Hepatitis E Virus Antigen Research Articles

Role of formalin fixed paraffin embedded liver tissues in the diagnosis of viral hepatitis E in patients with undiagnosed acute liver failure.

Viral hepatitis E is gaining importance as an emerging worldwide disease. Though viral hepatitis E (HEV) has been attributed as an etiology of acute liver failure (ALF), however its actual incidence and the immunopathogenesis are being under explored. The present study is aimed at detecting HEV in post mortem liver tissues of patients with undiagnosed ALF. Twenty six liver tissues of ALF patients died of unknown etiology are subjected to nested reverse transcriptase PCR with HEV ORF1 gene targeted primers and HEV RNA is detected in 30.4% (7/23) of ALF cases. Out of seven HEV RNA positive cases, three (42.8%) had HEV antigen positivity by immunohistochemistry on liver tissues using HEV ORF2 antibody. Histopathological examination by H&E staining shows multiacinar confluent hepatic necrosis, bile ductular proliferation, bridging hepatic and periportal necrosis in 4, 4, 2 and 1 cases respectively. The isolates were sequenced using RdRp gene specific primers and found to HEV genotype-1. Quantitative TaqMan real time PCR estimated the viral load ranged between 7.77 × 103 and 1.44 × 107 viral copies/µl. HEV has been associated with 30.4% (7/23) of undiagnosed ALF cases. Immuno-histochemistry along with molecular testing in FFPE biopsies might be useful for the detection of HEV in undiagnosed cases.

Application of Hepatitis E Virus-Related Markers on Samples from a Developing Country.

Nepal is an endemic area for hepatitis E virus (HEV) epidemics. The research on viral hepatitis in Nepal is limited. Serum samples from 170 patients presenting with symptoms of hepatitis were collected from April to May 2014 in Biratnagar, Nepal, and then transported to Xiamen, China, for further evaluation. All samples were tested for HEV RNA, HEV antigen, anti-HEV IgM, anti-HEV IgG and anti-HBc IgM, anti-HCV IgG, and anti-HAV IgM. Sixteen patients were identified as acute hepatitis E with the presence of ≥ 2 HEV acute phase markers (antigen, RNA, and anti-HEV IgM). HEV infection was the major cause of potential active viral hepatitis (59.2%, 16 of 27), followed by HBV (25.9%, 7 of 27, anti-HBc IgM positive), HAV (18.5%, 5 of 27, anti-HAV IgM positive), and HCV (3.7%, 1 of 27, anti-HCV antibodies). All 16 confirmed HE cases were positive for HEV antigen, while 5 cases were HEV RNA positive, as well as 15 anti-HEV IgM positive. The low positive rate of RNA might be related to the collection and/or the transportation of these samples. This study showed that HEV is a major cause of acute hepatitis in developing countries and regions. Application of immunoassay diagnostic kits, especially the HEV antigen tests, showed great potential for HE detection in these countries and regions.

Menace of Hepatitis C virus among multitransfused thalassemia patients in Balasore district of Odisha state in India.

Context:Hepatitis C virus (HCV) is a potential cause of morbidity and mortality worldwide. It is most commonly transmitted through injecting drug use; the reuse or inadequate sterilization of medical equipment and the transfusion of unscreened blood products. Management of thalassemia requires long-term blood transfusion. Though it improves the overall survival, it carries a definite risk of infection which is expected to be higher in resource limited settings.Aims:To find the percentage of transfusion-transmitted infections (TTIs) in multitransfused patients of thalassemia in Eastern India.Settings and Design:The study was conducted to assess blood safety in rural population in India by measuring the percentage of TTIs including HCV in multitransfused thalassemia patients.Methods and Materials:One hundred and twenty three patients with major beta-thalassemia were enrolled in this study. The blood samples were tested using ELISA technique for all TTIs. HIV fourth generation kits, HbsAg, HCV third generation kits, malaria and syphilis, parbovirus IgM and parbovirus IgG kits, HEV Antigen and IgM antibody were used.Statistical Analysis Used:Proportions and means were calculated for categorical and continuous variables, respectively. Chi-square test was applied and P value of <0.05 was taken as significant.Results:The mean age of patients was 9.5 years ± 5.2 years. Among various TTIs, Hepatitis C and HIV was prevalent among 59.3% and 4.1% of the study participants, respectively.Conclusions:The causes of high prevalence of HCV may be due to donors being usually asymptomatic in early stages, despite being screened for HCV possibly due to missing early window period infections. The screening methodology of TTIs particularly HCV at the district and village level and consequent increased prevalence of HCV in multitransfused rustic population of India shows the extent of blood safety.

Hepatitis E virus was not detected in feces and milk of cows in Hebei province of China: No evidence for HEV prevalence in cows

Hepatitis E virus (HEV) is an important human pathogen, with pigs and other species serving as natural animal reservoirs. Recently, the report of detection of genotype 4 HEV in dairy milk with high positive rate in Yunnan province of China has attracted extensive attention. To assess the zoonotic risk of cows as HEV reservoir and transmission of HEV through dairy milk, 467 fecal samples of cows, 276 fresh milk samples, and 140 retail milk samples were collected across Hebei Province, China, from March 2017 to May 2018, and detected for HEV RNA. Fecal samples of rabbit or pig were also collected for HEV detection from farms of mixed farming with cows or farms neighboring cow farms. HEV RNA was not detected in any cow feces or in any milk samples, but 9.3% feces of pigs and 18.9% feces of rabbits were positive for HEV RNA. In addition, all of the dairy milk samples undergone HEV antigen and anti-HEV antibody detections, but none was positive. Phylogenetic analysis showed that all of the HEV isolates from pigs belonged to genotype 4 and those from rabbits were genotype 3-rabbit HEV. The results indicate that, currently in Hebei province of China, HEV is not apparently prevalent in cows and hence there is no zoonotic transmission risk through dairy milk towards humans, albeit the genotype 4 and 3 (rabbit) HEV are prevalent in pigs and rabbits respectively.

Cynomolgus monkeys (Macaca fascicularis) experimentally and naturally infected with hepatitis E virus: The bone marrow as a possible new viral target.

Hepatitis E virus (HEV) transmission through infected blood and blood products has already been described. However, little is known about the bone marrow (BM) as source of HEV infection. Our study aimed to investigate the presence of HEV antigen (Ag) and histological changes in BM of cynomolgus monkeys (Macaca fascicularis) experimentally and naturally infected with HEV. Four cynomolgus monkeys with acute, and two with chronic hepatitis E ─ after immunosuppressive therapy with tacrolimus ─ were compared with one colony-bred animal naturally infected. Both, natural and experimental infections were characterized by anti-HEV IgG seroconversion detected by ELISA, and viral RNA isolation confirmed by RT-qPCR and qualitative nested RT-PCR. BM biopsies were collected from all animals, submitted to histology and indirect immunofluorescence techniques and observed, respectively, by light and confocal microscopy. The HEV Ag-fluorescent-labeled cells were detected from BM biopsies obtained from three monkeys with acute and one with chronic hepatitis E, and also from the naturally infected monkey. In the experimentally infected animals with acute hepatitis, HEV Ag detection occurred at 160 days post-infection, even after viral clearance in serum, feces, and liver. Double-stranded RNA, a replicative marker, was detected in BM cells from both acute and chronically infected animals. Major histological findings included vacuolization in mononuclear and endosteal cells, an absence of organized inflammatory infiltrates, and also some fields suggesting displasic focal BM disease. These findings support the hypothesis of BM cells as secondary target sites of HEV persistence. Further experimental studies should be carried out to confirm the assumption of HEV transmission through BM transplantation.

Clopidogrel-Induced Hepatotoxicity: A Case Report

Clopidogrel is an antiplatelet agent provided to patients undergoing percutaneous coronary intervention (PCI) to prevent stent thrombosis. It blocks P2Y12 receptors, thus inhibiting activation of GPIIb/IIIa receptor complex. Herein, we report a case of clopidogrel induced cholestatic hepatitis. Case Report A 75-year-old female status-post PCI with two drug eluting stents was started on clopidogrel 75mg daily. Six weeks later, she presented to clinic with nausea and the following labs: serum alanine aminotransferase (ALT) 469 U/L, aspartate aminotransferase (AST) 408 U/L, alkaline phosphatase (ALP) 335 U/L. Right upper quadrant ultrasound (RUQ US) showed gallstones but otherwise unremarkable. A week later she returned with emesis and TBILI of 3.2 mg/dL and lipase of 1248 U/L. MRCP was normal. She received 2 days of cephalosporins and underwent a cholecystectomy. Intra-operative cholangiogram revealed no choledocholithiasis. Six weeks post-procedure, she was jaundiced with TBILI of 11mg/d, ALP of 328U/L, AST of 79 U/L and ALT of 58 U/L. Hepatitis work-up including Hepatitis panel (A, B, C, E), ANA, Actin Antibody and Anti-Mitochondrial Antibody, HEV, CMV and histoplasma antigen, was negative. HIDA scan, repeat MRCP, blood and urine cultures were negative. Clopidogrel induced liver injury was suspected. It was replaced with ticagrelor. Liver enzymes continued to improve gradually and normalized at 24 weeks from discontinuation of clopidogrel. Discussion We report a rare case of clopidogrel induced severe cholestatic hepatitis. We used the Naranjo scale and Maria Victorino scale, in which our patient's scores were 7 and 14 respectively, indicating a probable drug induced hepatitis. Clopidogrel induced hepatotoxicity usually results in hepatocellular pattern of liver injury, though a few cases with mixed or cholestatic enzyme elevations have also been reported. The onset of symptoms with clopidogrel induced liver injury is usually within 2 to 24 weeks of starting clopidogrel, averaging 6 weeks as seen in our case, with fatigue and jaundice being the most common symptoms. The degree of hepatic injury from clopidogrel varies. In our literature review, we found one case of clopidogrel induced fulminant hepatitis that resulted in death. Hence, early recognition is crucial After identifying the potential cause, withdrawal of the offending agent is itself sufficient for recovery of liver function and normalization of liver enzymes in most cases.

Absence of Persistent Hepatitis E Virus Infection in Antibody-Deficient Patients Is Associated With Transfer of Antigen-Neutralizing Antibodies From Immunoglobulin Products.

Persistent hepatitis E virus (HEV) infection is described in a number of immunosuppressive conditions. We aimed to determine the risk of persistent HEV infection in patients with primary or secondary antibody deficiency. Two hundred forty-five antibody-deficient patients receiving regular immunoglobulin replacement therapy were tested for HEV RNA and anti-HEV immunoglobulin G (IgG). Immunoglobulin products and plasma specimens obtained from 9 antibody-deficient patients before and after intravenous immunoglobulin (IVIG) therapy, 5 recently treated patients with persistent HEV infection, and 5 healthy patients recovered from acute HEV infection were analyzed for anti-HEV IgG and for antibody reacting with HEV antigen. No antibody-deficient patient had detectable plasma HEV RNA. Anti-HEV IgG was detected in 38.8% of patients. All 10 immunoglobulin products tested contained anti-HEV capable of neutralizing HEV antigen. Plasma samples collected following IVIG infusion therapy demonstrated a higher anti-HEV IgG level and neutralizing activity, compared with samples collected before IVIG therapy. Neutralizing activity was similar to that in healthy patients with recent acute HEV infection. The risk of persistent HEV infection in patients with antibody deficiency appears extremely low. This may be due to passive seroprotection afforded by the ubiquitous presence of anti-HEV in immunoglobulin replacement products.

Long-term HEV carriers without antibody seroconversion among eligible immunocompetent blood donors

Hepatitis E virus (HEV) is emerging as a potential threat to the safety of blood transfusions. In many countries and regions endemic for HEV, such as China, blood donors are not routinely tested for HEV infection. In this study, 11747 eligible blood donors were screened for anti-HEV immunoglobulin M (IgM)/immunoglobulin G (IgG) and HEV RNA and antigen in China. Twenty-four donors who were positive for both HEV antigen and RNA were followed for ≥ 70 days, and none of these donors reported clinical hepatitis or illness. At least 1 follow-up sample was provided by 17 donors, including 10 with viremia and/or antigenemia for ≥ 70 days and 3 with antigen and RNA positivity for >90 days. Fourteen of the 17 donors did not present with an obvious serologic response during the follow-up period. These results differed from previous reports, in which viremia lasted for 68 days and elicited an antibody response. These donors showed atypical HEV infection progression that differed from that of hepatitis E patients. The presence of these donors presents a challenge for transfusion transmission screening.

Toward Systematic Screening for Persistent Hepatitis E Virus Infections in Transplant Patients.

Persistent hepatitis E virus genotype 3 (HEV G3) infections affect solid organ transplant (SOT) recipients and hematopoietic stem cell transplant (HSCT) recipients, but the burden in these cohorts in the United Kingdom is unknown. We established an audit to determine the point prevalence of HEV viremia in SOT and HSCT patients in the United Kingdom and compare different testing approaches to inform screening strategies. Between January 5, 2016, and September 21, 2016, 3044 patients undergoing therapeutic drug monitoring at a single transplant center were screened for HEV ribonucleic acid (RNA) in minipools. A total of 2822 patients who could be characterized included 2419 SOT patients, 144 HSCT patients and 259 patients with no available transplant history. HEV RNA-positive samples were characterized by serology and genomic phylogeny. HEV antigen (HEV-Ag) testing was performed on RNA-positive samples, 420 RNA-negative samples and 176 RNA-negative blood donor samples. Nineteen of 2822 patients were viremic with G3 HEV giving a prevalence of 0.67%. The median alanine aminotransferase was significantly higher in the HEV viremic patients (P < 0.0001); however, 2 viremic patients had an alanine aminotransferase value within the normal range at the time of screening. The HEV-Ag assay identified 18/19 viremic patients and all those patients with proven viremia longer than 4 weeks. Transplant recipients in the United Kingdom are at a low but significant risk of HEV infection. HEV-Ag detection could be an alternative to RNA detection where the goal is to identify established persistent HEV infection, particularly where expertise, facilities, or cost prohibit RNA testing.

Expanded Diagnostic Approach to Hepatitis E Virus Detection in Patients with Acute-on-Chronic Liver Failure: A Pilot Study

Introduction: Acute decompensation of pre-existing chronic liver disease (CLD), known as acute-on-chronic liver failure (ACLF), is associated with high mortality. Hepatitis E virus (HEV) as a potential cause was studied. Objectives: The objectives of this study are to evaluate the role of HEV in ACLF patients using an IgM anti-HEV antibody enzyme-linked immunosorbent assay (ELISA), HEV antigen ELISA, and a quantitative HEV polymerase chain reaction (PCR). Materials and Methods: In this prospective cross-sectional study, blood samples were collected from 50 ACLF (cases) as defined by the standard guidelines (APASL, 2014) and 50 patients with stable CLD (controls) from January 2015 to August 2016, after obtaining informed consent. Two IgM ELISAs (MP Diagnostics HEV IgM ELISA 3.0, Singapore and Wantai HEV IgM ELISA, Beijing, China) were compared using plasma from cases and controls. In addition, an HEV antigen detection by ELISA (Wantai, Beijing, China) and a real-time PCR for quantification of HEV RNA in plasma and stool were employed. Results: Ethanol was the leading cause of acute insult in ACLF (54%) cases. HEV infection accounted for 20% of cases. Ten ACLF patients (20%) had 1–3 markers of HEV versus two (4%) among controls (P = 0.0138). Among ACLF cases, one had HEV viraemia (403 IU/ml), faecal shedding (2790 IU/ml) and detectable HEV antigenaemia. Agreement between the two anti-HEV IgM ELISAs was 0.638 (kappa value). Conclusion: This study shows that alcohol is a major contributing factor for both underlying CLD and ACLF while HEV is the most common infectious cause for ACLF, suggesting a need for a vaccination in such patients, whenever made available.

SAT-386 - Hepatitis E virus lifecycle and identification of 3 forms of the ORF2 capsid protein

BACKGROUND & AIMS: Hepatitis E virus (HEV) infection is a major cause of acute hepatitis worldwide. Approximately 2 billion people live in areas endemic for HEV and are at risk of infection. The HEV genome encodes 3 proteins, including the ORF2 capsid protein. Detailed analyses of the HEV life cycle has been hampered by the lack of an efficient viral culture system. METHODS: We performed studies with gt3 HEV cell culture-produced particles and patient blood and stool samples. Samples were fractionated on iodixanol gradients and cushions. Infectivity assays were performed in vitro and in human liver chimeric mice. Proteins were analyzed by biochemical and proteomic approaches. Infectious particles were analyzed by transmission electron microscopy. HEV antigen levels were measured with the Wantai enzyme-linked immunosorbent assay. RESULTS: We developed an efficient cell culture system and isolated HEV particles that were infectious in vitro and in vivo. Using transmission electron microscopy, we defined the ultrastructure of HEV cell culture-produced particles and particles from patient sera and stool samples. We also identified the precise sequence of the infectious particle-associated ORF2 capsid protein. In cultured cells and in samples from patients, HEV produced 3 forms of the ORF2 capsid protein: infectious/intracellular ORF2 (ORF2i), glycosylated ORF2 (ORF2g), and cleaved ORF2 (ORF2c). The ORF2i protein associated with infectious particles, whereas the ORF2g and ORF2c proteins were massively secreted glycoproteins not associated with infectious particles. ORF2g and ORF2c were the most abundant antigens detected in sera from patients. CONCLUSIONS: We developed a cell culture system and characterized HEV particles; we identified 3 ORF2 capsid proteins (ORF2i, ORF2g, and ORFc). These findings will advance our understanding of the HEV life cycle and improve diagnosis.

Development and evaluation of a rapid point-of-care test for detecting the hepatitis E virus antigen

BackgroundHepatitis E virus (HEV)-caused acute viral hepatitis is a major threat to public health worldwide. Recently, an enzyme linked immunosorbent assay (ELISA) kit detecting the HEV antigen was reported to have good concordance with the HEV RNA load and showed good clinical performance. But the ELISA kits can barely satisfy the needs of community clinics. In this study, a fluorescent microbead-based immunoassay (FMIA) for detecting the HEV antigen was developed and evaluated. MethodsA mouse anti-HEV monoclonal antibody (mAb) conjugated with fluorescent microbeads was used as capturing antibody and another mouse mAb was used as detection antibody. Overall, 150 serum samples were collected from HEV-infected patients (n = 50) and non-HEV cases (n = 100) to evaluate the performance of the FMIA. ResultsThe FMIA results showed a strong linear correlation with the viral RNA load. The diagnostic sensitivity and specificity of the HEV antigen FMIA were 92.0% (46/50) and 100.0% (100/100), respectively, and the test was consistent (kappa = 0.937, p = 0.627) with the commercial HEV antigen ELISA. The FMIA also showed good consistency with the PCR results (kappa = 0.939, p = 0.134). ConclusionsAs a rapid point-of-care (POC) test, a FMIA that is developed with acceptable performance is suitable for acute hepatitis E diagnosis, especially in developing countries and regions, because of its reduced time and simplified operation.

Replication of hepatitis E virus in the ovary and promotion of oocyte apoptosis in rabbits infected with HEV-4.

Hepatitis E virus (HEV) infection can induce infertility and miscarriage in pregnant women and infect neonates through vertical transmission. However, the mechanism of infertility and vertical transmission remains unclear. In the present study, we evaluated the replication of HEV in the ovary and structural and molecular changes induced by HEV after intraperitoneal injection of HEV in rabbits. Positive- and negative-strand HEV RNA was detected in the ovaries at 28 and 49 days post-infection. Positive HEV open reading frames 2 and 3 signals were observed in the ovaries by immunohistochemistry staining. Histopathological changes of ovarian tissues were observed, including scattered cell necrosis and lymphocyte infiltration. The ratio of normal follicles decreased, whereas the ratio of atresia follicles increased in the HEV RNA-positive ovaries compared to the control group by counting the number of follicles at all levels. In addition, TUNEL results showed that apoptosis in follicle cells and oocytes was promoted by HEV infection. These results suggest that the ovary is one of the replication sites of HEV and that the expression of HEV RNA and antigen in ovarian tissue caused structural and molecular changes that promoted germ cell apoptosis. HEV can infect and replicate in the ovum at different stages, which is a novel mechanism for HEV vertical transmission.

Confirmation of specificity of reactivity in a solid phase ELISA for the detection of hepatitis E viral antigen improves utility of the assay

Genotype 3 hepatitis E virus (HEV) can lead to persistent infections in immunocompromised hosts. A recently available commercial assay for the detection of HEV antigen (HEV-Ag ELISA, Wantai diagnostics) may enable the study of HEV-Ag dynamics in such persistent infections, however currently there is no confirmatory test available. We generated a putative neutralising reagent from a pool of four convalescent blood donor samples and explored neutralising activity against HEV antigens from clinical samples, HEV tissue-culture and virus-like particles. Using this neutralisation method we were able to differentiate true reactivity from non-specific reactivity in plasma, stool and urine samples. This could also facilitate the introduction of HEV-Ag detection as a screening assay or the study of HEV-Ag in different body fluids.

Effects of mRNA secondary structure on the expression of HEV ORF2 proteins in Escherichia coli

BackgroundViral protein expression in Escherichia coli (E. coli) is a powerful tool for structural/functional studies as well as for vaccine and diagnostics development. However, numerous factors such as codon bias, mRNA secondary structure and nucleotides distribution, have been indentified to hamper this heterologous expression.ResultsIn this study, we combined computational and biochemical methods to analyze the influence of these factors on the expression of different segments of hepatitis E virus (HEV) ORF 2 protein and hepatitis B virus surface antigen (HBsAg). Three out of five HEV antigens were expressed while all three HBsAg fragments were not. The computational analysis revealed a significant difference in nucleotide distribution between expressed and non-expressed genes; and all these non-expressing constructs shared similar stable 5′-end mRNA secondary structures that affected the accessibility of both Shine-Dalgarno (SD) sequence and start codon AUG. By modifying the 5′-end of HEV and HBV non-expressed genes, there was a significant increase in the total free energy of the mRNA secondary structures that permitted the exposure of the SD sequence and the start codon, which in turn, led to the successful expression of these genes in E. coli.ConclusionsThis study demonstrates that the mRNA secondary structure near the start codon is the key limiting factor for an efficient expression of HEV ORF2 proteins in E. coli. It describes also a simple and effective strategy for the production of viral proteins of different lengths for immunogenicity/antigenicity comparative studies during vaccine and diagnostics development.

Persistence of hepatitis E virus in the liver of non-viremic naturally infected wild boar.

Hepatitis E virus (HEV) is an emerging zoonotic pathogen with pigs and wild boar serving as reservoirs for human infection through direct contact with infected animals or the consumption of raw or undercooked pork products. The liver is considered the main target site of HEV replication in swine and an important organ in the pathogenesis of the disease. The aim of this study was to characterize the target liver cells for HEV entry in naturally infected wild boar and to evaluate the type and severity of the pathological changes in order to reach a better understanding of the hepatic pathogenic mechanisms involved in hepatitis E. In total, 58 livers from hunted wild boar were histopathologically evaluated. The presence of specific HEV antibodies in serum was determined by indirect ELISA. Immunohistochemistry was used for the detection of HEV antigen and Real time RT-PCR to detect HEV RNA in liver and serum. HEV seroprevalence in these animals was of 5.197% (CI95%: 1.77–14.14). By Real time RT-PCR, HEV was detected in the liver tissue of four wild boar (6.8%; CI95%: 2.7–16.4) and only one animal was also positive in serum (1.7%; CI95%: 0.3–9.1). The non-viremic animals naturally infected with HEV presented evidence of liver infection, mainly in Kupffer cells and liver sinusoidal endothelial cells, without apparent associated hepatitis lesions. This study supports the hypothesis that low viral titers may persist in the liver of non-viremic individuals, giving thus the possibility of consumption of contaminated liver of animals diagnosed as HEV-negative in serum. Further immunopathogenic studies are necessary to elucidate the mechanisms responsible for this process and to evaluate the protocols of HEV diagnosis in animals destined for human consumption.

Hepatitis E Virus Lifecycle and Identification of 3 Forms of the ORF2 Capsid Protein

Hepatitis E virus (HEV) infection is a major cause of acute hepatitis worldwide. Approximately 2 billion people live in areas endemic for HEV and are at risk of infection. The HEV genome encodes 3 proteins, including the ORF2 capsid protein. Detailed analyses of the HEV life cycle has been hampered by the lack of an efficient viral culture system. We performed studies with gt3 HEV cell culture-produced particles and patient blood and stool samples. Samples were fractionated on iodixanol gradients and cushions. Infectivity assays were performed invitro and in human liver chimeric mice. Proteins were analyzed by biochemical and proteomic approaches. Infectious particles were analyzed by transmission electron microscopy. HEV antigen levels were measured with the Wantaï enzyme-linked immunosorbent assay. We developed an efficient cell culture system and isolated HEV particles that were infectious invitro and invivo. Using transmission electron microscopy, we defined the ultrastructure of HEV cell culture-produced particles and particles from patient sera and stool samples. We also identified the precise sequence of the infectious particle-associated ORF2 capsid protein. In cultured cells and in samples from patients, HEV produced 3 forms of the ORF2 capsid protein: infectious/intracellular ORF2 (ORF2i), glycosylated ORF2 (ORF2g), and cleaved ORF2 (ORF2c). The ORF2i protein associated with infectious particles, whereas the ORF2g and ORF2c proteins were massively secreted glycoproteins not associated with infectious particles. ORF2g and ORF2c were the most abundant antigens detected in sera from patients. We developed a cell culture system and characterized HEV particles; we identified 3 ORF2 capsid proteins (ORF2i, ORF2g, and ORFc). These findings will advance our understanding of the HEV life cycle and improve diagnosis.

Phage-displayed peptides that mimic epitopes of hepatitis E virus capsid.

Hepatitis E is an emerging zoonotic infection of increasing public health threat for the UK, especially for immunosuppressed individuals. A human recombinant vaccine has been licensed only in China and is not clear whether it protects against hepatitis E virus (HEV) genotype 3, the most prevalent in Europe. The aim of this study was to use phage display technology as a tool to identify peptides that mimic epitopes of HEV capsid (mimotopes). We identified putative linear and conformational mimotopes using sera from Scottish blood donors that have the immunological imprint of past HEV infection. Four mimotopes did not have homology with the primary sequence of HEV ORF2 capsid but competed effectively with a commercial HEV antigen for binding to anti-HEV reference serum. When the reactivity profile of each mimotope was compared with Wantai HEV-IgG ELISA, the most sensitive HEV immunoassay, mimotopes showed 95.2-100% sensitivity while the specificity ranged from 81.5 to 95.8%. PepSurf algorithm was used to map affinity-selected peptides onto the ORF2 crystal structure of HEV genotype 3, which predicted that these four mimototopes are clustered in the P domain of ORF2 capsid, near conformational epitopes of anti-HEV neutralising monoclonal antibodies. These HEV mimotopes may have potential applications in the design of structural vaccines and the development of new diagnostic tests.

Establishment of a real time quantitative reverse-transcription PCR method for detection of hepatitis E virus based on standard plasmid

Objective To establish a real-time quantitative reverse-transcription PCR (qRT-PCR) method for detection of hepatitis E virus (HEV) of different genotypes based on standard HEV DNA plasmid in order to promote its application in clinical laboratory. Methods Specific primers and probe of HEV were designed based on the conserved open reading frame 3 (ORF3) regions. HEV DNA plasmids were constructed and 10-fold serial dilutions of the plasmids were prepared and used as standards to establish one-step qRT-PCR. The established method was compared with HEV antigen, antibody and RT-nPCR assays. Some positive samples were sequenced and analyzed by evolutionary tree. Results The one-step qRT-PCR method for HEV detection in serum or feces samples was successfully establish. It could reach a sensitivity of 25 copies/test and 77.8% of its results were consistent with those by HEV antigen assay. Nine patients were infected with HEV of genotypes 4a, 4d or 4n as indicated by evolutionary tree. Conclusion The HEV qRT-PCR method based on its standard plasmid is successfully established, which paves the way for commercialization of clinical applications. Key words: HEV; Standard plasmid; qRT-PCR; RT-nPCR

Detection of Genotype 4 Swine Hepatitis E Virus in Systemic Tissues in Cross-Species Infected Rabbits.

Increasing evidence demonstrates that hepatitis E virus (HEV) can be transmitted across species. According to previous reports, swine HEV has two genotypes, genotype 3 and 4, and both can infect humans by the fecal-oral route. Thus, it is crucial for the control of HEV zoonotic transmission to evaluate the dynamics of viral shedding and distribution in different tissues during cross-species infection by HEV. In this study, rabbits were infected with genotype 4 swine HEV by the intraperitoneal route. The results showed that HEV RNA not only shed in the feces but also in the saliva of some rabbits during infection with swine HEV. Viremia appeared late after infection, and anti-HEV IgG was not obvious until the appearance of high viremia levels. After the rabbits were euthanized, a histopathological examination showed that the livers developed overt hepatitis accompanied by an elevation of alanine aminotransferase (ALT) and aspartate transaminase (AST). Furthermore, HEV RNA was detected in various tissues, especially in the salivary glands and tonsils. Subsequently, negative-stranded HEV RNA was practiced in tissues with positive HEV RNA, which demonstrated that HEV replicated in the tissues. Next, we harvested additional tissues from the liver, salivary gland, tonsil, spleen, thymus gland, lymph node and intestine, which are known as replication sites of swine HEV. Additionally, we also observed the HEV antigen distributed in the organs above through immunohistochemical staining. These results demonstrate that rabbits could be used as an animal model for researching cross-species infection of genotype 4 HEV. It is also noteworthy that HEV can shed in the saliva and presents the risk of droplet transmission. These new data provide valuable information for understanding cross-species infection by HEV.