Hepatitis E Virus

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.

Higher Risk of Chronic Hepatitis E Virus Infection in Patients with Human Immunodeficiency Virus-1: An Iranian Cross-sectional Study

Background & Objective

Occurrence of Hepatitis E Virus (HEV) infection may be common in Human Immunodeficiency Virus (HIV-1) patients and may lead to chronic infection as well as cirrhosis. We intended to determine the incidence of HEV infection among HIV-1 patients compared to individuals without HIV-1 infection.

Methods

In our cross-sectional study, 87 HIV-1-positive patients were compared to 93 healthy individuals in Kerman, Iran. Plasma and peripheral blood mononuclear cells (PBMCs) were obtained from all the participants. Plasma samples were evaluated for HEV IgM and IgG using the ELISA kit. Then, reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) was used in RNA extractions from PBMCs to check for the presence of HEV RNA.

Results

Among the subjects examined in our study, 61 (70.1%) and 71 (77.4%) out of patients with HIV-1 infection and healthy individuals were male, respectively. The average ages of patients with HIV-1 and the control group were 40.2 years and 39.9 years, respectively. No discernible differences were found between the two groups based on IgM and IgG seropositivity against the HEV. However, HEV-RNA was found in 8% of patients with HIV-1 and 1.1% of HIV-1-negative individuals (P=0.03). There was also an association between the HEV genome and anti-HEV and anti-HCV antibodies in HIV-1-positive patients (P=0.02 and P=0.014, respectively).

Conclusion

HEV infection may be more common in HIV-1 patients and may develop a chronic infection in immunocompromised individuals. Molecular-based HEV diagnostic tests, including RT-PCR assays, should be performed in HIV-1 patients with unknown impaired liver function tests.

Sero-molecular epidemiology of hepatitis E virus in pigs and human contacts in Ghana

BACKGROUND

Hepatitis E virus (HEV) is among the leading causes of viral hepatitis in most developing countries. Zoonotic acquisition of HEV genotype 3 from swine has come into focus more recently. Available studies on HEV in Ghana and other countries in the region do not provide enough information towards understanding the epidemiology of HEV in human and animal populations. Towards this end, we conducted a comparative cross-sectional study to determine the seroprevalence and risk factors associated with HEV exposure, both in swine and humans working on pig farms in typical local settings. The presence of viral RNA in human and swine samples was also evaluated, along with classification of viral sequences from HEV-positive samples.

METHODS

Structured questionnaires soliciting information on pigs reared, as well as socio-demographic information including age, sex and educational background of humans was collected. A total of 10 ml and 5 ml of whole blood was collected from pigs and human participants respectively. ELISA and real-time RT-PCR were performed on the sera for the qualitative detection of IgG antibodies to hepatitis E virus and viral RNA, respectively.

RESULTS

Five hundred and forty-four (544) human participants including 264 swine contacts and 280 swine non-contacts were enrolled in the study. Although the proportion of HEV IgG antibodies was higher in contact groups (114; 54.3%) than non-contact groups (96; 45.7%), a multivariate analysis did not show any significant difference. No HEV RNA was detected in human samples. Similarly, 720 pigs were sampled from 18 farms located in five regions in Ghana. Twenty-three (23) of the pigs (3.2, 95%CI = 2.0-4.8) were positive for HEV RNA by real-time RT-PCR testing. Sequences obtained from HEV-positive samples were found to share high sequence identities with each other and clustered with other genotype 3 viruses indicating the existence of circulating zoonotic genotype 3 viruses on farms. Although we did not find evidence of pig to human transmission of HEV genotype 3, the presence of this genotype in pigs shows the potential for possible zoonotic transmission in African farm settings and buttresses the importance of active surveillance for the infection among at risk populations.

Hepatitis E virus prevalence in Flemish blood donors

Transmission of hepatitis E virus (HEV) through transfusion of blood components has already been reported in several European countries. Here, we assessed the HEV prevalence in Flemish blood donors. This study is of importance in order to assess the risk of HEV transmission through blood transfusion. We analysed 38 137 blood donation samples that were collected by the Red Cross Flanders during the period May-June 2015. All samples were screened for the presence of HEV RNA and a selection for HEV-specific IgM/IgG. After pooling per 6, 11 pools reacted positive during RNA screening. Reactive pools were deconstructed, and individual samples were retested. After deconstruction, seven samples were confirmed as HEV RNA positive. Serological screening of the confirmed RNA-positive samples showed that six out of these seven samples were HEV IgM positive, of which three donors were also IgG positive. Serological screening was also performed on the samples that constituted the four initially HEV RNA reactive pools where RNA positivity was not confirmed on the individual level. In three pools, we found indirect evidence of recent HEV exposure. Within 356 randomly selected samples, 31 donations were HEV IgG positive. Here we show that at least 1:5448 of blood donations in Flanders may originate from donors that are actively infected with HEV. Upon transfusion, these donations may pose a major threat towards patients at risk. Finally, a serological analysis showed that the anti-HEV IgG prevalence in Flemish blood donors is 8.71%.

Blood Donor Screening for Hepatitis E Virus in the European Union

This review article summarises hepatitis E virus (HEV) blood donation screening strategies in effect in the European Union (EU). Since 2012, eight EU countries have implemented HEV screening. Local rates of seroprevalence, RNA incidence, and molecular epidemiology are variable and not usually directly comparable. We report a range of HEV-RNA reactivity rates from 1 in 744 donations (France) to 1 in 8,636 donations (Wales) with an overall EU rate of 1 in 3,109 donations (3.2 million donations screened). HEV genotypes 3c, 3e, and 3f are the most frequently reported subtypes. In these 8 countries, both universal (n = 5) and selective (n = 3) screening policies have been introduced utilising either individual donation (ID; n = 1) or mini-pool (MP; n = 7; MP-6, -16, -24, and -96) testing. We also describe the Irish experience of HEV screening utilising an ID-NAT-based donor screening algorithm which intercepts donations even from those with low-level viraemia; 21 of 56 donors (37.5%) had a viral load (VL) < 100 IU/mL. We performed a MP-24 experiment which may prove useful to colleagues in relation to donor screening and associated blood component transmissibility. Irish results indicate that 59% of donors with a HEV-VL < 450 IU/mL may have screened negative in a MP-24.

Hepatitis E virus blood donor NAT screening: as much as possible or as much as needed?

BACKGROUND

The cost-benefit question of general screening of blood products for the hepatitis E virus (HEV) is currently being discussed. One central question is the need for individual nucleic acid amplification techniques (NAT) screening (ID-NAT) versus minipool NAT screening (MP-NAT) approaches to identify all relevant viremias in blood donors. Here, the findings of ID-NAT versus MP-NAT in pools of 96 samples were compared.

STUDY DESIGN AND METHODS

From November 2017 to January 2018, a total of 10,141 allogenic blood donations from 7650 individual German blood donors were screened for the presence of HEV RNA using MP-NAT (96 samples) (RealStar HEV RT-PCR Kit) compared to ID-NAT (cobas HEV assay) on the fully automated cobas 6800 platform.

RESULTS

Parallel screening of MP (n = 122, 96 samples/MP) using both methods detected seven reactive pools. After pool resolution, 8 HEV RNA-positive donations were identified by the in-house detection method, whereas 17 HEV RNA-positive donations were identified by ID-NAT with the cobas HEV assay. This resulted in an incidence of 1:1268 donations (0.079%) for MP-NAT screening and 1:597 donations (0.168%) for ID-NAT screening.

CONCLUSIONS

The detection frequency of HEV RNA was approximately 50% higher if ID-NAT was used compared to MP-NAT. However, viral loads of ID-NAT-only samples were below 25 IU/mL and will often not result in transfusion-transmitted HEV (TT-HEV) infection, taking into account the currently known infectious dose of 5.0E + 04 IU inevitably resulting in TT-HEV infection. The clinical relevance and need for identification of these low-level HEV-positive donors still require further investigation.

Vaccine Development against Zoonotic Hepatitis E Virus: Open Questions and Remaining Challenges

Hepatitis E virus (HEV) is a fecal-orally transmitted foodborne viral pathogen that causes acute hepatitis in humans and is responsible for hepatitis E outbreaks worldwide. Since the discovery of HEV as a zoonotic agent, this virus has been isolated from a variety of hosts with an ever-expanding host range. Recently, a subunit HEV vaccine developed for the prevention of human disease was approved in China, but is not yet available to the rest of the world. Meanwhile, notable progress and knowledge has been made and revealed in recent years to better understand HEV biology and infection, including discoveries of quasi-enveloped HEV virions and of a new function of the HEV-ORF3 product. However, the impact of these new findings on the development of a protective vaccine against zoonotic HEV infection requires further discussion. In this review, hallmark characteristics of HEV zoonosis, the history of HEV vaccine development, and recent discoveries in HEV virology are described. Moreover, special attention is focused on quasi-enveloped HEV virions and the potential role of the HEV-ORF3 product as antibody-neutralization target on the surface of quasi-enveloped HEV virions to provide new insights for the future development of improved vaccines against zoonotic HEV infection.

Origin and dispersal of Hepatitis E virus

Hepatitis E virus (HEV, genus Orthohepevirus) is a common cause of hepatitis worldwide. Human-infecting HEV strains (Orthohepevirus A) include human-restricted and enzootic genotypes. Viruses in the Orthohepevirus A species also infect rabbits (HEV-3ra), camels, and swine. Using a selection-informed method, we dated the origin of the Orthohepevirus genus at least 21 million years ago, whereas the Orthohepevirus A species originated in Asia, most likely from a human-infecting ancestor that existed ~4500 to 6800 years ago. In this period, the appearance of large human settlements probably facilitated HEV emergence and spread. The earliest events in Orthohepevirus A evolutionary history involved the separation of the enzootic and human-restricted genotypes, as well as the split of the camel-infecting genotypes, which occurred during the time-frame of camel domestication. The place and timing of HEV-3ra divergence also correspond to the circumstances of rabbit domestication. This study clarifies the origin and historical events underlying HEV dispersal.

Transfusion-Transmitted Hepatitis E: NAT Screening of Blood Donations and Infectious Dose

The risk and importance of transfusion-transmitted hepatitis E virus (TT-HEV) infections by contaminated blood products is currently a controversial discussed topic in transfusion medicine. The infectious dose, in particular, remains an unknown quantity. In the present study, we illuminate and review this aspect seen from the viewpoint of a blood donation service with more than 2 years of experience in routine HEV blood donor screening. We systematically review the actual status of presently known cases of TT-HEV infections and available routine NAT-screening assays. The review of the literature revealed a significant variation regarding the infectious dose causing hepatitis E. We also present the outcome of six cases confronted with HEV-contaminated blood products, identified by routine HEV RNA screening of minipools using the highly sensitive RealStar HEV RT-PCR Kit (95% LOD: 4.7 IU/mL). Finally, the distribution of viral RNA in different blood components [plasma, red blood cell concentrate (RBC), platelet concentrates (PC)] was quantified using the first WHO international standard for HEV RNA for NAT-based assays. None of the six patients receiving an HEV-contaminated blood product from five different donors (donor 1: RBC, donor 2–5: APC) developed an acute hepatitis E infection, most likely due to low viral load in donor plasma (<100 IU/mL). Of note, the distribution of viral RNA in blood components depends on the plasma content of the component; nonetheless, HEV RNA could be detected in RBCs even when low viral plasma loads of 100–1,000 IU/mL are present. Comprehensive retrospective studies of TT-HEV infection offered further insights into the infectivity of HEV RNA-positive blood products. Minipool HEV NAT screening (96 samples) of blood donations should be adequate as a routine screening assay to identify high viremic donors and will cover at least a large part of viremic phases.

Hepatitis E and blood donation safety in selected European countries: a shift to screening?

The public health implications of hepatitis E virus (HEV) in Europe have changed due to increasing numbers of hepatitis E cases and recent reports of chronic, persistent HEV infections associated with progression to cirrhosis in immunosuppressed patients. The main infectious risk for such immunosuppressed patients is exposure to undercooked infected pork products and blood transfusion. We summarised the epidemiology of HEV infections among blood donors and also outlined any strategies to prevent transfusion-transmitted HEV, in 11 European countries. In response to the threat posed by HEV and related public and political concerns, most of the observed countries determined seroprevalence of HEV in donors and presence of HEV RNA in blood donations. France, Germany, Spain and the United Kingdom (UK) reported cases of transfusion-transmitted HEV. Ireland and the UK have already implemented HEV RNA screening of blood donations; the Netherlands will start in 2017. Germany and France perform screening for HEV RNA in several blood establishments or plasma donations intended for use in high-risk patients respectively and, with Switzerland, are considering implementing selective or universal screening nationwide. In Greece, Portugal, Italy and Spain, the blood authorities are evaluating the situation. Denmark decided not to implement the HEV screening of blood donations.

Clinical features of acute hepatitis E super-infections on chronic hepatitis B

AIM

To examine the clinical features and risk factors for adverse outcomes in chronic hepatitis B (CHB) superimposed with hepatitis E virus (HEV).

METHODS

This retrospective cohort study included 228 patients with acute HEV infection (showing clinical acute hepatitis symptomology and positivity for anti-HEV immunoglobulin M) with underlying CHB (confirmed by positivity for hepatitis B surface antigen and/or hepatitis B virus (HBV) DNA over 6 mo) who had been admitted to the Shanghai Public Health Clinical Center, which represents the regional tertiary hospital for infectious diseases in Shanghai city, China. Data for adverse outcomes were collected, and included severe liver diseases (defined as liver failure and/or acute liver decompensation) and liver-related mortality. Logistic regression modeling was performed to determine the risk factors for adverse outcomes.

RESULTS

The symptoms caused by superimposed acute hepatitis E (AHE) were much more severe in cirrhotic patients (n = 94) than in non-cirrhotic patients (n = 134), as evidenced by significantly higher liver complications (77.7% vs 28.4%, P < 0.001) and mortality rate (21.3% vs 7.5%, P = 0.002). Most of the cirrhotic patients (n = 85, 90.4%) had no prior decompensation. Among the non-cirrhotic patients, superimposed AHE caused progressively more severe diseases that corresponded with the CHB disease stages, from immune tolerant to immune reactivation phases. Few risk factors were identified in the cirrhotic patients, but risk factors for non-cirrhotic patients were found to be intermediate HBV DNA levels (OR: 5.1, P = 0.012), alcohol consumption (OR: 6.4, P = 0.020), and underlying diabetes (OR: 7.5, P = 0.003) and kidney diseases (OR: 12.7, P = 0.005). Only 28.7% of the cirrhotic patients and 9.0% of the non-cirrhotic patients had received anti-HBV therapy previously and, in all cases, the efficacy had been suboptimal.

CONCLUSION

CHB-related cirrhosis and intermediate HBV DNA level were associated with severe disease in superinfected patients, and successful antiviral treatment might counter this outcome.

Role of Envelopment in the HEV Life Cycle

Hepatitis E virus (HEV), an enterically transmitted hepatotropic virus, was thought to be non-enveloped for decades. However, recent studies have revealed that the virus circulating in the patient’s blood is completely cloaked in host membranes and resistant to neutralizing antibodies. The discovery of this novel enveloped form of HEV has raised a series of questions about the fundamental biology of HEV and the way this virus, which has been understudied in the past, interacts with its host. Here, we review recent advances towards understanding this phenomenon and discuss its potential impact on various aspects of the HEV life cycle and immunity.

Hepatitis E Virus Mutations: Functional and Clinical Relevance

Hepatitis E virus (HEV) infection is a major cause of acute hepatitis and affects more than 20 million individuals, with three million symptomatic cases and 56,000 recognized HEV-related deaths worldwide. HEV is endemic in developing countries and is gaining importance in developed countries, due to increased number of autochthone cases. Although HEV replication is controlled by the host immune system, viral factors (especially specific viral genotypes and mutants) can modulate HEV replication, infection and pathogenesis. Limited knowledge exists on the contribution of HEV genome variants towards pathogenesis, susceptibility and to therapeutic response. Nonsynonymous substitutions can modulate viral proteins structurally and thus dysregulate virus-host interactions. This review aims to compile knowledge and discuss recent advances on the casual role of HEV heterogeneity and its variants on viral morphogenesis, pathogenesis, clinical outcome and antiviral resistance.

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HEV causes acute hepatitis and recently comes into focus because of persistent infection in immunocompromised patients.

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HEV variability can be associated with clinical pathogenesis and transmission dynamics.

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Mutations in the HEV genome can influence HEV physiology and virus-host interaction.

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HEV mutations and variability are likely associated with fulminant hepatic failure and chronic hepatitis E.

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The Y1320H and G1634R/K mutations in the RdRp domain contribute to antiviral resistance through enhancing HEV replication.

We searched MEDLINE database and PubMed for articles from 1980 through June 30, 2016. Search terms used in various combinations were “hepatitis E”, “hepatitis E virus”, “hepatitis E virus infection”, “hepatitis E virus mutation”, “HEV variability”, “HEV genotype”, “HEV drug resistance”, “HEV replication” and “ribavirin”. Articles resulting from these searches and relevant references cited in those articles were selected based on their related topics and were reviewed. Abstracts and reports from meetings were also included. Articles published in English were included.