Hepatitis E virus genotype 3 in wild rats, United States

Rat hepatitis E virus cross-species infection and transmission in pigs

Strains of Rocahepevirus ratti, an emerging hepatitis E virus (HEV), have recently been found to be infectious to humans. Rats are a primary reservoir of the virus; thus, it is referred to as "rat HEV". Rats are often found on swine farms in close contact with pigs. Our goal was to determine whether swine may serve as a transmission host for zoonotic rat HEV by characterizing an infectious cDNA clone of a zoonotic rat HEV, strain LCK-3110, in vitro and in vivo. RNA transcripts of LCK-3110 were constructed and assessed for their replicative capacity in cell culture and in gnotobiotic pigs. Fecal suspension from rat HEV-positive gnotobiotic pigs was inoculated into conventional pigs co-housed with naïve pigs. Our results demonstrated that capped RNA transcripts of LCK-3110 rat HEV replicated in vitro and successfully infected conventional pigs that transmit the virus to co-housed animals. The infectious clone of rat HEV may afford an opportunity to study the genetic mechanisms of rat HEV cross-species infection and tissue tropism.

Detection of hepatitis E virus genotype 3 in an Algerian mouse (Mus spretus) in Portugal

Virus monitoring in small mammals is central to the design of epidemiological control strategies for rodent-borne zoonotic viruses. Synanthropic small mammals are versatile and may be potential carriers of several microbial agents. In the present work, a total of 330 fecal samples of small mammals were collected at two sites in the North of Portugal and screened for zoonotic hepatitis E virus (HEV, species Paslahepevirus balayani). Synanthropic small mammal samples (n = 40) were collected in a city park of Porto and belonged to the species Algerian mouse (Mus spretus) (n = 26) and to the greater white-toothed shrew (Crocidura russula) (n = 14). Furthermore, additional samples were collected in the Northeast region of Portugal and included Algerian mouse (n = 48), greater white-toothed shrew (n = 47), wood mouse (Apodemus sylvaticus) (n = 43), southwestern water vole (Arvicola sapidus) (n = 52), Cabrera's vole (Microtus cabrerae) (n = 49) and Lusitanian pine vole (Microtus lusitanicus) (n = 51). A nested RT-PCR targeting a part of open reading frame (ORF) 2 region of the HEV genome was used followed by sequencing and phylogenetic analysis. HEV RNA was detected in one fecal sample (0.3%; 95% confidence interval, CI: 0.01-1.68) from a synanthropic Algerian mouse that was genotyped as HEV-3, subgenotype 3e. This is the first study reporting the detection of HEV-3 in a synanthropic rodent, the Algerian mouse. The identified HEV isolate is probably the outcome of either a spill-over infection from domestic pigs or wild boars, or the result of passive viral transit through the intestinal tract. This finding reinforces the importance in the surveillance of novel potential hosts for HEV with a particular emphasis on synanthropic animals.

Genomic characterization of Rocahepevirus ratti hepatitis E virus genotype C1 in Yunnan province of China

The Rocahepevirus ratti hepatitis E virus genotype C1 (HEV-C1) has been documented to infect humans. However, the understanding of HEV-C1 remains constrained. This study aims to determine the prevalence and genomic characteristics of HEV-C1 in small animals in Yunnan province of southwestern China. A total of 444 liver tissues were collected from animals covering the orders Rodentia, Soricomorpha, Scandentia and Erinaceomorpha in three regions in Yunnan. Then Paslahepevirus balayani and Rocahepevirus were examined using RT-qPCR. The detection rate of Rocahepevirus was 12.95 % (36/278) in animals of order Rodentia, with 14.77 % (35/237) in Rattus tanezumi and 33.33 % (1/3) in Niviventer fulvescens. No Paslahepevirus balayani was detected. Additionally, two full-length Rocahepevirus sequences (MSE-17 and LHK-54) and thirty-three partial ORF1 sequences were amplified and determined to be HEV-C1. MSE-17 and LHK-54 shared moderate nucleotide identity (78.9 %-80.3 %) with HEV-C1 isolated in rats and humans. The HEV-C1 isolated from Niviventer fulvescens demonstrated a 100 % nucleotide identity with that from Rattus tanezumi. The rat HEV-C1 sequences isolated in our study and other Asian HEV-C1 sequences were phylogenetically distant from those isolated in North America and Europe. Furthermore, the two full-length sequences isolated in our study had less amino acid substitutions in the motifs of RNA-dependent RNA polymerase domain (F204L and L238F), compared with other Asian sequences. In summary, HEV-C1 commonly spreads in rats in Yunnan province of China. Our findings suggest a spatially associated phylogeny, and potential cross-species transmission of HEV-C1.

Rocahepevirus ratti as an Emerging Cause of Acute Hepatitis Worldwide

The hepatitis E virus (HEV) is a widespread human infection that causes mainly acute infection and can evolve to a chronic manifestation in immunocompromised individuals. In addition to the common strains of hepatitis E virus (HEV-A), known as Paslahepevirus balayani, pathogenic to humans, a genetically highly divergent rat origin hepevirus (RHEV) can cause hepatitis possessing a potential risk of cross-species infection and zoonotic transmission. Rocahepevirus ratti, formerly known as Orthohepevirus C, is a single-stranded RNA virus, recently reassigned to Rocahepevirus genus in the Hepeviridae family, including genotypes C1 and C2. RHEV primarily infects rats but has been identified as a rodent zoonotic virus capable of infecting humans through the consumption of contaminated food or water, causing both acute and chronic hepatitis cases in both animals and humans. This review compiles data concluding that 60% (295/489) of RHEV infections are found in Asia, being the continent with the highest zoonotic and transmission potential. Asia not only has the most animal cases but also 16 out of 21 human infections worldwide. Europe follows with 26% (128/489) of RHEV infections in animals, resulting in four human cases out of twenty-one globally. Phylogenetic analysis and genomic sequencing will be employed to gather global data, determine epidemiology, and assess geographical distribution. This information will enhance diagnostic accuracy, pathogenesis understanding, and help prevent cross-species transmission, particularly to humans.

First Insight into the Seroepidemiology of Hepatitis E Virus (HEV) in Dogs, Cats, Horses, Cattle, Sheep, and Goats from Bulgaria

In recent years, hepatitis E virus (HEV) infection has been found to be widespread among different animal species worldwide. In Bulgaria, high HEV seropositivity was found among pigs (60.3%), wild boars (40.8%), and East Balkan swine (82.5%). The aim of the present study was to establish the seroprevalence of HEV among dogs, cats, horses, cattle, sheep, and goats in Bulgaria. In total, 720 serum samples from six animal species were randomly collected: dogs-90 samples; cats-90; horses-180; cattle-180; sheep-90; and goats-90. The serum samples were collected from seven districts of the country: Burgas, Kardzhali, Pazardzhik, Plovdiv, Sliven, Smolyan, and Stara Zagora. The animal serum samples were tested for HEV antibodies using the commercial Wantai HEV-Ab ELISA kit (Beijing, China). The overall HEV seroprevalence among different animal species from Bulgaria was as follows: dogs-21.1%; cats-17.7%; horses-8.3%; cattle-7.7%; sheep-32.2%; and goats-24.4%. We found the lowest overall HEV seropositivity in Plovdiv district (6.2%; 4/64; p = 0.203) and Smolyan district (8.8%; 4/45; p = 0.129), vs. the highest in Pazardzhik district (21.6%; 29/134; p = 0.024) and Burgas district (28.8%; 26/90; p = 0.062). To the best of our knowledge, this is the first serological evidence of HEV infection in dogs, cats, horses, cattle, sheep, and goats from Bulgaria. We found high HEV seropositivity in small ruminants (sheep and goats), moderate seropositivity in pets (dogs and cats), and a low level of seropositivity in large animals (horses and cattle). Previous Bulgarian studies and the results of this research show that HEV infection is widespread among animals in our country. In this regard, the Bulgarian health authorities must carry out increased surveillance and control of HEV infection among animals in Bulgaria.

The Re-Emergence of Hepatitis E Virus in Europe and Vaccine Development

Hepatitis E virus (HEV) is one of the leading causes of acute viral hepatitis. Transmission of HEV mainly occurs via the fecal-oral route (ingesting contaminated water or food) or by contact with infected animals and their raw meat products. Some animals, such as pigs, wild boars, sheep, goats, rabbits, camels, rats, etc., are natural reservoirs of HEV, which places people in close contact with them at increased risk of HEV disease. Although hepatitis E is a self-limiting infection, it could also lead to severe illness, particularly among pregnant women, or chronic infection in immunocompromised people. A growing number of studies point out that HEV can be classified as a re-emerging virus in developed countries. Preventative efforts are needed to reduce the incidence of acute and chronic hepatitis E in non-endemic and endemic countries. There is a recombinant HEV vaccine, but it is approved for use and commercially available only in China and Pakistan. However, further studies are needed to demonstrate the necessity of applying a preventive vaccine and to create conditions for reducing the spread of HEV. This review emphasizes the hepatitis E virus and its importance for public health in Europe, the methods of virus transmission and treatment, and summarizes the latest studies on HEV vaccine development.

Hepatitis E Virus (HEV) Infection among Humans and Animals: Epidemiology, Clinical Characteristics, Treatment, and Prevention

The public health significance of hepatitis E is very important [...].

First Detection of Hepatitis E Virus (Rocahepevirus ratti Genotype C1) in Synanthropic Norway Rats (Rattus norvegicus) in Romania

Hepatitis E virus (HEV) is an emerging zoonotic pathogen with different viral genera and species reported in a wide range of animals. Rodents, particularly rats, carry the specific genus rat HEV (Rocahepevirus genus, genotype C1) and are exposed occasionally to HEV-3 (Paslahepevirus genus, genotype 3), a zoonotic genotype identified in humans and widely distributed in domestic and feral pigs. In this study, the presence of HEV was investigated in synanthropic Norway rats from Eastern Romania, in areas where the presence of HEV-3 was previously reported in pigs, wild boars and humans. Using methods capable of detecting different HEV species, the presence of HEV RNA was investigated in 69 liver samples collected from 52 rats and other animal species. Nine rat liver samples were identified as being positive for rat HEV RNA (17.3%). High sequence identity (85-89% nt) was found with other European Rocahepevirus. All samples tested from other animal species, within the same environment, were negative for HEV. This is the first study to demonstrate the presence of HEV in rats from Romania. Since rat HEV has been reported to cause zoonotic infections in humans, this finding supports the need to extend the diagnosis of Rocahepevirus in humans with suspicion of hepatitis.

Rodent-borne viruses in the region of Middle East

Rodents are one of the most abundant mammal species in the world. They form more than two-fifth of all mammal species and there are approximately 4600 existing rodent species. Rodents are capable of transmitting deadly diseases, especially those that are caused by viruses. Viruses and their consequences have plagued the world for the last two centuries, three pandemics occurred during the last century only. The Middle East is situated at the crossroads of Africa and Asia, along with the Mediterranean Sea and the Indian Ocean, its geographic importance is gained through the diversity of topographies, biosphere, as well as climate aspects that make the region vulnerable to host emerging diseases. Refugee crises also play a major role in expected epidemic outbreaks in the region. Public health has always been the most important priority, and our aim in this review is to raise awareness among public health organisations across the Middle East about the dangers of rodent borne diseases that have been reported or are suspected to be found in the region.

Hepatitis E Virus Research in Brazil: Looking Back and Forwards

Hepatitis E virus (HEV) has emerged as a public health concern in Brazil. From the first identification and characterization of porcine and human HEV-3 strains in the 2000s, new HEV subtypes have been identified from animal, human, and environmental isolates. As new potential animal reservoirs have emerged, there is a need to compile evidence on the zoonotic dissemination of the virus in animal hosts and the environment. The increasing amount of seroprevalence data on sampled and randomly selected populations must be systematically retrieved, interpreted, and considered under the One Health concept. This review focused on HEV seroprevalence data in distinct animal reservoirs and human populations reported in the last two decades. Furthermore, the expertise with experimental infection models using non-human primates may provide new insights into HEV pathogenesis, prevention, and environmental surveillance.

Detection of Hepatitis E Virus Genotype 3 in Feces of Capybaras (Hydrochoeris hydrochaeris) in Brazil

Hepatitis E virus (HEV) is an emerging zoonotic pathogen associated with relevant public health issues. The aim of this study was to investigate HEV presence in free-living capybaras inhabiting urban parks in São Paulo state, Brazil. Molecular characterization of HEV positive samples was undertaken to elucidate the genetic diversity of the virus in these animals. A total of 337 fecal samples were screened for HEV using RT-qPCR and further confirmed by conventional nested RT-PCR. HEV genotype and subtype were determined using Sanger and next-generation sequencing. HEV was detected in one specimen (0.3%) and assigned as HEV-3f. The IAL-HEV_921 HEV-3f strain showed a close relationship to European swine, wild boar and human strains (90.7-93.2% nt), suggesting an interspecies transmission. Molecular epidemiology of HEV is poorly investigated in Brazil; subtype 3f has been reported in swine. This is the first report of HEV detected in capybara stool samples worldwide.

Rat Hepatitis E Virus: Presence in Humans in South-Western France?

Background: Hepatitis E Virus (HEV) is one of the most common causes of hepatitis worldwide, and South-Western France is a high HEV seroprevalence area. While most cases of HEV infection are associated with the species Orthohepevirus-A, several studies have reported a few cases of HEV infections due to Orthohepevirus-C (HEV-C) that usually infects rats. Most of these human cases have occurred in immunocompromised patients. We have screened for the presence of HEV-C in our region. Methods and Results: We tested 224 sera, mostly from immunocompromised patients, for HEV-C RNA using an in-house real time RT-PCR. Liver function tests gave elevated results in 63% of patients: mean ALT was 159 IU/L (normal < 40 IU/L). Anti-HEV IgG (49%) and anti-HEV IgM (9.4%) were frequently present but none of the samples tested positive for HEV-C RNA. Conclusion: HEV-C does not circulate in the human population of South-Western France, despite the high seroprevalence of anti-HEV IgG.

Epidemiology of Hepatitis E in 2017 in Bavaria, Germany

In the last decade, the number of reported hepatitis E virus (HEV) infections in Germany, including Bavaria, has continued to rise. In order to identify risk factors associated with HEV infection, we investigated notified hepatitis E cases from Bavaria during 2017. The project "Intensified Hepatitis E Surveillance in Bavaria" included interviews with questionnaires, collection and genotyping of stool, serum and food samples. In addition, certain risk factors were examined in a sample comparison with healthy population using univariable analysis and logistic regression. In total, 135 hepatitis E cases from Bavaria were included in the analysis. Mean age for women was 46 (range 20-74) years and 47.5 (range 20-85) for men. 56 of the cases (41.5%) were asymptomatic. Among the symptomatic cases, both men and women were equally affected with symptoms like fever (16.3%), jaundice (18.8%) and upper abdominal pain (28.2%). 145 human samples (serum, stool) and 6 food samples were collected. 15.9% of the human samples (n = 23) were positive for HEV RNA by reverse-transcription quantitative real-time PCR (RT-qPCR). Identified risk factors significantly associated with hepatitis E were sausage consumption with odds ratio 9.6 (CI 1.3-70.1), fish with OR 2.2 (CI 1.1-4.4) and cat ownership with OR 1.9 (CI 1.3-3.0) in multivariable analyses. Further investigation is needed to confirm the role of fish in HEV transmission. Autochthonous HEV genotype 3 is prevalent in Bavaria and there could be more transmission routes contributing to the spread of HEV than previously known. Undercooked meat, offal, sausages, fish, shellfish and contact with animals and pets are possible sources for infection.

Presence and Diversity of Different Enteric Viruses in Wild Norway Rats (Rattus norvegicus)

Rodents are common reservoirs for numerous zoonotic pathogens, but knowledge about diversity of pathogens in rodents is still limited. Here, we investigated the occurrence and genetic diversity of enteric viruses in 51 Norway rats collected in three different countries in Europe. RNA of at least one virus was detected in the intestine of 49 of 51 animals. Astrovirus RNA was detected in 46 animals, mostly of rat astroviruses. Human astrovirus (HAstV-8) RNA was detected in one, rotavirus group A (RVA) RNA was identified in eleven animals. One RVA RNA could be typed as rat G3 type. Rat hepatitis E virus (HEV) RNA was detected in five animals. Two entire genome sequences of ratHEV were determined. Human norovirus RNA was detected in four animals with the genotypes GI.P4-GI.4, GII.P33-GII.1, and GII.P21. In one animal, a replication competent coxsackievirus A20 strain was detected. Additionally, RNA of an enterovirus species A strain was detected in the same animal, albeit in a different tissue. The results show a high detection rate and diversity of enteric viruses in Norway rats in Europe and indicate their significance as vectors for zoonotic transmission of enteric viruses. The detailed role of Norway rats and transmission pathways of enteric viruses needs to be investigated in further studies.

Hepatitis E Virus in the Food of Animal Origin: A Review

Hepatitis E virus (HEV) is a cosmopolitan foodborne pathogen. The viral agent infects humans through the consumption of contaminated food (uncooked or undercooked). Most cases of infection are asymptomatic and for this reason, this pathology is considered underdiagnosed. Domestic and wild animals are considered natural reservoirs: that is, domestic pig, wild boar, sheep, goat, deer, rabbit, and so on. Therefore, various work categories are at risk: that is, veterinarians, farmers, hunters, slaughterhouse workers, and so on. In these last decades, researchers found a high percentage of positivity to the molecular viral detection in several food matrices included: ready-to-eat products, processed meat products, milk, and shellfish. This review aims to provide an international scenario regarding HEV ribonucleic acid (RNA) detection in several foodstuffs. From this investigative perspective, the study aims to highlight various gaps of the current knowledge about technologies treatments' impact on viral loads. The purpose was also to provide an innovative point of view "One Health"-based, pointing out the strategic role of environmental safety.

The Role of Peridomestic Rodents as Reservoirs for Zoonotic Foodborne Pathogens

Although rodents are well-known reservoirs and vectors for a number of zoonoses, the functional role that peridomestic rodents serve in the amplification and transmission of foodborne pathogens is likely underappreciated. Clear links have been identified between commensal rodents and outbreaks of foodborne pathogens throughout Europe and Asia; however, comparatively little research has been devoted to studying this relationship in the United States. In particular, regional studies focused on specific rodent species and their foodborne pathogen reservoir status across the diverse agricultural landscapes of the United States are lacking. We posit that both native and invasive species of rodents associated with food-production pipelines are likely sources of seasonal outbreaks of foodborne pathogens throughout the United States. In this study, we review the evidence that identifies peridomestic rodents as reservoirs for foodborne pathogens, and we call for novel research focused on the metagenomic communities residing at the rodent-agriculture interface. Such data will likely result in the identification of new reservoirs for foodborne pathogens and species-specific demographic traits that might underlie seasonal enteric disease outbreaks. Moreover, we anticipate that a One Health metagenomic research approach will result in the discovery of new strains of zoonotic pathogens circulating in peridomestic rodents. Data resulting from such research efforts would directly inform and improve upon biosecurity efforts, ultimately serving to protect our food supply.

Infection dynamics and persistence of hepatitis E virus on pig farms - a review

Background

Hepatitis E virus (HEV) genotype 3 and 4 is a zoonosis that causes hepatitis in humans. Humans can become infected by consumption of pork or contact with pigs. Pigs are the main reservoir of the virus worldwide and the virus is present on most pig farms.

Main body

Though HEV is present on most farms, the proportion of infected pigs at slaughter and thus the level of exposure to consumers differs between farms and countries. Understanding the cause of that difference is necessary to install effective measures to lower HEV in pigs at slaughter. Here, HEV studies are reviewed that include infection dynamics of HEV in pigs and on farms, risk factors for HEV farm prevalence, and that describe mechanisms and sources that could generate persistence on farms. Most pigs become infected after maternal immunity has waned, at the end of the nursing or beginning of the fattening phase. Risk factors increasing the likelihood of a high farm prevalence or proportion of actively infected slaughter pigs comprise of factors such as farm demographics, internal and external biosecurity and immunomodulating coinfections. On-farm persistence of HEV is plausible, because of a high transmission rate and a constant influx of susceptible pigs. Environmental sources of HEV that enhance persistence are contaminated manure storages, water and fomites.

Conclusion

As HEV is persistently present on most pig farms, current risk mitigation should focus on lowering transmission within farms, especially between farm compartments. Yet, one should be aware of the paradox of increasing the proportion of actively infected pigs at slaughter by reducing transmission insufficiently. Vaccination of pigs may aid HEV control in the future.

Evidence of Hepatitis E Virus in Goat and Sheep Milk

Hepatitis E virus (HEV) is the etiological agent behind hepatitis E infection. Domestic pigs and wild boars are the main animal reservoirs of HEV. Very few papers describe HEV infection in goats and sheep. As the data pertaining to the presence of HEV virus in the milk of small ruminants in Europe are lacking, the aim of this paper was to examine a representative number of milk samples from these animals. The detection of HEV genome (HEV RNA) was performed using reverse transcriptase real-time polymerase chain reaction (RT-qPCR). HEV RNA was found in 2.8% of the examined samples. Positivity ranged from 10¹ to 10³ genome equivalents/mL (GE/mL) with a median of 9.99 × 10² GE/mL. On the basis of these results, the milk of small ruminants could represent a source of HEV infection to consumers.

Review of Hepatitis E Virus in Rats: Evident Risk of Species Orthohepevirus C to Human Zoonotic Infection and Disease

Hepatitis E virus (HEV) (family Hepeviridae) is one of the most common human pathogens, causing acute hepatitis and an increasingly recognized etiological agent in chronic hepatitis and extrahepatic manifestations. Recent studies reported that not only are the classical members of the species Orthohepevirus A (HEV-A) pathogenic to humans but a genetically highly divergent rat origin hepevirus (HEV-C1) in species Orthohepevirus C (HEV-C) is also able to cause zoonotic infection and symptomatic disease (hepatitis) in humans. This review summarizes the current knowledge of hepeviruses in rodents with special focus of rat origin HEV-C1. Cross-species transmission and genetic diversity of HEV-C1 and confirmation of HEV-C1 infections and symptomatic disease in humans re-opened the long-lasting and full of surprises story of HEV in human. This novel knowledge has a consequence to the epidemiology, clinical aspects, laboratory diagnosis, and prevention of HEV infection in humans.

Orthohepevirus C: An Expanding Species of Emerging Hepatitis E Virus Variants

Hepatitis E virus (HEV) is an emerging zoonotic pathogen that has received an increasing amount of attention from virologists, clinicians, veterinarians, and epidemiologists over the past decade. The host range and animal reservoirs of HEV are rapidly expanding and a plethora of emerging HEV variants have been recently identified, some of which have the potential for interspecies infection. In this review, the detection of genetically diverse HEV variants, classified into and presumably associated with the species Orthohepevirus C, currently comprising HEV genotypes C1 and C2, by either serological or molecular approach is summarized. The distribution, genomic variability, and evolution of Orthohepevirus C are analyzed. Moreover, the potential risk of cross-species infection and zoonotic transmission of Orthohepevirus C are discussed.

First evidence of hepatitis E virus infection in a small mammal (yellow-necked mouse) from Croatia

Since the role of wild rodents/small mammals in hepatitis E virus (HEV) epidemiology has been a subject of considerable debate, this study was conducted to investigate the potential presence of HEV RNA in small rodents collected within their natural habitats and to detect if they can be potential reservoirs of the virus. A total of 483 small rodents were captured using snap traps placed at 11 regions in Croatia. Sampling was undertaken in 2008 and repeated from 2010 to 2014. Liver samples were tested for the presence of HEV RNA. HEV RNA was detected in only one liver sample (0.21%) originated from Apodemus flavicollis from the location Medvednica, nearby Zagreb collected in 2014. According to the sequence analysis, the isolate has shown to be a member of Orthohepevirus A species, genotype HEV-3. The genotyping results confirmed grouping into subtype 3a, general cluster 3abchij.The detected HEV strain showed to be genetically highly related to strains found in humans and/or domestic pigs and wild boars from Croatia. Our finding indicates that wild small mammals could play a role in the epidemiology of HEV-3 infection and therefore should be taken under consideration as potential reservoirs or/and transmitters of the disease. However, further investigation is needed to recognize their potential for maintaining the infection in natural conditions.

Detection of hepatitis E virus RNA in rats caught in pig farms from Northern Italy

Hepatitis E virus (HEV) strains belonging to the Orthohepevirus genus are divided into four species (A-D). HEV strains included in the Orthohepevirus A species infect humans and several other mammals. Among them, the HEV-3 and HEV-4 genotypes are zoonotic and infect both humans and animals, of which, pigs and wild boar are the main reservoirs. Viruses belonging to the Orthohepevirus C species (HEV-C) have been considered to infect rats of different species and carnivores. Recently, two studies reported the detection of HEV-C1 (rat HEV) RNA in immunocompromised and immunocompetent patients, suggesting a possible transmission of rat HEV to humans. The role of rats and mice as reservoir of HEV and the potential zoonotic transmission is still poorly known and deserves further investigation. To this purpose, in this study, the presence of HEV RNA was investigated in the intestinal contents and liver samples from 47 Black rats (Rattus rattus) and 21 House mice (Mus musculus) captured in four pig farms in Northern Italy. The presence of both Orthohepevirus A and C was investigated by the real-rime RT-PCR specific for HEV-1 to HEV-4 genotypes of Orthohepevirus A species and by a broad spectrum hemi-nested RT-PCR capable of detecting different HEV species including rat HEV. The intestinal content from two Black rats resulted positive for HEV-C1 RNA and for HEV-3 RNA, respectively. None of the House mice was HEV RNA positive. Sequence analyses confirmed the detection of HEV-C1, genotype G1 and HEV-3 subtype e. The viral strain HEV-3e detected in the rat was identical to swine HEV strains detected in the same farm. Liver samples were negative for the detection of either rat HEV or HEV-3.

Genomic and spatial variability of a European common vole hepevirus

Rodents host different orthohepeviruses, namely orthohepevirus C genotype HEV-C1 (rat hepatitis E virus, HEV) and the additional putative genotypes HEV-C3 and HEV-C4. Here, we screened 2,961 rodents from Central Europe by reverse transcription polymerase chain reaction (RT-PCR) and identified HEV RNA in 13 common voles (Microtus arvalis) and one bank vole (Myodes glareolus) with detection rates of 2% (95% confidence interval [CI]: 1-3.4) and 0.08% (95% CI: 0.002-0.46), respectively. Sequencing of a 279-nucleotide RT-PCR amplicon corresponding to a region within open reading frame (ORF) 1 showed a high degree of similarity to recently described common vole-associated HEV (cvHEV) sequences from Hungary. Five novel complete cvHEV genome sequences from Central Europe showed the typical HEV genome organization with ORF1, ORF2 and ORF3 and RNA secondary structure. Uncommon features included a noncanonical start codon in ORF3, multiple insertions and deletions within ORF1 and ORF2/ORF3, and the absence of a putative ORF4. Phylogenetic analysis showed all of the novel cvHEV sequences to be monophyletic, clustering most closely with an unassigned bird-derived sequence and other sequences of the species Orthohepevirus C. The nucleotide and amino acid sequence divergence of the common vole-derived sequences was significantly correlated with the spatial distance between the trapping sites, indicating mostly local evolutionary processes. Detection of closely related HEV sequences in common voles in multiple localities over a distance of 800 kilometers suggested that common voles are infected by cvHEV across broad geographic distances. The common vole-associated HEV strain is clearly divergent from HEV sequences recently found in narrow-headed voles (Microtus gregalis) and other cricetid rodents.

Animal Models for Hepatitis E virus

Hepatitis E virus (HEV) is an underdiagnosed pathogen with approximately 20 million infections each year and currently the most common cause of acute viral hepatitis. HEV was long considered to be confined to developing countries but there is increasing evidence that it is also a medical problem in the Western world. HEV that infects humans belongs to the Orthohepevirus A species of the Hepeviridae family. Novel HEV-like viruses have been observed in a variety of animals and some have been shown to be able to cross the species barrier, causing infection in humans. Several cell culture models for HEV have been established in the past years, but their efficiency is usually relatively low. With the circulation of this virus and related viruses in a variety of species, several different animal models have been developed. In this review, we give an overview of these animal models, indicate their main characteristics, and highlight how they may contribute to our understanding of the basic aspects of the viral life cycle and cross-species infection, the study of pathogenesis, and the evaluation of novel preventative and therapeutic strategies.

Genetic Variability and Evolution of Hepatitis E Virus

Hepatitis E virus (HEV) is a single-stranded positive-sense RNA virus. HEV can cause both acute and chronic hepatitis, with the latter usually occurring in immunocompromised patients. Modes of transmission range from the classic fecal-oral route or zoonotic route, to relatively recently recognized but increasingly common routes, such as via the transfusion of blood products or organ transplantation. Extrahepatic manifestations, such as neurological, kidney and hematological abnormalities, have been documented in some limited cases, typically in patients with immune suppression. HEV has demonstrated extensive genomic diversity and a variety of HEV strains have been identified worldwide from human populations as well as growing numbers of animal species. The genetic variability and constant evolution of HEV contribute to its physiopathogenesis and adaptation to new hosts. This review describes the recent classification of the Hepeviridae family, global genotype distribution, clinical significance of HEV genotype and genomic variability and evolution of HEV.

The Current Host Range of Hepatitis E Viruses

Hepatitis E virus (HEV) is an emerging zoonotic pathogen transmitting both human to human via the fecal oral route and from animals to humans through feces, direct contact, and consumption of contaminated meat products. Understanding the host range of the virus is critical for determining where potential threats to human health may be emerging from and where potential reservoirs for viral persistence in the environment may be hiding. Initially thought to be a human specific disease endemic to developing countries, the identification of swine as a primary host for genotypes 3 and 4 HEV in industrialized countries has begun a long journey of discovering novel strains of HEV and their animal hosts. As we continue identifying new strains of HEV in disparate animal species, it is becoming abundantly clear that HEV has a broad host range and many of these HEV strains can cross between differing animal species. These cross-species transmitting strains pose many unique challenges to human health as they are often unrecognized as sources of viral transmission.

Hepatitis E virus strains infecting Swedish domestic pigs are unique for each pig farm and remain in the farm for at least 2 years

Hepatitis E virus (HEV) genotype 3 (HEV3) is distributed globally and infects both humans and animals, mainly domestic pigs and wild boars, which are the major reservoirs. In this study, the prevalence of HEV among Swedish pigs was investigated by HEV RNA analysis in 363 faecal samples from 3-month-old piglets sampled twice (2013 and 2014) in 30 Swedish pig farms. Four different types of farms were investigated; organic, conventional closed (keeping the sow), satellites in a sow pool (conventional farms sharing sows) and conventional non-closed farms (purchasing gilts). More than two-thirds (77%) of the farms had HEV-infected pigs. HEV RNA was found in faeces from 79 pigs (22%). Partial ORF1 could be sequenced in 46 strains. Phylogenetic analysis revealed a unique HEV3 strain for each farm. Strains sampled more than a year apart from the same farm were closely related, indicating that the same HEV strain is present for several years on the farm. Despite that only 4% of the Swedish pig farms were investigated, two farms had strains similar to those from humans, another had strains similar to wild boar HEV. The uniqueness of strains from each farm indicates a possibility to identify a source of infection down to farm level. This knowledge may be used by the farms to investigate the effectiveness of good hygiene routines to reduce the amount of HEV and thus the infection risk in the farm, and for Swedish public health authorities to identify cases of HEV transmissions from consumption of uncooked pork.

First detection of Hepatitis E virus (Orthohepevirus C) in wild brown rats (Rattus norvegicus) from Great Britain

In the United Kingdom, there has been an increase in the number of hepatitis E virus (HEV) infections in people annually since 2010. Most of these are thought to be indigenously acquired Orthohepevirus A genotype 3 (HEV G3), which has been linked to pork production and consumption. However, the dominant subgroup circulating in British pigs differs from that which is found in people; therefore, an alternative, potentially zoonotic, source is suspected as a possible cause of these infections. Rodents, brown rats (Rattus norvegicus) in particular, have been shown to carry HEV, both the swine HEV G3 genotype and Orthohepevirus C, genotype C1 (rat HEV). To investigate the prevalence of HEV in British rodents, liver tissue was taken from 307 rodents collected from pig farms (n = 12) and other locations (n = 10). The RNA from these samples was extracted and tested using a pan‐HEV nested RT‐PCR. Limited histopathology was also performed. In this study, 8/61 (13%, 95% CI, 5–21) of brown rat livers were positive for HEV RNA. Sequencing of amplicons demonstrated all infections to be rat HEV with 87%–92% nucleotide identity to other rat HEV sequences circulating within Europe and China (224 nt ORF‐1). Lesions and necrosis were observed histologically in 2/3 samples examined. No rat HEV RNA was detected in any other species, and no HEV G3 RNA was detected in any rodent in this study. This is the first reported detection of rat HEV in Great Britain. A human case of rat HEV infection has recently been reported in Asia, suggesting that rat HEV could pose a risk to public health.

Epidemiology and Transmission of Hepatitis A Virus and Hepatitis E Virus Infections in the United States

There are many similarities in the epidemiology and transmission of hepatitis A virus (HAV) and hepatitis E virus (HEV) genotype (gt)3 infections in the United States. Both viruses are enterically transmitted, although specific routes of transmission are more clearly established for HAV than for HEV: HAV is restricted to humans and primarily spread through the fecal-oral route, while HEV is zoonotic with poorly understood modes of transmission in the United States. New cases of HAV infection have decreased dramatically in the United States since infant vaccination was recommended in 1996. In recent years, however, outbreaks have occurred among an increasingly susceptible adult population. Although HEV is the most common cause of acute viral hepatitis in developing countries, it is rarely diagnosed in the United States.

The prevalence and genomic characteristics of hepatitis E virus in murine rodents and house shrews from several regions in China

Background

Urban rodents and house shrews are closely correlated in terms of location with humans and can transmit many pathogens to them. Hepatitis E has been confirmed to be a zoonotic disease. However, the zoonotic potential of rat HEV is still unclear. The aim of this study was to determine the prevalence and genomic characteristics of hepatitis E virus (HEV) in rodents and house shrews.

Results

We collected a total of 788 animals from four provinces in China. From the 614 collected murine rodents, 20.19% of the liver tissue samples and 45.76% of the fecal samples were positive for HEV. From the 174 house shrews (Suncus murinus), 5.17% fecal samples and 0.57% liver tissue samples were positive for HEV. All of the HEV sequences obtained in this study belonged to Orthohepevirus C1. However, we observed a lower percentage of identity in the ORF3 region upon comparing the amino acid sequences between Rattus norvegicus and Rattus losea. HEV derived from house shrews shared a high percentage of identity with rat HEV. Notably, the first near full-length of the HEV genome from Rattus losea is described in our study, and we also report the first near full-length rat HEV genomes in Rattus norvegicus from China.

Conclusion

HEV is prevalent among the three common species of murine rodents (Rattus. norvegicus, Rattus. tanezumi, and Rattus. losea) in China. HEV sequences detected from house shrews were similar to rat HEV sequences. The high identity of HEV from murine rodents and house shrews suggested that HEV can spread among different animal species.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1746-z) contains supplementary material, which is available to authorized users.

Different Outcomes of Experimental Hepatitis E Virus Infection in Diverse Mouse Strains, Wistar Rats, and Rabbits

Hepatitis E virus (HEV) is the causative agent of acute hepatitis E in humans in developing countries, but autochthonous cases of zoonotic genotype 3 (HEV-3) infection also occur in industrialized countries. In contrast to swine, rats, and rabbits, natural HEV infections in mice have not yet been demonstrated. The pig represents a well-established large animal model for HEV-3 infection, but a suitable small animal model mimicking natural HEV-3 infection is currently missing. Therefore, we experimentally inoculated C57BL/6 mice (wild-type, IFNAR^−/−, CD4^−/−, CD8^−/−) and BALB/c nude (nu/nu) mice, Wistar rats, and European rabbits with a wild boar-derived HEV-3 strain and monitored virus replication and shedding, as well as humoral immune responses. HEV RNA and anti-HEV antibodies were detected in one and two out of eight of the rats and all rabbits inoculated, respectively, but not in any of the mouse strains tested. Remarkably, immunosuppressive dexamethasone treatment of rats did not enhance their susceptibility to HEV infection. In rabbits, immunization with recombinant HEV-3 and ratHEV capsid proteins induced protection against HEV-3 challenge. In conclusion, the rabbit model for HEV-3 infection may serve as a suitable alternative to the non-human primate and swine models, and as an appropriate basis for vaccine evaluation studies.

Hepatitis E Virus: Animal Models and Zoonosis

Hepatitis E virus (HEV) is an important human pathogen that historically has been difficult to study. Limited levels of replication in vitro hindered our understanding of the viral life cycle. Sporadic and low-level virus shedding, lack of standardized detection methods, and subclinical infections made the development of animal models difficult. Better diagnostic techniques and understanding of the virus increased our ability to identify and characterize animal strains and animals that are amenable to model human-relevant infection. These advances are translating into the development of useful HEV animal models so that some of the greatest concerns associated with HEV infection, including host immunology, chronic infection, severe pregnancy mortality, and extrahepatic manifestations, can now be studied. Continued development of these animal models will be instrumental in understanding the many complex questions associated with HEV infection and for assessing therapeutics and prevention strategies to minimize HEV becoming a greater risk to the human population.

Cross-species infection of mice by rabbit hepatitis E virus

Rabbits are recognized as a zoonotic reservoir of hepatitis E virus (HEV) for transmission to humans and other zoonotic reservoirs such as swine. The purpose of this study was to assess the ability of rabbit HEV to cross the species barrier to infect mice and also the usefulness of this animal to study HEV transmission and pathogenesis. In this study, uninfected BALB/c mice were experimentally inoculated with rabbit HEV either via gavage or through contact-exposure with infected mice. Rabbit HEV propagation in mice was evaluated by studying fecal virus shedding, viremia, seroconversion and microscopic liver lesions. Rabbit HEV could be detected in all mice infected by gavage, but only in some contact-exposed mice, with some animals exhibiting fecal virus shedding, seroconversion or viremia (one mouse only). Compared with inoculated mice, anti-rabbit HEV antibody titers and viral copy numbers in fecal and serum samples were lower in contact-exposed mice. Infected mice mainly exhibited phlebitis, hepatocyte swelling and necrosis. Microscopic liver lesion scores for inoculated and contact-exposed infected mice were higher than scores for negative controls. This study therefore demonstrates that rabbit HEV could infect BALB/c mice both though inoculation via gavage and through contact-exposure.

Hiding in Plain Sight? It's Time to Investigate Other Possible Transmission Routes for Hepatitis E Virus (HEV) in Developed Countries

Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related ("autochthonous") cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal-oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.

Detection of rat hepatitis E virus, but not human pathogenic hepatitis E virus genotype 1-4 infections in wild rats from Lithuania

Rat hepatitis E virus (HEV) is an orthohepevirus which is related to other HEV found in humans and other mammals. It was first identified in Norway rats (Rattus norvegicus) from Germany in 2010, and later it has been detected in Black rats (Rattus rattus) and Norway rats from USA, China, Indonesia, Vietnam and many European countries. In this study, we describe molecular and serological investigations of Black and Norway rats trapped in Lithuania, Eastern Europe, for infections with rat HEV and human HEV genotypes 1-4. Rat HEV-specific real-time reverse transcription-PCR (RT-qPCR) analysis of rat liver samples revealed the presence of rat HEV in 9 of 109 (8.3%) samples. In contrast, a RT-qPCR specific for HEV genotypes 1-4 did not reveal any positive samples. A nested broad spectrum RT-PCR was used for a confirmation of rat HEV infection with a subsequent sequencing of the amplified rat HEV genome fragment. Phylogenetic analysis revealed a clustering of all newly identified rat HEV sequences with Norway rat-derived rat HEV sequences from Germany within the species Orthohepevirus C. An indirect ELISA using a yeast-expressed truncated rat HEV capsid protein variant revealed 31.2% seropositive samples indicating a high rate of rat HEV circulation in the rat population examined. In conclusion, the current investigation confirms rat HEV infections in Norway and Black rats in Lithuania, Eastern Europe, and the non-persistent nature of HEV infection.

Novel orthohepeviruses in wild rodents from São Paulo State, Brazil

The Hepeviridae comprise single-stranded positive-sense RNA viruses classified into two genera, Orthohepevirus and Piscihepevirus. Orthohepeviruses have a wide host range that includes rodents, but previous studies had been restricted to rodents of the Muridae family. In this study, we applied a high-throughput sequencing approach to examine the presence of orthohepeviruses in rodents from São Paulo State, Brazil. We also used RT-PCR to determine the frequency of orthohepeviruses in our sampled population. We identified novel orthohepeviruses in blood samples derived from Necromys lasiurus (1.19%) and Calomys tener (3.66%). Therefore, our results expand the host range and viral diversity of the Hepeviridae family.

Chevrier's Field Mouse (Apodemus chevrieri) and Père David's Vole (Eothenomys melanogaster) in China Carry Orthohepeviruses that form Two Putative Novel Genotypes Within the Species Orthohepevirus C

Hepatitis E virus (HEV) is the prototype of the family Hepeviridae and the causative agent of common acute viral hepatitis. Genetically diverse HEV-related viruses have been detected in a variety of mammals and some of them may have zoonotic potential. In this study, we tested 278 specimens collected from seven wild small mammal species in Yunnan province, China, for the presence and prevalence of orthohepevirus by broad-spectrum reverse transcription (RT)-PCR. HEV-related sequences were detected in two rodent species, including Chevrier's field mouse (Apodemus chevrieri, family Muridae) and Père David's vole (Eothenomys melanogaster, family Cricetidae), with the infection rates of 29.20% (59/202) and 7.27% (4/55), respectively. Further four representative full-length genomes were generated: two each from Chevrier's field mouse (named RdHEVAc14 and RdHEVAc86) and Père David's vole (RdHEVEm40 and RdHEVEm67). Phylogenetic analyses and pairwise distance comparisons of whole genome sequences and amino acid sequences of the gene coding regions showed that orthohepeviruses identified in Chinese Chevrier's field mouse and Père David's vole belonged to the species Orthohepevirus C but were highly divergent from the two assigned genotypes: HEV-C1 derived from rat and shrew, and HEV-C2 derived from ferret and possibly mink. Quantitative real-time RT-PCR demonstrated that these newly discovered orthohepeviruses had hepatic tropism. In summary, our work discovered two putative novel genotypes orthohepeviruses preliminarily named HEV-C3 and HEV-C4 within the species Orthohepevirus C, which expands our understanding of orthohepevirus infection in the order Rodentia and gives new insights into the origin, evolution, and host range of orthohepevirus.

Detection and Characterization of Homologues of Human Hepatitis Viruses and Pegiviruses in Rodents and Bats in Vietnam

Rodents and bats are now widely recognised as important sources of zoonotic virus infections in other mammals, including humans. Numerous surveys have expanded our knowledge of diverse viruses in a range of rodent and bat species, including their origins, evolution, and range of hosts. In this study of pegivirus and human hepatitis-related viruses, liver and serum samples from Vietnamese rodents and bats were examined by PCR and sequencing. Nucleic acids homologous to human hepatitis B, C, E viruses were detected in liver samples of 2 (1.3%) of 157 bats, 38 (8.1%), and 14 (3%) of 470 rodents, respectively. Hepacivirus-like viruses were frequently detected (42.7%) in the bamboo rat, Rhizomys pruinosus, while pegivirus RNA was only evident in 2 (0.3%) of 638 rodent serum samples. Complete or near-complete genome sequences of HBV, HEV and pegivirus homologues closely resembled those previously reported from rodents and bats. However, complete coding region sequences of the rodent hepacivirus-like viruses substantially diverged from all of the currently classified variants and potentially represent a new species in the Hepacivirus genus. Of the viruses identified, their routes of transmission and potential to establish zoonoses remain to be determined.

Assessing the Diversity of Rodent-Borne Viruses: Exploring of High-Throughput Sequencing and Classical Amplification/Sequencing Approaches

Rodents are distributed throughout the world and interact with humans in many ways. They provide vital ecosystem services, some species are useful models in biomedical research and some are held as pet animals. However, many rodent species can have adverse effects such as damage to crops and stored produce, and they are of health concern because of the transmission of pathogens to humans and livestock. The first rodent viruses were discovered by isolation approaches and resulted in break-through knowledge in immunology, molecular and cell biology, and cancer research. In addition to rodent-specific viruses, rodent-borne viruses are causing a large number of zoonotic diseases. Most prominent examples are reemerging outbreaks of human hemorrhagic fever disease cases caused by arena- and hantaviruses. In addition, rodents are reservoirs for vector-borne pathogens, such as tick-borne encephalitis virus and Borrelia spp., and may carry human pathogenic agents, but likely are not involved in their transmission to human. In our days, next-generation sequencing or high-throughput sequencing (HTS) is revolutionizing the speed of the discovery of novel viruses, but other molecular approaches, such as generic RT-PCR/PCR and rolling circle amplification techniques, contribute significantly to the rapidly ongoing process. However, the current knowledge still represents only the tip of the iceberg, when comparing the known human viruses to those known for rodents, the mammalian taxon with the largest species number. The diagnostic potential of HTS-based metagenomic approaches is illustrated by their use in the discovery and complete genome determination of novel borna- and adenoviruses as causative disease agents in squirrels. In conclusion, HTS, in combination with conventional RT-PCR/PCR-based approaches, resulted in a drastically increased knowledge of the diversity of rodent viruses. Future improvements of the used workflows, including bioinformatics analysis, will further enhance our knowledge and preparedness in case of the emergence of novel viruses. Classical virological and additional molecular approaches are needed for genome annotation and functional characterization of novel viruses, discovered by these technologies, and evaluation of their zoonotic potential.

Hepatitis E virus and related viruses in wild, domestic and zoo animals: A review

Hepatitis E is a human disease mainly characterized by acute liver illness, which is caused by infection with the hepatitis E virus (HEV). Large hepatitis E outbreaks have been described in developing countries; however, the disease is also increasingly recognized in industrialized countries. Mortality rates up to 25% have been described for pregnant women during outbreaks in developing countries. In addition, chronic disease courses could be observed in immunocompromised transplant patients. Whereas the HEV genotypes 1 and 2 are mainly confined to humans, genotypes 3 and 4 are also found in animals and can be zoonotically transmitted to humans. Domestic pig and wild boar represent the most important reservoirs for these genotypes. A distinct subtype of genotype 3 has been repeatedly detected in rabbits and a few human patients. Recently, HEV genotype 7 has been identified in dromedary camels and in an immunocompromised transplant patient. The reservoir animals get infected with HEV without showing any clinical symptoms. Besides these well-known animal reservoirs, HEV-specific antibodies and/or the genome of HEV or HEV-related viruses have also been detected in many other animal species, including primates, other mammals and birds. In particular, genotypes 3 and 4 infections are documented in many domestic, wildlife and zoo animal species. In most cases, the presence of HEV in these animals can be explained by spillover infections, but a risk of virus transmission through contact with humans cannot be excluded. This review gives a general overview on the transmission pathways of HEV to humans. It particularly focuses on reported serological and molecular evidence of infections in wild, domestic and zoo animals with HEV or HEV-related viruses. The role of these animals for transmission of HEV to humans and other animals is discussed.

Detection of rat hepatitis E virus in wild Norway rats (Rattus norvegicus) and Black rats (Rattus rattus) from 11 European countries

Rat hepatitis E virus (HEV) is genetically only distantly related to hepeviruses found in other mammalian reservoirs and in humans. It was initially detected in Norway rats (Rattus norvegicus) from Germany, and subsequently in rats from Vietnam, the USA, Indonesia, China, Denmark and France. Here, we report on a molecular survey of Norway rats and Black rats (Rattus rattus) from 12 European countries for ratHEV and human pathogenic hepeviruses. RatHEV-specific real-time and conventional RT-PCR investigations revealed the presence of ratHEV in 63 of 508 (12.4%) rats at the majority of sites in 11 of 12 countries. In contrast, a real-time RT-PCR specific for human pathogenic HEV genotypes 1-4 and a nested broad-spectrum (NBS) RT-PCR with subsequent sequence determination did not detect any infections with these genotypes. Only in a single Norway rat from Belgium a rabbit HEV-like genotype 3 sequence was detected. Phylogenetic analysis indicated a clustering of all other novel Norway and Black rat-derived sequences with ratHEV sequences from Europe, the USA and a Black rat-derived sequence from Indonesia within the proposed ratHEV genotype 1. No difference in infection status was detected related to age, sex, rat species or density of human settlements and zoological gardens. In conclusion, our investigation shows a broad geographical distribution of ratHEV in Norway and Black rats from Europe and its presence in all settlement types investigated.

Public health risks associated with hepatitis E virus (HEV) as a food-borne pathogen

Hepatitis E virus (HEV) is an important infection in humans in EU/EEA countries, and over the last 10 years more than 21,000 acute clinical cases with 28 fatalities have been notified with an overall 10-fold increase in reported HEV cases; the majority (80%) of cases were reported from France, Germany and the UK. However, as infection in humans is not notifiable in all Member States, and surveillance differs between countries, the number of reported cases is not comparable and the true number of cases would probably be higher. Food-borne transmission of HEV appears to be a major route in Europe; pigs and wild boars are the main source of HEV. Outbreaks and sporadic cases have been identified in immune-competent persons as well as in recognised risk groups such as those with pre-existing liver damage, immunosuppressive illness or receiving immunosuppressive treatments. The opinion reviews current methods for the detection, identification, characterisation and tracing of HEV in food-producing animals and foods, reviews literature on HEV reservoirs and food-borne pathways, examines information on the epidemiology of HEV and its occurrence and persistence in foods, and investigates possible control measures along the food chain. Presently, the only efficient control option for HEV infection from consumption of meat, liver and products derived from animal reservoirs is sufficient heat treatment. The development of validated quantitative and qualitative detection methods, including infectivity assays and consensus molecular typing protocols, is required for the development of quantitative microbial risk assessments and efficient control measures. More research on the epidemiology and control of HEV in pig herds is required in order to minimise the proportion of pigs that remain viraemic or carry high levels of virus in intestinal contents at the time of slaughter. Consumption of raw pig, wild boar and deer meat products should be avoided.

Wildlife Reservoir for Hepatitis E Virus, Southwestern France

Pigs are a reservoir for hepatitis E virus (HEV). To determine the relative contribution of game to the risk for human HEV infection in southwestern France, we tested wildlife samples. HEV RNA was in 3.3% of wildlife livers, indicating that in this region, eating game meat is as risky as eating pork.

Aboriginal and invasive rats of genus Rattus as hosts of infectious agents

From the perspective of ecology of zoonotic pathogens, the role of the Old World rats of the genus Rattus is exceptional. The review analyzes specific characteristics of rats that contribute to their important role in hosting pathogens, such as host-pathogen relations and rates of rat-borne infections, taxonomy, ecology, and essential factors. Specifically the review addresses recent taxonomic revisions within the genus Rattus that resulted from applications of new genetic tools in understanding relationships between the Old World rats and the infectious agents that they carry. Among the numerous species within the genus Rattus, only three species-the Norway rat (R. norvegicus), the black or roof rat (R. rattus), and the Asian black rat (R. tanezumi)-have colonized urban ecosystems globally for a historically long period of time. The fourth invasive species, R. exulans, is limited to tropical Asia-Pacific areas. One of the points highlighted in this review is the necessity to discriminate the roles played by rats as pathogen reservoirs within the land of their original diversification and in regions where only one or few rat species were introduced during the recent human history.

Molecular Investigation on the Presence of Hepatitis E Virus (HEV) in Wild Game in North-Western Italy

Meat products from HEV-infected reservoir animal species are capable of transmitting HEV to humans and represent a public health concern. Human HEV cases have been linked to the consumption of raw or undercooked pig liver sausages, pork, and game meats, such as wild boars and deer worldwide. Direct exposure to swine or wild game species might also represent a source of HEV transmission especially for veterinarians, hunters, or butchers. A limited amount of data is available on HEV prevalence in wild boars in Italy and no data are available for other wild game species intended for human consumption. In this study, the circulation of HEV in four different animal species hunted in north-western Italy was evaluated to gain insight into the infection levels and the genetic diversity of the virus in such animal populations. Liver samples of 372 wild boars, 30 roe deer, 47 European hares and 38 coypus were analyzed for HEV RNA by real-time RT-PCR; positive samples were then sequenced and submitted to phylogenetic analysis. HEV RNA was detected in the livers of 7/372 (1.9%) wild boars tested, while no sample was positive for roe deer, European hare, and coypu. Phylogenetic analysis showed that wild boar HEV sequences belonged to HEV subtypes 3e, 3c, and 3f. Our results indicate that HEV is circulating only in wild boar among the considered game species in north-western Italy and suggest a potential zoonotic risk related to handling and/or consumption of raw or undercooked meat and products made of the liver from this species.