited good specificity and sensitivity for anti-HEV genotype 4. Subsequently, this test was applied for analyzing serum samples from either swine herds or human populations in northern China. The overall seroprevalence rate of anti-HEV IgG reached up to 40.4% for swine and 8.1% for humans. A statistical difference was observed for humans in rural and urban areas, with a higher prevalence for people living in rural than urban areas. Moreover, sequencing confirmed that all RNA-positive samples belonged to genotype 4.

The serological prevalence and genetic diversity of hepatitis E virus in farmed rabbits in China

We identified and characterized a novel virus, designated rabbit hepatitis E virus (HEV), in rex rabbits farmed in China. Rabbit HEV is genetically related to but distinct from other known mammalian HEVs and avian HEV and may represent a novel genotype. To evaluate the spread and genetic variation of rabbit HEV, a total of 1094 serum samples were collected from various breeds of rabbits across ten counties in China. All sera were screened for the presence of anti-HEV antibody, HEV antigen and viral RNA. A total of 169 samples (15.4%), from nine of the ten counties, were found to be positive for HEV antibody. The seroprevalence was highest in Wuhan, Hunan Province (53.4%, 55/103). Samples positive for HEV antigen were detected in seven counties and the overall prevalence was 3.7% (41/1094). HEV RNA was detected in 22 samples and all but one of these samples was found to be positive for HEV antigen. Sequence analysis of the 304 bp amplicons within open reading frame 2 showed that all HEV isolates in this study clustered with known rabbit HEV strains, in a branch separate from genotypes 1 to 4. The rabbit HEV strains were genetically heterogeneous and divided into divergent groups. Strains from the same geographic region tended to cluster together. These results indicate that rabbit HEVs with considerable genetic diversity are prevalent in farmed rabbits in China. The potential zoonotic risk of rabbit HEV needs to be investigated and evaluated further.

Molecular and serological survey of hepatitis E virus infection among domestic pigs in Inner Mongolia, China

To evaluate the prevalence and characteristics of swine hepatitis E virus (HEV) infection in Inner Mongolia, China, serum samples obtained from 356 2- to 4-month-old pigs on 14 farms in Inner Mongolia were tested for the presence of anti-HEV antibodies and HEV RNA. Overall, 186 pigs (52%) tested positive for anti-HEV antibodies, while 30 pigs (8%) had detectable HEV RNA levels. The 30 HEV isolates recovered from the viremic pigs were phylogenetically classified into genotype 4 and differed from each other by up to 15.3% in a 412 nt sequence within ORF2. The Inner Mongolian swine HEV strains were most similar to human or swine HEV strains isolated in the other provinces of China but differed by 15.9-18.9% from those in Mongolia (formerly known as Outer Mongolia). These results indicate that farm pigs in Inner Mongolia are frequently infected with markedly divergent genotype 4 HEV strains that may be indigenous to China.