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Jiao C, Wang B, Chen P, Jiang Y, Liu J. Analysis of the conserved protective epitopes of hemagglutinin on influenza A viruses. Front Immunol 2023; 14:1086297. [PMID: 36875062 PMCID: PMC9981632 DOI: 10.3389/fimmu.2023.1086297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 02/07/2023] [Indexed: 02/19/2023] Open
Abstract
The conserved protective epitopes of hemagglutinin (HA) are essential to the design of a universal influenza vaccine and new targeted therapeutic agents. Over the last 15 years, numerous broadly neutralizing antibodies (bnAbs) targeting the HA of influenza A viruses have been isolated from B lymphocytes of human donors and mouse models, and their binding epitopes identified. This work has brought new perspectives for identifying conserved protective epitopes of HA. In this review, we succinctly analyzed and summarized the antigenic epitopes and functions of more than 70 kinds of bnAb. The highly conserved protective epitopes are concentrated on five regions of HA: the hydrophobic groove, the receptor-binding site, the occluded epitope region of the HA monomers interface, the fusion peptide region, and the vestigial esterase subdomain. Our analysis clarifies the distribution of the conserved protective epitope regions on HA and provides distinct targets for the design of novel vaccines and therapeutics to combat influenza A virus infection.
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Affiliation(s)
- Chenchen Jiao
- State Key Laboratory of Veterinary Biotechnology, National Poultry Laboratory Animal Resource Center, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Bo Wang
- State Key Laboratory of Veterinary Biotechnology, National Poultry Laboratory Animal Resource Center, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Pucheng Chen
- State Key Laboratory of Veterinary Biotechnology, National Poultry Laboratory Animal Resource Center, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yongping Jiang
- State Key Laboratory of Veterinary Biotechnology, National Poultry Laboratory Animal Resource Center, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Jinxiong Liu
- State Key Laboratory of Veterinary Biotechnology, National Poultry Laboratory Animal Resource Center, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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Abstract
The HA protein of influenza A viruses is the major viral antigen. In this study, we simultaneously introduced mutations at 17 amino acid positions of an H5 HA expected to affect antigenicity. Viruses with ≥13 amino acid changes in HA were viable, and some had altered antigenic properties. H5 HA can therefore accommodate many mutations in regions that affect antigenicity. The substantial plasticity of H5 HA may facilitate the emergence of novel antigenic variants. Since the emergence of highly pathogenic avian influenza viruses of the H5 subtype, the major viral antigen, hemagglutinin (HA), has undergone constant evolution, resulting in numerous genetic and antigenic (sub)clades. To explore the consequences of amino acid changes at sites that may affect the antigenicity of H5 viruses, we simultaneously mutated 17 amino acid positions of an H5 HA by using a synthetic gene library that, theoretically, encodes all combinations of the 20 amino acids at the 17 positions. All 251 mutant viruses sequenced possessed ≥13 amino acid substitutions in HA, demonstrating that the targeted sites can accommodate a substantial number of mutations. Selection with ferret sera raised against H5 viruses of different clades resulted in the isolation of 39 genotypes. Further analysis of seven variants demonstrated that they were antigenically different from the parental virus and replicated efficiently in mammalian cells. Our data demonstrate the substantial plasticity of the influenza virus H5 HA protein, which may lead to novel antigenic variants.
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Structural Biology of Influenza Hemagglutinin: An Amaranthine Adventure. Viruses 2020; 12:v12091053. [PMID: 32971825 PMCID: PMC7551194 DOI: 10.3390/v12091053] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 12/27/2022] Open
Abstract
Hemagglutinin (HA) glycoprotein is an important focus of influenza research due to its role in antigenic drift and shift, as well as its receptor binding and membrane fusion functions, which are indispensable for viral entry. Over the past four decades, X-ray crystallography has greatly facilitated our understanding of HA receptor binding, membrane fusion, and antigenicity. The recent advances in cryo-EM have further deepened our comprehension of HA biology. Since influenza HA constantly evolves in natural circulating strains, there are always new questions to be answered. The incessant accumulation of knowledge on the structural biology of HA over several decades has also facilitated the design and development of novel therapeutics and vaccines. This review describes the current status of the field of HA structural biology, how we got here, and what the next steps might be.
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Wu NC, Wilson IA. Influenza Hemagglutinin Structures and Antibody Recognition. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a038778. [PMID: 31871236 DOI: 10.1101/cshperspect.a038778] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hemagglutinin (HA) is most abundant glycoprotein on the influenza virus surface. Influenza HA promotes viral entry by engaging the receptor and mediating virus-host membrane fusion. At the same time, HA is the major antigen of the influenza virus. HA antigenic shift can result in pandemics, whereas antigenic drift allows human circulating strains to escape herd immunity. Most antibody responses against HA are strain-specific. However, antibodies that have neutralizing activities against multiple strains or even subtypes have now been discovered and characterized. These broadly neutralizing antibodies (bnAbs) target conserved regions on HA, such as the receptor-binding site and the stem domain. Structural studies of such bnAbs have provided important insight into universal influenza vaccine and therapeutic design. This review discusses the HA functions as well as HA-antibody interactions from a structural perspective.
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Affiliation(s)
- Nicholas C Wu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Ian A Wilson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037, USA.,The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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5
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Ross TM, DiNapoli J, Giel-Moloney M, Bloom CE, Bertran K, Balzli C, Strugnell T, Sá E Silva M, Mebatsion T, Bublot M, Swayne DE, Kleanthous H. A computationally designed H5 antigen shows immunological breadth of coverage and protects against drifting avian strains. Vaccine 2019; 37:2369-2376. [PMID: 30905528 DOI: 10.1016/j.vaccine.2019.03.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 03/05/2019] [Accepted: 03/11/2019] [Indexed: 02/07/2023]
Abstract
Since the first identification of the H5N1 Goose/Guangdong lineage in 1996, this highly pathogenic avian influenza virus has spread worldwide, becoming endemic in domestic poultry. Sporadic transmission to humans has raised concerns of a potential pandemic and underscores the need for a broad cross-protective influenza vaccine. Here, we tested our previously described methodology, termed Computationally Optimized Broadly Reactive Antigen (COBRA), to generate a novel hemagglutinin (HA) gene, termed COBRA-2, that was based on H5 HA sequences from 2005 to 2006. The COBRA-2 HA virus-like particle (VLP) vaccines were used to vaccinate chickens and the immune responses were compared to responses elicited by VLP's expressing HA from A/whooper swan/Mongolia/244/2005 (WS/05), a representative 2005 vaccine virus from clade 2.2. To support this evaluation a hemagglutination inhibition (HAI) breadth panel was developed consisting of phylogenetically and antigenically diverse H5 strains in circulation from 2005 to 2006, as well as recent drift variants (2008 - 2014). We found that the COBRA-2 VLP vaccines elicited robust HAI titers against this entire breadth panel, whereas the VLP vaccine based upon the recommended WS/05 HA only elicited HAI responses against a subset of strains. Furthermore, while all vaccines protected chickens against challenge with the WS/05 virus, only the human COBRA-2 VLP vaccinated birds were protected (80%) against a recent drifted clade 2.3.2.1B, A/duck/Vietnam/NCVD-672/2011 (VN/11) virus. This is the first report to demonstrate seroprotective antibody responses against genetically diverse clades and sub-clades of H5 viruses and protective efficacy against a recent drifted variant using a globular head based design strategy.
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Affiliation(s)
- Ted M Ross
- University of Georgia, Center for Vaccines and Immunology, Department of Infectious Diseases, Athens, GA 30602, USA
| | | | | | - Chalise E Bloom
- University of Georgia, Center for Vaccines and Immunology, Department of Infectious Diseases, Athens, GA 30602, USA
| | - Kateri Bertran
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, U.S. National Poultry Research Center, Agricultural Research Service, U.S. Department of Agriculture, Athens, GA 30602, USA
| | - Charles Balzli
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, U.S. National Poultry Research Center, Agricultural Research Service, U.S. Department of Agriculture, Athens, GA 30602, USA
| | - Tod Strugnell
- Sanofi-Pasteur, 38 Sidney Street, Cambridge, MA 02139, USA
| | | | | | - Michel Bublot
- Boehringer lngelheim, S.A.S., R&D, 69007 Lyon, France
| | - David E Swayne
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, U.S. National Poultry Research Center, Agricultural Research Service, U.S. Department of Agriculture, Athens, GA 30602, USA
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Steensels M, Rauw F, van den Berg T, Marché S, Gardin Y, Palya V, Lambrecht B. Protection Afforded by a Recombinant Turkey Herpesvirus-H5 Vaccine Against the 2014 European Highly Pathogenic H5N8 Avian Influenza Strain. Avian Dis 2017; 60:202-9. [PMID: 27309056 DOI: 10.1637/11126-050615-reg.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A highly pathogenic avian influenza (HPAI) H5N8 (clade 2.3.4.4) virus, circulating in Asia (South Korea, Japan, and southern China) since the beginning of 2014, reached the European continent in November 2014. Germany, the Netherlands, the United Kingdom, Italy, and Hungary confirmed H5N8 infection of poultry farms of different species and of several wild bird species. Unlike the Asian highly pathogenic (HP) H5N1, this HP H5N8 also went transatlantic and reached the American West Coast by the end of 2014, affecting wild birds as well as backyard and commercial poultry. This strain induces high mortality and morbidity in Galliformes, whereas wild birds seem only moderately affected. A recombinant turkey herpesvirus (rHVT) vector vaccine expressing the H5 gene of a clade 2.2 H5N1 strain (rHVT-H5) previously demonstrated a highly efficient clinical protection and reduced viral excretion against challenge with Asian HP H5N1 strains of various clades (2.2, 2.2.1, 2.2.1.1, 2.1.3, 2.1.3.2, and 2.3.2.1) and was made commercially available in various countries where the disease is endemic. To evaluate the protective efficacy of the rHVT-H5 vaccine against the first German H5N8 turkey isolate (H5N8 GE), a challenge experiment was set up in specific-pathogen-free (SPF) chickens, and the clinical and excretional protection was evaluated. SPF chickens were vaccinated subcutaneously at 1 day old and challenged oculonasally at 4 wk of age with two viral dosages, 10(5) and 10(6) 50% egg infective doses. Morbidity and mortality were monitored daily in unvaccinated and vaccinated groups, whereas viral shedding by oropharyngeal and cloacal routes was evaluated at 2, 5, 9, and 14 days postinoculation (dpi). Serologic monitoring after vaccination and challenge was also carried out. Despite its high antigenic divergence of the challenge H5N8 strain, a single rHVT-H5 vaccine administration at 1 day old resulted in a full clinical protection against challenge and a significant reduction of viral shedding in the vaccinated birds.
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Affiliation(s)
- M Steensels
- A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium
| | - F Rauw
- A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium
| | - Th van den Berg
- A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium
| | - S Marché
- A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium
| | - Y Gardin
- B Ceva Animal Health, Libourne, France
| | - V Palya
- C Ceva Animal Health, Budapest, Hungary
| | - B Lambrecht
- A Avian Virology & Immunology Service, Veterinary and Agrochemical Research Centre (CODA-CERVA), Groeselenberg, 99 B-1180 Brussels, Belgium
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7
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Visualization of Alternative Functional Configurations of Influenza Virus Hemagglutinin Facilitates Rapid Selection of Complementing Vaccines in Emergency Situations. Int J Mol Sci 2017; 18:ijms18040766. [PMID: 28375167 PMCID: PMC5412350 DOI: 10.3390/ijms18040766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/29/2017] [Accepted: 03/31/2017] [Indexed: 11/17/2022] Open
Abstract
Successful immunization against avian influenza virus (AIV) requires eliciting an adequate polyclonal response to AIV hemagglutinin (HA) subunit 1 (HA1) epitopes. Outbreaks of highly-pathogenic (HP) AIV subtype H5N1 can occur in vaccinated flocks in many endemic areas. Protection against emerging AIV is partly hindered by the limitations of vaccine production and transport, the use of leaky vaccines, and the use of multiple, and often antigenically-diverse, vaccines. It was hypothesized that the majority of alternative functional configurations (AFC) within the AIV HA1 can be represented by the pool of vaccine seed viruses currently in production because only a finite number of AFC are possible within each substructure of the molecule. Therefore, combinations of commercial vaccines containing complementing structural units (CSU) to each HA1 substructure can elicit responses to the totality of a given emerging AIV HA1 substructure isoforms. Analysis of homology-based 3D models of vaccine seed and emerging viruses facilitated the definition of HA1 AFC isoforms. CSU-based plots were used to predict which commercial vaccine combinations could have been used to cover nine selected AFC isoforms on recent Egyptian HP AIV H5N1 outbreak viruses. It is projected that expansion of the vaccine HA1 3D model database will improve international emergency responses to AIV.
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8
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Chai N, Swem LR, Park S, Nakamura G, Chiang N, Estevez A, Fong R, Kamen L, Kho E, Reichelt M, Lin Z, Chiu H, Skippington E, Modrusan Z, Stinson J, Xu M, Lupardus P, Ciferri C, Tan MW. A broadly protective therapeutic antibody against influenza B virus with two mechanisms of action. Nat Commun 2017; 8:14234. [PMID: 28102191 PMCID: PMC5253702 DOI: 10.1038/ncomms14234] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 12/12/2016] [Indexed: 01/12/2023] Open
Abstract
Influenza B virus (IBV) causes annual influenza epidemics around the world. Here we use an in vivo plasmablast enrichment technique to isolate a human monoclonal antibody, 46B8 that neutralizes all IBVs tested in vitro and protects mice against lethal challenge of all IBVs tested when administered 72 h post infection. 46B8 demonstrates a superior therapeutic benefit over Tamiflu and has an additive antiviral effect in combination with Tamiflu. 46B8 binds to a conserved epitope in the vestigial esterase domain of hemagglutinin (HA) and blocks HA-mediated membrane fusion. After passage of the B/Brisbane/60/2008 virus in the presence of 46B8, we isolated three resistant clones, all harbouring the same mutation (Ser301Phe) in HA that abolishes 46B8 binding to HA at low pH. Interestingly, 46B8 is still able to protect mice against lethal challenge of the mutant viruses, possibly owing to its ability to mediate antibody-dependent cellular cytotoxicity (ADCC). Influenza B virus (IBV) co-circulates with influenza A virus to cause annual epidemics. Here, Chai et al. isolate a human monoclonal antibody that binds to a conserved epitope in the viral HA protein, neutralizes IBV strains in vitro, and protects mice against IBV infection.
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Affiliation(s)
- Ning Chai
- Department of Infectious Diseases, Genentech, South San Francisco, California 94080, USA
| | - Lee R Swem
- Department of Infectious Diseases, Genentech, South San Francisco, California 94080, USA
| | - Summer Park
- Department of Translational Immunology, Genentech, South San Francisco, California 94080, USA
| | - Gerald Nakamura
- Department of Antibody Engineering, Genentech, South San Francisco, California 94080, USA
| | - Nancy Chiang
- Department of Antibody Engineering, Genentech, South San Francisco, California 94080, USA
| | - Alberto Estevez
- Department of Structural Biology, Genentech, South San Francisco, California 94080, USA
| | - Rina Fong
- Department of Structural Biology, Genentech, South San Francisco, California 94080, USA
| | - Lynn Kamen
- Department of BioAnalytical Sciences, Genentech, South San Francisco, California 94080, USA
| | - Elviza Kho
- Department of BioAnalytical Sciences, Genentech, South San Francisco, California 94080, USA
| | - Mike Reichelt
- Department of Pathology, Genentech, South San Francisco, California 94080, USA
| | - Zhonghua Lin
- Department of Translational Immunology, Genentech, South San Francisco, California 94080, USA
| | - Henry Chiu
- Department of Biochemical and Cellular Pharmacology, Genentech, South San Francisco, California 94080, USA
| | - Elizabeth Skippington
- Department of Bioinformatics and Computational Biology, Genentech, South San Francisco, California 94080, USA
| | - Zora Modrusan
- Department of Molecular Biology, Genentech, South San Francisco, California 94080, USA
| | - Jeremy Stinson
- Department of Molecular Biology, Genentech, South San Francisco, California 94080, USA
| | - Min Xu
- Department of Translational Immunology, Genentech, South San Francisco, California 94080, USA
| | - Patrick Lupardus
- Department of Structural Biology, Genentech, South San Francisco, California 94080, USA
| | - Claudio Ciferri
- Department of Structural Biology, Genentech, South San Francisco, California 94080, USA
| | - Man-Wah Tan
- Department of Infectious Diseases, Genentech, South San Francisco, California 94080, USA
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Gaiotto T, Hufton SE. Cross-Neutralising Nanobodies Bind to a Conserved Pocket in the Hemagglutinin Stem Region Identified Using Yeast Display and Deep Mutational Scanning. PLoS One 2016; 11:e0164296. [PMID: 27741319 PMCID: PMC5065140 DOI: 10.1371/journal.pone.0164296] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 09/22/2016] [Indexed: 12/20/2022] Open
Abstract
Cross-neutralising monoclonal antibodies against influenza hemagglutinin (HA) are of considerable interest as both therapeutics and diagnostic tools. We have recently described five different single domain antibodies (nanobodies) which share this cross-neutralising activity and suggest their small size, high stability, and cleft binding properties may present distinct advantages over equivalent conventional antibodies. We have used yeast display in combination with deep mutational scanning to give residue level resolution of positions in the antibody-HA interface which are crucial for binding. In addition, we have mapped positions within HA predicted to have minimal effect on antibody binding when mutated. Our cross-neutralising nanobodies were shown to bind to a highly conserved pocket in the HA2 domain of A(H1N1)pdm09 influenza virus overlapping with the fusion peptide suggesting their mechanism of action is through the inhibition of viral membrane fusion. We also note that the epitope overlaps with that of CR6261 and F10 which are human monoclonal antibodies in clinical development as immunotherapeutics. Although all five nanobodies mapped to the same highly conserved binding pocket we observed differences in the size of the epitope footprint which has implications in comparing the relative genetic barrier each nanobody presents to a rapidly evolving influenza virus. To further refine our epitope map, we have re-created naturally occurring mutations within this HA stem epitope and tested their effect on binding using yeast display. We have shown that a D46N mutation in the HA2 stem domain uniquely interferes with binding of R2b-E8. Further testing of this substitution in the context of full length purified HA from 1918 H1N1 pandemic (Spanish flu), 2009 H1N1 pandemic (swine flu) and highly pathogenic avian influenza H5N1 demonstrated binding which correlated with D46 whereas binding to seasonal H1N1 strains carrying N46 was absent. In addition, our deep sequence analysis predicted that binding to the emerging H1N1 strain (A/Christchurch/16/2010) carrying the HA2-E47K mutation would not affect binding was confirmed experimentally. This demonstrates yeast display, in combination with deep sequencing, may be able to predict antibody reactivity to emerging influenza strains so assisting in the preparation for future influenza pandemics.
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Affiliation(s)
- Tiziano Gaiotto
- Biotherapeutics Group, National Institute for Biological Standards and Control, a centre of the Medicines and Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Herts, EN6 3QG, United Kingdom
| | - Simon E. Hufton
- Biotherapeutics Group, National Institute for Biological Standards and Control, a centre of the Medicines and Healthcare Products Regulatory Agency, Blanche Lane, South Mimms, Potters Bar, Herts, EN6 3QG, United Kingdom
- * E-mail:
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10
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Ren H, Zhou P. Epitope-focused vaccine design against influenza A and B viruses. Curr Opin Immunol 2016; 42:83-90. [PMID: 27343703 DOI: 10.1016/j.coi.2016.06.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 06/07/2016] [Indexed: 01/19/2023]
Abstract
The threat of influenza A and B variants via antigenic drift and emerging novel influenza A and B strains in the human population via antigenic shift has spurred research efforts to improve upon current seasonal influenza vaccines. In recent years, a wave of novel technological breakthroughs has lead to the identification of many broadly anti-influenza hemagglutinin (HA) monoclonal antibodies (mAbs) and the elucidation of the conserved epitopes recognized by these mAbs in both the head and the stem of HA as well as the mechanisms of inhibition. These discoveries along with an improved understanding of how the immune system responds to influenza infection and vaccination has spurred great efforts on stem-based cross-subtype ('universal') vaccine design as well as RBS-based HA subtype-specific vaccine design.
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Affiliation(s)
- Huanhuan Ren
- Unit of Anti-Viral Immunity and Genetic Therapy, Institut Pasteur of Shanghai, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Paul Zhou
- Unit of Anti-Viral Immunity and Genetic Therapy, Institut Pasteur of Shanghai, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
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11
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Wang G, Shi B, Li T, Zuo T, Wang B, Si W, Xin J, Yang K, Shi X, Liu S, Liu H. Linear antigenic mapping of flagellin (FliC) from Salmonella enterica serovar Enteritidis with yeast surface expression system. Vet Microbiol 2016; 184:20-6. [PMID: 26854340 DOI: 10.1016/j.vetmic.2016.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/01/2015] [Accepted: 01/01/2016] [Indexed: 12/21/2022]
Abstract
Salmonella enterica serovar Enteritidis (S. Enteritidis) is a major cause of food-borne illness around the world and can have significant health implications in humans, poultry and other animals. Flagellin (FliC) is the primary component of bacterial flagella. It has been shown that the FliC of S. Enteritidis is a significant antigenic structure and can elicit strong humoral responses against S. Enteritidis infection in chickens. Here, we constructed a FliC antigen library using a yeast surface expression system. Yeast cells expressing FliC peptide antigens were labeled with chicken sera against S. Enteritidis and sorted using FACS. The analyses of FliC peptides revealed that the FliC linear antigenicity in chickens resided on three domains which were able to elicit strong humoral responses in vivo. Animal experiments further revealed that the antibodies elicited by these antigenic domains were able to significantly inhibit the invasion of S. Enteritidis into the liver and spleen of chickens. These findings will facilitate our better understanding of the humoral responses elicited by FliC in chickens upon infection by S. Enteritidis.
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Affiliation(s)
- Gaoling Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Bingtian Shi
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Tao Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China; College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Teng Zuo
- Comprehensive AIDS Research Center, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Bin Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China; College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Wei Si
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Jiuqing Xin
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Kongbin Yang
- Neurosurgery Department of the First Affiliated Hospital, Harbin Medical University, China
| | - Xuanlin Shi
- Comprehensive AIDS Research Center, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China.
| | - Henggui Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China.
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12
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Comprehensive Analysis and Characterization of Linear Antigenic Domains on HN Protein from Genotype VII Newcastle Disease Virus Using Yeast Surface Display System. PLoS One 2015; 10:e0131723. [PMID: 26121247 PMCID: PMC4488241 DOI: 10.1371/journal.pone.0131723] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/04/2015] [Indexed: 11/19/2022] Open
Abstract
Circulation of genotype VII Newcastle disease virus (NDV) has posed a great threat for the poultry industry worldwide. Antibodies against Hemagglutinin-neuraminidase (HN), a membrane protein of NDV with critical roles in NDV infection, have been reported to provide chickens protection from NDV infection. In this study, we comprehensively analyzed the in vivo antibody responses against the linear antigenic domains of the HN protein from genotype VII NDV using a yeast surface display system. The results revealed four distinct regions of HN, P1 (1-52aa), P2 (53-192aa), P3 (193-302aa) and P4 (303-571aa), respectively, according to their antigenic potency. Analysis by FACS and ELISA assay indicated P2 to be the dominant linear antigenic domain, with the immunogenic potency to protect the majority of chickens from NDV challenge. In contrast, the P1, P3 and P4 domains showed weak antigenicity in vivo and could not protect chickens from NDV challenge. These results provide important insight into the characteristic of humoral immune responses elicited by HN of NDV in vivo.
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13
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Fusaro A, Tassoni L, Hughes J, Milani A, Salviato A, Schivo A, Murcia PR, Bonfanti L, Cattoli G, Monne I. Evolutionary trajectories of two distinct avian influenza epidemics: Parallelisms and divergences. INFECTION GENETICS AND EVOLUTION 2015; 34:457-66. [PMID: 26003682 DOI: 10.1016/j.meegid.2015.05.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 05/05/2015] [Accepted: 05/19/2015] [Indexed: 11/27/2022]
Abstract
Influenza A virus can quickly acquire genetic mutations that may be associated with increased virulence, host switching or antigenic changes. To provide new insights into the evolutionary dynamics and the adaptive strategies of distinct avian influenza lineages in response to environmental and host factors, we compared two distinct avian influenza epidemics caused by the H7N1 and H7N3 subtypes that circulated under similar epidemiological conditions, including the same domestic species reared in the same densely populated poultry area for similar periods of time. The two strains appear to have experienced largely divergent evolution: the H7N1 viruses evolved into a highly pathogenic form, while the H7N3 did not. However, a more detailed molecular and evolutionary analysis revealed several common features: (i) the independent acquisition of 32 identical mutations throughout the entire genome; (ii) the evolution and persistence of two sole genetic groups with similar genetic characteristics; (iii) a comparable pattern of amino acid variability of the HA proteins during the low pathogenic epidemics; and (iv) similar rates of nucleotide substitutions. These findings suggest that the evolutionary trajectories of viruses with the same virulence level circulating in analogous epidemiological conditions may be similar. In addition, our deep sequencing analysis of 15 samples revealed that 17 of the 32 parallel mutations were already present at the beginning of the two epidemics, suggesting that fixation of these mutations may occur with different mechanisms, which may depend on the fitness gain provided by each mutation. This highlighted the difficulties in predicting the acquisition of mutations that can be correlated to viral adaptation to specific epidemiological conditions or to changes in virus virulence.
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Affiliation(s)
- Alice Fusaro
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy.
| | - Luca Tassoni
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy
| | - Joseph Hughes
- MRC-University of Glasgow Center for Virus Research, 464 Bearsden Road, Glasgow, United Kingdom
| | - Adelaide Milani
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy
| | - Annalisa Salviato
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy
| | - Alessia Schivo
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy
| | - Pablo R Murcia
- MRC-University of Glasgow Center for Virus Research, 464 Bearsden Road, Glasgow, United Kingdom
| | - Lebana Bonfanti
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy
| | - Giovanni Cattoli
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy
| | - Isabella Monne
- Istituto Zooprofilattico Sperimentale delle Venezie, viale dell'Università, 10, Legnaro (PD), Italy
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Xiong F, Xia L, Wang J, Wu B, Wang D, Yuan L, Cheng Y, Zhu H, Che X, Zhang Q, Zhao G, Wang Y. A high-affinity CDR-grafted antibody against influenza A H5N1 viruses recognizes a conserved epitope of H5 hemagglutinin. PLoS One 2014; 9:e88777. [PMID: 24558425 PMCID: PMC3928294 DOI: 10.1371/journal.pone.0088777] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 01/15/2014] [Indexed: 01/19/2023] Open
Abstract
Highly pathogenic avian influenza (HPAI) H5N1 virus infection is still a potential threat to public health worldwide. While vaccines and antiviral drugs are currently under development, neutralizing antibodies could offer an alternative strategy to prevent and treat H5N1 virus infection. In the present study, we had developed a humanized antibody against H5N1 viruses from mouse-derived hybridoma in order to minimize its immunogenicity for potential clinical application. The humanized antibody hH5M9 was generated by transferring the mouse complementarity determining region (CDR) residues together with four key framework region (FR) residues onto the FR of the human antibody. This humanized antibody exhibited high affinity and specificity comparable to the parental mouse or chimeric counterpart with broad and strong neutralization activity against all H5N1 clades and subclades except for Egypt clades investigated. Furthermore, through epitope mapping we identified a linear epitope on the top region of hemagglutinin (HA) that was H5N1 specific and conserved. Our results for the first time reported a humanized antibody against H5N1 viruses by CDR grafting method. With the expected lower immunogenicity, this humanized antibody was expected to be more efficacious than murine or human-mouse chimeric antibodies for future application in humans.
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Affiliation(s)
- Feifei Xiong
- School of Life Science and Technology, Tongji University, Shanghai, China
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Liliang Xia
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Jingfang Wang
- Shanghai Center for Systems Biomedicine, Shanghai Jiaotong University, Shanghai, China
| | - Biao Wu
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Dengyu Wang
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Longfang Yuan
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Yating Cheng
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Hongying Zhu
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Xiaoyan Che
- Central Laboratory, Zhujiang Hospital, The Southern Medical University, Guangzhou, China
| | - Qinghua Zhang
- School of Life Science and Technology, Tongji University, Shanghai, China
| | - Guoping Zhao
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
| | - Ying Wang
- Shanghai-MOST Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, China
- Shanghai Institute of Immunology, Shanghai Jiaotong University School of Medicine, Shanghai, China
- * E-mail:
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15
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Donis RO. Antigenic analyses of highly pathogenic avian influenza a viruses. Curr Top Microbiol Immunol 2014; 385:403-40. [PMID: 25190014 DOI: 10.1007/82_2014_422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
In response to the ongoing threat to animal and human health posed by HPAI endemic in poultry, Asia (H5N1) and North America (H7N3) have revived efforts to reduce pandemic risk by disease control at the source and improved pandemic vaccines. Discovery of conserved neutralization epitopes in the HA, which mediate broad protection within and across HA subtypes have changed the paradigm of "broadly reactive" or "universal" vaccine design. Development of such vaccines would benefit from comparative antigenic analysis of viruses with increasing divergence within (and between) HA subtypes. A review of recent work to define the antigenic properties of HPAI viruses revealed data generated through an array of experimental approaches. This information has supported diagnostics and vaccine development for animal and human health. Further harmonization of analytical methods is needed to determine the antigenic relationships among multiple lineages of rapidly evolving HPAI viruses.
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Affiliation(s)
- Ruben O Donis
- Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road NE Mailstop A20, Atlanta, GA, 30333, USA,
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16
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A unique and conserved neutralization epitope in H5N1 influenza viruses identified by an antibody against the A/Goose/Guangdong/1/96 hemagglutinin. J Virol 2013; 87:12619-35. [PMID: 24049169 DOI: 10.1128/jvi.01577-13] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Despite substantial efforts to control and contain H5N1 influenza viruses, bird flu viruses continue to spread and evolve. Neutralizing antibodies against conserved epitopes on the viral hemagglutinin (HA) could confer immunity to the diverse H5N1 virus strains and provide information for effective vaccine design. Here, we report the characterization of a broadly neutralizing murine monoclonal antibody, H5M9, to most H5N1 clades and subclades that was elicited by immunization with viral HA of A/Goose/Guangdong/1/96 (H5N1), the immediate precursor of the current dominant strains of H5N1 viruses. The crystal structures of the Fab' fragment of H5M9 in complexes with H5 HAs of A/Vietnam/1203/2004 and A/Goose/Guangdong/1/96 reveal a conserved epitope in the HA1 vestigial esterase subdomain that is some distance from the receptor binding site and partially overlaps antigenic site C of H3 HA. Further epitope characterization by selection of escape mutants and epitope mapping by flow cytometry analysis of site-directed mutagenesis of HA with a yeast cell surface display identified four residues that are critical for H5M9 binding. D53, Y274, E83a, and N276 are all conserved in H5N1 HAs and are not in H5 epitopes identified by other mouse or human antibodies. Antibody H5M9 is effective in protection of H5N1 virus both prophylactically and therapeutically and appears to neutralize by blocking both virus receptor binding and postattachment steps. Thus, the H5M9 epitope identified here should provide valuable insights into H5N1 vaccine design and improvement, as well as antibody-based therapies for treatment of H5N1 infection.
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17
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The antigenic architecture of the hemagglutinin of influenza H5N1 viruses. Mol Immunol 2013; 56:705-19. [PMID: 23933511 DOI: 10.1016/j.molimm.2013.07.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/06/2013] [Accepted: 07/14/2013] [Indexed: 11/22/2022]
Abstract
Human infection with the highly pathogenic avian influenza A virus H5N1 is associated with a high mortality and morbidity. H5N1 continues to transmit from poultry to the human population, raising serious concerns about its pandemic potential. Current influenza H5N1 vaccines are based upon the elicitation of a neutralizing antibody (Ab) response against the major epitope regions of the viral surface glycoprotein, hemagglutinin (HA). However, antigenic drift mutations in immune-dominant regions on the HA structure allow the virus to escape Ab neutralization. Epitope mapping using neutralizing monoclonal antibodies (mAb) helps define mechanisms of antigenic drift, neutralizing escape and can facilitate pre-pandemic vaccine design. This review explores the current knowledge base of the antigenic sites of the H5N1 HA molecule. The relationship between the epitope architecture of the H5N1 HA, antigenic evolution of the different H5N1 lineages and the antigenic complexity of the H5N1 virus lineages that constitute potential pandemic strains are discussed in detail.
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18
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Li Y, Zhang X, Xu Q, Fu Q, Zhu Y, Chen S, Peng D, Liu X. Characterisation and haemagglutinin gene epitope mapping of a variant strain of H5N1 subtype avian influenza virus. Vet Microbiol 2013; 162:614-622. [DOI: 10.1016/j.vetmic.2012.11.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 11/08/2012] [Accepted: 11/22/2012] [Indexed: 11/30/2022]
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19
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Huang JW, Lin WF, Yang JM. Antigenic sites of H1N1 influenza virus hemagglutinin revealed by natural isolates and inhibition assays. Vaccine 2012; 30:6327-37. [PMID: 22885274 DOI: 10.1016/j.vaccine.2012.07.079] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 05/16/2012] [Accepted: 07/30/2012] [Indexed: 11/19/2022]
Abstract
The antigenic sites of hemagglutinin (HA) are crucial for understanding antigenic drift and vaccine strain selection for influenza viruses. In 1982, 32 epitope residues (called laboratory epitope residues) were proposed for antigenic sites of H1N1 HA based on the monoclonal antibody-selected variants. Interestingly, these laboratory epitope residues only cover 28% (23/83) mutation positions for 9 H1N1 vaccine strain comparisons (from 1977 to 2009). Here, we propose the entropy and likelihood ratio to model amino acid diversity and antigenic variant score for inferring 41 H1N1 HA epitope residues (called natural epitope residues) with statistically significant scores according to 1572 HA sequences and 197 pairs of HA sequences with hemagglutination inhibition (HI) assays of natural isolates. By combining both natural and laboratory epitope residues, we identified 62 (11 overlapped) residues clustered into five antigenic sites (i.e., A-E) which are highly correlated to the antigenic sites of H3N2 HA. Our method recognizes sites A, B and C as critical sites for escaping from neutralizing antibodies in H1N1 virus. Experimental results show that the accuracies of our models are 81.2% and 82.2% using 41 and 62 epitope residues, respectively, for predicting antigenic variants on 197 paring HA sequences. In addition, our model can detect the emergence of epidemic strains and reflect the genetic diversity and antigenic variant between the vaccine and circulating strains. Finally, our model is theoretically consistent with the evolution rates of H3N2 and H1N1 viruses and is often consistent to WHO vaccine strain selections. We believe that our models and the inferred antigenic sites of HA are useful for understanding the antigenic drift and evolution of influenza A H1N1 virus.
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Affiliation(s)
- Jhang-Wei Huang
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu, 30050, Taiwan
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20
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Cai Z, Ducatez MF, Yang J, Zhang T, Long LP, Boon AC, Webby RJ, Wan XF. Identifying antigenicity-associated sites in highly pathogenic H5N1 influenza virus hemagglutinin by using sparse learning. J Mol Biol 2012; 422:145-55. [PMID: 22609437 DOI: 10.1016/j.jmb.2012.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 05/03/2012] [Accepted: 05/08/2012] [Indexed: 12/09/2022]
Abstract
Since the isolation of A/goose/Guangdong/1/1996 (H5N1) in farmed geese in southern China, highly pathogenic H5N1 avian influenza viruses have posed a continuous threat to both public and animal health. The non-synonymous mutation of the H5 hemagglutinin (HA) gene has resulted in antigenic drift, leading to difficulties in both clinical diagnosis and vaccine strain selection. Characterizing H5N1's antigenic profiles would help resolve these problems. In this study, a novel sparse learning method was developed to identify antigenicity-associated sites in influenza A viruses on the basis of immunologic data sets (i.e., from hemagglutination inhibition and microneutralization assays) and HA protein sequences. Twenty-one potential antigenicity-associated sites were identified. A total of 17 H5N1 mutants were used to validate the effects of 11 of these predicted sites on H5N1's antigenicity, including 7 newly identified sites not located in reported antibody binding sites. The experimental data confirmed that mutations of these tested sites lead to changes in viral antigenicity, validating our method.
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Affiliation(s)
- Zhipeng Cai
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA
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21
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Evidence for differing evolutionary dynamics of A/H5N1 viruses among countries applying or not applying avian influenza vaccination in poultry. Vaccine 2011; 29:9368-75. [PMID: 22001877 DOI: 10.1016/j.vaccine.2011.09.127] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 09/26/2011] [Accepted: 09/30/2011] [Indexed: 11/20/2022]
Abstract
Highly pathogenic avian influenza (HPAI) H5N1 (clade 2.2) was introduced into Egypt in early 2006. Despite the control measures taken, including mass vaccination of poultry, the virus rapidly spread among commercial and backyard flocks. Since the initial outbreaks, the virus in Egypt has evolved into a third order clade (clade 2.2.1) and diverged into antigenically and genetically distinct subclades. To better understand the dynamics of HPAI H5N1 evolution in countries that differ in vaccination policy, we undertook an in-depth analysis of those virus strains circulating in Egypt between 2006 and 2010, and compared countries where vaccination was adopted (Egypt and Indonesia) to those where it was not (Nigeria, Turkey and Thailand). This study incorporated 751 sequences (Egypt n=309, Indonesia n=149, Nigeria n=106, Turkey n=87, Thailand n=100) of the complete haemagglutinin (HA) open reading frame, the major antigenic determinant of influenza A virus. Our analysis revealed that two main Egyptian subclades (termed A and B) have co-circulated in domestic poultry since late 2007 and exhibit different profiles of positively selected codons and rates of nucleotide substitution. The mean evolutionary rate of subclade A H5N1 viruses was 4.07×10(-3) nucleotide substitutions per site, per year (HPD 95%, 3.23-4.91), whereas subclade B possessed a markedly higher substitution rate (8.87×10(-3); 95% HPD 7.0-10.72×10(-3)) and a stronger signature of positive selection. Although the direct association between H5N1 vaccination and virus evolution is difficult to establish, we found evidence for a difference in the evolutionary dynamics of H5N1 viruses among countries where vaccination was or was not adopted. In particular, both evolutionary rates and the number of positively selected sites were higher in virus populations circulating in countries applying avian influenza vaccination for H5N1, compared to viruses circulating in countries which had never used vaccination. We therefore urge a greater consideration of the potential consequences of inadequate vaccination on viral evolution.
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22
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Cattoli G, Milani A, Temperton N, Zecchin B, Buratin A, Molesti E, Aly MM, Arafa A, Capua I. Antigenic drift in H5N1 avian influenza virus in poultry is driven by mutations in major antigenic sites of the hemagglutinin molecule analogous to those for human influenza virus. J Virol 2011; 85:8718-24. [PMID: 21734057 PMCID: PMC3165837 DOI: 10.1128/jvi.02403-10] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 06/23/2011] [Indexed: 11/20/2022] Open
Abstract
H5N1 highly pathogenic avian influenza virus has been endemic in poultry in Egypt since 2008, notwithstanding the implementation of mass vaccination and culling of infected birds. Extensive circulation of the virus has resulted in a progressive genetic evolution and an antigenic drift. In poultry, the occurrence of antigenic drift in avian influenza viruses is less well documented and the mechanisms remain to be clarified. To test the hypothesis that H5N1 antigenic drift is driven by mechanisms similar to type A influenza viruses in humans, we generated reassortant viruses, by reverse genetics, that harbored molecular changes identified in genetically divergent viruses circulating in the vaccinated population. Parental and reassortant phenotype viruses were antigenically analyzed by hemagglutination inhibition (HI) test and microneutralization (MN) assay. The results of the study indicate that the antigenic drift of H5N1 in poultry is driven by multiple mutations primarily occurring in major antigenic sites at the receptor binding subdomain, similarly to what has been described for human influenza H1 and H3 subtype viruses.
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Affiliation(s)
- Giovanni Cattoli
- OIE/FAO Reference Laboratory for Avian Influenza and Newcastle Disease, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro (PD), Italy.
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23
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Recombinant trimeric HA protein immunogenicity of H5N1 avian influenza viruses and their combined use with inactivated or adenovirus vaccines. PLoS One 2011; 6:e20052. [PMID: 21655326 PMCID: PMC3104987 DOI: 10.1371/journal.pone.0020052] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 04/11/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The highly pathogenic avian influenza (HPAI) H5N1 virus continues to cause disease in poultry and humans. The hemagglutinin (HA) envelope protein is the primary target for subunit vaccine development. METHODOLOGY/PRINCIPAL FINDINGS We used baculovirus-insect cell expression to obtain trimeric recombinant HA (rHA) proteins from two HPAI H5N1 viruses. We investigated trimeric rHA protein immunogenicity in mice via immunizations, and found that the highest levels of neutralizing antibodies resulted from coupling with a PELC/CpG adjuvant. We also found that the combined use of trimeric rHA proteins with (a) an inactivated H5N1 vaccine virus, or (b) a recombinant adenovirus encoding full-length HA sequences for prime-boost immunization, further improved antibody responses against homologous and heterologous H5N1 virus strains. Data from cross-clade prime-boost immunization regimens indicate that sequential immunization with different clade HA antigens increased antibody responses in terms of total IgG level and neutralizing antibody titers. CONCLUSION/SIGNIFICANCE Our findings suggest that the use of trimeric rHA in prime-boost vaccine regimens represents an alternative strategy for recombinant H5N1 vaccine development.
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Han T, Sui J, Bennett AS, Liddington RC, Donis RO, Zhu Q, Marasco WA. Fine epitope mapping of monoclonal antibodies against hemagglutinin of a highly pathogenic H5N1 influenza virus using yeast surface display. Biochem Biophys Res Commun 2011; 409:253-9. [PMID: 21569761 PMCID: PMC3119598 DOI: 10.1016/j.bbrc.2011.04.139] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 04/28/2011] [Indexed: 11/27/2022]
Abstract
Highly pathogenic H5N1 avian influenza viruses pose a debilitating pandemic threat. Thus, understanding mechanisms of antibody-mediated viral inhibition and neutralization escape is critical. Here, a robust yeast display system for fine epitope mapping of viral surface hemagglutinin (HA)-specific antibodies is demonstrated. The full-length H5 subtype HA (HA0) was expressed on the yeast surface in a correctly folded conformation, determined by binding of a panel of extensively characterized neutralizing human monoclonal antibodies (mAbs). These mAbs target conformationally-dependent epitopes of influenza A HA, which are highly conserved across H5 clades and group 1 serotypes. By separately displaying HA1 and HA2 subunits on yeast, domain mapping of two anti-H5 mAbs, NR2728 and H5-2A, localized their epitopes to HA1. These anti-H5 mAb epitopes were further fine mapped by using a library of yeast-displayed HA1 mutants and selecting for loss of binding without prior knowledge of potential contact residues. By overlaying key mutant residues that impacted binding onto a crystal structure of HA, the NR2728 mAb was found to interact with a fully surface-exposed contiguous patch of residues at the receptor binding site (RBS), giving insight into the mechanism underlying its potent inhibition of virus binding. The non-neutralizing H5-2A mAb was similarly mapped to a highly conserved H5 strain-specific but poorly accessible location on a loop at the trimer HA interface. These data further augment our toolchest for studying HA antigenicity, epitope diversity and accessibility in response to natural and experimental influenza infection and vaccines.
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Affiliation(s)
- Thomas Han
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Harvard Medical School, 450 Brookline Ave., Boston, MA 02215, USA
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25
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Xu W, Han L, Lin Z. Screening of random peptide library of hemagglutinin from pandemic 2009 A(H1N1) influenza virus reveals unexpected antigenically important regions. PLoS One 2011; 6:e18016. [PMID: 21437206 PMCID: PMC3060926 DOI: 10.1371/journal.pone.0018016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 02/18/2011] [Indexed: 11/19/2022] Open
Abstract
The antigenic structure of the membrane protein hemagglutinin (HA) from the 2009 A(H1N1) influenza virus was dissected with a high-throughput screening method using complex antisera. The approach involves generating yeast cell libraries displaying a pool of random peptides of controllable lengths on the cell surface, followed by one round of fluorescence-activated cell sorting (FACS) against antisera from mouse, goat and human, respectively. The amino acid residue frequency appearing in the antigenic peptides at both the primary sequence and structural level was determined and used to identify "hot spots" or antigenically important regions. Unexpectedly, different antigenic structures were seen for different antisera. Moreover, five antigenic regions were identified, of which all but one are located in the conserved HA stem region that is responsible for membrane fusion. Our findings are corroborated by several recent studies on cross-neutralizing H1 subtype antibodies that recognize the HA stem region. The antigenic peptides identified may provide clues for creating peptide vaccines with better accessibility to memory B cells and better induction of cross-neutralizing antibodies than the whole HA protein. The scheme used in this study enables a direct mapping of the antigenic regions of viral proteins recognized by antisera, and may be useful for dissecting the antigenic structures of other viral proteins.
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Affiliation(s)
- Wanghui Xu
- Department of Chemical Engineering, Tsinghua University, Beijing, China
| | - Lu Han
- Department of Chemical Engineering, Tsinghua University, Beijing, China
| | - Zhanglin Lin
- Department of Chemical Engineering, Tsinghua University, Beijing, China
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26
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Chen N, Tong C, Li D, Wan J, Yuan X, Li X, Peng J, Fang W. Antigenic analysis of classical swine fever virus E2 glycoprotein using pig antibodies identifies residues contributing to antigenic variation of the vaccine C-strain and group 2 strains circulating in China. Virol J 2010; 7:378. [PMID: 21194462 PMCID: PMC3025870 DOI: 10.1186/1743-422x-7-378] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 12/31/2010] [Indexed: 11/10/2022] Open
Abstract
Background Glycoprotein E2, the immunodominant protein of classical swine fever virus (CSFV), can induce neutralizing antibodies and confer protective immunity in pigs. Our previous phylogenetic analysis showed that subgroup 2.1 viruses branched away from subgroup 1.1, the vaccine C-strain lineage, and became dominant in China. The E2 glycoproteins of CSFV C-strain and recent subgroup 2.1 field isolates are genetically different. However, it has not been clearly demonstrated how this diversity affects antigenicity of the protein. Results Antigenic variation of glycoprotein E2 was observed not only between CSFV vaccine C-strain and subgroup 2.1 strains, but also among strains of the same subgroup 2.1 as determined by ELISA-based binding assay using pig antisera to the C-strain and a representative subgroup 2.1 strain QZ-07 currently circulating in China. Antigenic incompatibility of E2 proteins markedly reduced neutralization efficiency against heterologous strains. Single amino acid substitutions of D705N, L709P, G713E, N723S, and S779A on C-strain recombinant E2 (rE2) proteins significantly increased heterologous binding to anti-QZ-07 serum, suggesting that these residues may be responsible for the antigenic variation between the C-strain and subgroup 2.1 strains. Notably, a G713E substitution caused the most dramatic enhancement of binding of the variant C-strain rE2 protein to anti-QZ-07 serum. Multiple sequence alignment revealed that the glutamic acid residue at this position is conserved within group 2 strains, while the glycine residue is invariant among the vaccine strains, highlighting the role of the residue at this position as a major determinant of antigenic variation of E2. A variant Simpson's index analysis showed that both codons and amino acids of the residues contributing to antigenic variation have undergone similar diversification. Conclusions These results demonstrate that CSFV vaccine C-strain and group 2 strains circulating in China differ in the antigenicity of their E2 glycoproteins. Systematic site-directed mutagenesis of the antigenic units has revealed residues that limit cross-reactivity. Our findings may be useful for the development of serological differential assays and improvement of immunogenicity of novel classical swine fever vaccines.
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Affiliation(s)
- Ning Chen
- Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310029, PR China
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27
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Adjuvant-free immunization with hemagglutinin-Fc fusion proteins as an approach to influenza vaccines. J Virol 2010; 85:3010-4. [PMID: 21191017 DOI: 10.1128/jvi.01241-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The hemagglutinins (HAs) of human H1 and H3 influenza viruses and avian H5 influenza virus were produced as recombinant fusion proteins with the human immunoglobulin Fc domain. Recombinant HA-human immunoglobulin Fc domain (HA-HuFc) proteins were secreted from baculovirus-infected insect cells as glycosylated oligomer HAs of the anticipated molecular mass, agglutinated red blood cells, were purified on protein A, and were used to immunize mice in the absence of adjuvant. Immunogenicity was demonstrated for all subtypes, with the serum samples demonstrating subtype-specific hemagglutination inhibition, epitope specificity similar to that seen with virus infection, and neutralization. HuFc-tagged HAs are potential candidates for gene-to-vaccine approaches to influenza vaccination.
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