scholarly journals HCV Glycoprotein Structure and Implications for B-Cell Vaccine Development

2020 ◽  
Vol 21 (18) ◽  
pp. 6781
Author(s):  
Luisa J. Ströh ◽  
Thomas Krey
Keyword(s):  
Binding Site ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Structural Features ◽  
Cell Vaccine ◽  
Receptor Binding Site ◽  
High Level ◽  
Direct Acting ◽  
Cd81 Binding

Despite the approval of highly efficient direct-acting antivirals in the last decade Hepatitis C virus (HCV) remains a global health burden and the development of a vaccine would constitute an important step towards the control of HCV. The high genetic variability of the viral glycoproteins E1 and E2, which carry the main neutralizing determinants, together with their intrinsic structural flexibility, the high level of glycosylation that shields conserved neutralization epitopes and immune evasion using decoy epitopes renders the design of an efficient vaccine challenging. Recent structural and functional analyses have highlighted the role of the CD81 receptor binding site on E2, which overlaps with those neutralization epitopes within E2 that have been structurally characterized to date. This CD81 binding site consists of three distinct segments including “epitope I”, “epitope II” and the “CD81 binding loop”. In this review we summarize the structural features of the HCV glycoproteins that have been derived from X-ray structures of neutralizing and non-neutralizing antibody fragments complexed with either recombinant E2 or epitope-derived linear peptides. We focus on the current understanding how neutralizing antibodies interact with their cognate antigen, the structural features of the respective neutralization epitopes targeted by nAbs and discuss the implications for informed vaccine design.

scholarly journals Structure-guided design of a synthetic mimic of an EPCR-binding PfEMP1 protein

2019 ◽  
Author(s):  
Natalie M. Barber ◽  
Clinton K. Y. Lau ◽  
Louise Turner ◽  
Gareth Watson ◽  
Susan Thrane ◽  
...  
Keyword(s):  
Binding Site ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Structural Features ◽  
Cross Reactivity ◽  
Endothelial Protein C Receptor ◽  
The Core ◽  
Immunogen Design ◽  
Structural Methods

AbstractStructure-guided vaccine design provides a route to elicit a focused immune response against the most functionally important regions of a pathogen surface. This can be achieved by identifying epitopes for neutralizing antibodies through structural methods and recapitulating these epitopes by grafting their core structural features onto smaller scaffolds. In this study, we have conducted a modified version of this protocol. We focused on the PfEMP1 protein family found on the surfaces of erythrocytes infected with Plasmodium falciparum. A subset of PfEMP1 proteins bind to endothelial protein C receptor (EPCR), and their expression correlates with development of the symptoms of severe malaria. Structural studies revealed the PfEMP1 to present a helix-kinked-helix motif which forms the core of the EPCR binding site. Using Rosetta-based design we successfully grafted this motif onto a three-helical bundle scaffold. We show that this synthetic binder interacts with EPCR with nanomolar affinity and adopts the expected structure. We also assessed its ability to bind to antibodies found in immunized animals and in humans from malaria endemic regions. Finally, we tested its capacity to effectively elicit antibodies that prevent EPCR binding and analysed the degree of cross-reactivity of these antibodies across a diverse repertoire of EPCR-binding PfEMP1. This provides a case study of immunogen design, assessing the effect of designing a focused immunogen that contains the core features of a ligand binding site, rather than those of a neutralizing antibody epitope.

scholarly journals Convergent structural features of respiratory syncytial virus neutralizing antibodies and plasticity of the site V epitope on prefusion F

2020 ◽  
Vol 16 (11) ◽  
pp. e1008943
Author(s):  
Wayne Harshbarger ◽  
Sai Tian ◽  
Newton Wahome ◽  
Ankita Balsaraf ◽  
Deep Bhattacharya ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Neutralizing Antibodies ◽  
Molecular Mechanisms ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Structural Features ◽  
Global Public Health ◽  
Public Health Burden ◽  
Functional Studies ◽  
Syncytial Virus

Respiratory syncytial virus (RSV) is a global public health burden for which no licensed vaccine exists. To aid vaccine development via increased understanding of the protective antibody response to RSV prefusion glycoprotein F (PreF), we performed structural and functional studies using the human neutralizing antibody (nAb) RSB1. The crystal structure of PreF complexed with RSB1 reveals a conformational, pre-fusion specific site V epitope with a unique cross-protomer binding mechanism. We identify shared structural features between nAbs RSB1 and CR9501, elucidating for the first time how diverse germlines obtained from different subjects can develop convergent molecular mechanisms for recognition of the same PreF site of vulnerability. Importantly, RSB1-like nAbs were induced upon immunization with PreF in naturally-primed cattle. Together, this work reveals new details underlying the immunogenicity of site V and further supports PreF-based vaccine development efforts.

scholarly journals A longitudinal study of SARS-CoV-2-infected patients reveals a high correlation between neutralizing antibodies and COVID-19 severity

2021 ◽  
Author(s):  
Vincent Legros ◽  
Solène Denolly ◽  
Manon Vogrig ◽  
Bertrand Boson ◽  
Eglantine Siret ◽  
...  
Keyword(s):  
Intensive Care ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Surface Protein ◽  
Humoral Response ◽  
Neutralizing Antibody ◽  
Rapid Decline ◽  
Serum Samples ◽  
Immune Correlates ◽  
Human Coronaviruses

AbstractUnderstanding the immune responses elicited by SARS-CoV-2 infection is critical in terms of protection against reinfection and, thus, for public health policy and vaccine development for COVID-19. In this study, using either live SARS-CoV-2 particles or retroviruses pseudotyped with the SARS-CoV-2 S viral surface protein (Spike), we studied the neutralizing antibody (nAb) response in serum samples from a cohort of 140 SARS-CoV-2 qPCR-confirmed infections, including patients with mild symptoms and also more severe forms, including those that required intensive care. We show that nAb titers correlated strongly with disease severity and with anti-spike IgG levels. Indeed, patients from intensive care units exhibited high nAb titers; conversely, patients with milder disease symptoms had heterogeneous nAb titers, and asymptomatic or exclusive outpatient-care patients had no or low nAbs. We found that nAb activity in SARS-CoV-2-infected patients displayed a relatively rapid decline after recovery compared to individuals infected with other coronaviruses. Moreover, we found an absence of cross-neutralization between endemic coronaviruses and SARS-CoV-2, indicating that previous infection by human coronaviruses may not generate protective nAbs against SARS-CoV-2. Finally, we found that the D614G mutation in the spike protein, which has recently been identified as the current major variant in Europe, does not allow neutralization escape. Altogether, our results contribute to our understanding of the immune correlates of SARS-CoV-2-induced disease, and rapid evaluation of the role of the humoral response in the pathogenesis of SARS-CoV-2 is warranted.

scholarly journals Antibody titers measured by commercial assays are correlated with neutralizing antibody titers calibrated by international standards

2021 ◽  
Author(s):  
Yu-An Kung ◽  
Chung-Guei Huang ◽  
Sheng-Yu Huang ◽  
Kuan-Ting Liu ◽  
Peng-Nien Huang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Geometric Mean ◽  
Neutralizing Antibody ◽  
Diagnostic Techniques ◽  
International Standards ◽  
World Health ◽  
Serum Samples ◽  
Antibody Titers ◽  
Health Organization

The World Health Organization (WHO) has highlighted the importance of an international standard (IS) for SARS-CoV-2 neutralizing antibody titer detection, with the aim of calibrating different diagnostic techniques. In this study, IS was applied to calibrate neutralizing antibody titers (IU/mL) and binding antibody titers (BAU/mL) in response to SARS-CoV-2 vaccines. Serum samples were collected from participants receiving the Moderna (n = 20) and Pfizer (n = 20) vaccines at three time points: pre-vaccination, after one dose, and after two doses. We obtained geometric mean titers of 1404.16 and 928.75 IU/mL for neutralizing antibodies after two doses of the Moderna and Pfizer vaccines, respectively. These values provide an important baseline for vaccine development and the implementation of non-inferiority trials. We also compared three commercially available kits from Roche, Abbott, and MeDiPro for the detection of COVID-19 antibodies based on binding affinity to S1 and/or RBD. Our results demonstrated that antibody titers measured by commercial assays are highly correlated with neutralizing antibody titers calibrated by IS.

scholarly journals Safety and Immunogenicity Evaluation of Inactivated whole-virus-SARS-COV-2 As Emerging Vaccine Development In Egypt

2021 ◽  
Author(s):  
Amani A. Saleh ◽  
Mohamed A. Saad ◽  
Islam Ryan ◽  
Magdy Amin ◽  
Mohamed I. Shindy ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Clinical Symptoms ◽  
Neutralizing Antibody ◽  
Positive Development ◽  
Virus Challenge ◽  
Cell Monolayers ◽  
Transmission Electron ◽  
Dose Concentration ◽  
Antibody Titers

AbstractThe current worldwide pandemic COVID-19 is causing severe human health problems, with high numbers of mortality rates and huge economic burdens that require an urgent demand for safe, and effective and vaccine development. Our study was the first trail to development and evaluation of safety and immune response to inactivated whole SARS-COV-2 virus vaccine adjuvanted with aluminium hydroxide. We used characterized SARS-COV-2 strain, severe acute respiratory syndrome coronavirus 2 isolates (SARS-CoV-2/human/EGY/Egy-SERVAC/2020) with accession numbers; MT981440; MT981439; MT981441; MT974071; MT974069 and MW250352 at GenBank that isolated from Egyptian patients SARS-CoV-2-positive. Development of the vaccine was carried out in a BSL - 3 facilities and the immunogenicity was determined in mice at two doses (55µg and 100µg per dose). All vaccinated mice were received a booster dose 14 days post first immunization. Our results demonstrated distinct cytopathic effect on the vero cell monolayers induced through SARS-COV-2 propagation and the viral particles were identified as Coronaviridae by transmission electron microscopy. SARS-CoV-2 was identified by RT-PCR performed on the cell culture. Immunogenicity of the developed vaccine indicated the high antigen-binding and neutralizing antibody titers, regardless the dose concentration, with excellent safety profiles.However, no deaths or clinical symptoms in mice groups. The efficacy of the inactivated vaccine formulation was tested by wild virus challenge the vaccinated mice and detection of viral replication in lung tissues. Vaccinated mice recorded complete protection from challenge infection three weeks post second dose. SARS-COV-2 replication was not observed in the lungs of mice following SARS-CoV-2 challenge, regardless of the level of serum neutralizing antibodies. This finding will support the future trials for evaluation an applicable SARS-CoV-2 vaccine candidate.

Prevalence and Persistence of Maternal Dengue Neutralizing Antibodies in Infants From Central and Southern Thailand: A Retrospective Cohort Study

2019 ◽  
Vol 31 (4) ◽  
pp. 288-295 ◽  
Author(s):  
Adrienne Guignard ◽  
François Haguinet ◽  
Stéphanie Wéry ◽  
Phirangkul Kerdpanich
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Geometric Mean ◽  
Neutralizing Antibody ◽  
Maternal Antibodies ◽  
Childhood Immunization ◽  
Serum Samples ◽  
Denv Serotypes ◽  
Antibody Titers ◽  
Antibody Kinetics

Understanding maternal dengue virus (DENV) neutralizing antibody kinetics in infants remains timely to develop a safe and effective childhood immunization. This retrospective study evaluated the prevalence and persistence of maternal antibody titers against DENV serotypes 1 to 4 in 139 Thai infants at 2, 6, and 7 months of age, using serum samples collected in a vaccination trial ( http://clinicaltrials.gov ; NCT00197275). Neutralizing antibodies against all 4 DENV serotypes were detected in 87.8% and 22.9% of infants at 2 and 7 months, respectively. At 2 months, DENV-4 neutralizing antibody geometric mean titers were notably lower (80) compared with DENV-1 to DENV-3 (277-471). Our results corroborate previous findings that DENV-1 to DENV-4 maternal antibodies persist at 7 months despite titers decrease from 2 months onwards. As persisting maternal antibodies may inhibit immune responses in DENV-vaccinated infants, a comprehensive understanding of DENV antibody kinetics is required in the perspective of vaccine development for infants.

scholarly journals Broad Neutralization of Viral Pathogens

2014 ◽  
Vol 70 (a1) ◽  
pp. C245-C245
Author(s):  
Ian Wilson
Keyword(s):  
Hepatitis C ◽  
Binding Site ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Functional Characterization ◽  
Antigenic Site ◽  
Soluble Form ◽  
Receptor Binding Site ◽  
Fusion Domain ◽  
Hiv 1

Influenza, Hepatitis C, and HIV-1 continue to constitute significant threats to global health. We have structurally and functionally characterized several potent, broadly neutralizing antibodies (bnAbs) against HIV-1, influenza and hepatitis C viruses. The surface antigens of these viruses are the main target of neutralizing antibodies. However, most antibodies are strain-specific and protect only against highly related strains within the same subtype. Recently, a number of antibodies have been identified that are much broader and neutralize across multiple subtypes and types of these viruses through binding to functionally conserved sites, such as the receptor binding site or the fusion domain. For example, co-crystal structures of bnAbs with influenza hemagglutinin (HA) identified highly conserved sites in the fusion domain (stem) and in the receptor binding site (head) as target for broad neutralization[1]. HCV is also genetically diverse, but some antibodies have potent neutralizing activity across most genotypes of the virus. One family of these antibodies targets a conserved antigenic site on the HCV E2 envelope glycoprotein that overlaps with the CD81 receptor-binding site[2]. For HIV-1, structural and functional characterization of different families of bnAbs have led to identification of novel epitopes on HIV-1 Env, many of which involve glycans. These glycan-dependent Abs have unique features that enable them to penetrate the glycan shield and bind complex epitopes that consist of sugars and underlying protein segments on gp120 on HIV-1 Env. Recent x-ray[3] and EM structures of a soluble form of HIV-1 Env have revealed that the epitopes are more extensive and complex than previously appreciated. This structural information is now being used to aid in structure-assisted vaccine design for HIV-1, HCV and for a more universal flu vaccine. IAW is supported by NIH grants AI100663, AI082362, AI84817, AI099275 and GM094586 and the Crucell Vaccine Institute.

scholarly journals Structural flexibility at a major conserved antibody target on hepatitis C virus E2 antigen

2016 ◽  
Vol 113 (45) ◽  
pp. 12768-12773 ◽  
Author(s):  
Leopold Kong ◽  
David E. Lee ◽  
Rameshwar U. Kadam ◽  
Tong Liu ◽  
Erick Giang ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Vaccine Design ◽  
Neutralizing Antibody ◽  
Md Simulations ◽  
Receptor Binding Site ◽  
Structural Investigations ◽  
Thermophilic Organisms

Hepatitis C virus (HCV) is a major cause of liver disease, affecting over 2% of the world’s population. The HCV envelope glycoproteins E1 and E2 mediate viral entry, with E2 being the main target of neutralizing antibody responses. Structural investigations of E2 have produced templates for vaccine design, including the conserved CD81 receptor-binding site (CD81bs) that is a key target of broadly neutralizing antibodies (bNAbs). Unfortunately, immunization with recombinant E2 and E1E2 rarely elicits sufficient levels of bNAbs for protection. To understand the challenges for eliciting bNAb responses against the CD81bs, we investigated the E2 CD81bs by electron microscopy (EM), hydrogen–deuterium exchange (HDX), molecular dynamics (MD), and calorimetry. By EM, we observed that HCV1, a bNAb recognizing the N-terminal region of the CD81bs, bound a soluble E2 core construct from multiple angles of approach, suggesting components of the CD81bs are flexible. HDX of multiple E2 constructs consistently indicated the entire CD81bs was flexible relative to the rest of the E2 protein, which was further confirmed by MD simulations. However, E2 has a high melting temperature of 84.8 °C, which is more akin to proteins from thermophilic organisms. Thus, recombinant E2 is a highly stable protein overall, but with an exceptionally flexible CD81bs. Such flexibility may promote induction of nonneutralizing antibodies over bNAbs to E2 CD81bs, underscoring the necessity of rigidifying this antigenic region as a target for rational vaccine design.

scholarly journals Comparative Immunogenicity of Subtype A Human Immunodeficiency Virus Type 1 Envelope Exhibiting Differential Exposure of Conserved Neutralization Epitopes

2009 ◽  
Vol 84 (5) ◽  
pp. 2573-2584 ◽  
Author(s):  
Catherine A. Blish ◽  
D. Noah Sather ◽  
George Sellhorn ◽  
Leonidas Stamatatos ◽  
Yide Sun ◽  
...  
Keyword(s):  
Antibody Response ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Immunodeficiency Virus ◽  
Cd4 Binding Site ◽  
Variable Loops ◽  
Linear Epitopes ◽  
Subtype A ◽  
Hiv 1

ABSTRACT Development of broadly cross-reactive neutralizing antibodies (NAbs) remains a major goal of HIV-1 vaccine development, but most candidate envelope immunogens have had limited ability to cross-neutralize heterologous strains. To evaluate the immunogenicity of subtype A variants of HIV-1, rabbits were immunized with pairs of closely related subtype A envelopes from the same individual. In each immunogen pair, one variant was readily neutralized by a variety of monoclonal antibodies and plasma antibodies, while the other was neutralization resistant, suggesting differences in the exposures of key epitopes. The breadth of the antibody response was evaluated against subtype A, B, C, and D variants of HIV-1. The specificity of the immunogen-derived neutralizing antibody response was also compared to that of the infected individuals from whom these variants were cloned. None of the immunogens produced broad neutralizing antibodies in immunized animals, and most of the neutralizing antibodies were directed to the variable loops, particularly the V3 loop. No detectable antibodies to either of the potentially exposed conserved epitopes, the membrane proximal external region, or the CD4 binding site were found with immunized rabbits. In contrast, relatively little of the neutralizing activity within the plasma samples of the infected individuals was directed to linear epitopes within the variable loops. These data indicate that immunogens designed to expose conserved regions did not enhance generation of broadly neutralizing antibodies in comparison with the immunogens that failed to expose those regions using this immunization approach.

scholarly journals A Rapid Bead-Based Assay For Screening Of SARS-CoV-2 Neutralising Antibodies

2021 ◽  
Author(s):  
Santhik SL ◽  
Pramod Darvin ◽  
Aneesh Chandrasekharan ◽  
Shanakara Narayanan Varadarajan ◽  
Soumya Jaya Divakaran ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Fluorescent Protein ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Life Time ◽  
Cost Effective ◽  
Fluorescent Imaging ◽  
Antibody Detection ◽  
Screening Assay ◽  
Live Virus

Quantitative determination of neutralizing antibodies against SARS CoV2 is of paramount importance in immunodiagnostics, vaccine efficacy testing, and immune response profiling among the vaccinated population. Cost effective, rapid, easy-to-perform assays are essential to support the vaccine development process and immunosurveillance studies. Here, we describe a bead based screening assay for S1 neutralization using recombinant fluorescent proteins of hACE2 and SARS CoV2 S1, immobilized on solid beads employing nanobodies /metal-affinity tags. Nanobody-mediated capture of SARS CoV2 Spike (S1) on agarose beads served as the trap for soluble recombinant ACE2-GFPSpark, inhibited by neutralizing antibody. The first approach demonstrates single color fluorescent imaging of ACE2 GFPspark binding to His tagged S1 Receptor Binding Domain (RBD His) immobilized beads. The second approach is dual color imaging of soluble ACE2 GFPSpark to S1 Orange Fluorescent Protein (S1 OFPSpark) beads. Both methods showed a good correlation with the gold standard pseudovirion assay and can be adapted to any fluorescent platforms for screening. Life time imaging of the ACE2 GFPSpark confirmed the interaction of ACE2 and S1 OFPSpark on beads. The self-renewable source of secreted recombinant proteins from stable cells and its direct use without necessitating purification renders the platform a cost-effective and rapid one than the popular pseudovirion assay and live virus-based assays. Any laboratory with minimum expertise can rapidly perform this bead assay for neutralizing antibody detection using stable engineered cells.

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