Hepatitis E virus infections

Hepatitis E virus(HEV)infection is now endemic worldwide.Most patients with acute infection recover uneventfully.Outbreaks and sporadic cases,particularly in high-risk individuals are emerging increasingly.The patients with risk factors like pregnancy and pre-existing chronic liver disease,present with or progress rapidly to severe disease.Immuno-suppression in post-transplant patients is an additional risk factor.Standardized FDA-approved diagnostic tests are the need of the hour.Further studies are needed to establish guideline-based treatment regimen and outbreak preparedness for HEV to decrease global morbidity,mortality,and healthcare burden.Policies for screening donors and transplant cases are requi-red.

Pathogenesis and clinical features of severe hepatitis E virus infection

The hepatitis E virus(HEV),a member of the Hepeviridae family,is a small,non-enveloped icosahedral virus divided into eight distinct genotypes(HEV-1 to HEV-8).Only genotypes 1 to 4 are known to cause diseases in humans.Genotypes 1 and 2 commonly spread via fecal-oral transmission,often through the consum-ption of contaminated water.Genotypes 3 and 4 are known to infect pigs,deer,and wild boars,often transferring to humans through inadequately cooked meat.Acute hepatitis caused by HEV in healthy individuals is mostly asymptomatic or associated with minor symptoms,such as jaundice.However,in immunosup-pressed individuals,the disease can progress to chronic hepatitis and even escalate to cirrhosis.For pregnant women,an HEV infection can cause fulminant liver failure,with a potential mortality rate of 25%.Mortality rates also rise amongst cirrhotic patients when they contract an acute HEV infection,which can even trigger acute-on-chronic liver failure if layered onto pre-existing chronic liver disease.As the prevalence of HEV infection continues to rise worldwide,highlighting the particular risks associated with severe HEV infection is of major medical interest.This text offers a brief summary of the characteristics of hepatitis developed by patient groups at an elevated risk of severe HEV infection.

Current perspectives of viral hepatitis

Viral hepatitis represents a major danger to public health,and is a globally leading cause of death.The five liver-specific viruses:Hepatitis A virus,hepatitis B virus,hepatitis C virus,hepatitis D virus,and hepatitis E virus,each have their own unique epidemiology,structural biology,transmission,endemic patterns,risk of liver complications,and response to antiviral therapies.There remain few options for treatment,in spite of the increasing prevalence of viral-hepatitiscaused liver disease.Furthermore,chronic viral hepatitis is a leading worldwide cause of both liver-related morbidity and mortality,even though effective treatments are available that could reduce or prevent most patients’complications.In 2016,the World Health Organization released its plan to eliminate viral hepatitis as a public health threat by the year 2030,along with a discussion of current gaps and prospects for both regional and global eradication of viral hepatitis.Today,treatment is sufficiently able to prevent the disease from reaching advanced phases.However,future therapies must be extremely safe,and should ideally limit the period of treatment necessary.A better understanding of pathogenesis will prove beneficial in the development of potential treatment strategies targeting infections by viral hepatitis.This review aims to summarize the current state of knowledge on each type of viral hepatitis,together with major innovations.

Animal models of hepatitis E infection: Advances and challenges

Hepatitis E virus(HEV)is one of the leading causes of acute viral hepatitis worldwide.Although most of HEV infections are asymptomatic,some patients will develop the symptoms,especially pregnant women,the elderly,and patients with preexisting liver diseases,who often experience anorexia,nausea,vom-iting,malaise,abdominal pain,and jaundice.HEV infection may become chronic in immunosuppressed individuals.In addition,HEV infection can also cause several extrahepatic manifestations.HEV exists in a wide range of hosts in nature and can be transmitted across species.Hence,animals susceptible to HEV can be used as models.The establishment of animal models is of great significance for studying HEV transmission,clinical symptoms,extrahepatic manifestations,and therapeutic strategies,which will help us understand the pathogenesis,prevention,and treatment of hepatitis E.This review summarized the animal models of HEV,including pigs,monkeys,rabbits,mice,rats,and other animals.For each animal species,we provided a concise summary of the HEV genotypes that they can be infected with,the cross-species transmission pathways,as well as their role in studying extrahepatic manifestations,prevention,and treatment of HEV infection.The advantages and disadvantages of these animal models were also emphasized.This review offers new perspectives to enhance the current understanding of the research landscape surrounding HEV animal models.

Hepatitis E virus: Epidemiology, diagnosis, clinical manifestations, and treatment

The hepatitis E virus(HEV)is the fifth known form of viral hepatitis and was first recognized as the cause of an epidemic of unexplained acute hepatitis in the early 1980s.Globally,it is one of the most frequent causes of acute viral hepatitis.The majority of HEV infections are asymptomatic and lead to the spontaneous clearance of the virus.Among the eight different genotypes identified to date,HEV genotype 1(HEV1),HEV2,HEV3,and HEV4 are the most frequent genotypes causing infections in humans.HEV1 and HEV2 are prevalent in developing regions and able to result in large-scale outbreaks originating from contaminated water supplies.They are also responsible for severe hepatitis in pregnant patients and infants.In contrast,HEV3 and HEV4 are zoonotic,and the transmission of these genotypes to humans occurs mainly through the fecal contamination of water and consumption of contaminated meat from infected animals.Their main reservoir is the pig,and they are mostly encountered in developed countries.The major risk groups for HEV infection and its ensuing adverse consequences are pregnant women,infants,older people,immunocompromised individuals,patients with underlying chronic liver diseases,and workers that come into close contact with HEV-infected animals.In the clinical perspective,HEV infections have diverse clinical manifestations including acute and self-limiting hepatitis,acute-on-chronic liver disease,chronic hepatitis,cirrhosis,and liver failure.Although HEV mainly results in acute selflimiting infection,chronic HEV infection may occur among immunocompromised patients(e.g.,solid-organ transplant recipients).Additionally,HEV-associated extrahepatic manifestations involving various organs have been reported in the last decade,although the causal link for many of them still needs to be proven.Ribavirin and interferon-alpha are the most widely used agents for the treatment of HEV infections with a certain level of success.However,ribavirin is contraindicated in pregnant patients,and interferon-alpha cannot be used in most transplant recipients.Therefore,there is an urgent need for novel antiviral compounds that are safe and effective particularly for patients having contraindications for ribavirin or interferon-alpha and infected by the ribavirinresistant HEV.In this review article,a literature search using PubMed and MEDLINE databases was performed,up to March 2020.Only the articles published in English were reviewed.

Hepatitis B virus pre S1 deletion is related to viral replication increase and disease progression

AIM:To investigate the clinical implications of hepatitis B virus(HBV) pre S1 deletion.METHODS:We developed a fluorescence resonance energy transfer-based real-time polymerase chain reaction(RT-PCR) that can detect four genotypes(wild type, 15-bp, 18-bp and 21-bp deletion).The PCR method was used in two cohorts of Korean chronic HBV subjects with genotype C infections.Cohort Ⅰ included 292 chronic HBV subjects randomly selected from Cheju National University Hospital(Jeju, South Korea) or Seoul National University Hospital(Seoul, South Korea), and cohort Ⅱ included 90 consecutive chronic HBV carriers recruited from Konkuk University Hospital(Seoul, South Korea); the cohort Ⅱ patients did not have hepatocellular carcinoma or liver cirrhosis.RESULTS:The method proposed in this study identified 341 of 382 samples(89.3%).Deletion variants were identified in 100(29.3%) of the 341 detected samples.In both cohorts, the subjects with deletions had a significantly higher Hepatitis B virus e antigen(HBe Ag)-positive seroprevalence [cohort Ⅰ, wild(51.0%) vs deletion(75.0%), P < 0.001; cohort Ⅱ, wild(69.2%) vs deletion(92.9%), P = 0.002] and higher HBV DNA levels [cohort Ⅰ, wild(797.7 pg/m L) vs deletion(1678.9 pg/m L), P = 0.013; cohort Ⅱ, wild(8.3 × 108 copies/m L) vs deletion(2.2 × 109 copies/m L), P = 0.049], compared to subjects with wild type HBV.CONCLUSION:HBV genotype C pre S1 deletion may affect disease progression in chronic HBV subjects through an extended duration of HBe Ag seropositive status and increased HBV replications.

mi R-29a promotes hepatitis B virus replication and expression by targeting SMARCE1 in hepatoma carcinoma

AIM To investigate the functional role and underlying molecular mechanism of mi R-29 a in hepatitis B virus(HBV) expression and replication.METHODS The levels of mi R-29 a and SMARCE1 in HBV-infected Hep G2.2.15 cells were measured by quantitative real-time PCR and western blot analysis. HBV DNA replication was measured by quantitative PCR and Southern blot analysis. The relative levels of hepatitis B surface antigen and hepatitis B e antigen were detected by enzyme-linked immunosorbent assay. The Cell Counting Kit-8(CCK-8) was used to detect the viability of Hep G2.2.15 cells. The relationship between mi R-29 a and SMARCE1 were identified by target prediction and luciferase reporter analysis.RESULTS mi R-29 a promoted HBV replication and expression, w h i le S MA R C E 1 r e p r e s s e d H B V r e p lic a t io n a n d expression. Cell viability detection indicated that mi R-29 a transfection had no adverse effect on the host cells. Moreover, SMARCE1 was identified and validated to be a functional target of mi R-29 a. Furthermore, restored expression of SMARCE1 could relieve the increased HBV replication and expression caused by mi R-29 a overexpression.CONCLUSION mi R-29 a promotes HBV replication and expression through regulating SMARCE1. As a potential regulator of HBV replication and expression, mi R-29 a could be a promising therapeutic target for patients with HBV infection.

A truncated hepatitis E virus ORF2 protein expressed in tobacco plastids is immunogenic in mice

AIM： To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3＇-portion of hepatitis E virus （HEV） open reading frame 2 （ORF2） in plastids of tobacco （Nicotiana tabacum cv. SR1）, to investigate the transgene expression and pE2 accumulation in plastids, and to evaluate the antigenic effect of the plastid-derived pE2 in mice. METHODS： Plastid-targeting vector pRB94-E2 containing the E2 fragment driven by rice psbA promoter was constructed. Upon delivery into tobacco plastids, this construct could initiate homologous recombination in psaB-trnfM and trnG-psbC fragments in plastid genome, and result in transgene inserted between the two fragments. The pRB94-E2 was delivered with a biolistic particle bombardment method, and the plastid-transformed plants were obtained following the regeneration of the bombarded leaf tissues on a spectinomycin-supplemented medium. Transplastomic status of the regenerated plants was confirmed by PCR and Southern blot analysis, transgene expression was investigated by Northern blot analysis, and accumulation of pE2 was measured by ELISA. Furthermore, protein extracts were used to immunize mice, and the presence of the pE2-reactive antibodies in serum samples of the immunized mice was studied by ELISA. RESULTS： Transplastomic lines confirmed by PCR and Southern blot analysis could actively transcribe the E2 mRNA. The pE2 polypeptide was accumulated to a level as high as 13.27 μg/g fresh leaves. The pE2 could stimulate the immunized mice to generate pE2-specific antibodies. CONCLUSION： HEV-E2 fragment can be inserted into the plastid genome and the recombinant pE2 antigen derived is antigenic in mice. Hence, plastids may be a novel source for cost-effective production of HEV vaccines.

Significance of serum IgA in patients with acute hepatitis E virus infection

AIM： To study the significance of serum anti-hepatitis E virus （HEV） IgA in patients with hepatitis E. METHODS： A new method was established to assay anti-HEY IgA, which could be detected in the middle phase of the infection. We compared anti-HEV IgA assay with anti-HEV IgM and anti-HEV IgG assay in sera from 60 patients with positive HEV-RNA. RESULTS： The 60 patients with positive HEV-RNA had both anti-HEV IgA and anti-HEV IgM and 410 patients with negative HEV-RNA were used as control. Periodic serum samples obtained from 60 patients with hepatitis E were tested for HEV RNA, anti-HEV IgM, anti-HEV IgA and anti-HEV IgG. Their HEV-RNA was detectable in the serum until 20 ±11 d. We used anti-HEV IgM and anti-HEV IgA assay to detect HEV infection and positive results were found in 90 ± 15 d and 120 ±23 d respectively, the positive rate of anti-HEV IgA was higher than that of anti-HEV IgM and HEV-RNA （P 〈0.05）. CONCLUSION： The duration of anti-HEV IgA in serum is longer than that of anti-HEV IgM, and anti-HEV IgA assay is a good method to detect HEV infection.

Clinical features of HBs Ag seroclearance in hepatitis B virus carriers in South Korea: A retrospective longitudinal study

AIM To investigate the characteristic features of hepatitis B surface antigen(HBs Ag) seroclearance among Korean hepatitis B virus(HBV) carriers.METHODS Carriers with HBs Ag seroclearance were selected by analyzing longitudinal data collected from 2003 to 2015. The period of time from enrollment to the negative conversion of HBs Ag(HBs Ag-NC) was compared by stratifying various factors, including age, sex, hepatitis B e antigen(HBe Ag), HBV DNA, sequential changes in the signal-to-cutoff ratio of HBs Ag(HBs Ag-SCR), as measured by qualitative HBs Ag assay, and chronic liver disease on ultrasonography(US-CLD). Quantification of HBV DNA and HBs Ag(HBs Ag-QNT) in the serum was performed by commercial assay.RESULTS Among the 1919 carriers, 90(4.7%) exhibited HBs AgNC at 6.2 ± 3.6 years after registration, with no differences observed among the different age groups. Among these carriers, the percentages of those with asymptomatic liver cirrhosis(LC) and hepatocellular carcinoma(HCC) at registration were 31% and 7.8%, respectively. The frequency of HBs Ag-NC significantly differed according to the HBV DNA titer and US-CLD. HBe Ag influenced HBs Ag-NC in the 40-50 and 50-60 year age groups. HBs Ag-SCR < 1000 was correlated with an HBs Ag-QNT < 200 IU/m L. A gradual decrease in the HBs Ag-SCR to < 1000 predicted HBs Ag-NC. Six patients developed HCC after registration, including two before and four after HBs Ag-NC. The rate at which the patients developed new HCC after HBs Ag seroclearance was 4.8%. LC with excessive drinking and vertical infection were found to be risk factors for HCC in the HBs Ag-NC group.CONCLUSION HCC surveillance should be continued after HBs Ag seroclearance. An HBs Ag-SCR < 1000 and its decrease in sequential testing are worth noting as predictive markers of HBs Ag loss.

Oxidative stress modulation in hepatitis C virus infected cells

Hepatitis C virus(HCV) replication is associated with the endoplasmic reticulum, where the virus can induce cellular stress. Oxidative cell damage plays an important role in HCV physiopathology. Oxidative stress is triggered when the concentration of oxygen species in the extracellular or intracellular environment exceeds antioxidant defenses. Cells are protected and modulate oxidative stress through the interplay of intracellular antioxidant agents, mainly glutathione system(GSH) and thioredoxin; and antioxidant enzyme systems such as superoxide dismutase, catalase, GSH peroxidase, and heme oxygenase-1. Also, the use of natural and synthetic antioxidants(vitamin C and E, N-acetylcysteine, glycyrrhizin, polyenylphosphatidyl choline, mitoquinone, quercetin, S-adenosylmethionine and silymarin) has already shown promising results as co-adjuvants in HCV therapy. Despite all the available information, it is not known how different agents with antiviral activity can interfere with the modulation of the cell redox state induced by HCV and decrease viral replication. This review describes an evidence-based consensus on molecular mechanisms involved in HCV replication and their relationship with cell damage induced by oxidative stress generated by the virus itself and cell antiviral machinery. It also describes some molecules that modify the levels of oxidative stress in HCV-infected cells.

Hepatitis E virus is a leading cause of acute-on-chronic liver disease:experience from a tertiary centre in Bangladesh

BACKGROUND:Acute-on-chronic liver failure(ACLF) is common in Bangladesh.Acute viral E hepatitis is sporadically encountered in this country each year,with a rising incidence in the rainy season.This study aimed to identify the etiology of ACLF in Bangladesh. METHODS:In this retrospective study,69 ACLF patients were included.They presented to our department at the Bangabandhu Sheikh Mujib Medical University in Dhaka.History of diseases was recorded and appropriate investigations were conducted in all patients. RESULTS:Acute hepatitis E virus(HEV)infection was positive in 21.7%(15/69)of the patients,while 14.5% (10/69)had septicemia.Upper gastrointestinal tract hemorrhage was seen in 4.3%of the patients(3/69),while another 4.3%(3/69)had a positive history for alcohol or drugs.None of the patients tested positive for hepatitis A virus infection and no evidence of hepatitis B virus flare was found in any patient.No specific cause for ACLF could be identified. CONCLUSIONS:Acute HEV infection is a leading cause of ACLF in Bangladesh.Many patients were thought to have decompensation of cirrhosis,but subsequently were recognized as having ACLF by a retrospective review according to the definition of the Asian Pacific Association for the Study of the Liver Working Party Meeting on ACLF in New Delhi in early 2008.

Experimental infection of Z:ZCLA Mongolian gerbils with human hepatitis E virus

AIM:To investigate whether Z:ZCLA Mongolian gerbils are readily susceptible to infection by human hepatitis E virus(HEV).METHODS:Z:ZCLA Mongolian gerbils were infected with a clinical HEV strain isolated from an acutehepati tis E patient,and virus pathogenesis was assessed in this host.Non-infected gerbils served as the control group.Feces samples from gerbils were collected weekly for reverse transcription-nested polymerase chain reaction.Serum anti-HEV Ig G and alanine aminotransferase(ALT) were detected by enzyme linked immunosorbent assay.At sacrifice,each animal's liver,spleen and kidney were collected for histopathologic examination.RESULTS:HEV-infected gerbils showed fatigue,with histopathological changes observed in the liver,spleen and kidney.HEV RNA was detected in fecal samples taken at day 7 after inoculation and the detectable levels lasted out to day 42 after inoculation.Interestingly,ALT levels were only moderately increased in the HEV-infected animals compared with the noninfected control group.CONCLUSION:Z:ZCLA Mongolian gerbils are susceptible to human HEV.

Interaction of hepatitis C virus envelope glycoprotein E2 with the large extracellular loop of tupaia CD81

AIM: To further analyze the interaction of tupaia CD81 with hepatitis C virus (HCV) envelope protein E2. METHODS: A tupaia CD81 large extracellular loop (CD81 LEL), which binds to HCV E2 protein, was cloned and expressed as a GST-fusion protein, and interaction of HCV E2 protein with a tupaia CD81 LEL was evaluated by enzyme-linked immunosorbent assay (EIA). RESULTS: Although tupaia and human CD81 LEL differed in 6 amino acid changes, tupaia CD81 LEL was strongly recognized by anti-CD81 antibodies against human CD81 LEL conformation-dependent epitopes. Investigating LEL CD81-E2 interactions by EIA, we demonstrated that binding of tupaia CD81 LEL GST fusion protein to recombinant HCV E2 protein was markedly reduced compared to binding of human CD81 LEL GST fusion protein to recombinant HCV E2 protein. CONCLUSION: These data suggest that the structural differences in-between the tupaia and human CD81 may alter the interaction of the large extracellular loop with HCV envelope glycoprotein E2. These findings may be important for the understanding of the mechanisms of binding and entry of HCV to PTHs.

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

AIM: To investigate the seroprevalence and evolutionary dynamics of hepatitis E virus (HEV) and assess the ancestor of HEVs in China&#x02019;s Shandong Province.

Genetic diversity of the hepatitis C virus: Impact and issues inthe antiviral therapy

The hepatitis C Virus (HCV) presents a high degree of genetic variability which is explained by the combination of a lack of proof reading by the RNA dependant RNA polymerase and a high level of viral replication. The re- sulting genetic polymorphism defines a classification in clades, genotypes, subtypes, isolates and quasispecies. This diversity is known to reflect the range of responses to Interferon therapy. The genotype is one of the pre- dictive parameters currently used to define the antiviral treatment strategy and the chance of therapeutic suc- cess. Studies have also reported the potential impact of the viral genetic polymorphism in the outcome of antivi- ral therapy in patients infected by the same HCV geno- type. Both structural and non structural genomic regions of HCV have been suggested to be involved in the Inter- feron pathway and the resistance to antiviral therapy. In this review, we first detail the viral basis of HCV diversity. Then, the HCV genetic regions that may be implicated in resistance to therapy are described, with a focus on the structural region encoded by the E2 gene and the non- structural genes NS3, NS5A and NS5B. Both mechanisms of the Interferon resistance and of the new antiviral drugs are described in this review.

Neurological manifestations of hepatitis E virus infection:An overview

Hepatitis E virus(HEV)is an important cause of repeated waterborne outbreaks of acute hepatitis.Recently,several extrahepatic manifestations(EHMs)have been described in patients with HEV infection.Of these,neurological disorders are the most common EHM associated with HEV.The involvement of both the peripheral nervous system and central nervous system can occur together or in isolation.Patients can present with normal liver function tests,which can often be misleading for physicians.There is a paucity of data on HEV-related neurological manifestations;and these data are mostly described as case reports and case series.In this review,we analyzed data of 163 reported cases of HEV-related neurological disorders.The mechanisms of pathogenesis,clinico-demographic profile,and outcomes of the HEV-related neurological disorders are described in this article.Nerve root and plexus disorder were found to be the most commonly reported disease,followed by meningoencephalitis.

Seroepidemiology and genetic characterization of hepatitis E virus in western Yunnan Province

Objective:To investigate the seroepidemiology and genetic characterization of hepatitis E virus(HEV) in western Yunnan Province.Methods:Questionnaire survey was conducted among1638 residents in western Yunnan Province using stratified sampling method.Enzyme-linked immunosorbent assay was used to detect serum anti-HEV IgG and IgM.HEV RNA was extracted from patients with serum anti-HEV IgM positive.The open reading flame 2(ORF2) of HEV that was amplified by nested RT-PCR was sequenced and compared with standard HEV genotypes 1-4.Results:Serum anti-HEV positive was found in 13.929(228/1638) residents.The HEV infection rate in males was significantly higher than that in females with a ratio of 1.47(P<0.01).20-30 and30-40 years old young men showed the highest incidence.20.57%and 20.78%.respectively.While10-20 and 20-30 years old young women exhibited the highest infection rate,11.85%and 15.60%,respectively.According to occupation,the highest HEV infection rate was observed in farmers(20.35%) and migrants(16.50%).We isolated 10 individual HEV isolates from 31 patients with serum anti-HEV IgM positive.Homology analysis and phylogenetic analysis indicated that these10 HEV isolates belonged to HEV genotype 4 with the homology of 78.65%-94.71%.Conclusions:The HEV infection rate is high in western Yunnan Province.HEV genotype 4 is the leading cause of HEV infection and young farmers and migrants are the main infected population.

Genetic characteristics and pathogenicity of human hepatitis E virus in Nanjing,China

AIM： To investigate the genetic characteristics and pathogenicity of hepatitis E virus （HEV） and assess the potential risk factors for sporadic hepatitis E.