Epidemiology and genotype 3 subtype dynamics of hepatitis E virus in Belgium, 2010 to 2017

Hepatitis E virus in wild and domestic rabbits from Portugal: a combined molecular and longitudinal serological study

Hepatitis E virus (HEV), species Paslahepevirus balayani, poses a global public health threat, especially in developing countries, by causing acute enterically transmitted hepatitis. HEV infects various mammalian hosts and belongs to the genus Paslahepevirus in the family Hepeviridae. While swine are recognized as the main hosts of HEV, rabbits, which can also be affected by swine HEV-3 related strains, serve as the primary reservoir for the distinct emerging and zoonotic HEV-3ra subtype. In Portugal, where the European wild rabbit is abundant, their role in HEV epidemiology remains unclear. The primary aim of the present research was to evaluate the circulation and the potential for HEV infection within these species. This study employed a molecular and longitudinal serological approach to investigate HEV in Portuguese rabbits. Among the 205 wild rabbits tested, a seroprevalence of 2.44% (95% CI: 0.80-5.60) was found, with no significant associations with age, sex, localization, or sampling dates. Seropositive animals were found in the south and center regions of the country. HEV RNA was not detected in 120 fecal samples, suggesting a natural, low level, and widespread viral circulation. The study underscores the need for further research to comprehend HEV dynamics in these species, which is crucial for assessing potential transmission risks to humans.

Subclinical hepatitis E virus genotype 1 infection: The concept of "dynamic human reservoir"

Hepatitis E virus (HEV) is hyperendemic in South Asia and Africa accounting for half of total Global HEV burden. There are eight genotypes of HEV. Among them, the four common ones known to infect humans, genotypes 1 and 2 are prevalent in the developing world and genotypes 3 and 4 are causing challenge in the industrialized world. Asymptomatic HEV viremia in the general population, especially among blood donors, has been reported in the literature worldwide. The clinical implications related to this asymptomatic viremia are unclear and need further exploration. Detection of viremia due to HEV genotype 1 infection, apparently among healthy blood donors is also reported without much knowledge about its infection rate. Similarly, while HEV genotype 3 is known to be transmitted via blood transfusion in humans and has been subjected to screening in many European nations, instances of transmission have also been documented albeit without significant clinical consequences. Epidemiology of HEV genotype 1 in endemic areas often show waxing and waning pattern. Occasional sporadic occurrence of HEV infection interrupted by outbreaks have been frequently seen. In absence of known animal reservoir, where HEV exists in between outbreak is a mystery that needs further exploration. However, occurrence of asymptomatic HEV viremia due to HEV genotype 1 during epidemiologically quiescent period may explain that this phenomenon may act as a dynamic reservoir. Since HEV genotype 1 infection cannot cause chronicity, subclinical transient infection and transmission of virus might be the reason it sustains in interepidemic period. This might be the similar phenomenon with SARS COVID-19 corona virus infection which is circulating worldwide in distinct phases with peaks and plateaus despite vaccination against it. In view of existing evidence, we propose the concept of "Dynamic Human Reservoir." Quiescent subclinical infection of HEV without any clinical consequences and subsequent transmission may contribute to the existence of the virus in a community. The potential for transmitting HEV infection by asymptomatic HEV infected individuals by fecal shedding of virus has not been reported in literature. This missing link may be a key to Pandora's box in understanding epidemiology of HEV infection in genotype 1 predominant region.

Evidence of Circulation and Phylogenetic Analysis of Hepatitis E Virus (HEV) in Wild Boar in South-East Italy

Hepatitis E virus (HEV) is an important cause of acute viral hepatitis in humans worldwide. The food-borne transmission of HEV appears to be a major route in Europe through the consumption of pork and wild boar meat. HEV epidemiology in wild boars has been investigated mainly in Northern and Central Italian regions, whilst information from Southern Italy is limited. We investigated the occurrence of HEV in wild boar in the Apulia and Basilicata regions (Southern Italy). Thirteen (10.4%) out of one hundred and twenty-five wild boar samples tested positive for HEV using a quantitative reverse transcription PCR. HEV prevalence was 12% in Apulia and 9.3% in Basilicata. Seven samples were genotyped, and different subtypes (c, f, m) of genotype 3 were identified. The complete genome of a 3m strain was determined, and the virus showed the highest nucleotide identity to a human HEV strain identified in France in 2017. These findings demonstrate the substantial circulation of HEV in the wild boar population in Italian Southern regions. Gathering information on the HEV strains circulating in different geographical areas is useful for tracking the origin of HEV outbreaks and assessing the epidemiological role of wild boar as a potential virus reservoir for domestic pigs.

A Comparison of Clinical Manifestations and Outcomes between Acute Sporadic Hepatitis A and Hepatitis E Infections in Thailand

Hepatitis A virus (HAV) and hepatitis E virus (HEV) infections often present as acute hepatitis with prodromal symptoms. These infections, transmitted via the oral-enteral route, constitute significant public health challenges, particularly in developing countries with subpar sanitary systems. The aim of the study was to describe the clinical manifestations, laboratory findings, and outcomes of hepatitis A and hepatitis E infections in Thailand. We conducted a retrospective chart review and analysis of 152 patients diagnosed with acute hepatitis A or hepatitis E from January 2007 to August 2018 at Siriraj Hospital. The hepatitis E cohort was older with a greater prevalence of comorbidities (hypertension, diabetes mellitus, chronic kidney disease, chronic hepatitis B, and post-kidney transplantation status) than the hepatitis A cohort. While the majority of hepatitis A patients presented with fever (98%) and jaundice (96%), these symptoms were less pronounced in hepatitis E patients. Furthermore, hepatitis A patients exhibited significantly higher aminotransferase and total bilirubin levels. However, clinical outcomes, such as hospitalization rates, progression to acute liver failure, and mortality, were comparable across both groups. In conclusion, although the clinical manifestations of hepatitis A and hepatitis E were similar, fever and jaundice were more prevalent and aminotransferase and bilirubin levels were higher in the HAV-infected group.

Molecular characterisation of a rabbit Hepatitis E Virus strain detected in a chronically HEV-infected individual from Germany

In immunocompromised individuals persisting viremia frequently leads to a chronic hepatitis E virus (HEV) infection. Zoonotic transmission of HEV from pigs and wild boar to humans is proven and sporadic infections with rabbit HEV (raHEV) have recently been reported. Here, the molecular characterisation of a raHEV strain isolated from an immunocompromised, chronically HEV-infected, heart-transplanted patient is described. After successful ribavirin (RBV) treatment of a HEV infection in 2019, the patient was again tested HEV positive in 2021 and received a second RBV therapy cycle. Full-length HEV genome amplification and next generation sequencing was performed on a plasma sample taken between first and second cycle of RBV therapy and a stool sample taken two months after starting the second cycle. The sequence of plasma (raHEV-83) and stool (raHEV-99) derived virus showed the highest nucleotide sequence identity to a Chinese raHEV and a phylogenetic relationship to a raHEV strain isolated from a French patient. Furthermore, sequence analysis revealed the presence of RBV-associated substitutions V1479I and G1634K in the HEV sequences from plasma and additionally K1398R from stool. The results underline the role of rabbits as putative sources of HEV infection and emphasize the need of a one health concept for a better understanding of HEV epidemiology and to develop tools for prevention and control of HEV infection.

Nationwide epidemiologic and genetic surveillance of hepatitis E in Japan, 2014-2021

Hepatitis E virus (HEV) is an emerging causative agent of acute hepatitis. To clarify the epidemiology of HEV and characterize the genetic diversity of the virus in Japan, nationwide enhanced surveillance and molecular characterization studies of HEV in Japan were undertaken from 2014 to 2021. In total, 2770 hepatitis E cases were reported, of which 88% were domestic cases, while only 4.1% represented cases following infection abroad. In addition, 57% of domestic infections occurred in males aged in their 40s-70s. For domestic cases, infection via pork meat consumption continued to be the most reported route. Analysis of the 324 sequences detected between 2016 and 2021 showed that the majority of domestic HEV strains belong to Genotype 3a (G3a) and G3b. In contrast, six of eight cases of G1 HEV reflected infection abroad. Our results suggest that HEV is circulating widely in Japan, with genotypes G3a and G3b being most prevalent. Continued surveillance is necessary to monitor future trends and changes in the epidemiology of HEV in Japan.

Absence of Hepatitis E Virus (HEV) in Italian Lagomorph Species Sampled between 2019 and 2021

The zoonotic hepatitis E virus genotype 3 (HEV-3) causes most autochthonous human hepatitis E cases in Europe, which are due to the consumption of raw or undercooked food products of animal origin. Pigs and wild boars are considered the main reservoirs of this genotype, while rabbits are the reservoir of a distinct phylogenetic group named HEV-3ra, which is classified within the HEV-3 genotype but in a separate clade. Evidence for the zoonotic potential of HEV-3ra was suggested by its detection in immunocompromised patients in several European countries. HEV-3ra infection was found in farmed and feral rabbit populations worldwide and its circulation was reported in a few European countries, including Italy. Furthermore, Italy is one of the major rabbit meat producers and consumers across Europe, but only a few studies investigated the presence of HEV in this reservoir. The aim of this study was to assess the presence of HEV in 328 Italian hares and 59 farmed rabbits collected in 3 Italian macro-areas (North, North-Central, and South-Central), between 2019 and 2021. For this purpose, liver samples were used to detect HEV RNA using broad-range real-time RT-PCR and nested RT-PCR. Using 28 liver transudates from hares, the ELISA test for anti-HEV IgG detection was also performed. Neither HEV RNA nor anti-HEV antibodies were detected. Further studies will be conducted to assess the HEV presence in Italian lagomorphs to establish the role of this host and the possible risk of transmission for workers with occupational exposure, to pet owners and via food.

A Randomized Large-Scale Cross-Sectional Serological Survey of Hepatitis E Virus Infection in Belgian Pig Farms

Hepatitis E virus (HEV) is the causative agent of hepatitis E disease in humans. While sporadic HEV infections, which occur in industrialised countries and are typically due to HEV genotypes 3 or 4, are asymptomatic and self-limiting, a chronic form of the disease can lead to liver cirrhosis in immunocompromised individuals. Pigs share HEV 3 and 4 genotypes and are thus considered a major animal reservoir for human infection. A subset of animals has been shown to carry HEV particles at the age of slaughter, rendering raw or undercooked pig products potential vectors for human infection. To provide an overview of the current dissemination of HEV in Belgian pig herds, this study was designed as a randomized, robust, large-scale, cross-sectional, serological survey. HEV genotypes and subtypes recently circulating in Belgium (2020-2021) were investigated. Sample stratification as well as epidemiological investigation through the available demographic data of the sampled herds showed that HEV widely circulated in the Belgian pig population during this time and that a change in the circulating HEV strains may have occurred in the last decade. Herd size and type were identified as risk factors for HEV herd-seropositivity. Identifying farms at risk of being HEV-positive is an important step in controlling HEV spread and human infection.

Viral clade is associated with severity of symptomatic genotype 3 hepatitis E virus infections in Belgium, 2010-2018

BACKGROUND & AIMS

HEV genotype (gt) 3 infections are prevalent in high-income countries and display a wide spectrum of clinical presentations. Host - but not viral - factors are reported to be associated with worse clinical outcomes.

METHODS

Demographic, clinical, and biochemical data laboratory-confirmed HEV infections (by PCR and/or a combination of IgM and IgG serology) at the Belgian National Reference Centre between January 2010 and June 2018 were collected using standardised case report forms. Genotyping was based on HEV open reading frame 2 sequences. Serum CXCL10 levels were measured by a magnetic bead-based assay. H&E staining was performed on liver biopsies.

RESULTS

A total of 274 HEV-infected individuals were included. Subtype assignment was possible for 179/218 viraemic cases, confirming gt3 as dominant with an almost equal representation of clades abchijklm and efg. An increased hospitalisation rate and higher peak serum levels of alanine aminotransferase, bilirubin, and alkaline phosphatase were found in clade efg-infected individuals in univariate analyses. In multivariable analyses, clade efg infections remained more strongly associated with severe disease presentation than any of the previously identified host risk factors, being associated with a 2.1-fold higher risk of hospitalisation (95% CI 1.1-4.4, p = 0.034) and a 68.2% higher peak of bilirubin levels (95% CI 13.3-149.9, p = 0.010), independently of other factors included in the model. In addition, acute clade efg infections were characterised by higher serum CXCL10 levels (p = 0.0005) and a more pronounced liver necro-inflammatory activity (p = 0.022).

CONCLUSIONS

In symptomatic HEV gt3 infections, clade efg is associated with a more severe disease presentation, higher serum CXCL10 levels, and liver necro-inflammatory activity, irrespective of known host risk factors.

CLINICAL TRIAL REGISTRATION

The protocol was submitted to clinicaltrials.gov (NCT04670419).

IMPACT AND IMPLICATIONS

HEV genotype (gt) 3 infections display a wide spectrum of clinical presentations currently ascribed to host factors. Here we examined the role of viral factors on liver disease outcomes by combining viral phylogeny with clinical, biochemical, cytokine, and histological data from 274 Belgian adults infected with HEV presenting between 2010 and 2018. HEV gt 3 clade efg infections were associated with a more severe disease presentation, higher serum CXCL10 levels and liver necro-inflammatory activity, irrespective of known host risk factors. HEV gt3 clade-dependent clinical outcomes call for broad HEV gt3 subtyping in clinical practice and research to help identify those at higher risk for worse outcomes and to further unravel underlying virus-host interactions.

Hepatitis E Virus (HEV): Identification of Subtypes 3b and 3m in Wild Boar Population in Liguria Region, Italy

The wild boar is an important natural reservoir for the zoonotic transmission of the hepatitis E virus (HEV) around the world. In particular, HEV genotypes 3 and 4 are an emerging problem in industrialized countries, as the number of wild boars has increased, and their territory is ever closer to farms and populated areas. This study describes the HEV prevalence and geographic circulation among wild boar populations in the Ligurian region (Italy) during the period 2019-2022. Liver samples from 849 wild boars were analyzed for HEV RNA using real-time RT-PCR; positive samples were then subjected to sequencing and phylogenetic analysis. Overall, 6.7% of the wild boars were positive for HEV RNA; however, in the last two years, the percentage of positive animals almost doubled. Phylogenetic analysis showed that wild boar HEV sequences belonged to genotype 3 and clustered within subtypes 3a and 3c, and, for the first time in Italy, subtypes 3b and 3m were identified. Interestingly, 13 sequences could not be assigned to a recognized subtype. Furthermore, the results showed different circulations of identified subtypes across the territory. These findings increase the knowledge of HEV-3 heterogeneity in Italy and describe the role of wild boars in maintaining an active viral circulation in the environment.

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.

Molecular epidemiology and genotype-specific disease severity of hepatitis E virus infections in Germany, 2010-2019

Zoonotic hepatitis E virus (HEV) is endemic in Europe. Genotype 3 (HEV-3) is predominant but information on subtype distribution, trends and clinical implications in Germany is scarce. We analysed 936 HEV RNA positive samples of human origin and corresponding national surveillance data from 2010 to 2019. Samples were referred to the National Consultant Laboratory and sequenced in at least one of four genomic regions. Sequences were analysed using bioinformatics methods and compared to the latest HEV reference set. 1,656 sequences were obtained from 300 female, 611 male and 25 of unknown sex aged 3–92 years (median 55 years). HEV-3c was predominant (67.3%) followed by HEV-3f, HEV-3e and HEV-3i(-like) with 14.3%, 9.7% and 4.0% (other subtypes ≤1.1%). The proportion of HEV-3 group 2 (3abchijklm) strains increased over time. Jaundice, upper abdominal pain, fever, hospitalization, and death due to HEV were significantly more often reported for patients infected with HEV-3 group 1 (3efg) compared to group 2. Larger spatio-temporal clusters of identical sequences were not observed. HEV-3 group 1 infections are more severe as compared to the predominant group 2. Detection of group 2 strains increased over the last years, possibly due to more frequent diagnosis of asymptomatic and mild courses. The diversity of strains and the space–time distribution is compatible with a foodborne zoonosis with supra-regional distribution of the infection vehicle (pork products).

Hepatitis E virus genotype 3 microbiological surveillance by the Spanish Reference Laboratory: geographic distribution and phylogenetic analysis of subtypes from 2009 to 2019

Background

Hepatitis E virus genotype 3 (HEV-3) is widely distributed throughout Europe, with incidence of infections increasing in many countries. Belgium, Bulgaria, France, Germany, Italy, the Netherlands and the United Kingdom have reported the distribution of HEV-3 subtypes in cohorts of patients with hepatic disease.

Aim

To describe the distribution of the HEV-3 subtypes in Spain at national and autonomous community (AC) levels between 2009 and 2019. The study was also extended to Andorra.

Methods

Of 5,197 samples received by the National Reference Laboratory during the study, 409 were HEV-RNA-positive. Among these, 294 (71.9%) were further typed based on an ORF2 sequence fragment, or, for a subset of 74, based on the full-coding genome sequence.

Results

HEV-3 was detected in 291 samples. The dominant subtype in Spain was HEV-3f (88.3%; 257/291), which occurred in all ACs, with no change in detection level over time. Within this subtype, three subclusters were characterised: HEV-3f-B, HEV-3f-A1 and HEV-3f-A2. The second most common HEV subtype was the recently described HEV-3m (7%; 21/291), with two subclusters identified: HEV-3m-A, which has been known since 2010, and HEV-3m-B, since 2014. The third most encountered subtype was HEV-3c (4.1%; 12/291), with a frequency not increasing over time, unlike observations in some European countries.

Conclusion

The importance of the surveillance of HEV-3 subtype and subcluster circulation is yet to be assessed. This surveillance together with the comprehensive epidemiological characterisation of clinical cases, could support the identification of sources of transmission and the establishment of control measures nationally and internationally.

Trends in hepatitis E virus infection: Analyses of the long-term screening of blood donors in Hokkaido, Japan, 2005-2019

BACKGROUND

After experiencing several cases of transfusion-transmitted hepatitis E (TT-HE) in Hokkaido, Northern Japan, hepatitis E virus (HEV) screening in blood donors, using a nucleic acid amplification test (NAT), was introduced in 2005.

STUDY DESIGN AND METHODS

The frequency of HEV RNA-positive donations (2005-2019) was investigated, and the HEV RNA-positive specimens were phylogenetically analyzed. In August 2014, the 20-pooled NAT (20P-NAT) was replaced with an individual-NAT (ID-NAT) system.

RESULTS

Until 2019, the frequency of HEV RNA-positive donors was 0.011% (289/2,638,685) with 20P-NAT and 0.043% (597/1,379,750) with ID-NAT, and no TT-HE cases were observed in Hokkaido. The prevalence among male, but not female donors, increased significantly between 2015 and 2019. Eighty-nine percent of HEV isolates from donors were genotype 3 and the remainder were genotype 4, and many clusters existed in each genotype. ALT levels at the time of donation were significantly higher in donors with genotype 4. Four subgenotypes, namely 3a (37%), 3b (41%), 3e (6%), and 4c (10%), comprised 94% of the total. During this period, the most identified subgenotype, 3a, transitioned to 3b. Majority of the HEV strains within the same clusters were detected in the same geographical region around the same period. Many of the human HEV isolates were shown to coexist closely with animal HEV isolates phylogenetically.

CONCLUSION

In Hokkaido, multiple divergent HEV strains have been circulating, and small outbreaks of hepatitis E have occurred in the last 15 years. The results suggested that HEV NAT can contribute significantly in ensuring safety during blood transfusions.

Global molecular diversity of Hepatitis E virus in wild boar and domestic pig

Our study aim was to describe and characterize the global Hepatitis E virus (HEV) molecular and genotype geographical distribution in domestic pig and wild boar, which could facilitate the traceability of human cases. We performed a systematic sequence search for HEVs identified in domestic pig and wild boar from the available data in GenBank. Only sequences with lengths greater than 300 nt were included. For all sequences, the sequence length, host (i.e., domestic pig or wild boar), country of origin, and HEV genotype/subtype were recorded. Genotypes were assigned by the HEVnet typing tool. The genotype distributions were described by country and host. In countries with sequences available for both species, the genotype coincidences between both animal populations were analyzed. A total of 1404 viral sequences were included: 32.6% from wild boar and 67.4% from domestic pig. Most sequences were consistent with HEV genotype 3 (n = 1165). Genotype 4 was represented by 193 sequences, while genotypes 5 and 6 were represented by only 6 sequences. Sequences were identified in 39 countries, which included all continents except Antarctica. The genotypes with a wide distribution were 3a and 3f. Twenty-five countries had sequences that were found only in domestic pig, three countries only in wild boar, and 11 countries had sequences in both populations. In all countries with available sequences in both populations, the same viral genotype was identified. Our study shows that the number of swine HEV sequences is small, which limits direct comparisons with the sequences identified in humans. The global distribution of genotype 3, together with the wide distribution of genotype 4 in Asia, strongly limits the interpretation of the molecular analysis in the absence of an epidemiological survey of the cases. Increased HEV sequencing in swine should be a priority.

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Our study shows that the number of swine HEV sequences is small.

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The global distribution of genotype 3 strongly limits the interpretation of the molecular analysis.

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Increased HEV sequencing in swine should be a priority.

Seroprevalence and phylogenetic characterization of hepatitis E virus in pig farms in Southern Italy

Hepatitis E virus (HEV) infection is an emerging public health problem in industrialized countries. The infection is associated with waterborne epidemics and transmitted via faecal-oral route. Zoonotic cases of HEV in humans have increased in Europe, and HEV genotype 3 (HEV-3) is the most frequent among humans and animals. Nevertheless, HEV surveillance in the Italian pig farming industry is patchy. Here, HEV prevalence in pig farms located in the Calabria region in Southern Italy was investigated. A total of 692 serum samples were collected from 26 farms and tested for anti-HEV IgG antibody detection. The percentage of HEV-seropositive pigs was 56.8 %. Small farm size, farrow-to-finishing production, and infrequent cleaning procedures were associated with higher HEV seroprevalence. In 12 of the HEV-seropositive farms, 67 faecal samples were collected and 10 of these (10.6 %) tested positive for HEV RNA. Seven of 10 viral RNA sequences were genotyped for phylogenetic analysis, five of which belonged to subtype HEV-3f and two to subtype HEV-3e. The high HEV seroprevalence and the circulation of HEV-3 strains among domestic pigs in the Calabria region pose a risk for the zoonotic transmission of HEV from pigs to occupational exposed workers.

Analyses of Clinical and Biological Data for French and Belgian Immunocompetent Patients Infected With Hepatitis E Virus Genotypes 4 and 3

Hepatitis E virus (HEV) genotypes 3 and 4 are the major causes of acute hepatitis in industrialized countries. Genotype 3 is mainly found in Europe and America, while genotype 4 is predominant in Asia. Several Japanese studies have suggested that genotype 4 is more virulent than genotype 3. We investigated this aspect by analyzing the clinical and biological data for 27 French and Belgian immunocompetent patients infected with HEV genotype 4. Their infections were probably acquired locally, since none of these patients reported traveling outside France or Belgium during the 2–8 weeks before symptoms onset. Each patient was matched for age (±5 years) and gender with two patients infected with HEV genotype 3. Bivariate analysis indicated that the HEV genotype 4-infected patients had significantly higher alanine aminotransferase (ALT) (2067 IU/L) and aspartate aminotransferase (AST) (1581 IU/L) activities and total bilirubin concentrations (92.4 μmol/L) than did those infected with HEV genotype 3 (1566 IU/L, p = 0.016; 657 IU/L, p = 0.003 and 47 μmol/L, p = 0.046) at diagnosis. In contrast, more patients infected with HEV genotype 3 reported dark urine (71% vs. 39%, p = 0.02) and experienced asthenia (89% vs. 58%, p < 0.01) than did those infected with HEV genotype 4. Two HEV genotype 4-infected patients died of multi-organ failure, while none of the genotype 3-infected patients died (p = 0.035). Finally, stepwise regression analysis retained only a greater increase in ALT (odds-ratio: 1.0005, 95% confidence interval: 1.00012–1.00084) and less frequent fever (odds-ratio = 0.1244; 95% confidence interval: 0.01887–0.82020) for patients infected with HEV genotype 4. We conclude that HEV-4 infections are likely to be associated with higher ALT activity than HEV-3 infections. Additional immunological and virological studies are required to confirm these findings and better understand the influence, if any, of genotype on HEV pathophysiology.

Autochthonous and Travel Acquired Hepatitis E Virus in Australia

BACKGROUND

Hepatitis E virus (HEV) is a common cause of acute viral hepatitis with significant morbidity and mortality, particularly in pregnant women. There are four major genotypes which can cause disease in humans. Genotypes 1 and 2 are usually associated with outbreaks and spread via facal/oral route or contaminated water. Genotypes 3 and 4 are zoonotic and usually associated with handling of pigs or consumption of contaminated pork. The strains circulating in Australia have never been characterized.

RATIONALE/AIMS

The aims for this project are to identify the HEV genotypes found in Australia and link them to possible sources of transmission by phylogenetic analysis.

MATERIALS AND METHODS

Between 2015 and 2020, 91 HEV isolates were sequenced and genotyped using an in-house PCR. Sixty-six of these were also sequenced by using the international HEVnet primers. Genotypes were determined using the BLASTn program. Relatedness to other strains in Australia was determined by phylogenetic analyses of the HEVnet sequences. Isolates were also stratified by state of origin, gender, age, predisposing factors and travel history (if known).

RESULTS

Of the 91 HEV isolates sequenced, 55 (60.4%) were genotype 1. There were 34 (37.4%) genotype 3 strains and two genotype 4 (2.2%). At least 20 of the genotype 1 strains have been linked to travel in India, and another three with Pakistan. Five of the "Indian" strains were closely related and are suspected to have originated in Gujarat. Phylogenetic analysis also showed that 12 genotype 3 strains were genetically related and potentially acquired in/from New South Wales, Australia. The two genotype 4 strains may have originated in China.

DISCUSSION

This is the first study to describe the HEV isolates identified in Australia. The results infer that HEV may be acquired during overseas travel as well as locally, presumably from consumption of pork or pork-related products. The phylogenetic analyses also reveal clusters of infection originating from India and Pakistan. This study provides some insight into the source and epidemiology of HEV infection in Australia which may be used to guide public health procedure and enable the implementation of measures to deal with potential outbreaks of infection.

Classification of the Zoonotic Hepatitis E Virus Genotype 3 Into Distinct Subgenotypes

Hepatitis E virus (HEV) genotype 3 is the most common genotype linked to HEV infections in Europe and America. Three major clades (HEV-3.1, HEV-3.2, and HEV-3.3) have been identified but the overlaps between intra-subtype and inter-subtype p-distances make subtype classification inconsistent. Reference sequences have been proposed to facilitate communication between researchers and new putative subtypes have been identified recently. We have used the full or near full-length HEV-3 genome sequences available in the Genbank database (April 2020; n = 503) and distance analyses of clades HEV-3.1 and HEV-3.2 to determine a p-distance cut-off (0.093 nt substitutions/site) in order to define subtypes. This could help to harmonize HEV-3 genotyping, facilitate molecular epidemiology studies and investigations of the biological and clinical differences between HEV-3 subtypes.

Development and Clinical Validation of a Pangenotypic PCR-Based Assay for the Detection and Quantification of Hepatitis E Virus (Orthohepevirus A Genus)

The objective of this study was to design a pangenotypic PCR-based assay for the detection and quantification of hepatitis E virus (HEV) RNA from across the entire spectrum of described genotypes belonging to the Orthohepevirus A genus. The optimal conditions and the performance of the assay were determined by testing the WHO standard strain (6219/10) and the WHO HEV panel (8578/13). Similarly, performance comparisons were made with two commercial assays (Real Star HEV RT-PCR 2.0 and ampliCube HEV 2.0 Quant) to detect HEV RNA at concentrations below 1,000 IU/ml with viral strains from the WHO and to test samples from 54 patients with acute hepatitis. The assay presented in this study was able to detect the entire spectrum of described genotypes belonging to the Orthohepevirus A genus, demonstrating better performance than both commercial kits. This procedure may represent a significant improvement in the molecular diagnosis of HEV infection.

Th1/Th2 Cells and Associated Cytokines in Acute Hepatitis E and Related Acute Liver Failure

Background and Aims

The involvement of cellular immunity in the development of hepatitis E virus (HEV) infection is rare. We aimed to study the roles of viral load and Th cell responses in acute hepatitis E (AHE) and HEV-related acute liver failure (HEV-ALF).

Methods

We evaluated viral load and Th1/Th2 cytokine levels in 34 patients with HEV infection, including 17 each with AHE or HEV-ALF. Seventeen healthy controls (HCs) were also included who were negative for anti-HEV IgM and IgG.

Results

There was no significant difference in viral load and HEV RNA in the AHE and HEV-ALF groups (both P > 0.05). The Th lymphocyte levels (CD3+, CD4+) in the AHE and HEV-ALF groups were significantly higher than those in the HC group (both P < 0.05), but there was no significant difference between the AHE and HEV-ALF groups (P > 0.05). Both IFN-γ and IL-10 showed gradual upward trend from the HC group to the AHE (both P < 0.01), but IFN-γ showed a sharp downward trend from the AHE group to the HEV-ALF group (P < 0.01) and IL-4 showed gradual upward trend from the AHE group to the HEV-ALF group (P < 0.01).There was no significant difference in Th1 and Th2 cytokines between the HEV RNA(+) group and HEV RNA(-) group (all P > 0.05). Th2 bias was observed from the AHE (ratio = 58.65) to HEV-ALF (ratio = 1.20) groups. The level of IFN-γ was associated with the outcome of HEV-ALF patients.

Conclusions

HEV viral load was not associated with aggravation of AHE, and the HEV-ALF patients showed significant Th2 bias, which may be involved in the aggravation of AHE.

Stable HEV IgG seroprevalence in Belgium between 2006 and 2014

Recent European studies suggest an emergence of hepatitis E virus (HEV) infection. We evaluated trends in birth cohort-specific HEV seroprevalence and regional differences in Belgium. HEV IgG seroprevalence was analysed on national serum banks (1579 and 2087 samples for 2006 and 2014, respectively. Hepatitis E virus antigen was tested on positive samples. Observed data were modelled using a generalized additive model with a complementary log-log link. No significant differences between birth cohorts or sexes were found. Modelling identified the individual's age and province as relevant factors. The probability of HEV seropositivity increases significantly with age. An estimated total of 434 819 (yearly rate of 54,352) (sero-)infections were found between 2006 and 2014. Overall, HEV IgG seroprevalences were 4.1% (64/1579, 95% CI 3.1-5.1) and 5.8% (121/2087, CI 4.8-6.9) in 2006 and 2014, respectively. Observed HEV antigen seroprevalence was 0.027% (1/3666) for the entire cohort. These results show stable HEV IgG seroprevalence in Belgium.

Hepatitis E 3ra Genotype Infection in People Living With HIV in Spain

Background

The objective of our study was to assess the prevalence and incidence of HEV in people living with HIV (PLWH) in a Spanish national cohort.

Methods

Retrospective longitudinal study including PLWH recruited in the cohort of adult HIV-infected patients of the AIDS Research Network in follow-up at 28 Spanish hospitals with available serum samples in 2014 and 2015. All samples were tested for HEV IgG, IgM, and RNA. Samples with detectable HEV viral loads were genotyped. Prevalence and incidence of HEV infection were calculated.

Results

The study sample comprised 845 PLWH. At baseline, 101 patients were positive for HEV IgG antibodies (11.9%), none had HEV IgM antibodies, and 2 presented detectable HEV RNA (0.23%). Forty-two seroconverted for IgG, supposing a cumulative incidence of 5.7%. One subject was positive for IgM (0.13%), and 2 showed detectable HEV RNA (0.27%). One case was infected by the emergent HEV genotype 3ra.

Conclusion

Our study identifies one case of HEV 3ra genotype infection, the main host of which is rabbit, showing a potential zoonotic role of this emerging genotype in Spain.

Recent data on hepatitis E

PURPOSE OF REVIEW

Hepatitis E virus (HEV) has gained increased global recognition in recent years, particularly in developed countries. We summarized here a selection of the literature published since the 1st of June, 2017.

RECENT FINDINGS

Longitudinal studies are increasingly conducted in Europe, to determine trends in HEV prevalence. The spectrum of mammals infected with HEV and potentially capable to transmit it to humans has widened. New virological data on HEV repCon and pathogenicity have been reported and clinical features of HEV infections have been precised or newly described. Finally, there are some new data on the therapeutic management of HEV infections in various clinical settings.

SUMMARY

HEV emergence in developed countries appears to be based on improved diagnosis tools and increased awareness of clinicians that HEV transmission is essentially autochthonous and is a possible cause of life-threatening acute hepatitis, chronic hepatitis, cirrhosis, and extra-hepatic symptoms. In addition, the distribution of HEV strains evolves. Ribavirin remains to date the only specific treatment recommended for HEV infection, being efficient in the majority but not in all cases.

Subtype-specific differences in the risk of hospitalisation among patients infected with hepatitis E virus genotype 3 in Belgium, 2010-2018

Some European countries recently reported an increase in hepatitis E virus genotype 3 (HEV-3) of the subtype 3c. No link between HEV-3 subtypes and severity is established to date. Here, we report that patients infected with HEV-3c were at lower risk of hospitalisation, compared to those infected with HEV-3f, the other main subtype circulating in Belgium.

Molecular Characterization of HEV Genotype 3 in Italy at Human/Animal Interface

Hepatitis E virus (HEV) is an emerging public health issue in industrialized countries. In the last decade the number of autochthonous human infections has increased in Europe. Genotype 3 (HEV-3) is typically zoonotic, being foodborne the main route of transmission to humans, and is the most frequently detected in Europe in both humans and animals (mainly pigs and wild boars). In Italy, the first autochthonous human case was reported in 1999; since then, HEV-3 has been widely detected in both humans and animals. Despite the zoonotic characteristic of HEV-3 is well established, the correlation between animal and human strains has been poorly investigated in Italy. In the present study, we compared the subtype distribution of HEV-3 in humans and animals (swine and wild boar) in the period 2000-2018 from Italy. The dataset for this analysis included a total of 96 Italian ORF2 sequences (300 nt long), including both NCBI database-derived (n = 64) and recent sequences (2016-2018, n = 32) obtained in this study. The results show that subtype 3f is the most frequent in humans and pigs, followed by the HEV-3e, HEV-3c and other unassignable HEV-3 strains. Diversely, in wild boar a wider group of HEV-3 subtypes have been detected, including HEV-3a, which has also been detected for the first time in a human patient in Central Italy in 2017, and a wide group of unassignable HEV-3 strains. The phylogenetic analysis including, besides Italian strains, also sequences from other countries retrieved from the NCBI database, indicated that human Italian sequences, in particular those of HEV-3f and HEV-3e, form significant clusters mainly with sequences of animal origin from the same country. Nevertheless, for HEV-3c, rarely detected in Italian pigs, human sequences from Italy are more correlated to human sequences from other European countries. Furthermore, clusters of near-identical human strains identified in a short time interval in Lazio Region (Central Italy) can be recognized in the phylogenetic tree, suggesting that multiple infections originating from a common source have occurred, and confirming the importance of sequencing support to HEV surveillance.

Absence of Hepatitis E virus circulation in wild rabbits (Oryctolagus cuniculus) and Iberian hares (Lepus granatensis) in Mediterranean ecosystems in Spain

In recent decades, cases of autochthonous hepatitis E (HE) have sharply increased in European countries where foodborne transmission is considered the main route of HE virus (HEV) transmission. Although rabbits are considered the main reservoir of the zoonotic HEV-3ra subtype, information on the role of wild lagomorphs in the epidemiology of HEV remains scarce. The aim of this study therefore was to assess the circulation of HEV in European wild rabbits (Oryctolagus cuniculus) and Iberian hares (Lepus granatensis), the most important lagomorph species in Spanish Mediterranean ecosystems. Liver samples from 372 wild rabbits and 78 Iberian hares were analysed using a broad-spectrum RT-PCR that detects HEV genotypes 1-8. None of the 450 lagomorphs tested were positive for HEV infection. To the best of our knowledge, this is the first study to assess HEV circulation in wild rabbits in Spain and the first to evaluate HEV infection in Iberian hares. Our results indicate absence of HEV circulation in wild rabbits and Iberian hares in southern Spain during the study period, which suggests that the risk of transmission of HEV from wild lagomorphs to other species, including humans, is low.

Ribavirin as a First Treatment Approach for Hepatitis E Virus Infection in Transplant Recipient Patients

The hepatitis E virus (HEV) is the major cause of acute hepatitis of viral origin worldwide. Despite its usual course as an asymptomatic self-limited hepatitis, there are highly susceptible populations, such as those with underlying immunosuppression, which could develop chronic hepatitis. In this situation, implementation of therapy is mandatory in the sense to facilitate viral clearance. Currently, there are no specific drugs approved for HEV infection, but ribavirin (RBV), the drug of choice, is used for off-label treatment. Here, we present two cases of chronic HEV infection in transplant patients, reviewing and discussing the therapeutic approach available in the literature. The use of RBV for the treatment of an HEV infection in organ transplant patients seems to be effective. The recommendation of 12 weeks of therapy is adequate in terms of efficacy. Nevertheless, there are important issues that urgently need to be assessed, such as optimal duration of therapy and drug dosage.

Mode and tempo of human hepatitis virus evolution

Human viral hepatitis, a major cause of morbidity and mortality worldwide, is caused by highly diverse viruses with different genetic, ecological, and pathogenetic features. Technological advances that allow throughput sequencing of viral genomes, as well as the development of computational tools to analyze such genome data, have largely expanded our knowledge on the host range and evolutionary history of human hepatitis viruses. Thus, with the exclusion of hepatitis D virus, close or distant relatives of these human pathogens were identified in a number of domestic and wild mammals. Also, sequences of human viral strains isolated from different geographic locations and over different time-spans have allowed the application of phylogeographic and molecular dating approaches to large viral phylogenies. In this review, we summarize the most recent insights into our understanding of the evolutionary events and ecological contexts that determined the origin and spread of human hepatitis viruses.

Design and immunogenicity analysis of the combined vaccine against zoonotic hepatitis E and foot-and-mouth disease

AIM

Design and immunogenicity assessment of the combined vaccine candidate against zoonotic hepatitis E virus (HEV) and foot-and-mouth disease virus (FMDV).

METHODS

Using the molecular cloning technology, we produced and purified 9 HEV ORF2-truncated proteins (HEV genotype 4). Then, we compared their thermal stability, antigenicity, and immunogenicity to select the best HEV immunogen. Next, we used the adjuvant Montanide ISA-206 to prepare different formulations of HEV vaccine alone, FMDV vaccine alone and HEV-FMDV combined vaccine. The formulations were injected into mice and the induced humoral immune responses were monitored up 12 weeks post-immunization.

RESULTS

The HEV p222 protein could self-assemble into VLPs (∼34 nm) and showed higher stability and better antigenicity/immunogenicity than the other HEV antigens, thus it was selected as the best HEV immunogen. Mice immunization with the FMDV vaccine alone induced high FMDV-specific antibody titers in a dose-dependent manner; the HEV p222 protein also induced high levels of anti-HEV antibodies but in a dose-independent manner. The HEV-FMDV combination induced anti-FMDV antibody titers 7-16-fold higher than the titers induced by the FMDV vaccine alone, and HEV-specific antibody titers 2.4-fold higher than those induced by the HEV p222 antigen alone.

CONCLUSION

Herein, we proposed a new approach for the control of zoonotic HEV infection through its control in its main host (pig). We also designed the first HEV-FMDV combined vaccine and the preliminary analyses revealed a synergistic effect on the immunogenicity of both HEV and FMDV antigens.