Hepatitis E virus genome detection in commercial pork livers and pork meat products in Germany

Persistence of hepatitis E virus (HEV) subtypes 3c and 3e: Long-term cold storage and heat treatments

Hepatitis E virus (HEV) is the causative agent of foodborne infections occurring in high income countries mainly by consumption of undercooked and raw pork products. The virus is zoonotic with pigs and wild boars as the main reservoirs. Several studies proved the presence of HEV-RNA in pork liver sausages, pâté and other pork by-products. However, the detection of HEV nucleic acids does not necessary correspond to infectious virus and information on the persistence of the virus in the food is still limited. To which extent and how long the virus can survive after conventional industrial and home-made conservation and cooking procedures is largely unknown. In the present study, we investigated the persistence of two subtypes of HEV-3, by measuring the viral RNA on cell supernatant of infected A549 cells, after long-term storage at +4 °C and -20 °C and after heating for short or long-time span. Results confirmed that either low temperature storage (+4 °C) or freezing (-20 °C) do not influence the survival of the virus, and only a moderate reduction of presence of its RNA after 12 weeks at +4 °C was observed. To the other side, heating at 56 °C for long time (1 h) or at higher temperatures (>65 °C) for shorter time inactivated the virus successfully.

Prevalence, Genetic Diversity, and Quantification of the RNA Genome of the Hepatitis E Virus in Slaughtered Pigs in Serbia

The goal of this study conducted in Serbia was to detect HEV in pig liver samples from slaughterhouses, retail outlets, and environmental swabs over the course of a year. All positive HEV samples were measured and expressed as HEV gene copy numbers per gram of sample, and a representative number of samples were sequenced using the Sanger approach. A total of 45 HEV-positive samples were re-amplified using nested RT-PCR employing CODEHOP primers targeting ORF2 (493 nucleotides). The average prevalence of the HEV genotype 3 in all pig liver samples from the slaughterhouses was 29%, while HEV prevalence was 44% in liver samples from animals younger than 3 months. HEV RNA was found in thirteen out of sixty (22%) environmental swab samples that were taken from different surfaces along the slaughter line. Our findings confirmed seasonal patterns in HEV prevalence, with two picks (summer and winter periods) during the one-year examination. Among HEV-positive samples, the average viral particles for all positive liver samples was 4.41 ± 1.69 log10 genome copies per gram. Phylogenetic analysis revealed the majority of HEV strains (43/45) from Serbia were grouped in the HEV-3a subtype, while two strains were classified into the HEV-3c subtype, and one strain could not be classified into any of the HEV-3 subtypes.

Development of a Sensitive and Specific Quantitative RT-qPCR Method for the Detection of Hepatitis E Virus Genotype 3 in Porcine Liver and Foodstuff

As an international and zoonotic cause of hepatitis, hepatitis E virus (HEV) poses a significant risk to public health. However, the frequency of occurrence and the degree of contamination of food of animal origin require further research. The aim of this study was to develop and validate a highly sensitive quantitative RT-qPCR assay for the detection and quantification of HEV contamination in porcine liver and food. The focus was on genotype 3, which is most common as a food contaminant in developed countries and Europe. The selected assay has its target sequence in the open reading frame 1 (ORF1) of the HEV genome and showed good results in inclusivity testing, especially for HEV genotype 3. The developed assay seems to show high efficiency and a low intercept when compared to other assays, while having a comparable limit of detection (LOD). In addition, a standard curve was generated using artificially spiked liver to provide more accurate quantitative results for contamination assessment and tracking in this matrix. Application of the assay to test 67 pig livers from different origins resulted in a positivity rate of 7.5%, which is consistent with the results of numerous other prevalence studies. Quantitative detection of the viral genome in the food chain, particularly in pig livers, is essential for understanding the presence and evolution of HEV contamination and thus ensures consumer safety.

Detection of hepatitis E RNA in pork products at point of retail in Ireland - Are consumers at risk?

Hepatitis E (HEV), a zoonotic virus, is the leading cause of acute viral hepatitis in Europe. The presence of HEV in domestic pigs can result in infections in humans through consumption of pork products which are undercooked or where processing methods are insufficient to inactivate the virus. In Ireland, pork accounts for 34 % of all meat consumption (CSO, 2022) and the prevalence of HEV in products at point of retail has not previously been characterised. A sampling strategy was designed in which high pork content sausages, fresh pork liver and raw fermented sausages were systematically purchased from three types of retailers between May 2018 and March 2019. In total, 200 pork products were tested using a lysing agent to release the HEV from the product for detection. RT-PCR for HEV was performed on samples with an extraction efficiency >1 % (n = 188/200) (94 %). Low level HEV RNA was detected in 9/188 (4.8 %) pork products tested. The highest incidence of HEV RNA was in pork liver where 6/25 (24 %) samples were positive. The concentration of HEV ranged from 0.02 - to 9.4 genome copies/g of pork. Based on these data an exposure assessment was performed which found that if consumers followed advice from the Food Safety Authority of Ireland to achieve core temperatures of 70 °C or higher when cooking, the risk was likely to be negligible.

Metabarcoding of Hepatitis E Virus Genotype 3 and Norovirus GII from Wastewater Samples in England Using Nanopore Sequencing

Norovirus is one of the largest causes of gastroenteritis worldwide, and Hepatitis E virus (HEV) is an emerging pathogen that has become the most dominant cause of acute viral hepatitis in recent years. The presence of norovirus and HEV has been reported within wastewater in many countries previously. Here we used amplicon deep sequencing (metabarcoding) to identify norovirus and HEV strains in wastewater samples from England collected in 2019 and 2020. For HEV, we sequenced a fragment of the RNA-dependent RNA polymerase (RdRp) gene targeting genotype three strains. For norovirus, we sequenced the 5' portion of the major capsid protein gene (VP1) of genogroup II strains. Sequencing of the wastewater samples revealed eight different genotypes of norovirus GII (GII.2, GII.3, GII.4, GII.6, GII.7, GII.9, GII.13 and GII.17). Genotypes GII.3 and GII.4 were the most commonly found. The HEV metabarcoding assay was able to identify HEV genotype 3 strains in some samples with a very low viral concentration determined by RT-qPCR. Analysis showed that most HEV strains found in influent wastewater were typed as G3c and G3e and were likely to have originated from humans or swine. However, the small size of the HEV nested PCR amplicon could cause issues with typing, and so this method is more appropriate for samples with high CTs where methods targeting longer genomic regions are unlikely to be successful. This is the first report of HEV RNA in wastewater in England. This study demonstrates the utility of wastewater sequencing and the need for wider surveillance of norovirus and HEV within host species and environments.

A Multifaceted Approach for Evaluating Hepatitis E Virus Infectivity In Vitro: Cell Culture and Innovative Molecular Methods for Integrity Assessment

Hepatitis E virus is a prominent cause of viral hepatitis worldwide. In Western countries, most infections are asymptomatic. However, acute self-limiting hepatitis and chronic cases in immunocompromised individuals can occur. Studying HEV is challenging due to its difficulty to grow in cell culture. Consequently, the detection of the virus mainly relies on RT-qPCR, which cannot differentiate between infectious and non-infectious particles. To overcome this problem, methods assessing viral integrity offer a possible solution to differentiate between intact and damaged viruses. This study aims at optimizing existing HEV cell culture models and RT-qPCR-based assays for selectively detecting intact virions to establish a reliable model for assessing HEV infectivity. In conclusion, these newly developed methods hold promise for enhancing food safety by identifying approaches for inactivating HEV in food processing, thereby increasing food safety measures.

The hepatitis E virus ORF1 hypervariable region confers partial cyclophilin dependency

Hepatitis E virus (HEV) is an emerging pathogen responsible for more than 20 million cases of acute hepatitis globally per annum. Healthy individuals typically have a self-limiting infection, but mortality rates in some populations such as pregnant women can reach 30 %. A detailed understanding of the virus lifecycle is lacking, mainly due to limitations in experimental systems. In this regard, the cyclophilins are an important family of proteins that have peptidyl-prolyl isomerase activity and play roles in the replication of a number of positive-sense RNA viruses, including hepatotropic viruses such as hepatitis C virus (HCV). Cyclophilins A and B (CypA/B) are the two most abundant Cyps in hepatocytes and are therefore potential targets for pan-viral therapeutics. Here, we investigated the importance of CypA and CypB for HEV genome replication using sub-genomic replicons. Using a combination of pharmacological inhibition by cyclosporine A (CsA), and silencing by small hairpin RNA we find that CypA and CypB are not essential for HEV replication. However, we find that silencing of CypB reduces replication of some HEV isolates in some cells. Furthermore, sensitivity to Cyp silencing appears to be partly conferred by the sequence within the hypervariable region of the viral polyprotein. These data suggest HEV is atypical in its requirements for cyclophilin for viral genome replication and that this phenomenon could be genotype- and sequence-specific.

Detection of Hepatitis E Virus in Rabbits and Rabbit Meat from Slaughterhouses in Hebei Province of China

Background: Hepatitis E virus (HEV) is a zoonotic pathogen. HEV has been found to be widely prevalent in rabbits. Its isolates are classified into HEV-3, rabbit subgenotype (HEV-3ra). The routes of human infection with HEV-3ra remain unclear; however, foodborne transmission is possible when asymptomatically infected animals enter the food chain. The prevalence of HEV infection in slaughtered rabbits and the presence of HEV in rabbit meat were evaluated in this study. Materials and Methods: In three slaughterhouses in Hebei province, China, samples of rabbit blood were collected during the slaughter process, and muscle, liver, and cavity juice were collected from the rabbit carcasses. Anti-HEV antibody in serum samples was detected using enzyme-linked immunosorbent assay. HEV RNA was tested in all samples by reverse transcription nested PCR (RT-nested PCR). The final amplicons of RT-nested PCR were sequenced and phylogenetically analyzed. Results: Of the 459 serum samples, 50 [10.9%, 95% confidence interval (CI): 8.1-13.7] were positive for anti-HEV antibody, and 17 (3.7%, 95% CI: 2.0-5.4) were positive for HEV RNA. HEV RNA was detected in 7 of 60 liver samples (11.7%, 95% CI: 3.3-20) and 2 cavity juice samples from semi-eviscerated carcasses, but was not detected in any muscle sample from either the eviscerated or semi-eviscerated carcasses. All the detected HEV strains belonged to HEV-3ra and related most closely with the rabbit HEV sequence previously reported in China. Conclusion: A portion of rabbits were in the viremia period of HEV infection at the slaughter age, resulting in the possibility of HEV carriage by rabbit carcass, particularly semi-eviscerated carcass containing liver. These findings suggest a potential risk of HEV transmission from raw rabbit products entering the food chain, whereas the presence of HEV appeared to be lower in the eviscerated carcass than in the semi-eviscerated carcass.

An Update in Knowledge of Pigs as the Source of Zoonotic Pathogens

The available data indicate that the human world population will constantly grow in the subsequent decades. This constant increase in the number of people on the Earth will lead to growth in food demand, especially in food of high nutritional value. Therefore, it is expected that the world livestock population will also increase. Such a phenomenon enhances the risk of transmitting pathogens to humans. As pig production is one of the most significant branches of the world's livestock production, zoonoses of porcine origins seem to be of particular importance. Therefore, in this review, we aim to introduce the latest data concerning, among other things, epidemiology and available preventive measures to control the most significant porcine zoonoses of viral, bacterial, and parasitic origin.

High Hepatitis E Virus (HEV) Seroprevalence and No Evidence of HEV Viraemia in Vietnamese Blood Donors

The prevalence of hepatitis E virus (HEV) in the Vietnamese population remains underestimated. The aim of the present study was to investigate the seroprevalence of HEV IgG/IgM antibodies and the presence of HEV RNA in blood donors as a part of epidemiological surveillance for transfusion-transmitted viruses. Serum samples from blood donors (n = 553) were analysed for markers of past (anti-HEV IgG) and recent/ongoing (anti-HEV IgM) HEV infections. In addition, all serum samples were subsequently tested for HEV RNA positivity. The overall prevalence of anti-HEV IgG was 26.8% (n = 148/553), while the seroprevalence of anti-HEV IgM was 0.5% (n = 3/553). Anti-HEV IgG seroprevalence in male and female donors was similar (27.1% and 25.5%, respectively). A higher risk of hepatitis E exposure was observed with increasing age. None of the blood donors were HEV RNA positive, and there was no evidence of HEV viraemia. Although the absence of HEV viraemia in blood donors from Northern Vietnam is encouraging, further epidemiological surveillance in other geographical regions is warranted to rule out transfusion-transmitted HEV.

Hepatitis A Virus and Hepatitis E Virus as Food- and Waterborne Pathogens-Transmission Routes and Methods for Detection in Food

Foodborne viruses are an important threat to food safety and public health. Globally, there are approximately 5 million cases of acute viral hepatitis due to hepatitis A virus (HAV) and hepatitis E virus (HEV) every year. HAV is responsible for numerous food-related viral outbreaks worldwide, while HEV is an emerging pathogen with a global health burden. The reported HEV cases in Europe have increased tenfold in the last 20 years due to its zoonotic transmission through the consumption of infected meat or meat products. HEV is considered the most common cause of acute viral hepatitis worldwide currently. This review focuses on the latest findings on the foodborne transmission routes of HAV and HEV and the methods for their detection in different food matrices.

Risk Factors for Hepatitis E Virus Infection and Eating Habits in Kidney Transplant Recipients

There is a significant risk for ongoing and treatment-resistant courses of hepatitis E virus (HEV) infection in patients after solid organ transplantation. The aim of this study was to identify risk factors for the development of hepatitis E, including the dietary habits of patients. We conducted a retrospective single-center study with 59 adult kidney and combined kidney transplant recipients who were diagnosed with HEV infection between 2013 and 2020. The outcomes of HEV infections were analyzed during a median follow-up of 4.3 years. Patients were compared with a control cohort of 251 transplant patients with elevated liver enzymes but without evidence of an HEV infection. Patients' alimentary exposures during the time before disease onset or diagnosis were assessed. Previous intense immunosuppression, especially treatment with high-dose steroids and rituximab, was a significant risk factor to acquire hepatitis E after solid organ transplantation. Only 11 out of 59 (18.6%) patients reached remission without further ribavirin (RBV) treatment. A total of 48 patients were treated with RBV, of which 19 patients (39.6%) had either viral rebounds after the end of treatment or did not reach viral clearance at all. Higher age (>60 years) and a BMI ≤ 20 kg/m² were risk factors for RBV treatment failure. Deterioration in kidney function with a drop in eGFR (p = 0.046) and a rise in proteinuria was more common in patients with persistent hepatitis E viremia. HEV infection was associated with the consumption of undercooked pork or pork products prior to infection. Patients also reported processing raw meat with bare hands at home more frequently than the controls. Overall, we showed that the intensity of immunosuppression, higher age, a low BMI and the consumption of undercooked pork meat correlated with the development of hepatitis E.

[Viral zoonoses in Germany: a One Health perspective]

The COVID-19 pandemic and the increasing occurrence of monkeypox (mpox) diseases outside Africa have illustrated the vulnerability of populations to zoonotic pathogens. In addition, other viral zoonotic pathogens have gained importance in recent years.This review article addresses six notifiable viral zoonotic pathogens as examples to highlight the need for the One Health approach in order to understand the epidemiology of the diseases and to derive recommendations for action by the public health service. The importance of environmental factors, reservoirs, and vectors is emphasized, the diseases in livestock and wildlife are analyzed, and the occurrence and frequency of diseases in the population are described. The pathogens selected here differ in their reservoirs and the role of vectors for transmission, the impact of infections on farm animals, and the disease patterns observed in humans. In addition to zoonotic pathogens that have been known in Germany for a long time or were introduced recently, pathogens whose zoonotic potential has only lately been shown are also considered.For the pathogens discussed here, there are still large knowledge gaps regarding the transmission routes. Future One Health-based studies must contribute to the further elucidation of their transmission routes and the development of prevention measures. The holistic approach does not necessarily include a focus on viral pathogens/diseases, but also includes the question of the interaction of viral, bacterial, and other pathogens, including antibiotic resistance and host microbiomes.

Hepatitis E virus in pork meat products and exposure assessment in Belgium

Zoonotic hepatitis E virus (HEV) genotype 3 infections are the predominant cause of acute viral hepatitis in Europe, mostly associated with the consumption of HEV contaminated pork meat. In this study we looked at the HEV RNA positivity rate of pork meat products readily available from Belgian supermarkets and evaluated the overall HEV consumer exposure in a Belgian context. Two basic assessments were performed in a 'worst-case' scenario setting: one solely focusing on the contamination level of the product itself (ingredients and processing parameters) and another estimating the overall consumer exposure, taking into account consumption habits in Belgium. Non-thermal-processed ready-to-eat (i.e. ready for consumption without additional cooking step by consumer) pork meat products (e.g. raw dried sausages), had a high estimated HEV contamination level, while thermal-processed ready-to-eat pork meat products (e.g. pork liver pâté) had the highest overall consumer exposure estimates. Following these assessments, pork liver pâtés, raw dried hams and raw dried sausages (n = 54) were purchased from Belgian supermarkets (n = 3) and analyzed for HEV RNA by RT-PCR. In total, 31 % (n = 17) products tested positive. HEV RNA was found in 65 % of the pork liver pâtés, 15 % of raw dried hams and 0 % of raw dried sausages. Phylogenetic analysis of four isolates (all gt3c) from pork liver pâté samples showed similarities with human clinical cases from Germany and Belgium.

Animal reservoirs for hepatitis E virus within the Paslahepevirus genus

Hepatitis E virus (HEV) is responsible for acute hepatitis in humans. It is a single-stranded, positive-sense RNA virus that belongs to the Hepeviridae family. The majority of concerning HEV genotypes belong to the Paslahepevirus genus and are subsequently divided into eight genotypes. HEV genotypes 1 and 2 exclusively infect humans and primates while genotypes 3 and 4 infect both humans and other mammals. Whereas HEV genotypes 5 and 6 are isolated from wild boars and genotypes 7 and 8 were identified from camels in the United Arab Emirates and China, respectively. HEV mainly spreads from humans to humans via the fecal-oral route. However, some genotypes with the capability of zoonotic transmissions, such as 3 and 4 transmit from animals to humans through feces, direct contact, and ingestion of contaminated meat products. As we further continue to uncover novel HEV strains in various animal species, it is becoming clear that HEV has a broad host range. Therefore, understanding the potential animal reservoirs for this virus will allow for better risk management and risk mitigation of infection with HEV. In this review, we mainly focused on animal reservoirs for the members of the species Paslahepevirus balayani and provided a comprehensive list of the host animals identified to date.

Transmission of Hepatitis E Virus

Transmission of hepatitis E virus (HEV) occurs predominantly by the fecal-oral route. Large epidemics of hepatitis E in the developing countries of Asia and Africa are waterborne and spread through contaminated drinking water. The reservoir of HEV in developed countries is believed to be in animals with zoonotic transmission to humans, possibly through direct contact or the consumption of undercooked contaminated meat. And HEV transmission through blood transfusion, organ transplantation, and vertical transmission has been reported.

Prevalence of Hepatitis E Virus (HEV) in Feral and Farmed Wild Boars in Xinjiang, Northwest China

Hepatitis E virus (HEV) causes infections in humans and a wide range of animal hosts. Wild boar is an important natural reservoir of HEV genotypes 3−6 (HEV-3−HEV-6), but comparative analysis of HEV infections in both feral and farmed wild boars remains limited. In this study, samples from 599 wild boars were collected during 2017−2020, including 121 feral wild boars (collected 121 fecal, 121 serum, and 89 liver samples) and 478 farmed wild boars (collected 478 fecal and 478 serum samples). The presence of anti-HEV IgG antibodies were detected by the HEV-IgG enzyme-linked immunosorbent assay (ELISA) kit. HEV RNA was detected by reverse transcription polymerase chain reaction (RT-PCR), targeting the partial ORF1 genes from fecal and liver samples, and the obtained genes were further genotyped by phylogenetic analysis. The results showed that 76.2% (95% CI 72.1−79.9) of farmed wild boars tested anti-HEV IgG seropositive, higher than that in feral wild boars (42.1%, 95% CI 33.2−51.5, p < 0.001). HEV seropositivity increased with age. Wild boar HEV infection presented a significant geographical difference (p < 0.001), but not between sex (p = 0.656) and age (p = 0.347). HEV RNA in fecal samples was detected in 13 (2.2%, 95% CI 1.2−3.7) out of 599 wild boars: 0.8% (95% CI 0.0−4.5, 1/121) of feral wild boars and 2.5% (95% CI 1.3−4.3, 12/478) of farmed wild boars. Phylogenetic analysis showed that all these viruses belonged to genotype HEV-4, and further grouped into sub-genotypes HEV-4a, HEV-4d, and HEV-4h, of which HEV-4a was first discovered in the wild boar populations in China. Our results suggested that farms could be a setting for amplification of HEV. The risk of HEV zoonotic transmission via rearing and consumption of farmed wild boars should be further assessed.

Serological Evidence of Hepatitis E Virus (HEV) Infection Among Ruminant Farmworkers: A Retrospective Study from Malaysia

Background

As scant data are available about Hepatitis E virus (HEV) infection in Malaysia, this study aimed to determine the seroprevalence of HEV amongst ruminant farmworkers in Malaysia.

Methods

A total of 87 farmworkers provided serum samples, which were collected from eight farms. All serum samples were tested for anti-HEV IgG and anti-HEV IgM by an enzyme-linked immunosorbent assay (ELISA) using the Wantai HEV-IgG and HEV-IgM ELISA kits from Beijing Wantai Biological Pharmacy Enterprise Co., Ltd, Beijing, China.

Results

Farmworkers from six cattle farms, one sheep farm and one goat farm were investigated in this study. Only one farm practices zero-grazing, with the rest using rotational grazing. Of the 87 farmworkers, males comprised 83.9%, and almost half (47.1%) were aged 20-35 years old. By ethnic group, the vast majority were Malay. Most of the farmworkers have good hygiene practices; washing or changing their clothes and showering after dealing with farm animals were common. None of the farmworker serum samples had anti-HEV IgM and IgG detected (95% confidence interval (CI): 0, 0.0415).

Conclusion

The finding suggests that the farmworkers had no previous exposure to Hepatitis E, and were not at risk of occupational exposure to HEV infection. Our findings suggest that a zero seroprevalence of HEV infection among ruminant farmworkers in the Muslim majority country. Good farm management, hygiene practices and the absence of contact with swine-related contamination might have contributed to the no or minimal zoonotic risks of HEV amongst farmworkers surveyed in this study.

In silico study on the Hepatitis E virus RNA Helicase and its inhibition by silvestrol, rocaglamide and other flavagline compounds

Hepatitis E Virus (HEV) follows waterborne or zoonotic/foodborne transmission. Genotype 3 HEV infections are worldwide spread, especially in swine populations, representing an emerging threat for human health, both for farm workers and pork meat consumers. Unfortunately, HEV in vitro culture and analysis are still difficult, resulting in a poor understanding of its biology and hampering the implementation of counteracting strategies. Indeed, HEV encodes for only one non-structural multifunctional and multidomain protein (ORF1), which might be a good candidate for anti-HEV drugging strategies. In this context, an in silico molecular modelling approach that consisted in homology modelling to derive the 3D model target, docking study to simulate the binding event, and molecular dynamics to check complex stability over time was used. This workflow succeeded to describe ORF1 RNA Helicase domain from a molecular standpoint allowing the identification of potential inhibitory compounds among natural plant-based flavagline-related molecules such as silvestrol, rocaglamide and derivatives thereof. In the context of scouting potential anti-viral compounds and relying on the outcomes presented, further dedicated investigations on silvestrol, rocaglamide and a promising oxidized derivative have been suggested. For the sake of data reproducibility, the 3D model of HEV RNA Helicase has been made publicly available.

Characterization of a Near Full-Length Hepatitis E Virus Genome of Subtype 3c Generated from Naturally Infected South African Backyard Pigs

Eight genotypes of the hepatitis E virus (Orthohepevirus A; HEV) designated HEV-1 to HEV-8 have been reported from various mammalian hosts. Notably, domestic pigs and wild boars are the natural reservoirs of HEV-3 and HEV-4 genotypes with zoonotic propensity. Since HEV infection in domestic pigs is usually subclinical, it may remain undetected, facilitating zoonotic spillover of HEV to the exposed human populations. A previous study from our group in 2021, using deep sequencing of a pooled saliva sample, generated various swine enteric virus genomes, including a near full-length swine HEV genome (7040 nt; 97.7% genome coverage) from five-month-old grower pigs at a backyard pig farm in the uMgungundlovu District, KwaZulu-Natal, South Africa. In the present study, we describe the further characterization, including genotyping and subtyping of the swine HEV isolate using phylogenetics and ‘HEVnet Typing Tool’. Our analyses confirmed that the South African swine HEV genome characterized in this study belonged to HEV genotype 3 subtype 3c (HEV-3c). While HEV-3c infections in domestic pigs have been previously reported from Brazil, Germany, Italy, and the Netherlands, they only generated partial genome sequences of open reading frame 1 (ORF1) and/or ORF2. To our knowledge, this is the first near full-length swine HEV-3c genome generated from naturally infected domestic pigs (Sus scrofa domesticus) in South Africa. However, due to the gap in the information on the HEV-3c genome sequences in various geographical locations worldwide, including South Africa, the epidemiology of the South African swine HEV genome characterized in this study remains inconclusive. Molecular and genomic surveillance of HEV in domestic pig populations in South Africa would be useful to determine their prevalence, circulating subtypes, and zoonosis risk.

Isolation of 15 hepatitis E virus strains lacking ORF1 rearrangements from wild boar and pig organ samples and efficient replication in cell culture

As a zoonotic pathogen, the hepatitis E virus (HEV) leads to numerous infections in humans with different clinical manifestations. Especially genotype 3, as causative agent of a foodborne zoonosis, is transmitted to humans by ingestion of undercooked or raw meat containing liver from HEV-infected animals. Although the virus' prevalence and dissemination in hosts like wild boar and pig have been well characterized, HEV is greatly understudied on a molecular level and reliable cell culture models are lacking. For this reason, the present study concentrated on the isolation and subsequent characterization of porcine HEV from tissue samples derived from wild boar and domestic pigs: 222 wild boars hunted in Northern Germany were investigated for the presence of HEV RNA with a detection rate of 5.9%. Three additional HEV-positive wild boar liver samples as well as an HEV-positive spleen and a positive kidney from domestic pigs were included. After inoculation of positive samples onto the human hepatoma cell line PLC/PRF/5, cells were grown for several weeks. Successful isolation was confirmed by RT-qPCR, virus passage, immunofluorescence staining and titration. Overall, 15 strains from a total of 18 RNA-positive organ samples could be obtained and viral loads >10⁹  RNA copies/ml were measured in cell culture supernatants. Accordingly, 83.3% of the HEV RNA-positive samples contained infectious hepatitis E viral particles and therefore must be considered as a potential source for human infections. Phylogenetic analyses revealed that all isolated strains belong to genotype 3. Further genetic characterization showed a high degree of sequence variability, but no sequence insertions, in the hypervariable region within the open reading frame 1.

[Hepatitis E virus-a zoonotic virus: distribution, transmission pathways, and relevance for food safety]

Das Hepatitis-E-Virus (HEV) ist ein Erreger einer akuten Hepatitis beim Menschen. Darüber hinaus treten zunehmend auch chronische Infektionen mit fataler Leberzirrhose bei immunsupprimierten Transplantationspatienten auf. Die Zahl der gemeldeten Hepatitis-E-Fälle in Deutschland hat in den vergangenen Jahren stark zugenommen. Hier kommt vor allem der Genotyp 3 vor, der zoonotisch von Tieren auf den Menschen übertragen werden kann. Haus- und Wildschweine, die ohne die Ausbildung klinischer Symptome infiziert werden, stellen das Hauptreservoir dar. In diesem Artikel werden die Verbreitung von HEV in Tieren in Deutschland, mögliche Übertragungswege des Virus und insbesondere die Bedeutung von Lebensmitteln bei der Übertragung anhand der aktuellen wissenschaftlichen Literatur dargestellt.

HEV ist in Haus- und Wildschweinen in Deutschland stark verbreitet und wird hauptsächlich über direkten Kontakt oder den Verzehr von Lebensmitteln, die aus diesen Tieren hergestellt wurden, auf den Menschen übertragen. Beim HEV-RNA-Nachweis in spezifischen Lebensmitteln bleibt allerdings oft unklar, ob das enthaltene Virus noch infektiös ist oder durch die Herstellungsbedingungen inaktiviert wurde. Neuere Studien weisen auf eine hohe Stabilität des HEV unter verschiedenen physikochemischen Bedingungen hin, wohingegen eine Inaktivierung unter anderem durch Erhitzung erreicht wird. Generell wird deshalb ein ausreichendes Erhitzen von Schweinefleisch und -leber vor dem Verzehr empfohlen und für Risikogruppen zusätzlich der Verzicht auf den Verzehr kurzgereifter Rohwürste.

Weitere Forschungen sind nötig, um relevante Risikolebensmittel zu identifizieren, alternative Übertragungswege zu untersuchen und effiziente Maßnahmen zu entwickeln, die eine zoonotische Virusübertragung zukünftig verringern oder vermeiden.

Risk of transfusion-transmitted hepatitis E virus infection from pool-tested platelets and plasma

BACKGROUND AND AIMS

Immunocompromised patients are at risk of chronic hepatitis E which can be acquired by blood transfusions. Currently, screening of blood donors (BDs) for HEV RNA with a limit of detection (LOD) of 2,000 IU/ml is required in Germany. However, this may result in up to 440,000 IU of HEV RNA in blood products depending on their plasma volume. We studied the residual risk of transfusion-transmitted (tt) HEV infection when an LOD of 2,000 IU/ml is applied.

METHODS

Highly sensitive individual donor testing for HEV RNA on the Grifols Procleix Panther system (LOD 7.89 IU/ml) was performed. HEV loads were quantified by real-time PCR.

RESULTS

Of 16,236 donors, 31 (0.19%) were HEV RNA positive. Three BDs had viral loads between 710 and 2,000 IU/ml, which pose a significant risk of tt hepatitis E with any type of blood product. Eight BDs had viral loads of >32 to 710 IU/ml, which pose a risk of tt hepatitis E with platelet or plasma transfusions because of their higher plasma volume compared to red blood cell concentrates. Eight of these 11 potentially infectious BDs were seronegative for HEV, indicating a recent infection. Only 8 of 31 donors had viral loads >2,000 IU/ml that would also have been detected by the required screening procedure and 12 had very low HEV loads (<32 IU/ml).

CONCLUSIONS

Screening of BDs with an LOD of 2,000 IU/ml reduced the risk of tt HEV infection by about 73% for red blood cell concentrates but by just 42% for platelet and fresh frozen plasma transfusions. Single donor screening (LOD <32 IU/ml) should lead to an almost 100% risk reduction.

LAY SUMMARY

Immunocompromised patients, such as solid organ or hematopoietic stem cell recipients, are at risk of chronic hepatitis E, which can be acquired via blood transfusions. The risk of transfusion-transmitted hepatitis E in these patients may not be sufficiently controlled by (mini-)pool hepatitis E virus RNA screening of blood donors. Single donor screening should be considered to improve the safety of blood products.

Estimating the burden and modeling mitigation strategies of pork-related hepatitis E virus foodborne transmission in representative European countries

Hepatitis E virus (HEV) is an emerging zoonotic pathogen posing global health burden, and the concerns in Europe are tremendously growing. Pigs serve as a main reservoir, contributing to pork-related foodborne transmission. In this study, we aim to specifically simulate this foodborne transmission route and to assess potential interventions. We firstly established a dose-response relationship between the risk of transmission to human and the amount of ingested viruses. We further estimated the incidence of HEV infection specifically attributed to pork-related foodborne transmission in four representative European countries. Finally, we demonstrated a proof-of-concept of mitigating HEV transmission by implementing vaccination in human and pig populations. Our modeling approach bears essential implications for better understanding the transmission of pork-related foodborne HEV and for developing mitigation strategies.

Cell Culture Isolation and Whole Genome Characterization of Hepatitis E Virus Strains from Wild Boars in Germany

Infection with hepatitis E virus (HEV) can cause acute and chronic hepatitis in humans. The HEV genotype 3 can be zoonotically transmitted from animals to humans, with wild boars representing an important reservoir species. Cell culture isolation of HEV is generally difficult and mainly described for human isolates so far. Here, five sera and five liver samples from HEV-RNA-positive wild boar samples were inoculated onto PLC/PRF/5 cells, incubated for 3 months and thereafter passaged for additional 6 weeks. As demonstrated by RT-qPCR, immunofluorescence and immune electron microscopy, virus was successfully isolated from two liver samples, which originally contained high HEV genome copy numbers. Both isolates showed slower growth than the culture-adapted HEV strain 47832c. In contrast to this strain, the isolated strains had no insertions in their hypervariable genome region. Next generation sequencing using an HEV sequence-enriched library enabled full genome sequencing. Strain Wb108/17 belongs to subtype 3f and strain Wb257/17 to a tentative novel subtype recently described in Italian wild boars. The results indicate that HEV can be successfully isolated in cell culture from wild boar samples containing high HEV genome copy numbers. The isolates may be used further to study the zoonotic potential of wild boar-derived HEV subtypes.

Low Prevalence of HEV Infection and No Associated Risk of HEV Transmission from Mother to Child among Pregnant Women in Vietnam

Infections with HEV in low- and middle-income countries (LMICs) are associated with increased rates of preterm birth, miscarriage, and stillbirth. The aim of the present study was to investigate HEV infections in pregnant women and the possibility of mother-to-child transmission, and associated outcomes. A total of 183 pregnant women in their third trimester were recruited and followed until delivery. Anti-HEV IgG and IgM were determined via enzyme-linked immunosorbent assay (ELISA), and HEV nucleic acids were detected in stool and cord blood samples. HEV genotypes were identified by Sanger sequencing, and phylogenetic analyses were performed. Mother-to-child transmission and associated adverse outcomes were not observed. Only 2% of patients (n = 4/183) tested positive for anti-HEV IgM, and 8% (n = 14/183) tested positive for anti-HEV IgG antibodies. Cord blood (n = 150) analysis showed that there was no IgM detected, while 4% (n = 6/150) tested positive for anti-HEV IgG, which was consistent with mothers testing positive for anti-HEV IgG. Nucleic acid tests for HEV RNA yielded 2% (n = 4/183) from the serum and stool of pregnant women, and none from cord blood. The HEV isolates belonged to the genotype HEV-3a, with 99% homology with humans and 96% with pigs. No association was found between the risk of HEV infection and pregnancy outcomes or HEV transmission from mother to child. HEV-3 infections of zoonotic origin in pregnancy might have eventually resolved without complications.

Hepatitis E: An update on One Health and clinical medicine

The hepatitis E virus (HEV) is one of the main causes of acute hepatitis and the de facto global burden is underestimated. HEV-related clinical complications are often undetected and are not considered in the differential diagnosis. Convincing findings from studies suggest that HEV is clinically relevant not only in developing countries but also in industrialized countries. Eight HEV genotypes (HEV-1 to HEV-8) with different human and animal hosts and other HEV-related viruses are in circulation. Transmission routes vary by genotype and location, with large waterborne outbreaks in developing countries and zoonotic food-borne infections in developed countries. An acute infection can be aggravated in pregnant women, organ transplant recipients, patients with pre-existing liver disease and immunosuppressed patients. HEV during pregnancy affects the fetus and newborn with an increased risk of vertical transmission, preterm and stillbirth, neonatal jaundice and miscarriage. Hepatitis E is associated with extrahepatic manifestations that include neurological disorders such as neuralgic amyotrophy, Guillain-Barré syndrome and encephalitis, renal injury and haematological disorders. The risk of transfusion-transmitted HEV is increasingly recognized in Western countries where the risk may be because of a zoonosis. RNA testing of blood components is essential to determine the risk of transfusion-transmitted HEV. There are currently no approved drugs or vaccines for HEV infections. This review focuses on updating the latest developments in zoonoses, screening and diagnostics, drugs in use and under development, and vaccines.

Genetic Diversity and Epidemiological Significance of Wild Boar HEV-3 Strains Circulating in Poland

The wild boar is the most important reservoir of zoonotic HEV-3 strains among different wildlife species. The aim of the study was subtype identification of wild boar HEV-3 strains circulating in Poland. Wild boar liver was used in the study in the form of homogenates prepared from 57 samples positive for HEV in a real-time RT-PCR. These samples were collected from juvenile and adult wild boars hunted in the jurisdictions of different Regional Directorates of State Forests (RDSF) across Poland. Subtype identification of detected HEV strains was based on a phylogenetic analysis of the most conserved HEV ORF2 genome fragment. Out of 57 tested samples, consensus HEV ORF2 sequences of 348 bp were obtained for 45 strains. Nineteen strains were identified and belonged to the HEV gt 3a and 3i subtypes, whereas 26 were not assigned to any virus subtype. HEV gt 3i strains prevailed in the Polish wild boar population, 16 of such were identified, and they were significantly more often observed in the RDSF Katowice area (χ² = 28.6, p = 0.027 (<0.05)) compared to other regions of the country. Circulation of 3a strains was limited only to the RDSF Gdańsk territory (χ² = 48, p = 0.000 (<0.05)). The virus strains detected in the Polish population of wild boars representing previously identified HEV subtypes in wild boars, pigs, or humans in Europe are of epidemiological importance for public health.

The Risk of Transfusion-Transmitted Hepatitis E Virus: Evidence from Seroprevalence Screening of Blood Donations

Throughout the world, there has been growing concern over the risk of hepatitis E virus (HEV) transmission via blood transfusion. The present study screened blood donor samples for anti-HEV immunoglobulin M (IgM) and immunoglobulin G (IgG). The prevalence of HEV infection was assessed on a total of 1,003 archived serum samples obtained from the National Blood Centre, Malaysia. The samples were collected from healthy blood donor from Klang Valley between 2017 and 2018. All samples were tested for IgM and IgG antibodies to HEV using enzyme-linked immunosorbent assays (ELISA). HEV-specific IgG antibodies were detected in 31/1003 (3.1%; 95% confidence interval [CI] 2.1%–4.4%) and IgM in 9/1003 (0.9%; 95% CI 0.4%–1.7%) samples. In bivariate analysis, there was no significant difference in the prevalence of anti-HEV IgG with respect to gender and district of origin. Although not statistically significant, males had higher odds of having anti-HEV IgG than females (odds ratio [OR] = 2.86; 95% CI 0.95–8.64). All anti-HEV IgG positive individuals were people of Chinese descent. Anti-HEV IgG increased significantly with age, from 0.6% (95% CI 0.1%–2.6%) of 18–30-year-old donors to 7.4% (95% CI 2.7%–17.0%) of donors older than 50 years and was highest among non-professional workers (5.3%; 95% CI 2.5%–10.5%). Increasing age and a non-professional occupation remained significant predictors for anti-HEV IgG in the multivariable analysis. Screening of blood donations for HEV in Malaysia is important to safeguard the health of transfusion recipients. The higher rates of HEV infection in blood from older donors and donors who are non-professional workers may provide insights into targeted groups for blood screening.

Interlaboratory Validation of a Detection Method for Hepatitis E Virus RNA in Pig Liver

Background: In the last years, the number of notified hepatitis E cases in humans has continuously increased in Europe. Foodborne infection with the zoonotic hepatitis E virus (HEV) genotype 3 is considered the major cause of this disease. Undercooked liver and raw sausages containing the liver of pigs and wild boar are at high risk of containing HEV. However, so far, no standardized method for the detection of HEV-RNA in pig liver is available. Methods: An international collaborative study on method reproducibility involving 11 laboratories was performed for an HEV-RNA detection method, which consists of steps of sample homogenization, RNA extraction and real-time RT-PCR detection, including a process control. Naturally contaminated pork liver samples containing two different amounts of HEV and a HEV-negative pork liver sample were tested by all laboratories using the method. Results: Valid results were retrieved from 10 laboratories. A specificity of 100% and a sensitivity of 79% were calculated for the method. False negative results were only retrieved from the sample containing very low HEV amounts near the detection limit. Conclusions: The results show that the method is highly specific, sufficiently sensitive and robust for use in different laboratories. The method can, therefore, be applied to routine food control as well as in monitoring studies.