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Hypervariable region 1 and N-linked glycans of hepatitis C regulate virion neutralization by modulating envelope conformations

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@article{91cd1d25393e495aa729d3e0e562efe0,
title = "Hypervariable region 1 and N-linked glycans of hepatitis C regulate virion neutralization by modulating envelope conformations",
abstract = "About two million new cases of hepatitis C virus (HCV) infections annually underscore the urgent need for a vaccine. However, this effort has proven challenging because HCV evades neutralizing antibodies (NAbs) through molecular features of viral envelope glycoprotein E2, including hypervariable region 1 (HVR1) and N-linked glycans. Here, we observe large variation in the effects of removing individual E2 glycans across HCV strains H77(genotype 1a), J6(2a), and S52(3a) in Huh7.5 cell infections. Also, glycan-mediated effects on neutralization sensitivity were completely HVR1-dependent, and neutralization data were consistent with indirect protection of epitopes, as opposed to direct steric shielding. Indeed, the effect of removing each glycan was similar both in type (protective or sensitizing) and relative strength across four nonoverlapping neutralization epitopes. Temperature-dependent neutralization (e.g., virus breathing) assays indicated that both HVR1 and protective glycans stabilized a closed, difficult to neutralize, envelope conformation. This stabilizing effect was hierarchical as removal of HVR1 fully destabilized closed conformations, irrespective of glycan status, consistent with increased instability at acidic pH and high temperatures. Finally, we observed a strong correlation between neutralization sensitivity and scavenger receptor BI dependency during viral entry. In conclusion, our study indicates that HVR1 and glycans regulate HCV neutralization by shifting the equilibrium between open and closed envelope conformations. This regulation appears tightly linked with scavenger receptor BI dependency, suggesting a role of this receptor in transitions from closed to open conformations during entry. This importance of structural dynamics of HCV envelope glycoproteins has critical implications for vaccine development and suggests that similar phenomena could contribute to immune evasion of other viruses.",
keywords = "Envelope breathing, Envelope protein 2, Hepatitis C virus, N-linked glycans, Neutralizing antibodies",
author = "Jannick Prentoe and Rodrigo Vel{\'a}zquez-Moctezuma and Augestad, {Elias H.} and Andrea Galli and Richard Wang and Mansun Law and Harvey Alter and Jens Bukh",
year = "2019",
month = "5",
day = "14",
doi = "10.1073/pnas.1822002116",
language = "English",
volume = "116",
pages = "10039--10047",
journal = "National Academy of Sciences. Proceedings",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "20",

}

RIS

TY - JOUR

T1 - Hypervariable region 1 and N-linked glycans of hepatitis C regulate virion neutralization by modulating envelope conformations

AU - Prentoe, Jannick

AU - Velázquez-Moctezuma, Rodrigo

AU - Augestad, Elias H.

AU - Galli, Andrea

AU - Wang, Richard

AU - Law, Mansun

AU - Alter, Harvey

AU - Bukh, Jens

PY - 2019/5/14

Y1 - 2019/5/14

N2 - About two million new cases of hepatitis C virus (HCV) infections annually underscore the urgent need for a vaccine. However, this effort has proven challenging because HCV evades neutralizing antibodies (NAbs) through molecular features of viral envelope glycoprotein E2, including hypervariable region 1 (HVR1) and N-linked glycans. Here, we observe large variation in the effects of removing individual E2 glycans across HCV strains H77(genotype 1a), J6(2a), and S52(3a) in Huh7.5 cell infections. Also, glycan-mediated effects on neutralization sensitivity were completely HVR1-dependent, and neutralization data were consistent with indirect protection of epitopes, as opposed to direct steric shielding. Indeed, the effect of removing each glycan was similar both in type (protective or sensitizing) and relative strength across four nonoverlapping neutralization epitopes. Temperature-dependent neutralization (e.g., virus breathing) assays indicated that both HVR1 and protective glycans stabilized a closed, difficult to neutralize, envelope conformation. This stabilizing effect was hierarchical as removal of HVR1 fully destabilized closed conformations, irrespective of glycan status, consistent with increased instability at acidic pH and high temperatures. Finally, we observed a strong correlation between neutralization sensitivity and scavenger receptor BI dependency during viral entry. In conclusion, our study indicates that HVR1 and glycans regulate HCV neutralization by shifting the equilibrium between open and closed envelope conformations. This regulation appears tightly linked with scavenger receptor BI dependency, suggesting a role of this receptor in transitions from closed to open conformations during entry. This importance of structural dynamics of HCV envelope glycoproteins has critical implications for vaccine development and suggests that similar phenomena could contribute to immune evasion of other viruses.

AB - About two million new cases of hepatitis C virus (HCV) infections annually underscore the urgent need for a vaccine. However, this effort has proven challenging because HCV evades neutralizing antibodies (NAbs) through molecular features of viral envelope glycoprotein E2, including hypervariable region 1 (HVR1) and N-linked glycans. Here, we observe large variation in the effects of removing individual E2 glycans across HCV strains H77(genotype 1a), J6(2a), and S52(3a) in Huh7.5 cell infections. Also, glycan-mediated effects on neutralization sensitivity were completely HVR1-dependent, and neutralization data were consistent with indirect protection of epitopes, as opposed to direct steric shielding. Indeed, the effect of removing each glycan was similar both in type (protective or sensitizing) and relative strength across four nonoverlapping neutralization epitopes. Temperature-dependent neutralization (e.g., virus breathing) assays indicated that both HVR1 and protective glycans stabilized a closed, difficult to neutralize, envelope conformation. This stabilizing effect was hierarchical as removal of HVR1 fully destabilized closed conformations, irrespective of glycan status, consistent with increased instability at acidic pH and high temperatures. Finally, we observed a strong correlation between neutralization sensitivity and scavenger receptor BI dependency during viral entry. In conclusion, our study indicates that HVR1 and glycans regulate HCV neutralization by shifting the equilibrium between open and closed envelope conformations. This regulation appears tightly linked with scavenger receptor BI dependency, suggesting a role of this receptor in transitions from closed to open conformations during entry. This importance of structural dynamics of HCV envelope glycoproteins has critical implications for vaccine development and suggests that similar phenomena could contribute to immune evasion of other viruses.

KW - Envelope breathing

KW - Envelope protein 2

KW - Hepatitis C virus

KW - N-linked glycans

KW - Neutralizing antibodies

UR - http://www.scopus.com/inward/record.url?scp=85065699673&partnerID=8YFLogxK

U2 - 10.1073/pnas.1822002116

DO - 10.1073/pnas.1822002116

M3 - Journal article

VL - 116

SP - 10039

EP - 10047

JO - National Academy of Sciences. Proceedings

JF - National Academy of Sciences. Proceedings

SN - 0027-8424

IS - 20

ER -

ID: 57282504