scholarly journals Conformational Flexibility in the Immunoglobulin-Like Domain of the Hepatitis C Virus Glycoprotein E2

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Ieva Vasiliauskaite ◽  
Ania Owsianka ◽  
Patrick England ◽  
Abdul Ghafoor Khan ◽  
Sarah Cole ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Binding Site ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Asymptomatic Infection ◽  
Effective Vaccine ◽  
Viral Glycoprotein ◽  
Direct Acting Antiviral ◽  
Glycoprotein E2

ABSTRACT The hepatitis C virus (HCV) glycoprotein E2 is the major target of neutralizing antibodies and is therefore highly relevant for vaccine design. Its structure features a central immunoglobulin (Ig)-like β-sandwich that contributes to the binding site for the cellular receptor CD81. We show that a synthetic peptide corresponding to a β-strand of this Ig-like domain forms an α-helix in complex with the anti-E2 antibody DAO5, demonstrating an inside-out flip of hydrophobic residues and a secondary structure change in the composite CD81 binding site. A detailed interaction analysis of DAO5 and cross-competing neutralizing antibodies with soluble E2 revealed that the Ig-like domain is trapped by different antibodies in at least two distinct conformations. DAO5 specifically captures retrovirus particles bearing HCV glycoproteins (HCVpp) and infectious cell culture-derived HCV particles (HCVcc). Infection of cells by DAO5-captured HCVpp can be blocked by a cross-competing neutralizing antibody, indicating that a single virus particle simultaneously displays E2 molecules in more than one conformation on its surface. Such conformational plasticity of the HCV E2 receptor binding site has important implications for immunogen design. IMPORTANCE Recent advances in the treatment of hepatitis C virus (HCV) infection with direct-acting antiviral drugs have enabled the control of this major human pathogen. However, due to their high costs and limited accessibility in combination with the lack of awareness of the mostly asymptomatic infection, there is an unchanged urgent need for an effective vaccine. The viral glycoprotein E2 contains regions that are crucial for virus entry into the host cell, and antibodies that bind to these regions can neutralize infection. One of the major targets of neutralizing antibodies is the central immunoglobulin (Ig)-like domain within E2. We show here that this Ig-like domain is conformationally flexible at the surface of infectious HCV particles and pseudoparticles. Our study provides novel insights into the interactions of HCV E2 with the humoral immune system that should aid future vaccine development. IMPORTANCE Recent advances in the treatment of hepatitis C virus (HCV) infection with direct-acting antiviral drugs have enabled the control of this major human pathogen. However, due to their high costs and limited accessibility in combination with the lack of awareness of the mostly asymptomatic infection, there is an unchanged urgent need for an effective vaccine. The viral glycoprotein E2 contains regions that are crucial for virus entry into the host cell, and antibodies that bind to these regions can neutralize infection. One of the major targets of neutralizing antibodies is the central immunoglobulin (Ig)-like domain within E2. We show here that this Ig-like domain is conformationally flexible at the surface of infectious HCV particles and pseudoparticles. Our study provides novel insights into the interactions of HCV E2 with the humoral immune system that should aid future vaccine development.

scholarly journals Hepatitis C virus vaccine development: old challenges and new opportunities

2015 ◽  
Vol 2 (3) ◽  
pp. 285-295 ◽  
Author(s):  
Dapeng Li ◽  
Zhong Huang ◽  
Jin Zhong
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Chronic Hepatitis C ◽  
Vaccine Development ◽  
Rna Virus ◽  
Antiviral Agents ◽  
Resistance Mutations ◽  
Direct Acting Antiviral ◽  
Direct Acting

Abstract Hepatitis C virus (HCV), an enveloped positive-sense single-stranded RNA virus, can cause chronic and end-stage liver diseases. Approximately 185 million people worldwide are infected with HCV. Tremendous progress has been achieved in the therapeutics of chronic hepatitis C thanks to the development of direct-acting antiviral agents (DAAs), but the worldwide use of these highly effective DAAs is limited due to their high treatment cost. In addition, drug-resistance mutations remain a potential problem as DAAs are becoming a standard therapy for chronic hepatitis C. Unfortunately, no vaccine is available for preventing new HCV infection. Therefore, HCV still imposes a big threat to human public health, and the worldwide eradication of HCV is critically dependent on an effective HCV vaccine. In this review, we summarize recent progresses on HCV vaccine development and present our views on the rationale and strategy to develop an effective HCV vaccine.

scholarly journals Convergent antibody responses associated with broad neutralization of hepatitis C virus and clearance of infection

2021 ◽  
Author(s):  
Nicole E. Skinner ◽  
Clinton O. Ogega ◽  
Nicole Frumento ◽  
Kaitlyn E. Clark ◽  
Srinivasan Yegnasubramanian ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
B Cell ◽  
Early Development ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
High Plasma ◽  
Spontaneous Clearance ◽  
Cell Repertoire ◽  
Molecular Features

AbstractEarly development of broadly neutralizing antibodies (bNAbs) targeting the hepatitis C virus (HCV) envelope glycoprotein E2 is associated with spontaneous clearance of infection, so induction of bNAbs is a major goal of HCV vaccine development. However, much remains to be learned at a molecular level about protective E2-reactive antibodies, since HCV infection persists in some individuals despite early development of broadly neutralizing plasma. To examine B cell repertoire features associated with broad neutralization and viral clearance, we performed RNA sequencing of the B cell receptors (BCRs) of HCV E2-reactive B cells of people with cleared or persistent HCV, including subjects with high or low plasma neutralizing breadth in both clearance and persistence groups. We identified many E2-reactive public BCR clonotypes, which are antibody clones with the same V and J-genes and identical CDR3 sequences, shared among subjects grouped by either clearance or neutralization status. The majority (89) of these public clonotypes were shared by two subjects with broad plasma neutralizing activity and cleared infection, but not found in subjects with high plasma neutralizing breadth and persistent infection. We cloned a potent, cross-reactive neutralizing monoclonal antibody (mAb) by pairing the most abundant public heavy and light chains from these two subjects, providing evidence that broadly E2-reactive public clonotypes arise in a subset of individuals with broadly neutralizing plasma and spontaneous clearance of infection. Further characterization of the molecular features and function of these antibodies can inform HCV vaccine development.

scholarly journals A Point Mutation Leading to Hepatitis C Virus Escape from Neutralization by a Monoclonal Antibody to a Conserved Conformational Epitope

2008 ◽  
Vol 82 (12) ◽  
pp. 6067-6072 ◽  
Author(s):  
Zhen-Yong Keck ◽  
Oakley Olson ◽  
Meital Gal-Tanamy ◽  
Jinming Xia ◽  
Arvind H. Patel ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Vaccine Development ◽  
Human Monoclonal Antibody ◽  
Conformational Epitope ◽  
Single Amino Acid ◽  
Effective Vaccine ◽  
Linear Sequence ◽  
Virus Escape

ABSTRACT A challenge in hepatitis C virus (HCV) vaccine development is defining conserved protective epitopes. A cluster of these epitopes comprises an immunodominant domain on the E2 glycoprotein, designated domain B. CBH-2 is a neutralizing human monoclonal antibody to a domain B epitope that is highly conserved. Alanine scanning demonstrated that the epitope involves residues G523, G530, and D535 that are also contact residues for E2 binding to CD81, a coreceptor required for virus entry into cells. However, another residue, located at position 431 and thus at a considerable distance in the linear sequence of E2, also contributes to the CBH-2 epitope. A single amino acid substitution at this residue results in escape from CBH-2-mediated neutralization in a genotype 1a virus. These results highlight the challenges inherent in developing HCV vaccines and show that an effective vaccine must induce antibodies to both conserved and more invariant epitopes to minimize virus escape.

scholarly journals Structure-Based Design of Hepatitis C Virus E2 Glycoprotein Improves Serum Binding and Cross-Neutralization

2020 ◽  
Vol 94 (22) ◽  
Author(s):  
Brian G. Pierce ◽  
Zhen-Yong Keck ◽  
Ruixue Wang ◽  
Patrick Lau ◽  
Kyle Garagusi ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Viral Escape ◽  
Envelope Glycoproteins ◽  
Effective Vaccine ◽  
Immunogenic Region ◽  
Antigenic Properties ◽  
Cross Neutralization

ABSTRACT An effective vaccine for hepatitis C virus (HCV) is a major unmet need, and it requires an antigen that elicits immune responses to key conserved epitopes. Based on structures of antibodies targeting HCV envelope glycoprotein E2, we designed immunogens to modulate the structure and dynamics of E2 and favor induction of broadly neutralizing antibodies (bNAbs) in the context of a vaccine. These designs include a point mutation in a key conserved antigenic site to stabilize its conformation, as well as redesigns of an immunogenic region to add a new N-glycosylation site and mask it from antibody binding. Designs were experimentally characterized for binding to a panel of human monoclonal antibodies (HMAbs) and the coreceptor CD81 to confirm preservation of epitope structure and preferred antigenicity profile. Selected E2 designs were tested for immunogenicity in mice, with and without hypervariable region 1, which is an immunogenic region associated with viral escape. One of these designs showed improvement in polyclonal immune serum binding to HCV pseudoparticles and neutralization of isolates associated with antibody resistance. These results indicate that antigen optimization through structure-based design of the envelope glycoproteins is a promising route to an effective vaccine for HCV. IMPORTANCE Hepatitis C virus infects approximately 1% of the world’s population, and no vaccine is currently available. Due to the high variability of HCV and its ability to actively escape the immune response, a goal of HCV vaccine design is to induce neutralizing antibodies that target conserved epitopes. Here, we performed structure-based design of several epitopes of the HCV E2 envelope glycoprotein to engineer its antigenic properties. Designs were tested in vitro and in vivo, demonstrating alteration of the E2 antigenic profile in several cases, and one design led to improvement of cross-neutralization of heterologous viruses. This represents a proof of concept that rational engineering of HCV envelope glycoproteins can be used to modulate E2 antigenicity and optimize a vaccine for this challenging viral target.

scholarly journals The core domain of hepatitis C virus glycoprotein E2 generates potent cross-neutralizing antibodies in guinea pigs

Hepatology ◽  
2017 ◽  
Vol 65 (4) ◽  
pp. 1117-1131 ◽  
Author(s):  
Patricia T. Vietheer ◽  
Irene Boo ◽  
Jun Gu ◽  
Kathleen McCaffrey ◽  
Stirling Edwards ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Guinea Pigs ◽  
Neutralizing Antibodies ◽  
Core Domain ◽  
Virus Glycoprotein ◽  
The Core ◽  
Glycoprotein E2

scholarly journals Genetic and structural insights into broad neutralization of hepatitis C virus by human VH1-69 antibodies

2019 ◽  
Vol 5 (1) ◽  
pp. eaav1882 ◽  
Author(s):  
Netanel Tzarum ◽  
Erick Giang ◽  
Leopold Kong ◽  
Linling He ◽  
Jannick Prentoe ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Gene Family ◽  
Neutralizing Antibodies ◽  
Germ Line ◽  
Affinity Maturation ◽  
Effective Vaccine ◽  
Immune Recognition ◽  
Sequencing Analysis ◽  
Cross Neutralization

An effective vaccine to the antigenically diverse hepatitis C virus (HCV) must target conserved immune epitopes. Here, we investigate cross-neutralization of HCV genotypes by broadly neutralizing antibodies (bNAbs) encoded by the relatively abundant human gene familyVH1-69. We have deciphered the molecular requirements for cross-neutralization by this unique class of human antibodies from crystal structures of HCV E2 in complex with bNAbs. An unusually high binding affinity is found for germ line–reverted versions of VH1-69 precursor antibodies, and neutralization breadth is acquired during affinity maturation. Deep sequencing analysis of an HCV-immune B cell repertoire further demonstrates the importance of theVH1-69gene family in the generation of HCV bNAbs. This study therefore provides critical insights into immune recognition of HCV with important implications for rational vaccine design.

scholarly journals Structural Flexibility of a Conserved Antigenic Region in Hepatitis C Virus Glycoprotein E2 Recognized by Broadly Neutralizing Antibodies

2014 ◽  
Vol 89 (4) ◽  
pp. 2170-2181 ◽  
Author(s):  
Annalisa Meola ◽  
Alexander W. Tarr ◽  
Patrick England ◽  
Luke W. Meredith ◽  
C. Patrick McClure ◽  
...  
Keyword(s):  
Amino Acids ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Neutralizing Antibodies ◽  
Antigenic Site ◽  
Conformational Flexibility ◽  
Structural Flexibility ◽  
Viral Spread ◽  
Antigenic Region ◽  
Glycoprotein E2

ABSTRACTNeutralizing antibodies (NAbs) targeting glycoprotein E2 are important for the control of hepatitis C virus (HCV) infection. One conserved antigenic site (amino acids 412 to 423) is disordered in the reported E2 structure, but a synthetic peptide mimicking this site forms a β-hairpin in complex with three independent NAbs. Our structure of the same peptide in complex with NAb 3/11 demonstrates a strikingly different extended conformation. We also show that residues 412 to 423 are essential for virus entry but not for E2 folding. Together with the neutralizing capacity of the 3/11 Fab fragment, this indicates an unexpected structural flexibility within this epitope. NAbs 3/11 and AP33 (recognizing the extended and β-hairpin conformations, respectively) display similar neutralizing activities despite converse binding kinetics. Our results suggest that HCV utilizes conformational flexibility as an immune evasion strategy, contributing to the limited immunogenicity of this epitope in patients, similar to the conformational flexibility described for other enveloped and nonenveloped viruses.IMPORTANCEApproximately 180 million people worldwide are infected with hepatitis C virus (HCV), and neutralizing antibodies play an important role in controlling the replication of this major human pathogen. We show here that one of the most conserved antigenic sites within the major glycoprotein E2 (amino acids 412 to 423), which is disordered in the recently reported crystal structure of an E2 core fragment, can adopt different conformations in the context of the infectious virus particle. Recombinant Fab fragments recognizing different conformations of this antigenic site have similar neutralization activities in spite of converse kinetic binding parameters. Of note, an antibody response targeting this antigenic region is less frequent than those targeting other more immunogenic regions in E2. Our results suggest that the observed conformational flexibility in this conserved antigenic region contributes to the evasion of the humoral host immune response, facilitating chronicity and the viral spread of HCV within an infected individual.

scholarly journals Structure-Based Design of Hepatitis C Virus Vaccines That Elicit Neutralizing Antibody Responses to a Conserved Epitope

2017 ◽  
Vol 91 (20) ◽  
Author(s):  
Brian G. Pierce ◽  
Elisabeth N. Boucher ◽  
Kurt H. Piepenbrink ◽  
Monir Ejemel ◽  
Chelsea A. Rapp ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Therapeutic Options ◽  
Effective Vaccine ◽  
Sequence Variability ◽  
Peptide Epitope ◽  
Conserved Epitope

ABSTRACT Despite recent advances in therapeutic options, hepatitis C virus (HCV) remains a severe global disease burden, and a vaccine can substantially reduce its incidence. Due to its extremely high sequence variability, HCV can readily escape the immune response; thus, an effective vaccine must target conserved, functionally important epitopes. Using the structure of a broadly neutralizing antibody in complex with a conserved linear epitope from the HCV E2 envelope glycoprotein (residues 412 to 423; epitope I), we performed structure-based design of immunogens to induce antibody responses to this epitope. This resulted in epitope-based immunogens based on a cyclic defensin protein, as well as a bivalent immunogen with two copies of the epitope on the E2 surface. We solved the X-ray structure of a cyclic immunogen in complex with the HCV1 antibody and confirmed preservation of the epitope conformation and the HCV1 interface. Mice vaccinated with our designed immunogens produced robust antibody responses to epitope I, and their serum could neutralize HCV. Notably, the cyclic designs induced greater epitope-specific responses and neutralization than the native peptide epitope. Beyond successfully designing several novel HCV immunogens, this study demonstrates the principle that neutralizing anti-HCV antibodies can be induced by epitope-based, engineered vaccines and provides the basis for further efforts in structure-based design of HCV vaccines. IMPORTANCE Hepatitis C virus is a leading cause of liver disease and liver cancer, with approximately 3% of the world's population infected. To combat this virus, an effective vaccine would have distinct advantages over current therapeutic options, yet experimental vaccines have not been successful to date, due in part to the virus's high sequence variability leading to immune escape. In this study, we rationally designed several vaccine immunogens based on the structure of a conserved epitope that is the target of broadly neutralizing antibodies. In vivo results in mice indicated that these antigens elicited epitope-specific neutralizing antibodies, with various degrees of potency and breadth. These promising results suggest that a rational design approach can be used to generate an effective vaccine for this virus.

scholarly journals Interplay between Basic Residues of Hepatitis C Virus Glycoprotein E2 with Viral Receptors, Neutralizing Antibodies and Lipoproteins

PLoS ONE ◽  
2012 ◽  
Vol 7 (12) ◽  
pp. e52651 ◽  
Author(s):  
George Koutsoudakis ◽  
Jakub Dragun ◽  
Sofia Pérez-del-Pulgar ◽  
Mairene Coto-Llerena ◽  
Laura Mensa ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Neutralizing Antibodies ◽  
Virus Glycoprotein ◽  
Glycoprotein E2 ◽  
Viral Receptors
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