scholarly journals In Vitro and In Vivo Mutational Analysis of the 3′-Terminal Regions of Hepatitis E Virus Genomes and Replicons

2005 ◽  
Vol 79 (2) ◽  
pp. 1017-1026 ◽  
Author(s):  
Judith Graff ◽  
Hanh Nguyen ◽  
Chaiyan Kasorndorkbua ◽  
Patrick G. Halbur ◽  
Marisa St. Claire ◽  
...  
Keyword(s):  
Hepatitis E Virus ◽  
Cultured Cells ◽  
Mutational Analysis ◽  
Rna Replication ◽  
Hepatitis E ◽  
Human Strain ◽  
Full Length ◽  
Genotype 1

ABSTRACT Hepatitis E virus (HEV) replication is not well understood, mainly because the virus does not infect cultured cells efficiently. However, Huh-7 cells transfected with full-length genomes produce open reading frame 2 protein, indicative of genome replication (6). To investigate the role of 3′-terminal sequences in RNA replication, we constructed chimeric full-length genomes with divergent 3′-terminal sequences of genotypes 2 and 3 replacing that of genotype 1 and transfected them into Huh-7 cells. The production of viral proteins by these full-length chimeras was indistinguishable from that of the wild type, suggesting that replication was not impaired. In order to better quantify HEV replication in cell culture, we constructed an HEV replicon with a reporter (luciferase). Luciferase production was cap dependent and RNA-dependent RNA polymerase dependent and increased following transfection of Huh-7 cells. Replicons harboring the 3′-terminal intergenotypic chimera sequences were also assayed for luciferase production. In spite of the large sequence differences among the 3′ termini of the viruses, replication of the chimeric replicons was surprisingly similar to that of the parental replicon. However, a single unique nucleotide change within a predicted stem structure at the 3′ terminus substantially reduced the efficiency of replication: RNA replication was partially restored by a covariant mutation. Similar patterns of replication were obtained when full-length genomes were inoculated into rhesus macaques, suggesting that the in vitro system could be used to predict the effect of 3′-terminal mutations in vivo. Incorporation of the 3′-terminal sequences of the swine strain of HEV into the genotype 1 human strain did not enable the human strain to infect swine.

scholarly journals Hepatitis E Virus Immunopathogenesis

Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1180
Author(s):  
Kush Kumar Yadav ◽  
Scott P. Kenney
Keyword(s):  
Hepatitis E Virus ◽  
Organ Transplant ◽  
Hepatitis E ◽  
Oral Route ◽  
Solid Organ ◽  
Immunocompromised Patients ◽  
In Vivo Models ◽  
Transplant Patients

Hepatitis E virus is an important emerging pathogen producing a lethal impact on the pregnant population and immunocompromised patients. Starting in 1983, it has been described as the cause for acute hepatitis transmitted via the fecal–oral route. However, zoonotic and blood transfusion transmission of HEV have been reported in the past few decades, leading to the detailed research of HEV pathogenesis. The reason behind HEV being highly virulent to the pregnant population particularly during the third trimester, leading to maternal and fetal death, remains unknown. Various host factors (immunological, nutritional, hormonal) and viral factors have been studied to define the key determinants assisting HEV to be virulent in pregnant and immunocompromised patients. Similarly, chronic hepatitis is seen particularly in solid organ transplant patients, resulting in fatal conditions. This review describes recent advances in the immunopathophysiology of HEV infections in general, pregnant, and immunocompromised populations, and further elucidates the in vitro and in vivo models utilized to understand HEV pathogenesis.

scholarly journals Construction and characterization of infectious cDNA clones of a chicken strain of hepatitis E virus (HEV), avian HEV

2005 ◽  
Vol 86 (9) ◽  
pp. 2585-2593 ◽  
Author(s):  
F. F. Huang ◽  
F. W. Pierson ◽  
T. E. Toth ◽  
X. J. Meng
Keyword(s):  
Hepatitis E Virus ◽  
Hepatitis E ◽  
Cdna Clones ◽  
Virus Shedding ◽  
Rna Transcripts ◽  
Successful Infection ◽  
The Usa ◽  
Avian Hev

Hepatitis E virus (HEV), the causative agent of hepatitis E, is an important human pathogen. Increasing evidence indicates that hepatitis E is a zoonosis. Avian HEV was recently discovered in chickens with hepatitis–splenomegaly syndrome in the USA. Like swine HEV from pigs, avian HEV is also genetically and antigenically related to human HEV. The objective of this study was to construct and characterize an infectious cDNA clone of avian HEV for future studies of HEV replication and pathogenesis. Three full-length cDNA clones of avian HEV, pT7-aHEV-5, pT7G-aHEV-10 and pT7G-aHEV-6, were constructed and their infectivity was tested by in vitro transfection of leghorn male hepatoma (LMH) chicken liver cells and by direct intrahepatic inoculation of specific-pathogen-free (SPF) chickens with capped RNA transcripts from the three clones. The results showed that the capped RNA transcripts from each of the three clones were replication competent when transfected into LMH cells as demonstrated by detection of viral antigens with avian HEV-specific antibodies. SPF chickens intrahepatically inoculated with the capped RNA transcripts from each of the three clones developed active avian HEV infections as evidenced by seroconversion to avian HEV antibodies, viraemia and faecal virus shedding. The infectivity was further confirmed by successful infection of naïve chickens with the viruses recovered from chickens inoculated with the RNA transcripts. The results indicated that all three cDNA clones of avian HEV are infectious both in vitro and in vivo. The availability of these infectious clones for a chicken strain of HEV now affords an opportunity to study the mechanisms of HEV cross-species infection and tissue tropism by constructing chimeric viruses among human, swine and avian HEVs.

scholarly journals Full-length cardiac Na+/Ca2+ exchanger 1 protein is not phosphorylated by protein kinase A

2011 ◽  
Vol 300 (5) ◽  
pp. C989-C997 ◽  
Author(s):  
Pimthanya Wanichawan ◽  
William E. Louch ◽  
Kristin H. Hortemo ◽  
Bjørg Austbø ◽  
Per Kristian Lunde ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Caspase 3 ◽  
Fluorescent Protein ◽  
Mutational Analysis ◽  
Phosphorylation Site ◽  
Full Length ◽  
Kinase A

The cardiac Na+/Ca2+ exchanger 1 (NCX1) is an important regulator of intracellular Ca2+ homeostasis and cardiac function. Several studies have indicated that NCX1 is phosphorylated by the cAMP-dependent protein kinase A (PKA) in vitro, which increases its activity. However, this finding is controversial and no phosphorylation site has so far been identified. Using bioinformatic analysis and peptide arrays, we screened NCX1 for putative PKA phosphorylation sites. Although several NCX1 synthetic peptides were phosphorylated by PKA in vitro, only one PKA site (threonine 731) was identified after mutational analysis. To further examine whether NCX1 protein could be PKA phosphorylated, wild-type and alanine-substituted NCX1-green fluorescent protein (GFP)-fusion proteins expressed in human embryonic kidney (HEK)293 cells were generated. No phosphorylation of full-length or calpain- or caspase-3 digested NCX1-GFP was observed with purified PKA-C and [γ-32P]ATP. Immunoblotting experiments with anti-PKA substrate and phosphothreonine-specific antibodies were further performed to investigate phosphorylation of endogenous NCX1. Phospho-NCX1 levels were also not increased after forskolin or isoproterenol treatment in vivo, in isolated neonatal cardiomyocytes, or in total heart homogenate. These data indicate that the novel in vitro PKA phosphorylation site is inaccessible in full-length as well as in calpain- or caspase-3 digested NCX1 protein, suggesting that NCX1 is not a direct target for PKA phosphorylation.

scholarly journals Early secretory pathway localization and lack of processing for hepatitis E virus replication protein pORF1

2013 ◽  
Vol 94 (4) ◽  
pp. 807-816 ◽  
Author(s):  
Julia Perttilä ◽  
Pirjo Spuul ◽  
Tero Ahola
Keyword(s):  
Hepatitis E Virus ◽  
Secretory Pathway ◽  
Hepatitis E ◽  
Proteolytic Processing ◽  
Full Length ◽  
Replication Protein ◽  
Positive Strand ◽  
Early Secretory Pathway ◽  
Positive Strand Rna

Hepatitis E virus (HEV) is a positive-strand RNA virus and a major causative agent of acute sporadic and epidemic hepatitis. HEV replication protein is encoded by ORF1 and contains the predicted domains of methyltransferase (MT), protease, macro domain, helicase (HEL) and polymerase (POL). In this study, the full-length protein pORF1 (1693 aa) and six truncated variants were expressed by in vitro translation and in human HeLa and hepatic Huh-7 cells by using several vector systems. The proteins were visualized by three specific antisera directed against the MT, HEL and POL domains. In vitro translation of full-length pORF1 yielded smaller quantities of two fragments. However, these fragments were not observed after pORF1 expression and pulse–chase studies in human cells, and their production was not dependent on the predicted protease domain in pORF1. The weight of evidence supports the proposition that pORF1 is not subjected to specific proteolytic processing, which is unusual among animal positive-strand RNA viruses but common for plant viruses. pORF1 was membrane associated in cells and localized to a perinuclear region, where it partially overlapped with localization of the endoplasmic reticulum (ER) marker BAP31 and was closely interspersed with staining of the ER–Golgi intermediate compartment marker protein ERGIC-53. Co-localization with BAP31 was enhanced by treatment with brefeldin A. Therefore, HEV may utilize modified early secretory pathway membranes for replication.

scholarly journals Mutational Analysis of the Hypervariable Region of Hepatitis E Virus Reveals Its Involvement in the Efficiency of Viral RNA Replication

2011 ◽  
Vol 85 (19) ◽  
pp. 10031-10040 ◽  
Author(s):  
R. S. Pudupakam ◽  
S. P. Kenney ◽  
L. Cordoba ◽  
Y.-W. Huang ◽  
B. A. Dryman ◽  
...  
Keyword(s):  
Hepatitis E Virus ◽  
Mutational Analysis ◽  
Hypervariable Region ◽  
Rna Replication ◽  
Hepatitis E ◽  
Viral Rna

Molecular biology and pathogenesis of hepatitis E virus

1999 ◽  
Vol 1 (18) ◽  
pp. 1-16 ◽  
Author(s):  
Shahid Jameel
Keyword(s):  
Viral Genome ◽  
Hepatitis E Virus ◽  
Hepatitis E ◽  
Open Reading Frame ◽  
Reading Frame ◽  
Host Interactions ◽  
Processing Enzymes ◽  
Open Reading Frame 2

Hepatitis E virus (HEV) infection results in hepatitis E, an acute and self-limited disease. The virus is transmitted in a faecal–oral manner and is a major cause of viral hepatitis in much of the developing world, where it causes rampant sporadic infections and large epidemics. A curious feature of hepatitis E is the unusually high rates of mortality that are observed in pregnant women, in whom the disease is exacerbated by the development of fulminant liver disease. In the absence of viable in vitro propagation systems, several geographical isolates of HEV have been maintained in vivo in nonhuman primates and, subsequently, the viral genome has been cloned and sequenced. HEV has been classified provisionally into a separate family known as the HEV-like viruses, which has at least four recognised genotypes, but has only a single serotype. The viral genome is a positive-stranded (+)RNA of ~7.5 kb and encodes at least three proteins. Open reading frame 1 (ORF1) encodes the viral nonstructural polyprotein, which has domains that are homologous to some of the replication and processing enzymes found in other +RNA viruses. The HEV protein itself remains poorly characterised. The protein encoded by open reading frame 2 (ORF2) is the major HEV capsid protein, and the protein encoded by open reading frame 3 (ORF3) appears to be involved in virus–host interactions. Several questions related to the biology, epidemiology and pathogenesis of HEV remain unanswered; the progress of a few of these is reviewed here.

scholarly journals Ectopic Expression of Genotype 1 Hepatitis E Virus ORF4 Increases Genotype 3 HEV Viral Replication in Cell Culture

Viruses ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 75
Author(s):  
Kush K. Yadav ◽  
Patricia A. Boley ◽  
Zachary Fritts ◽  
Scott P. Kenney
Keyword(s):  
Cell Culture ◽  
Viral Replication ◽  
Pregnant Women ◽  
Cell Lines ◽  
Hepatitis E Virus ◽  
Hepatitis E ◽  
Target Cells ◽  
Genotype 1 ◽  
Orf4 Protein

Hepatitis E virus (HEV) can account for up to a 30% mortality rate in pregnant women, with highest incidences reported for genotype 1 (gt1) HEV. Reasons contributing to adverse maternal-fetal outcome during pregnancy in HEV-infected pregnant women remain elusive in part due to the lack of a robust tissue culture model for some strains. Open reading frame (ORF4) was discovered overlapping ORF1 in gt1 HEV whose protein expression is regulated via an IRES-like RNA element. To experimentally determine whether gt3 HEV contains an ORF4-like gt1, gt1 and gt3 sequence comparisons were performed between the gt1 and the homologous gt3 sequence. To assess whether ORF4 protein could enhance gt3 replication, Huh7 cell lines constitutively expressing ORF4 were created and used to assess the replication of the Kernow-C1 gt3 and sar55 gt1 HEV. Virus stocks from transfected Huh7 cells with or without ORF4 were harvested and infectivity assessed via infection of HepG2/C3A cells. We also studied the replication of gt1 HEV in the ORF4-expressing tunicamycin-treated cell line. To directly show that HEV transcripts have productively replicated in the target cells, we assessed events at the single-cell level using indirect immunofluorescence and flow cytometry. Despite not naturally encoding ORF4, replication of gt3 HEV was enhanced by the presence of gt1 ORF4 protein. These results suggest that the function of ORF4 protein from gt1 HEV is transferrable, enhancing the replication of gt3 HEV. ORF4 may be utilized to enhance replication of difficult to propagate HEV genotypes in cell culture. IMPORTANCE: HEV is a leading cause of acute viral hepatitis (AVH) around the world. The virus is a threat to pregnant women, particularly during the second and third trimester of pregnancy. The factors enhancing virulence to pregnant populations are understudied. Additionally, field strains of HEV remain difficult to culture in vitro. ORF4 was recently discovered in gt1 HEV and is purported to play a role in pregnancy related pathology and enhanced replication. We present evidence that ORF4 protein provided in trans enhances the viral replication of gt3 HEV even though it does not encode ORF4 naturally in its genome. These data will aid in the development of cell lines capable of supporting replication of non-cell culture adapted HEV field strains, allowing viral titers sufficient for studying these strains in vitro. Furthermore, development of gt1/gt3 ORF4 chimeric virus may shed light on the role that ORF4 plays during pregnancy.

scholarly journals The natural compound silvestrol inhibits hepatitis E virus (HEV) replication in vitro and in vivo

2018 ◽  
Vol 157 ◽  
pp. 151-158 ◽  
Author(s):  
Daniel Todt ◽  
Nora Moeller ◽  
Dimas Praditya ◽  
Volker Kinast ◽  
Martina Friesland ◽  
...  
Keyword(s):  
Hepatitis E Virus ◽  
Natural Compound ◽  
Hepatitis E

scholarly journals Release of Genotype 1 Hepatitis E Virus from Cultured Hepatoma and Polarized Intestinal Cells Depends on Open Reading Frame 3 Protein and Requires an Intact PXXP Motif

2010 ◽  
Vol 84 (18) ◽  
pp. 9059-9069 ◽  
Author(s):  
Suzanne U. Emerson ◽  
Hanh T. Nguyen ◽  
Udana Torian ◽  
Danielle Burke ◽  
Ronald Engle ◽  
...  
Keyword(s):  
Hepatitis E Virus ◽  
Cultured Cells ◽  
Hepatitis E ◽  
Open Reading Frame ◽  
Intestinal Cells ◽  
Protein Accumulation ◽  
Genotype 1 ◽  
Virus Genotype ◽  
Reading Frame ◽  
Orf3 Protein

ABSTRACT Hepatitis E virus genotype 1 strain Sar55 replicated in subcloned Caco-2 intestinal cells and Huh7 hepatoma cells that had been transfected with in vitro transcribed viral genomes, and hepatitis E virions were released into the culture medium of both cell lines. Virus egress from cells depended on open reading frame 3 (ORF3) protein, and a proline-rich sequence in ORF3 was important for egress from cultured cells and for infection of macaques. Both intracellular ORF3 protein accumulation and virus release occurred at the apical membrane of polarized Caco-2 cells. ORF3 protein and lipids were intimately associated with virus particles produced in either cell line; ORF2 epitopes were masked in these particles and could not be immunoprecipitated with anti-ORF2.

scholarly journals Antiviral Candidates for Treating Hepatitis E Virus Infection

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Natalie E. Netzler ◽  
Daniel Enosi Tuipulotu ◽  
Subhash G. Vasudevan ◽  
Jason M. Mackenzie ◽  
Peter A. White
Keyword(s):  
Hepatitis E Virus ◽  
Drug Repurposing ◽  
Hepatitis E ◽  
Genotype 1 ◽  
Rna Quantification ◽  
Half Maximal Effective Concentration ◽  
Combinational Treatment ◽  
Further Development ◽  
Rna Levels

ABSTRACT Globally, hepatitis E virus (HEV) causes significant morbidity and mortality each year. Despite this burden, there are no specific antivirals available to treat HEV patients, and the only licensed vaccine is not available outside China. Ribavirin and alpha interferon are used to treat chronic HEV infections; however, severe side effects and treatment failure are commonly reported. Therefore, this study aimed to identify potential antivirals for further development to combat HEV infection. We selected 16 compounds from the nucleoside and nonnucleoside antiviral classes that range in developmental status from late preclinical to FDA approved and evaluated them as potential antivirals for HEV infection, using genotype 1 replicon luminescence studies and replicon RNA quantification. Two potent inhibitors of HEV replication included NITD008 (half-maximal effective concentration [EC50], 0.03 μM; half-maximal cytotoxic concentration [CC50], >100 μM) and GPC-N114 (EC50, 1.07 μM, CC50, >100 μM), and both drugs reduced replicon RNA levels in cell culture (>50% reduction with either 10 μM GPC-N114 or 2.50 μM NITD008). Furthermore, GPC-N114 and NITD008 were synergistic in combinational treatment (combination index, 0.4) against HEV replication, allowing for dose reduction indices of 20.42 and 8.82 at 50% inhibition, respectively. Sofosbuvir has previously exhibited mixed results against HEV as an antiviral, both in vitro and in a few clinical applications; however, in this study it was effective against the HEV genotype 1 replicon (EC50, 1.97 μM; CC50, >100 μM) and reduced replicon RNA levels (47.2% reduction at 10 μM). Together these studies indicate drug repurposing may be a promising pathway for development of antivirals against HEV infection.

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