Computational Prediction of the Heterodimeric and Higher-Order Structure of gpE1/gpE2 Envelope Glycoproteins Encoded by Hepatitis C Virus

Freedman, Holly; Logan, Michael; Hockman, Darren; Leman, Julia Koehler; Law, John Lok Man; Houghton, Michael

doi:10.1128/jvi.02309-16

Cited by 33 publications

(33 citation statements)

References 102 publications

(160 reference statements)

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“…E2 is presented on the surface of HCV virions as a heterodimer with a partner glycoprotein E1. These E1E2 dimers form higher-order oligomers, likely to be a trimer [8,9], which drive the processes of attachment, receptor engagement and fusion, to achieve virus entry. The molecular mechanisms by which E1E2 performs entry remain poorly understood, however, current evidence suggests that E2 is responsible for receptor engagement, whereas E1 is likely to contain the fusogen [8,10,11].…”

Section: Introductionmentioning

confidence: 99%

Flexibility and intrinsic disorder are conserved features of hepatitis C virus E2 glycoprotein

et al. 2020

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The glycoproteins of hepatitis C virus, E1E2, are unlike any other viral fusion machinery yet described, and are the current focus of immunogen design in HCV vaccine development; thus, making E1E2 both scientifically and medically important. We used pre-existing, but fragmentary, structures to model a complete ectodomain of the major glycoprotein E2 from three strains of HCV. We then performed molecular dynamic simulations to explore the conformational landscape of E2, revealing a number of important features. Despite high sequence divergence, and subtle differences in the models, E2 from different strains behave similarly, possessing a stable core flanked by highly flexible regions, some of which perform essential functions such as receptor binding. Comparison with sequence data suggest that this consistent behaviour is conferred by a network of conserved residues that act as hinge and anchor points throughout E2. The variable regions (HVR-1, HVR-2 and VR-3) exhibit particularly high flexibility, and bioinformatic analysis suggests that HVR-1 is a putative intrinsically disordered protein region. Dynamic cross-correlation analyses demonstrate intramolecular communication and suggest that specific regions, such as HVR-1, can exert influence throughout E2. To support our computational approach we performed small-angle X-ray scattering with purified E2 ectodomain; this data was consistent with our MD experiments, suggesting a compact globular core with peripheral flexible regions. This work captures the dynamic behaviour of E2 and has direct relevance to the interaction of HCV with cell-surface receptors and neutralising antibodies.

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Section: Introductionmentioning

confidence: 99%

Flexibility and intrinsic disorder are conserved features of hepatitis C virus E2 glycoprotein

et al. 2020

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“…In contrast, glycoproteins of many enveloped viruses display a high proportion of these immature forms of N -glycans (20-22). While HCV E2 has fewer N -glycosylation sites (around 11) than the HIV glycoprotein gp120 (which has between 20 and 30 depending on the strain), E2 is likely present on the surface of HCV at a higher density and thus provides higher local concentrations of HMGs (41). Further studies are necessary to reveal a threshold HMG concentration which enables efficient interaction between AvFc and the surfaces of cells or viruses.…”

Section: Discussionmentioning

confidence: 99%

Safety and Efficacy of Avaren-Fc Lectibody Targeting HCV High-Mannose Glycans in a Human Liver Chimeric Mouse Model

Dent

Hamorsky

Vausselin

et al. 2020

Preprint

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21Infection with hepatitis C virus (HCV) remains to be a major cause of morbidity and mortality 22 worldwide despite the recent advent of highly effective direct-acting antivirals. The envelope 23 glycoproteins of HCV are heavily glycosylated with a high proportion of high-mannose glycans 24 (HMGs), which serve as a shield against neutralizing antibodies and assist in the interaction with 25 cell-entry receptors. However, currently there is no approved therapeutic targeting this 26 potentially druggable biomarker. Here, we investigated the therapeutic potential of the lectibody 27 Avaren-Fc (AvFc), a HMG-binding lectin-Fc fusion protein. In vitro assays showed AvFc's 28 capacity to neutralize cell culture-derived HCV in a genotype independent manner with IC 50 29 values in the low nanomolar range. A histidine buffer-based AvFc formulation was developed 30 for in vivo studies using the PXB human liver chimeric mouse model. Systemic administration 31 of AvFc was well tolerated; after 11 consecutive doses every other day at 25 mg/kg, there were 32 no significant changes in body or liver weights, nor any impact noted in blood human albumin 33 levels or serum alanine aminotransferase activity. Gross necropsy and liver pathology further 34 confirmed the lack of discernible toxicity. This treatment regimen successfully prevented 35 genotype 1a HCV infection in all animals, while an AvFc mutant lacking HMG binding activity 36 failed to block the infection. These results suggest that targeting envelope HMGs is a promising 37 therapeutic approach against HCV infection. In particular, AvFc may provide a safe and 38 efficacious means to prevent recurrent infection upon liver transplantation in HCV-related end-39 stage liver disease patients. 42family Flaviviridae and the causative agent of hepatitis C disease. Its genome encodes three 43 structural (core, E1, E2) and seven non-structural proteins (p7, NS2, NS3, NS4A, NS4B, NS5A, 44 NS5B) (1). HCV is highly heterogenous and globally distributed, consisting of seven genotypes 45 each further subdivided into multiple subtypes. Genotype 1 is the predominant genotype 46 worldwide and particularly concentrated in high-income and upper-middle income countries, 47 whereas genotype 3 and 4 are more common in lower-middle and low-income countries (2). In 48 the United States, injection drug use represents the primary risk factor for contracting HCV 49 infection (3, 4). Around 15-25% of people acutely infected with HCV will clear the virus, while 50 the remainder will develop chronic infection that can persist largely unnoticed for decades. 51Indeed, many HCV carriers discover their chronic infection after they have developed cirrhosis 52 (5). Chronic HCV infection is also associated with the development of hepatocellular carcinoma, 53 and those with the disease are more likely to develop cryoglobulinemia and non-Hodgkin's 54 lymphoma (6). 55There is no vaccine currently available for HCV. Prior to 2011, the standard chronic 56 HCV treatment was a non-specific antiviral medica...

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“…These results confirm the involvement of E1 region from aa 290 to 306 in E1E2 interaction, as observed in the computational prediction of the E1E2 heterodimer structure proposed by Freedman at al. (30). Thus, although interactions between E1 and E2 transmembrane domains are essential for E1E2 heterodimerization, several residues in their ectodomains also contribute to the interaction.…”

Section: Discussionmentioning

confidence: 99%

Functional Study of the C-Terminal Part of the Hepatitis C Virus E1 Ectodomain

Moustafa

Haddad

Linna

et al. 2018

J Virol

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In the hepatitis C virus (HCV) envelope glycoproteins E1 and E2, which form a heterodimer, E2 is the receptor binding protein and the major target of neutralizing antibodies, whereas the function of E1 remains less characterized. To investigate E1 functions, we generated a series of mutants in the conserved residues of the C-terminal region of the E1 ectodomain in the context of an infectious clone. We focused our analyses on two regions of interest. The first region is located in the middle of the E1 glycoprotein (between amino acid [aa] 270 and aa 291), which contains a conserved hydrophobic sequence and was proposed to constitute a putative fusion peptide. The second series of mutants was generated in the region from aa 314 to aa 342 (the aa314-342 region), which has been shown to contain two α helices (α2 and α3) by nuclear magnetic resonance studies. Of the 22 generated mutants, 20 were either attenuated or noninfectious. Several mutations modulated the virus's dependence on claudin-1 and the scavenger receptor BI coreceptors for entry. Most of the mutations in the putative fusion peptide region affected virus assembly. Conversely, mutations in the α-helix aa 315 to 324 (315-324) residues M318, W320, D321, and M322 resulted in a complete loss of infectivity without any impact on E1E2 folding and on viral assembly. Further characterization of the W320A mutant in the HCVpp model indicated that the loss of infectivity was due to a defect in viral entry. Together, these results support a role for E1 in modulating HCV interaction with its coreceptors and in HCV assembly. They also highlight the involvement of α-helix 315-324 in a late step of HCV entry. HCV is a major public health problem worldwide. The virion harbors two envelope proteins, E1 and E2, which are involved at different steps of the viral life cycle. Whereas E2 has been extensively characterized, the function of E1 remains poorly defined. We characterized here the function of the putative fusion peptide and the region containing α helices of the E1 ectodomain, which had been previously suggested to be important for virus entry. We could confirm the importance of these regions for the virus infectivity. Interestingly, we found several residues modulating the virus's dependence on several HCV receptors, thus highlighting the role of E1 in the interaction of the virus with cellular receptors. Whereas mutations in the putative fusion peptide affected HCV infectivity and morphogenesis, several mutations in the α2-helix region led to a loss of infectivity with no effect on assembly, indicating a role of this region in virus entry.

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Computational Prediction of the Heterodimeric and Higher-Order Structure of gpE1/gpE2 Envelope Glycoproteins Encoded by Hepatitis C Virus

Cited by 33 publications

References 102 publications

Flexibility and intrinsic disorder are conserved features of hepatitis C virus E2 glycoprotein

Flexibility and intrinsic disorder are conserved features of hepatitis C virus E2 glycoprotein

Safety and Efficacy of Avaren-Fc Lectibody Targeting HCV High-Mannose Glycans in a Human Liver Chimeric Mouse Model

Functional Study of the C-Terminal Part of the Hepatitis C Virus E1 Ectodomain

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