151
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Abstract
A fascinating aspect of viral evolution relates to the ability of viruses to escape the adaptive immune response. The widely held view has been that the great variability of viral glycoproteins would be an absolute obstacle to the development of antibody-based therapies or vaccines that could confer broad and long-lasting protection. In the past five years, new approaches have been developed to interrogate human memory B cells and plasma cells with high efficiency and to isolate several broadly neutralizing antiviral antibodies against highly variable pathogens such as HIV-1 and influenza virus. These antibodies not only provide new tools for prophylaxis and therapy for viral diseases but also identify conserved epitopes that may be used to design new vaccines capable of conferring broader protection.
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Affiliation(s)
- Davide Corti
- Institute for Research in Biomedicine IRB, 6500 Bellinzona, Switzerland.
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152
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Obara CJ, Dowd KA, Ledgerwood JE, Pierson TC. Impact of viral attachment factor expression on antibody-mediated neutralization of flaviviruses. Virology 2013; 437:20-7. [PMID: 23312596 DOI: 10.1016/j.virol.2012.11.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 09/13/2012] [Accepted: 11/12/2012] [Indexed: 01/01/2023]
Abstract
Neutralization of flaviviruses requires engagement of the virion by antibodies with a stoichiometry that exceeds a required threshold. Factors that modulate the number of antibodies bound to an individual virion when it contacts target cells impact neutralization potency. However, the contribution of cellular factors to the potency of neutralizing antibodies has not been explored systematically. Here we investigate the relationship between expression level of a viral attachment factor on cells and the neutralizing potency of antibodies. Analysis of the attachment factor DC-SIGNR on cells in neutralization studies failed to identify a correlation between DC-SIGNR expression and antibody-mediated protection. Furthermore, neutralization potency was equivalent on a novel Jurkat cell line induced to express DC-SIGNR at varying levels. Finally, blocking virus-attachment factor interactions had no impact on neutralization activity. Altogether, our studies suggest that cellular attachment factor expression is not a significant contributor to the potency of neutralizing antibodies to flaviviruses.
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Affiliation(s)
- Christopher J Obara
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institute of Allergy & Infectious Diseases, NIH, Bethesda, MD 20852, USA
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153
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Dubey KD, Chaubey AK, Ojha RP. Stability of trimeric DENV envelope protein at low and neutral pH: An insight from MD study. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:53-64. [DOI: 10.1016/j.bbapap.2012.08.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 08/13/2012] [Accepted: 08/14/2012] [Indexed: 01/29/2023]
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154
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155
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Differential targeting of viral components by CD4+ versus CD8+ T lymphocytes in dengue virus infection. J Virol 2012; 87:2693-706. [PMID: 23255803 DOI: 10.1128/jvi.02675-12] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Dengue virus (DENV) is the principal arthropod-borne viral pathogen afflicting human populations. While repertoires of antibodies to DENV have been linked to protection or enhanced infection, the role of T lymphocytes in these processes remains poorly defined. This study provides a comprehensive overview of CD4(+) and CD8(+) T cell epitope reactivities against the DENV 2 proteome in adult patients experiencing secondary DENV infection. Dengue virus-specific T cell responses directed against an overlapping 15mer peptide library spanning the DENV 2 proteome were analyzed ex vivo by enzyme-linked immunosorbent spot assay, and recognition of individual peptides was further characterized in specific T cell lines. Thirty novel T cell epitopes were identified, 9 of which are CD4(+) and 21 are CD8(+) T cell epitopes. We observe that whereas CD8(+) T cell epitopes preferentially target nonstructural proteins (NS3 and NS5), CD4(+) epitopes are skewed toward recognition of viral components that are also targeted by B lymphocytes (envelope, capsid, and NS1). Consistently, a large proportion of dengue virus-specific CD4(+) T cells have phenotypic characteristics of circulating follicular helper T cells (CXCR5 expression and production of interleukin-21 or gamma interferon), suggesting that they are interacting with B cells in vivo. This study shows that during a dengue virus infection, the protein targets of human CD4(+) and CD8(+) T cells are largely distinct, thus highlighting key differences in the immunodominance of DENV proteins for these two cell types. This has important implications for our understanding of how the two arms of the human adaptive immune system are differentially targeted and employed as part of our response to DENV infection.
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156
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A hydrogen peroxide-inactivated virus vaccine elicits humoral and cellular immunity and protects against lethal West Nile virus infection in aged mice. J Virol 2012; 87:1926-36. [PMID: 23221549 DOI: 10.1128/jvi.02903-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
West Nile virus (WNV) is an emerging pathogen that is now the leading cause of mosquito-borne and epidemic encephalitis in the United States. In humans, a small percentage of infected individuals develop severe neuroinvasive disease, with the greatest relative risk being in the elderly and immunocompromised, two populations that are difficult to immunize effectively with vaccines. While inactivated and subunit-based veterinary vaccines against WNV exist, currently there is no vaccine or therapy available to prevent or treat human disease. Here, we describe the generation and preclinical efficacy of a hydrogen peroxide (H(2)O(2))-inactivated WNV Kunjin strain (WNV-KUNV) vaccine as a candidate for further development. Both young and aged mice vaccinated with H(2)O(2)-inactivated WNV-KUNV produced robust adaptive B and T cell immune responses and were protected against stringent and lethal intracranial challenge with a heterologous virulent North American WNV strain. Our studies suggest that the H(2)O(2)-inactivated WNV-KUNV vaccine is safe and immunogenic and may be suitable for protection against WNV infection in vulnerable populations.
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157
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Heinz F, Stiasny K. Flaviviruses and their antigenic structure. J Clin Virol 2012; 55:289-95. [DOI: 10.1016/j.jcv.2012.08.024] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 08/25/2012] [Indexed: 12/13/2022]
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158
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Abstract
St. Louis encephalitis virus (SLEV) is a mosquito-borne flavivirus responsible for several human encephalitis outbreaks over the last 80 years. Mature flavivirus virions are coated with dimeric envelope (E) proteins that mediate attachment and fusion with host cells. E is a class II fusion protein, the hallmark of which is a distinct dimer-to-trimer rearrangement that occurs upon endosomal acidification and insertion of hydrophobic fusion peptides into the endosomal membrane. Herein, we report the crystal structure of SLEV E in the posfusion trimer conformation. The structure revealed specific features that differentiate SLEV E from trimers of related flavi- and alphaviruses. SLEV E fusion loops have distinct intermediate spacing such that they are positioned further apart than previously observed in flaviviruses but closer together than Semliki Forest virus, an alphavirus. Domains II and III (DII and DIII) of SLEV E also adopt different angles relative to DI, which suggests that the DI-DII joint may accommodate spheroidal motions. However, trimer interfaces are well conserved among flaviviruses, so it is likely the differences observed represent structural features specific to SLEV function. Analysis of surface potentials revealed a basic platform underneath flavivirus fusion loops that may interact with the anionic lipid head groups found in membranes. Taken together, these results highlight variations in E structure and assembly that may direct virus-specific interactions with host determinants to influence pathogenesis.
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159
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Heinz FX, Stiasny K. Flaviviruses and flavivirus vaccines. Vaccine 2012; 30:4301-6. [PMID: 22682286 DOI: 10.1016/j.vaccine.2011.09.114] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 09/16/2011] [Accepted: 09/23/2011] [Indexed: 12/28/2022]
Abstract
Several human-pathogenic flaviviruses (including yellow fever, dengue, Japanese encephalitis, West Nile and tick-borne encephalitis viruses) have a significant public health impact in different parts of the world and the potential of emerging in previously non-endemic regions. For some viruses, the structure of the most important immunogen, the envelope protein E, has been determined to atomic resolution by X-ray crystallography, and the architecture of virus particles has been resolved by cryo-electron microscopy. Through the combination of structural and immunological investigations, we now have a detailed understanding of the mechanisms of virus neutralization and antibody-dependent enhancement (ADE) of infectivity at a molecular level. The latter phenomenon has been proposed to play an important role in the immunopathology of severe forms of dengue virus infections (hemorrhagic dengue fever and dengue shock syndrome) and is therefore of special relevance in the context of dengue vaccines. Effective human vaccines are in use for the prophylaxis of yellow fever (live attenuated), Japanese encephalitis (live attenuated and inactivated whole virus), and tick-borne encephalitis (inactivated whole virus). Although dengue is the most important flavivirus with respect to global disease incidence, the development and use of vaccines has been hampered so far by the theoretical risk of vaccine-related adverse events such as immune enhancement of infection and the requirement to induce a long-lasting protective immune response against all four dengue serotypes simultaneously. Currently, several kinds of dengue vaccines are in development, but only one of these candidates (a chimeric dengue-yellow fever live attenuated vaccine) has reached the stage of phase 3 clinical trials.
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Affiliation(s)
- Franz X Heinz
- Department of Virology, Medical University of Vienna, Kinderspitalgasse 15, 1095 Vienna, Austria.
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160
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Austin SK, Dowd KA, Shrestha B, Nelson CA, Edeling MA, Johnson S, Pierson TC, Diamond MS, Fremont DH. Structural basis of differential neutralization of DENV-1 genotypes by an antibody that recognizes a cryptic epitope. PLoS Pathog 2012; 8:e1002930. [PMID: 23055922 PMCID: PMC3464233 DOI: 10.1371/journal.ppat.1002930] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 08/13/2012] [Indexed: 01/07/2023] Open
Abstract
We previously developed a panel of neutralizing monoclonal antibodies against Dengue virus (DENV)-1, of which few exhibited inhibitory activity against all DENV-1 genotypes. This finding is consistent with reports observing variable neutralization of different DENV strains and genotypes using serum from individuals that experienced natural infection or immunization. Herein, we describe the crystal structures of DENV1-E111 bound to a novel CC' loop epitope on domain III (DIII) of the E protein from two different DENV-1 genotypes. Docking of our structure onto the available cryo-electron microscopy models of DENV virions revealed that the DENV1-E111 epitope was inaccessible, suggesting that this antibody recognizes an uncharacterized virus conformation. While the affinity of binding between DENV1-E111 and DIII varied by genotype, we observed limited correlation with inhibitory activity. Instead, our results support the conclusion that potent neutralization depends on genotype-dependent exposure of the CC' loop epitope. These findings establish new structural complexity of the DENV virion, which may be relevant for the choice of DENV strain for induction or analysis of neutralizing antibodies in the context of vaccine development.
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Affiliation(s)
- S. Kyle Austin
- Department of Pathology & Immunology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Kimberly A. Dowd
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Bimmi Shrestha
- Department of Medicine (Infectious Diseases), Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Christopher A. Nelson
- Department of Pathology & Immunology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Melissa A. Edeling
- Department of Pathology & Immunology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Syd Johnson
- MacroGenics, Rockville, Maryland, United States of America
| | - Theodore C. Pierson
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Michael S. Diamond
- Department of Pathology & Immunology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Medicine (Infectious Diseases), Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail: (MSD); (DHF)
| | - Daved H. Fremont
- Department of Pathology & Immunology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail: (MSD); (DHF)
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161
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Lobigs M, Diamond MS. Feasibility of cross-protective vaccination against flaviviruses of the Japanese encephalitis serocomplex. Expert Rev Vaccines 2012; 11:177-87. [PMID: 22309667 DOI: 10.1586/erv.11.180] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Serological cross-reactivity providing cross-protective immunity between antigenically related viruses is a cornerstone of vaccination. It was the immunological basis for the first human vaccine against smallpox introduced more than 200 years ago, and continues to underpin modern vaccine development as has recently been shown for human papillomavirus vaccines, which confer cross-protection against other oncogenic papillomavirus types not present in the vaccine. Here, we review the feasibility of cross-protective vaccination against an antigenic group of clinically important viruses belonging to the Japanese encephalitis serocomplex in the Flaviviridae family. We will discuss evidence suggesting that 'new generation' flavivirus vaccines may provide effective cross-protective immunity against heterologous Japanese encephalitis serocomplex viruses, and appraise potential risks associated with cross-reactive vaccine immunity. The review will also focus on the structural and mechanistic basis for cross-protective immunity among this group of flaviviruses, which is predominantly mediated by antibodies against a single viral surface protein.
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Affiliation(s)
- Mario Lobigs
- Department of Emerging Pathogens & Vaccines, John Curtin School of Medical Research, The Australian National University, PO Box 334, Canberra, 2600, ACT, Australia.
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162
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Midgley CM, Flanagan A, Tran HB, Dejnirattisai W, Chawansuntati K, Jumnainsong A, Wongwiwat W, Duangchinda T, Mongkolsapaya J, Grimes JM, Screaton GR. Structural analysis of a dengue cross-reactive antibody complexed with envelope domain III reveals the molecular basis of cross-reactivity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 188:4971-9. [PMID: 22491255 PMCID: PMC3364712 DOI: 10.4049/jimmunol.1200227] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Dengue virus infections are still increasing at an alarming rate in tropical and subtropical countries, underlying the need for a dengue vaccine. Although it is relatively easy to generate Ab responses to dengue virus, low avidity or low concentrations of Ab may enhance infection of FcR-bearing cells with clinical impact, posing a challenge to vaccine production. In this article, we report the characterization of a mAb, 2H12, which is cross-reactive to all four serotypes in the dengue virus group. Crystal structures of 2H12-Fab in complex with domain III of the envelope protein from three dengue serotypes have been determined. 2H12 binds to the highly conserved AB loop of domain III of the envelope protein that is poorly accessible in the mature virion. 2H12 neutralization varied between dengue serotypes and strains; in particular, dengue serotype 2 was not neutralized. Because the 2H12-binding epitope was conserved, this variation in neutralization highlights differences between dengue serotypes and suggests that significant conformational changes in the virus must take place for Ab binding. Surprisingly, 2H12 facilitated little or no enhancement of infection. These data provide a structural basis for understanding Ab neutralization and enhancement of infection, which is crucial for the development of future dengue vaccines.
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Affiliation(s)
- Claire M. Midgley
- Department of Medicine, Hammersmith Hospital Campus, Imperial College London, UK
| | - Aleksandra Flanagan
- Division of Structural Biology and Oxford Protein Production Facility, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Hai Bac Tran
- Department of Medicine, Hammersmith Hospital Campus, Imperial College London, UK
| | | | | | - Amonrat Jumnainsong
- Department of Medicine, Hammersmith Hospital Campus, Imperial College London, UK
| | - Wiyada Wongwiwat
- Department of Medicine, Hammersmith Hospital Campus, Imperial College London, UK
| | - Thaneeya Duangchinda
- Medical Biotechnology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani, Thailand
| | - Juthathip Mongkolsapaya
- Department of Medicine, Hammersmith Hospital Campus, Imperial College London, UK
- Dengue Hemorrhagic Fever Research Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Jonathan M. Grimes
- Division of Structural Biology and Oxford Protein Production Facility, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
- Science Division, Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, UK
| | - Gavin R. Screaton
- Department of Medicine, Hammersmith Hospital Campus, Imperial College London, UK
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163
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Li C, Zhang LY, Sun MX, Li PP, Huang L, Wei JC, Yao YL, Isahg H, Chen PY, Mao X. Inhibition of Japanese encephalitis virus entry into the cells by the envelope glycoprotein domain III (EDIII) and the loop3 peptide derived from EDIII. Antiviral Res 2012; 94:179-83. [DOI: 10.1016/j.antiviral.2012.03.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/27/2012] [Accepted: 03/05/2012] [Indexed: 11/28/2022]
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164
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Approaches for the development of rapid serological assays for surveillance and diagnosis of infections caused by zoonotic flaviviruses of the Japanese encephalitis virus serocomplex. J Biomed Biotechnol 2012; 2012:379738. [PMID: 22570528 PMCID: PMC3337611 DOI: 10.1155/2012/379738] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 01/24/2012] [Accepted: 01/29/2012] [Indexed: 11/17/2022] Open
Abstract
Flaviviruses are responsible for a number of important mosquito-borne diseases of man and animals globally. The short vireamic period in infected hosts means that serological assays are often the diagnostic method of choice. This paper will focus on the traditional methods to diagnose flaviviral infections as well as describing the modern rapid platforms and approaches for diagnostic antigen preparation.
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165
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Lelli D, Moreno A, Brocchi E, Sozzi E, Capucci L, Canelli E, Barbieri I, Zeller H, Cordioli P. West Nile virus: characterization and diagnostic applications of monoclonal antibodies. Virol J 2012; 9:81. [PMID: 22500562 PMCID: PMC3366889 DOI: 10.1186/1743-422x-9-81] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 04/13/2012] [Indexed: 11/12/2022] Open
Abstract
Background Diagnosis of West Nile virus (WNV) infections is often difficult due to the extensive antigenic cross-reactivity among flaviviruses, especially in geographic regions where two or more of these viruses are present causing sequential infections. The purpose of this study was to characterize a panel of monoclonal antibodies (MAbs) produced against WNV to verify their applicability in WNV diagnosis and in mapping epitope targets of neutralizing MAbs. Methods Six MAbs were produced and characterized by isotyping, virus-neutralization, western blotting and MAb-epitope competition. The MAb reactivity against various WNVs belonging to lineage 1 and 2 and other related flaviviruses was also evaluated. The molecular basis of epitopes recognized by neutralizing MAbs was defined through the selection and sequencing of MAb escape mutants. Competitive binding assays between MAbs and experimental equine and chicken sera were designed to identify specific MAb reaction to epitopes with high immunogenicity. Results All MAbs showed stronger reactivity with all WNVs tested and good competition for antigen binding in ELISA tests with WNV-positive equine and chicken sera. Four MAbs (3B2, 3D6, 4D3, 1C3) resulted specific for WNV, while two MAbs (2A8, 4G9) showed cross-reaction with Usutu virus. Three MAbs (3B2, 3D6, 4D3) showed neutralizing activity. Sequence analysis of 3B2 and 3D6 escape mutants showed an amino acid change at E307 (Lys → Glu) in the E protein gene, whereas 4D3 variants identified mutations encoding amino acid changed at E276 (Ser → Ile) or E278 (Thr → Ile). 3B2 and 3D6 mapped to a region on the lateral surface of domain III of E protein, which is known to be a specific and strong neutralizing epitope for WNV, while MAb 4D3 recognized a novel specific neutralizing epitope on domain II of E protein that has not previously been described with WNV MAbs. Conclusions MAbs generated in this study can be applied to various analytical methods for virological and serological WNV diagnosis. A novel WNV-specific and neutralizing MAb (4D3) directed against the unknown epitope on domain II of E protein can be useful to better understand the role of E protein epitopes involved in the mechanism of WNV neutralization.
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Affiliation(s)
- Davide Lelli
- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Via Bianchi 9, 25124 Brescia, Italy.
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166
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Degrees of maturity: the complex structure and biology of flaviviruses. Curr Opin Virol 2012; 2:168-75. [PMID: 22445964 DOI: 10.1016/j.coviro.2012.02.011] [Citation(s) in RCA: 162] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/20/2012] [Accepted: 02/22/2012] [Indexed: 11/21/2022]
Abstract
Flaviviruses are small enveloped virions that enter target cells in a pH-dependent fashion. Virus attachment, entry, and membrane fusion are orchestrated by the envelope (E) and pre-membrane (prM) proteins, the two structural proteins displayed on the surface of virions. Flaviviruses assemble as an immature non-infectious form onto which prM and E form trimeric spikes. During egress from infected cells, flaviviruses undergo dramatic structural changes characterized by the formation of a herringbone arrangement of E proteins that lie flat against the surface of the virion and cleavage of the prM protein by the cellular protease furin. The result is a relatively smooth, infectious mature virion. This dynamic process is now understood in structural detail at the atomic level. However, recent studies indicate that many of the virions released from cells share structural features of both immature and mature virus particles. These mosaic partially mature virions are infectious and interact uniquely with target cells and the host immune response. Here, we will discuss recent advances in our understanding of the biology and significance of partially mature flaviviruses.
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167
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Thibodeaux BA, Garbino NC, Liss NM, Piper J, Schlesinger JJ, Blair CD, Roehrig JT. A humanized IgG but not IgM antibody is effective in prophylaxis and therapy of yellow fever infection in an AG129/17D-204 peripheral challenge mouse model. Antiviral Res 2012; 94:1-8. [PMID: 22366350 DOI: 10.1016/j.antiviral.2012.02.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 01/24/2012] [Accepted: 02/02/2012] [Indexed: 11/27/2022]
Abstract
Yellow fever virus (YFV), a member of the genus Flavivirus, is a mosquito-borne virus found in tropical regions of Africa and South America that causes severe hepatic disease and death in humans. Despite the availability of effective vaccines, YFV is responsible for an estimated 200,000 cases and 30,000 deaths annually. There are currently no prophylactic or therapeutic strategies approved for use in human YFV infections. Furthermore, implementation of YFV 17D-204 vaccination campaigns has become problematic due to an increase in reported post-vaccinal adverse events. We have created human/murine chimeric MAbs of a YFV-reactive murine monoclonal antibody (mMAb), 2C9, that was previously shown to protect mice from lethal YFV infection and to have therapeutic activity. The new chimeric (cMAbs) were constructed by fusion of the m2C9 IgG gene variable regions with the constant regions of human IgG and IgM and expressed in Sp2 murine myelomas. The 2C9 cMAbs (2C9-cIgG and 2C9-cIgM) reacted with 17D-204 vaccine strain in an enzyme-linked immunosorbent assay and neutralized virus in vitro similarly to the parent m2C9. Both m2C9 and 2C9-cIgG when administered prophylactically 24h prior to infection protected AG129 mice from peripheral 17D-204 challenge at antibody concentrations ≥1.27 μg/mouse; however, the 2C9-cIgM did not protect even at a dose of 127 μg/mouse. The 17D-204 infection of AG129 mice is otherwise uniformly lethal. While the m2C9 was shown previously to be therapeutically effective in YFV-infected BALB/c mice at day 4 post-infection, the m2C9 and 2C9-cIgG demonstrated therapeutic activity only when administered 1 day post-infection in 17D-204-infected AG129 mice.
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Affiliation(s)
- Brett A Thibodeaux
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, 80523, USA
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168
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Luca VC, AbiMansour J, Nelson CA, Fremont DH. Crystal structure of the Japanese encephalitis virus envelope protein. J Virol 2012; 86:2337-46. [PMID: 22156523 PMCID: PMC3302414 DOI: 10.1128/jvi.06072-11] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 11/22/2011] [Indexed: 12/13/2022] Open
Abstract
Japanese encephalitis virus (JEV) is the leading global cause of viral encephalitis. The JEV envelope protein (E) facilitates cellular attachment and membrane fusion and is the primary target of neutralizing antibodies. We have determined the 2.1-Å resolution crystal structure of the JEV E ectodomain refolded from bacterial inclusion bodies. The E protein possesses the three domains characteristic of flavivirus envelopes and epitope mapping of neutralizing antibodies onto the structure reveals determinants that correspond to the domain I lateral ridge, fusion loop, domain III lateral ridge, and domain I-II hinge. While monomeric in solution, JEV E assembles as an antiparallel dimer in the crystal lattice organized in a highly similar fashion as seen in cryo-electron microscopy models of mature flavivirus virions. The dimer interface, however, is remarkably small and lacks many of the domain II contacts observed in other flavivirus E homodimers. In addition, uniquely conserved histidines within the JEV serocomplex suggest that pH-mediated structural transitions may be aided by lateral interactions outside the dimer interface in the icosahedral virion. Our results suggest that variation in dimer structure and stability may significantly influence the assembly, receptor interaction, and uncoating of virions.
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Affiliation(s)
- Vincent C. Luca
- Department of Pathology and Immunology
- Program in Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | | | | | - Daved H. Fremont
- Department of Pathology and Immunology
- Program in Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
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169
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A novel approach for the rapid mutagenesis and directed evolution of the structural genes of west nile virus. J Virol 2012; 86:3501-12. [PMID: 22258236 DOI: 10.1128/jvi.06435-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Molecular clone technology has proven to be a powerful tool for investigating the life cycle of flaviviruses, their interactions with the host, and vaccine development. Despite the demonstrated utility of existing molecular clone strategies, the feasibility of employing these existing approaches in large-scale mutagenesis studies is limited by the technical challenges of manipulating relatively large molecular clone plasmids that can be quite unstable when propagated in bacteria. We have developed a novel strategy that provides an extremely rapid approach for the introduction of mutations into the structural genes of West Nile virus (WNV). The backbone of this technology is a truncated form of the genome into which DNA fragments harboring the structural genes are ligated and transfected directly into mammalian cells, bypassing entirely the requirement for cloning in bacteria. The transfection of cells with this system results in the rapid release of WNV that achieves a high titer (∼10(7) infectious units/ml in 48 h). The suitability of this approach for large-scale mutagenesis efforts was established in two ways. First, we constructed and characterized a library of variants encoding single defined amino acid substitutions at the 92 residues of the "pr" portion of the precursor-to-membrane (prM) protein. Analysis of a subset of these variants identified a mutation that conferred resistance to neutralization by an envelope protein-specific antibody. Second, we employed this approach to accelerate the identification of mutations that allow escape from neutralizing antibodies. Populations of WNV encoding random changes in the E protein were produced in the presence of a potent monoclonal antibody, E16. Viruses resistant to neutralization were identified in a single passage. Together, we have developed a simple and rapid approach to produce infectious WNV that accelerates the process of manipulating the genome to study the structure and function of the structural genes of this important human pathogen.
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170
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Lin HE, Tsai WY, Liu IJ, Li PC, Liao MY, Tsai JJ, Wu YC, Lai CY, Lu CH, Huang JH, Chang GJ, Wu HC, Wang WK. Analysis of epitopes on dengue virus envelope protein recognized by monoclonal antibodies and polyclonal human sera by a high throughput assay. PLoS Negl Trop Dis 2012; 6:e1447. [PMID: 22235356 PMCID: PMC3250511 DOI: 10.1371/journal.pntd.0001447] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 11/07/2011] [Indexed: 11/21/2022] Open
Abstract
Background The envelope (E) protein of dengue virus (DENV) is the major target of neutralizing antibodies and vaccine development. While previous studies on domain III or domain I/II alone have reported several epitopes of monoclonal antibodies (mAbs) against DENV E protein, the possibility of interdomain epitopes and the relationship between epitopes and neutralizing potency remain largely unexplored. Methodology/Principal Findings We developed a dot blot assay by using 67 alanine mutants of predicted surface-exposed E residues as a systematic approach to identify epitopes recognized by mAbs and polyclonal sera, and confirmed our findings using a capture-ELISA assay. Of the 12 mouse mAbs tested, three recognized a novel epitope involving residues (Q211, D215, P217) at the central interface of domain II, and three recognized residues at both domain III and the lateral ridge of domain II, suggesting a more frequent presence of interdomain epitopes than previously appreciated. Compared with mAbs generated by traditional protocols, the potent neutralizing mAbs generated by a new protocol recognized multiple residues in A strand or residues in C strand/CC′ loop of DENV2 and DENV1, and multiple residues in BC loop and residues in DE loop, EF loop/F strand or G strand of DENV1. The predominant epitopes of anti-E antibodies in polyclonal sera were found to include both fusion loop and non-fusion residues in the same or adjacent monomer. Conclusions/Significance Our analyses have implications for epitope-specific diagnostics and epitope-based dengue vaccines. This high throughput method has tremendous application for mapping both intra and interdomain epitopes recognized by human mAbs and polyclonal sera, which would further our understanding of humoral immune responses to DENV at the epitope level. Dengue virus is the leading cause of arboviral diseases worldwide. The envelope protein is the major target of neutralizing antibodies and vaccine development. While previous studies have reported several epitopes on envelope protein, the possibility of interdomain epitopes and the relationship of epitopes to neutralizing potency remain unexplored. We developed a high throughput dot blot assay by using 67 alanine mutants of surface-exposed envelope residues as a systematic approach to identify epitopes recognized by mouse monoclonal antibodies and polyclonal human sera. Our results suggested the presence of interdomain epitopes more frequent than previously appreciated. Compared with monoclonal antibodies generated by traditional protocol, the potent neutralizing monoclonal antibodies generated by a new protocol showed several unique features of their epitopes. Moreover, the predominant epitopes of antibodies against envelope protein in polyclonal sera can be identified by this assay. These findings have implications for future development of epitope-specific diagnostics and epitope-based dengue vaccine, and add to our understanding of humoral immune responses to dengue virus at the epitope level.
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Affiliation(s)
- Hong-En Lin
- Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wen-Yang Tsai
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - I-Ju Liu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Pi-Chun Li
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Mei-Ying Liao
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Jih-Jin Tsai
- Tropical Medicine Center and Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yi-Chieh Wu
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Chih-Yun Lai
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Chih-Hsuan Lu
- Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jyh-Hsiung Huang
- Department of Health, Center for Disease Control, Taipei, Taiwan
| | - Gwong-Jen Chang
- Division of Vector-Borne Diseases, Department of Health and Human Service, Center for Disease Control and Prevention, Fort Collins, Colorado, United States of America
| | - Han-Chung Wu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Wei-Kung Wang
- Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
- * E-mail:
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171
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Affiliation(s)
- Pyung Ok Lim
- Department of Science Education, Jeju National University, Jeju, Korea
| | - Tae Hee Lee
- Department of Microbiology and Immunology, Chonbuk National University Medical School, Chonju, Chonbuk, Korea
- Institute for Medical Science, Chonbuk National University Medical School, Chonju, Chonbuk, Korea
| | - Kyung Min Chung
- Department of Microbiology and Immunology, Chonbuk National University Medical School, Chonju, Chonbuk, Korea
- Institute for Medical Science, Chonbuk National University Medical School, Chonju, Chonbuk, Korea
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172
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Persistence of circulating memory B cell clones with potential for dengue virus disease enhancement for decades following infection. J Virol 2011; 86:2665-75. [PMID: 22171265 DOI: 10.1128/jvi.06335-11] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Symptomatic dengue virus infection ranges in disease severity from an influenza-like illness to life-threatening shock. One model of the mechanism underlying severe disease proposes that weakly neutralizing, dengue serotype cross-reactive antibodies induced during a primary infection facilitate virus entry into Fc receptor-bearing cells during a subsequent secondary infection, increasing viral replication and the release of cytokines and vasoactive mediators, culminating in shock. This process has been termed antibody-dependent enhancement of infection and has significantly hindered vaccine development. Much of our understanding of this process has come from studies using mouse monoclonal antibodies (MAbs); however, antibody responses in mice typically exhibit less complexity than those in humans. A better understanding of the humoral immune response to natural dengue virus infection in humans is sorely needed. Using a high-efficiency human hybridoma technology, we isolated 37 hybridomas secreting human MAbs to dengue viruses from 12 subjects years or even decades following primary or secondary infection. The majority of the human antibodies recovered were broadly cross-reactive, directed against either envelope or premembrane proteins, and capable of enhancement of infection in vitro; few exhibited serotype-specific binding or potent neutralizing activity. Memory B cells encoding enhancing antibodies predominated in the circulation, even two or more decades following infection. Mapping the epitopes and activity of naturally occurring dengue antibodies should prove valuable in determining whether the enhancing and neutralizing activity of antibodies can be separated. Such principles could be used in the rational design of vaccines that enhance the induction of neutralizing antibodies, while lowering the risk of dengue shock syndrome.
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173
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Purtha WE, Tedder TF, Johnson S, Bhattacharya D, Diamond MS. Memory B cells, but not long-lived plasma cells, possess antigen specificities for viral escape mutants. ACTA ACUST UNITED AC 2011; 208:2599-606. [PMID: 22162833 PMCID: PMC3244041 DOI: 10.1084/jem.20110740] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Memory B cells (MBCs) and long-lived plasma cells (LLPCs) persist after clearance of infection, yet the specific and nonredundant role MBCs play in subsequent protection is unclear. After resolution of West Nile virus infection in mice, we demonstrate that LLPCs were specific for a single dominant neutralizing epitope, such that immune serum poorly inhibited a variant virus that encoded a mutation at this critical epitope. In contrast, a large fraction of MBC produced antibody that recognized both wild-type (WT) and mutant viral epitopes. Accordingly, antibody produced by the polyclonal pool of MBC neutralized WT and variant viruses equivalently. Remarkably, we also identified MBC clones that recognized the mutant epitope better than the WT protein, despite never having been exposed to the variant virus. The ability of MBCs to respond to variant viruses in vivo was confirmed by experiments in which MBCs were adoptively transferred or depleted before secondary challenge. Our data demonstrate that class-switched MBC can respond to variants of the original pathogen that escape neutralization of antibody produced by LLPC without a requirement for accumulating additional somatic mutations.
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Affiliation(s)
- Whitney E Purtha
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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174
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Conservation of the DENV-2 type-specific and DEN complex-reactive antigenic sites among DENV-2 genotypes. Virology 2011; 422:386-92. [PMID: 22153298 DOI: 10.1016/j.virol.2011.10.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 08/29/2011] [Accepted: 10/20/2011] [Indexed: 11/23/2022]
Abstract
The envelope (E) protein is composed of three domains (ED1, ED2 and ED3) with ED3 targeted by the most potent neutralizing antibodies. DENV-2 strains can be divided into six genotypes. Comparison of ED3 of representative strains of the six genotypes revealed that there are nine variable residues that are specific to a given genotype. Recombinant ED3s (rED3s) of six different DENV-2 strains representing all nine variable residues were expressed, and their reactivity against a panel of two DENV-2 type-specific and three DENV complex-reactive monoclonal antibodies (mAbs) were compared. The differences in binding affinity to the rED3s representing different DENV-2 genotypes were relatively small, with the exception of type-specific-mAb 3H5 that showed up to 10-fold differences in binding between genotypes. Overall the binding differences did not lead to detectable differences in neutralization. Based on these results, DENV-2 ED3-specific neutralizing antibodies will likely be effective against DENV-2 strains from all six genotypes.
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175
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Cockburn JJB, Navarro Sanchez ME, Goncalvez AP, Zaitseva E, Stura EA, Kikuti CM, Duquerroy S, Dussart P, Chernomordik LV, Lai CJ, Rey FA. Structural insights into the neutralization mechanism of a higher primate antibody against dengue virus. EMBO J 2011; 31:767-79. [PMID: 22139356 DOI: 10.1038/emboj.2011.439] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 10/31/2011] [Indexed: 11/09/2022] Open
Abstract
The four serotypes of dengue virus (DENV-1 to -4) cause the most important emerging viral disease. Protein E, the principal viral envelope glycoprotein, mediates fusion of the viral and endosomal membranes during virus entry and is the target of neutralizing antibodies. However, the epitopes of strongly neutralizing human antibodies have not been described despite their importance to vaccine development. The chimpanzee Mab 5H2 potently neutralizes DENV-4 by binding to domain I of E. The crystal structure of Fab 5H2 bound to E from DENV-4 shows that antibody binding prevents formation of the fusogenic hairpin conformation of E, which together with in-vitro assays, demonstrates that 5H2 neutralizes by blocking membrane fusion in the endosome. Furthermore, we show that human sera from patients recovering from DENV-4 infection contain antibodies that bind to the 5H2 epitope region on domain I. This study, thus, provides new information and tools for effective vaccine design to prevent dengue disease.
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Affiliation(s)
- Joseph J B Cockburn
- Département de Virologie, Institut Pasteur, Unité de Virologie Structurale, Paris, France.
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176
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Sabo MC, Luca VC, Ray SC, Bukh J, Fremont DH, Diamond MS. Hepatitis C virus epitope exposure and neutralization by antibodies is affected by time and temperature. Virology 2011; 422:174-84. [PMID: 22078164 DOI: 10.1016/j.virol.2011.10.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 10/14/2011] [Accepted: 10/22/2011] [Indexed: 01/22/2023]
Abstract
A recent study with flaviviruses suggested that structural dynamics of the virion impact antibody neutralization via exposure of ostensibly cryptic epitopes. To determine whether this holds true for the distantly related hepatitis C virus (HCV), whose neutralizing epitopes may be obscured by a glycan shield, apolipoprotein interactions, and the hypervariable region on the E2 envelope protein, we assessed how time and temperature of pre-incubation altered monoclonal antibody (MAb) neutralization of HCV. Notably, several MAbs showed increased inhibitory activity when pre-binding was performed at 37°C or after longer pre-incubation periods, and a corresponding loss-of-neutralization was observed when pre-binding was performed at 4°C. A similar profile of changes was observed with acute and chronic phase sera from HCV-infected patients. Our data suggest that time and temperature of incubation modulate epitope exposure on the conformational ensembles of HCV virions and thus, alter the potency of antibody neutralization.
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Affiliation(s)
- Michelle C Sabo
- Department of Pathology & Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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177
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Lee TH, Song BH, Yun SI, Woo HR, Lee YM, Diamond MS, Chung KM. A cross-protective mAb recognizes a novel epitope within the flavivirus NS1 protein. J Gen Virol 2011; 93:20-26. [PMID: 21918007 DOI: 10.1099/vir.0.036640-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Despite a resurgence of flavivirus infections worldwide, no approved therapeutic agent exists for any member of the genus. While cross-reactive antibodies with therapeutic potential against flaviviruses have been generated, the majority of them are anti-E antibodies with the potential to cause antibody-dependent enhancement of flavivirus infection and disease. We described previously mAbs against the non-structural NS1 protein of the West Nile virus (WNV) that were protective in mice when administered pre- or post-infection of WNV. Here, we demonstrate that one of these mAbs (16NS1) cross-reacted with Japanese encephalitis virus (JEV) and exhibited protective activity against a lethal JEV infection. Overlapping peptide mapping analysis combined with site-specific mutations identified a novel epitope ¹¹⁶KAWGKSILFA¹²⁵ and critical amino acid residues (¹¹⁸W and ¹²²I) for 16NS1 mAb binding. These results may facilitate the development of a broadly therapeutic mAb that lacks enhancing potential and/or subunit-based vaccine against flaviviruses that target the NS1 protein.
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Affiliation(s)
- Tae Hee Lee
- Institute for Medical Science, Chonbuk National University Medical School, Chonju, Chonbuk 561-180, Republic of Korea.,Department of Microbiology and Immunology, Chonbuk National University Medical School, Chonju, Chonbuk 561-180, Republic of Korea
| | - Byung-Hak Song
- Department of Animal, Dairy, and Veterinary Sciences and Utah Science Technology and Research (USTAR), College of Agriculture, Utah State University, Logan, UT 84322-4815, USA.,Department of Microbiology, College of Medicine, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Sang-Im Yun
- Department of Animal, Dairy, and Veterinary Sciences and Utah Science Technology and Research (USTAR), College of Agriculture, Utah State University, Logan, UT 84322-4815, USA.,Department of Microbiology, College of Medicine, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Hye Ryun Woo
- Department of Biology, Chungnam National University, Daejeon 305-764, Republic of Korea
| | - Young-Min Lee
- Department of Animal, Dairy, and Veterinary Sciences and Utah Science Technology and Research (USTAR), College of Agriculture, Utah State University, Logan, UT 84322-4815, USA.,Department of Microbiology, College of Medicine, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Michael S Diamond
- Departments of Medicine, Molecular Microbiology, Pathology & Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Kyung Min Chung
- Institute for Medical Science, Chonbuk National University Medical School, Chonju, Chonbuk 561-180, Republic of Korea.,Department of Microbiology and Immunology, Chonbuk National University Medical School, Chonju, Chonbuk 561-180, Republic of Korea
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178
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The infectivity of prM-containing partially mature West Nile virus does not require the activity of cellular furin-like proteases. J Virol 2011; 85:12067-72. [PMID: 21880759 DOI: 10.1128/jvi.05559-11] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Cleavage of the flavivirus prM protein by a cellular furin-like protease is a hallmark of virion maturation. While this cleavage is a required step in the viral life cycle, it can be inefficient. Virions that retain uncleaved prM may be infectious. We investigated whether cleavage by furin of prM on partially mature West Nile virus (WNV) during virus entry contributes to infectivity. Using quantitative assays of WNV infection, we found that virions incorporating considerable amounts of uncleaved prM protein were insensitive to treatment of cells with a potent inhibitor of furin activity. Thus, partially mature WNV does not require furin-like proteases for infectivity.
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179
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A fusion-loop antibody enhances the infectious properties of immature flavivirus particles. J Virol 2011; 85:11800-8. [PMID: 21880758 DOI: 10.1128/jvi.05237-11] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Flavivirus-infected cells secrete a mixture of mature, partially immature, and fully immature particles into the extracellular space. Although mature virions are highly infectious, prM-containing fully immature virions are noninfectious largely because the prM protein inhibits the cell attachment and fusogenic properties of the virus. If, however, cell attachment and entry are facilitated by anti-prM antibodies, immature flavivirus becomes infectious after efficient processing of the prM protein by the endosomal protease furin. A recent study demonstrated that E53, a cross-reactive monoclonal antibody (MAb) that engages the highly conserved fusion-loop peptide within the flavivirus envelope glycoprotein, preferentially binds to immature flavivirus particles. We investigated here the infectious potential of fully immature West Nile virus (WNV) and dengue virus (DENV) particles opsonized with E53 MAb and observed that, like anti-prM antibodies, this anti-E antibody also has the capacity to render fully immature flaviviruses infectious. E53-mediated enhancement of both immature WNV and DENV depended on efficient cell entry and the enzymatic activity of the endosomal furin. Furthermore, we also observed that E53-opsonized immature DENV particles but not WNV particles required a more acidic pH for efficient cleavage of prM by furin, adding greater complexity to the dynamics of antibody-mediated infection of immature flavivirus virions.
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180
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Cross-linking of rotavirus outer capsid protein VP7 by antibodies or disulfides inhibits viral entry. J Virol 2011; 85:10509-17. [PMID: 21849465 DOI: 10.1128/jvi.00234-11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Antibodies that neutralize rotavirus infection target outer coat proteins VP4 and VP7 and inhibit viral entry. The structure of a VP7-Fab complex (S. T. Aoki, et al., Science 324:1444-1447, 2009) led us to reclassify epitopes into two binding regions at inter- and intrasubunit boundaries of the calcium-dependent trimer. It further led us to show that antibodies binding at the intersubunit boundary inhibit uncoating of the virion outer layer. We have now tested representative antibodies for each of the defined structural epitope regions and find that antibodies recognizing epitopes in either binding region neutralize by cross-linking VP7 trimers. Antibodies that bind at the intersubunit junction neutralize as monovalent Fabs, while those that bind at the intrasubunit region require divalency. The VP7 structure has also allowed us to design a disulfide cross-linked VP7 mutant which recoats double-layered particles (DLPs) as efficiently as does wild-type VP7 but which yields particles defective in cell entry as determined both by lack of infectivity and by loss of α-sarcin toxicity in the presence of recoated particles. We conclude that dissociation of the VP7 trimer is an essential step in viral penetration into cells.
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181
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Schneeweiss A, Chabierski S, Salomo M, Delaroque N, Al-Robaiy S, Grunwald T, Bürki K, Liebert UG, Ulbert S. A DNA vaccine encoding the E protein of West Nile Virus is protective and can be boosted by recombinant domain DIII. Vaccine 2011; 29:6352-7. [DOI: 10.1016/j.vaccine.2011.04.116] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 04/18/2011] [Accepted: 04/29/2011] [Indexed: 01/12/2023]
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182
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Rothman AL. Immunity to dengue virus: a tale of original antigenic sin and tropical cytokine storms. Nat Rev Immunol 2011; 11:532-43. [PMID: 21760609 DOI: 10.1038/nri3014] [Citation(s) in RCA: 531] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Dengue is a mosquito-borne viral disease of expanding geographical range and incidence. The existence of four viral serotypes and the association of prior dengue virus infection with an increased risk for more severe disease have presented significant obstacles to vaccine development. An increased understanding of the adaptive immune response to natural dengue virus infection and candidate dengue vaccines has helped to define the specific antibody and T cell responses that are associated with either protective or pathological immunity during dengue infection. Further characterization of immunological correlates of disease outcome and the validation of these findings in vaccine trials will be invaluable for developing effective dengue vaccines.
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Affiliation(s)
- Alan L Rothman
- Institute for Immunology and Informatics and Department of Cell and Molecular Biology, University of Rhode Island, Providence, Rhode Island 02903, USA.
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183
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Abstract
BACKGROUND Infection by mosquito-borne flaviviruses (family Flaviviridae) is increasing in prevalence worldwide. The vast global, social and economic impact due to the morbidity and mortality associated with the diseases caused by these viruses necessitates therapeutic intervention. There is currently no effective clinical treatment for any flaviviral infection. Therefore, there is a great need for the identification of novel inhibitors to target the virus life cycle. DISCUSSION In this article, we discuss structural and nonstructural viral proteins that are the focus of current target validation and drug discovery efforts. Both inhibition of essential enzymatic activities and disruption of necessary protein–protein interactions are considered. In addition, we address promising new targets for future research. CONCLUSION As our molecular and biochemical understanding of the flavivirus life cycle increases, the number of targets for antiviral therapeutic discovery grows and the possibility for novel drug discovery continues to strengthen.
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184
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Zheng Y, Sánchez-San Martín C, Qin ZL, Kielian M. The domain I-domain III linker plays an important role in the fusogenic conformational change of the alphavirus membrane fusion protein. J Virol 2011; 85:6334-42. [PMID: 21543498 PMCID: PMC3126531 DOI: 10.1128/jvi.00596-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 04/25/2011] [Indexed: 11/20/2022] Open
Abstract
The alphavirus Semliki Forest virus (SFV) infects cells through a low-pH-dependent membrane fusion reaction mediated by the virus fusion protein E1. Acidic pH initiates a series of E1 conformational changes that culminate in membrane fusion and include dissociation of the E1/E2 heterodimer, insertion of the E1 fusion loop into the target membrane, and refolding of E1 to a stable trimeric hairpin conformation. A highly conserved histidine (H3) on the E1 protein was previously shown to promote low-pH-dependent E1 refolding. An SFV mutant with an alanine substitution at this position (H3A) has a lower pH threshold and reduced efficiency of virus fusion and E1 trimer formation than wild-type SFV. Here we addressed the mechanism by which H3 promotes E1 refolding and membrane fusion. We identified E1 mutations that rescue the H3A defect. These revertants implicated a network of interactions that connect the domain I-domain III (DI-DIII) linker region with the E1 core trimer, including H3. In support of the importance of these interactions, mutation of residues in the network resulted in more acidic pH thresholds and reduced efficiencies of membrane fusion. In vitro studies of truncated E1 proteins demonstrated that the DI-DIII linker was required for production of a stable E1 core trimer on target membranes. Together, our results suggest a critical and previously unidentified role for the DI-DIII linker region during the low-pH-dependent refolding of E1 that drives membrane fusion.
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Affiliation(s)
- Yan Zheng
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA.
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185
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Dowd KA, Jost CA, Durbin AP, Whitehead SS, Pierson TC. A dynamic landscape for antibody binding modulates antibody-mediated neutralization of West Nile virus. PLoS Pathog 2011; 7:e1002111. [PMID: 21738473 PMCID: PMC3128118 DOI: 10.1371/journal.ppat.1002111] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 04/24/2011] [Indexed: 12/03/2022] Open
Abstract
Neutralizing antibodies are a significant component of the host's protective response against flavivirus infection. Neutralization of flaviviruses occurs when individual virions are engaged by antibodies with a stoichiometry that exceeds a required threshold. From this “multiple-hit” perspective, the neutralizing activity of antibodies is governed by the affinity with which it binds its epitope and the number of times this determinant is displayed on the surface of the virion. In this study, we investigated time-dependent changes in the fate of West Nile virus (WNV) decorated with antibody in solution. Experiments with the well-characterized neutralizing monoclonal antibody (MAb) E16 revealed a significant increase in neutralization activity over time that could not be explained by the kinetics of antibody binding, virion aggregation, or the action of complement. Additional kinetic experiments using the fusion-loop specific MAb E53, which has limited neutralizing activity because it recognizes a relatively inaccessible epitope on mature virions, identified a role of virus “breathing” in regulating neutralization activity. Remarkably, MAb E53 neutralized mature WNV in a time- and temperature-dependent manner. This phenomenon was confirmed in studies with a large panel of MAbs specific for epitopes in each domain of the WNV envelope protein, with sera from recipients of a live attenuated WNV vaccine, and in experiments with dengue virus. Given enough time, significant inhibition of infection was observed even for antibodies with very limited, or no neutralizing activity in standard neutralization assays. Together, our data suggests that the structural dynamics of flaviviruses impacts antibody-mediated neutralization via exposure of otherwise inaccessible epitopes, allowing for antibodies to dock on the virion with a stoichiometry sufficient for neutralization. Neutralizing antibodies are a critical aspect of protection from flavivirus infection. The primary targets of neutralizing antibodies are the envelope (E) proteins incorporated into virions. The neutralizing activity of antibodies is determined by the affinity with which they interact with the virion, and the total number of sites available for binding. In this study, we investigate the impact of dynamic motion of the viral E proteins on antibody-mediated neutralization. Using panels of monoclonal antibodies and immune sera, we demonstrate that the dynamic motion of virions significantly impacts antibody-mediated neutralization of West Nile and dengue viruses by modulating epitope accessibility. Increasing the length of the interactions between antibody and virus resulted in increased neutralization reflecting engagement of epitopes that are not exposed on the surface of the virion in its average state, but instead become accessible through the dynamic motion of E proteins. While examples of the impact of structural dynamics on antibody binding have been described previously, our data suggests this phenomenon plays a role in neutralization by all antibodies that bind the array of E proteins on the virion. Our data identifies epitope accessibility as a critical, yet dynamic, factor that governs the neutralizing activity of anti-flavivirus antibodies.
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Affiliation(s)
- Kimberly A. Dowd
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Christiane A. Jost
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Anna P. Durbin
- Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Stephen S. Whitehead
- Laboratory of Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Theodore C. Pierson
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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186
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Abstract
Dengue virus (DENV) is a mosquito-borne member of the Flavivirus genus and includes four serotypes (DENV-1, DENV-2, DENV-3, and DENV-4), each of which is capable of causing dengue fever and dengue hemorrhagic fever/dengue shock syndrome. Serious disease can be seen during primary infection but is more frequent following second infection with a serotype different from that of a previous infection. Infection with wild-type DENV induces high-titered neutralizing antibody that can provide long-term immunity to the homotypic virus and can provide short-term immunity (only several months duration) to a heterotypic DENV. The high level of virus replication seen during both secondary infection with a heterotypic virus and during primary DENV infection in late infancy is a direct consequence of antibody-dependent enhancement of replication. This enhanced virus replication is mediated primarily by preexisting, nonneutralizing, or subneutralizing antibodies to the virion surface antigens that enhance access of the virion-antibody complex to FcγR-bearing cells. Vaccines will need to provide long-term protection against each of the four DENV serotypes by inducing neutralizing antibodies, and live, attenuated and various nonliving virus vaccines are in development.
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Affiliation(s)
- Brian R Murphy
- Laboratory of Infectious Diseases, National Institutes of Allergy and Infectious Diseases, Bethesda, Maryland 20892, USA
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187
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Kuo SC, Chen YJ, Wang YM, Kuo MD, Jinn TR, Chen WS, Chang YC, Tung KL, Wu TY, Lo SJ. Cell-based analysis of Chikungunya virus membrane fusion using baculovirus-expression vectors. J Virol Methods 2011; 175:206-15. [PMID: 21619896 DOI: 10.1016/j.jviromet.2011.05.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2010] [Revised: 04/30/2011] [Accepted: 05/10/2011] [Indexed: 01/30/2023]
Abstract
Chikungunya virus infection has emerged in many countries over the past decade. There are no effective drugs for controlling the disease. To develop cell-based system for screening anti-virus drugs, a bi-cistronic baculovirus expression system was utilized to co-express viral structural proteins C (capsid), E2 and E1 and the enhanced green fluorescence protein (EGFP) in Spodoptera frugiperda insect cells (Sf21). The EGFP-positive Sf21 cells fused with each other and with uninfected cells to form a syncytium, allowing characterization of cholesterol and low pH requirements for syncytium formation. Western blot analysis showed three structural proteins were expressed in baculovirus infected cells. The structural proteins of Chikungunya virus that is required for cell fusion was determined with various recombinant baculoviruses bearing different lengths of the viral structural protein genes. Protein E1 was required for cell fusion and indicating that Chikungunya viral membrane fusion was a class II membrane fusion. It was also demonstrated that the heterologous expression of alphavirus monomeric E1 can induce insect cell fusions. Furthermore, this cell-based system provides a model for studying class II viral membrane fusion.
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Affiliation(s)
- Szu-Cheng Kuo
- Division of Microbiology, Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan 333, Taiwan
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188
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Neutralizing monoclonal antibodies against hepatitis C virus E2 protein bind discontinuous epitopes and inhibit infection at a postattachment step. J Virol 2011; 85:7005-19. [PMID: 21543495 DOI: 10.1128/jvi.00586-11] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The E2 glycoprotein of hepatitis C virus (HCV) mediates viral attachment and entry into target hepatocytes and elicits neutralizing antibodies in infected patients. To characterize the structural and functional basis of HCV neutralization, we generated a novel panel of 78 monoclonal antibodies (MAbs) against E2 proteins from genotype 1a and 2a HCV strains. Using high-throughput focus-forming reduction or luciferase-based neutralization assays with chimeric infectious HCV containing structural proteins from both genotypes, we defined eight MAbs that significantly inhibited infection of the homologous HCV strain in cell culture. Two of these bound E2 proteins from strains representative of HCV genotypes 1 to 6, and one of these MAbs, H77.39, neutralized infection of strains from five of these genotypes. The three most potent neutralizing MAbs in our panel, H77.16, H77.39, and J6.36, inhibited infection at an early postattachment step. Receptor binding studies demonstrated that H77.39 inhibited binding of soluble E2 protein to both CD81 and SR-B1, J6.36 blocked attachment to SR-B1 and modestly reduced binding to CD81, and H77.16 blocked attachment to SR-B1 only. Using yeast surface display, we localized epitopes for the neutralizing MAbs on the E2 protein. Two of the strongly inhibitory MAbs, H77.16 and J6.36, showed markedly reduced binding when amino acids within hypervariable region 1 (HVR1) and at sites ∼100 to 200 residues away were changed, suggesting binding to a discontinuous epitope. Collectively, these studies help to define the structural and functional complexity of antibodies against HCV E2 protein with neutralizing potential.
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189
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Julander JG, Perry ST, Shresta S. Important advances in the field of anti-dengue virus research. Antivir Chem Chemother 2011; 21:105-16. [PMID: 21233532 DOI: 10.3851/imp1690] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There are currently no licensed antivirals available for the treatment of dengue virus (DENV), which causes significant morbidity and mortality throughout tropical areas of the world and is now encroaching on the southern United States. Recent improvements in existing animal models and cell culture systems have been very important in elucidating the mechanisms of DENV pathogenesis in humans, including the identification of potential viral and host proteins that might be targeted for the treatment of DENV infection. The AG129 mouse model is a major advance in the development of antiviral and vaccine candidates for clinical use. It allows for testing of potential therapeutics in a relevant system that exhibits some aspects of disease that are similar to those observed in humans. This review focuses on recent developments in the AG129 mouse model and discusses compounds that have been found to be active in available cell and animal model systems within the past year.
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Affiliation(s)
- Justin G Julander
- Institute for Antiviral Research, Utah State University, Logan, UT, USA.
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190
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Rodenhuis-Zybert IA, Wilschut J, Smit JM. Partial maturation: an immune-evasion strategy of dengue virus? Trends Microbiol 2011; 19:248-54. [DOI: 10.1016/j.tim.2011.02.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 02/02/2011] [Accepted: 02/04/2011] [Indexed: 12/22/2022]
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191
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Martina BEE, van den Doel P, Koraka P, van Amerongen G, Spohn G, Haagmans BL, Provacia LBV, Osterhaus ADME, Rimmelzwaan GF. A recombinant influenza A virus expressing domain III of West Nile virus induces protective immune responses against influenza and West Nile virus. PLoS One 2011; 6:e18995. [PMID: 21541326 PMCID: PMC3082541 DOI: 10.1371/journal.pone.0018995] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 03/21/2011] [Indexed: 12/11/2022] Open
Abstract
West Nile virus (WNV) continues to circulate in the USA and forms a threat to the rest of the Western hemisphere. Since methods for the treatment of WNV infections are not available, there is a need for the development of safe and effective vaccines. Here, we describe the construction of a recombinant influenza virus expressing domain III of the WNV glycoprotein E (Flu-NA-DIII) and its evaluation as a WNV vaccine candidate in a mouse model. FLU-NA-DIII-vaccinated mice were protected from severe body weight loss and mortality caused by WNV infection, whereas control mice succumbed to the infection. In addition, it was shown that one subcutaneous immunization with 105 TCID50 Flu-NA-DIII provided 100% protection against challenge. Adoptive transfer experiments demonstrated that protection was mediated by antibodies and CD4+T cells. Furthermore, mice vaccinated with FLU-NA-DIII developed protective influenza virus-specific antibody titers. It was concluded that this vector system might be an attractive platform for the development of bivalent WNV-influenza vaccines.
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192
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Dowd KA, Pierson TC. Antibody-mediated neutralization of flaviviruses: a reductionist view. Virology 2011; 411:306-15. [PMID: 21255816 PMCID: PMC3100196 DOI: 10.1016/j.virol.2010.12.020] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 12/11/2010] [Indexed: 12/28/2022]
Abstract
Flaviviruses are a group of ~70 small RNA viruses responsible for significant morbidity and mortality across the globe. Efforts to develop effective vaccines for several clinically important flaviviruses are underway. Antibodies are a significant component of the host's protective response against flavivirus infection with the potential to contribute to immunity via several distinct mechanisms, including an ability to directly neutralize virus infection. Conversely, virus-reactive antibodies have been implicated in the increased risk of severe clinical manifestations following secondary dengue virus infection. In this review, we will discuss recent progress toward understanding the molecular basis of antibody-mediated neutralization of flaviviruses. Neutralization requires engagement of the virion with a stoichiometry that exceeds a required threshold. From this perspective, we will discuss viral and host factors that impact the number of antibody molecules bound to the virus particle and significantly modulate the potency of neutralizing antibodies.
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Affiliation(s)
- Kimberly A. Dowd
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Theodore C. Pierson
- Viral Pathogenesis Section, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
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193
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Zlatkovic J, Stiasny K, Heinz FX. Immunodominance and functional activities of antibody responses to inactivated West Nile virus and recombinant subunit vaccines in mice. J Virol 2011; 85:1994-2003. [PMID: 21147919 PMCID: PMC3067796 DOI: 10.1128/jvi.01886-10] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 12/01/2010] [Indexed: 12/30/2022] Open
Abstract
Factors controlling the dominance of antibody responses to specific sites in viruses and/or protein antigens are ill defined but can be of great importance for the induction of potent immune responses to vaccines. West Nile virus and other related important human-pathogenic flaviviruses display the major target of neutralizing antibodies, the E protein, in an icosahedral shell at the virion surface. Potent neutralizing antibodies were shown to react with the upper surface of domain III (DIII) of this protein. Using the West Nile virus system, we conducted a study on the immunodominance and functional quality of E-specific antibody responses after immunization of mice with soluble protein E (sE) and isolated DIII in comparison to those after immunization with inactivated whole virions. With both virion and sE, the neutralizing response was dominated by DIII-specific antibodies, but the functionality of these antibodies was almost four times higher after virion immunization. Antibodies induced by the isolated DIII had an at least 15-fold lower specific neutralizing activity than those induced by the virion, and only 50% of these antibodies were able to bind to virus particles. Our results suggest that immunization with the tightly packed E in virions focuses the DIII antibody response to the externally exposed sites of this domain which are the primary targets for virus neutralization, different from sE and isolated DIII, which also display protein surfaces that are cryptic in the virion. Despite its low potency for priming, DIII was an excellent boosting antigen, suggesting novel vaccination strategies that strengthen and focus the antibody response to critical neutralizing sites in DIII.
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Affiliation(s)
- Juergen Zlatkovic
- Department of Virology, Medical University of Vienna, Vienna A-1095, Austria
| | - Karin Stiasny
- Department of Virology, Medical University of Vienna, Vienna A-1095, Austria
| | - Franz X. Heinz
- Department of Virology, Medical University of Vienna, Vienna A-1095, Austria
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194
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Abstract
Three-dimensional (3D) cryoelectron microscopy reconstruction methods are uniquely able to reveal structures of many important macromolecules and macromolecular complexes. EMDataBank.org, a joint effort of the Protein Databank in Europe (PDBe), the Research Collaboratory for Structural Bioinformatics (RCSB), and the National Center for Macromolecular Imaging (NCMI), is a "one-stop shop" resource for global deposition and retrieval of cryo-EM map, model, and associated metadata. The resource unifies public access to the two major EM Structural Data archives: EM Data Bank (EMDB) and Protein Data Bank (PDB), and facilitates use of EM structural data of macromolecules and macromolecular complexes by the wider scientific community.
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Affiliation(s)
- Catherine L Lawson
- Department of Chemistry and Chemical Biology and Research Collaboratory for Structural Bioinformatics, Rutgers, The State University of New Jersey, USA
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195
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Deng YQ, Dai JX, Ji GH, Jiang T, Wang HJ, Yang HO, Tan WL, Liu R, Yu M, Ge BX, Zhu QY, Qin ED, Guo YJ, Qin CF. A broadly flavivirus cross-neutralizing monoclonal antibody that recognizes a novel epitope within the fusion loop of E protein. PLoS One 2011; 6:e16059. [PMID: 21264311 PMCID: PMC3019176 DOI: 10.1371/journal.pone.0016059] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 12/06/2010] [Indexed: 11/18/2022] Open
Abstract
Flaviviruses are a group of human pathogenic, enveloped RNA viruses that includes dengue (DENV), yellow fever (YFV), West Nile (WNV), and Japanese encephalitis (JEV) viruses. Cross-reactive antibodies against Flavivirus have been described, but most of them are generally weakly neutralizing. In this study, a novel monoclonal antibody, designated mAb 2A10G6, was determined to have broad cross-reactivity with DENV 1–4, YFV, WNV, JEV, and TBEV. Phage-display biopanning and structure modeling mapped 2A10G6 to a new epitope within the highly conserved flavivirus fusion loop peptide, the 98DRXW101 motif. Moreover, in vitro and in vivo experiments demonstrated that 2A10G6 potently neutralizes DENV 1–4, YFV, and WNV and confers protection from lethal challenge with DENV 1–4 and WNV in murine model. Furthermore, functional studies revealed that 2A10G6 blocks infection at a step after viral attachment. These results define a novel broadly flavivirus cross-reactive mAb with highly neutralizing activity that can be further developed as a therapeutic agent against severe flavivirus infections in humans.
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Affiliation(s)
- Yong-Qiang Deng
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jian-Xin Dai
- International Joint Cancer Institute, Second Military Medical University, Shanghai, China
- State Key Laboratory of Antibody Medicine and Targeted Therapy, Shanghai, China
| | - Guang-Hui Ji
- International Joint Cancer Institute, Second Military Medical University, Shanghai, China
| | - Tao Jiang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Hua-Jing Wang
- International Joint Cancer Institute, Second Military Medical University, Shanghai, China
- State Key Laboratory of Antibody Medicine and Targeted Therapy, Shanghai, China
| | - Hai-ou Yang
- State Key Laboratory of Antibody Medicine and Targeted Therapy, Shanghai, China
| | - Weng-Long Tan
- State Key Laboratory of Antibody Medicine and Targeted Therapy, Shanghai, China
| | - Ran Liu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Man Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Bao-Xue Ge
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Qing-Yu Zhu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - E-De Qin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ya-Jun Guo
- International Joint Cancer Institute, Second Military Medical University, Shanghai, China
- State Key Laboratory of Antibody Medicine and Targeted Therapy, Shanghai, China
- * E-mail: (YJG); (CFQ)
| | - Cheng-Feng Qin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (YJG); (CFQ)
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196
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Fuchs A, Lin TY, Beasley DW, Stover CM, Schwaeble WJ, Pierson TC, Diamond MS. Direct complement restriction of flavivirus infection requires glycan recognition by mannose-binding lectin. Cell Host Microbe 2010; 8:186-95. [PMID: 20709295 DOI: 10.1016/j.chom.2010.07.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 05/11/2010] [Accepted: 06/07/2010] [Indexed: 01/08/2023]
Abstract
An intact complement system is crucial for limiting West Nile virus (WNV) dissemination. Herein, we define how complement directly restricts flavivirus infection in an antibody-independent fashion. Mannose-binding lectin (MBL) recognized N-linked glycans on the structural proteins of WNV and Dengue virus (DENV), resulting in neutralization through a C3- and C4-dependent mechanism that utilized both the canonical and bypass lectin activation pathways. For WNV, neutralization occurred with virus produced in insect cells, whereas for DENV, neutralization of insect and mammalian cell-derived virus was observed. Mechanism of action studies suggested that the MBL-dependent neutralization occurred, in part, by blocking viral fusion. Experiments in mice showed an MBL-dependent accelerated intravascular clearance of DENV or a WNV mutant with two N-linked glycans on its E protein, but not with wild-type WNV. Our studies show that MBL recognizes terminal mannose-containing carbohydrates on flaviviruses, resulting in neutralization and efficient clearance in vivo.
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Affiliation(s)
- Anja Fuchs
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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197
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Nelson MH, Winkelmann E, Ma Y, Xia J, Mason PW, Bourne N, Milligan GN. Immunogenicity of RepliVAX WN, a novel single-cycle West Nile virus vaccine. Vaccine 2010; 29:174-82. [PMID: 21055493 DOI: 10.1016/j.vaccine.2010.10.069] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 10/21/2010] [Accepted: 10/23/2010] [Indexed: 12/28/2022]
Abstract
We recently reported that immunization with RepliVAX WN, a single-cycle West Nile virus (WNV) vaccine, protected mice against WNV challenge. We have extended these studies by characterizing the RepliVAX WN-elicited antibody and T cell responses. WNV-specific IgG antibody responses comprised predominantly of IgG(2c) and IgG(2b) subclasses were detected 8 months after immunization. Vigorous WNV-specific CD4(+) and CD8(+) T cell responses directed at both structural and nonstructural WNV proteins were detected which were characterized by cytolytic activity and secretion of IFN-γ and TNF-α. Importantly, RepliVAX WN immunization resulted in vigorous CD8(+) memory T cell responses detected at 8 months after immunization.
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Affiliation(s)
- Michelle H Nelson
- Department of Microbiology and Immunology. University of Texas Medical Branch, Galveston, TX 77555, USA
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198
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Bogachek MV, Zaitsev BN, Sekatskii SK, Protopopova EV, Ternovoi VA, Ivanova AV, Kachko AV, Ivanisenko VA, Dietler G, Loktev VB. Characterization of glycoprotein E C-end of West Nile virus and evaluation of its interaction force with alphaVbeta3 integrin as putative cellular receptor. BIOCHEMISTRY (MOSCOW) 2010; 75:472-80. [PMID: 20618137 DOI: 10.1134/s0006297910040115] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Recombinant polypeptide containing the 260-466 amino acid sequence of West Nile virus (WNV) strain LEIV-Vlg99-27889-human glycoprotein E (gpE, E(260-466)) was constructed. Immunochemical similarity between the E(260-466) and gpE of WNV was proven by enzyme immunoassay (EIA), immunoblot, competitive EIA, hemagglutination inhibition, and neutralization tests using polyclonal and monoclonal antibodies against the viral gpE and recombinant E(260-466). Polypeptide E(260-466) induced formation of virus neutralizing and cross-reactive antibodies that were interactive with various epitopes of this recombinant protein. It is shown by evaluation of the interaction of E(260-466) with one of the proposed cell receptors of WNV that average E(260-466)-alphaVbeta3 integrin-specific interaction force measured using atomic force spectroscopy was 80 and 140 pN for single and double interactions, correspondingly. Taken together with previously described interaction between laminin-binding protein (LBP) and WNV gpE domain II, it is proposed that WNV gpE can interact specifically with two cellular proteins (LBP and alphaVbeta3 integrin) during virus entry.
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Affiliation(s)
- M V Bogachek
- FSRI State Research Center of Virology and Biotechnology Vector, Koltsovo, Novosibirsk Region, 630559, Russia
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199
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Lawson CL, Baker ML, Best C, Bi C, Dougherty M, Feng P, van Ginkel G, Devkota B, Lagerstedt I, Ludtke SJ, Newman RH, Oldfield TJ, Rees I, Sahni G, Sala R, Velankar S, Warren J, Westbrook JD, Henrick K, Kleywegt GJ, Berman HM, Chiu W. EMDataBank.org: unified data resource for CryoEM. Nucleic Acids Res 2010; 39:D456-64. [PMID: 20935055 PMCID: PMC3013769 DOI: 10.1093/nar/gkq880] [Citation(s) in RCA: 192] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Cryo-electron microscopy reconstruction methods are uniquely able to reveal structures of many important macromolecules and macromolecular complexes. EMDataBank.org, a joint effort of the Protein Data Bank in Europe (PDBe), the Research Collaboratory for Structural Bioinformatics (RCSB) and the National Center for Macromolecular Imaging (NCMI), is a global ‘one-stop shop’ resource for deposition and retrieval of cryoEM maps, models and associated metadata. The resource unifies public access to the two major archives containing EM-based structural data: EM Data Bank (EMDB) and Protein Data Bank (PDB), and facilitates use of EM structural data of macromolecules and macromolecular complexes by the wider scientific community.
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Affiliation(s)
- Catherine L Lawson
- Department of Chemistry and Chemical Biology and Research Collaboratory for Structural Bioinformatics, Rutgers, The State University of New Jersey, 610 Taylor Road Piscataway, NJ 08854, USA.
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200
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Carayannopoulos LN, Barks JL, Yokoyama WM, Riley JK. Murine trophoblast cells induce NK cell interferon-gamma production through KLRK1. Biol Reprod 2010; 83:404-14. [PMID: 20484740 PMCID: PMC2924803 DOI: 10.1095/biolreprod.110.084509] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/05/2010] [Accepted: 05/06/2010] [Indexed: 12/21/2022] Open
Abstract
Murine models suggest that natural killer (NK) cells are important for normal implantation site development, in part, through the production of interferon gamma (IFNG). As KLRK1 (NKG2D) is expressed on human and murine uterine NK (uNK) cells, we examined the role of KLRK1 in the interaction between murine trophoblasts and NK cells. Flow cytometric analysis revealed that both murine trophoblast stem (TS) cells and differentiated trophoblast giant cells expressed the KLRK1 ligand retinoic acid early transcript 1, or RAET1. Coculture of activated NK cells with either TS cells or giant cells led to the production of IFNG, as measured by ELISA. In addition, coculture with TS cells led to the downregulation of KLRK1. Both responses were inhibited by soluble KLRK1 ligand, but not by irrelevant protein. Further studies demonstrated the presence of KLRK1 ligand on uterine cells derived from either virgin or pregnant mice, although uterine RAET1 protein expression was upregulated in vitro by progesterone, but not estradiol. We suggest that the interaction of KLRK1 and RAET1 may be involved in IFNG production by uNK cells, and thus, this receptor-ligand pair may contribute to successful murine implantation site development.
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Affiliation(s)
- Leonidas N. Carayannopoulos
- Department of Obstetrics and Gynecology, Division of Pulmonary and Critical Care Medicine, Division of Rheumatology and Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri
| | - Jennifer L. Barks
- Department of Obstetrics and Gynecology, Division of Pulmonary and Critical Care Medicine, Division of Rheumatology and Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri
| | - Wayne M. Yokoyama
- Department of Obstetrics and Gynecology, Division of Pulmonary and Critical Care Medicine, Division of Rheumatology and Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri
| | - Joan K. Riley
- Department of Obstetrics and Gynecology, Division of Pulmonary and Critical Care Medicine, Division of Rheumatology and Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri
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