1
|
Reuter N, Chen X, Kropff B, Peter AS, Britt WJ, Mach M, Überla K, Thomas M. SARS-CoV-2 Spike Protein Is Capable of Inducing Cell-Cell Fusions Independent from Its Receptor ACE2 and This Activity Can Be Impaired by Furin Inhibitors or a Subset of Monoclonal Antibodies. Viruses 2023; 15:1500. [PMID: 37515187 PMCID: PMC10384293 DOI: 10.3390/v15071500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 06/27/2023] [Accepted: 06/30/2023] [Indexed: 07/30/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was responsible for the COVID-19 pandemic, efficiently spreads cell-to-cell through mechanisms facilitated by its membrane glycoprotein spike. We established a dual split protein (DSP) assay based on the complementation of GFP and luciferase to quantify the fusogenic activity of the SARS-CoV-2 spike protein. We provide several lines of evidence that the spike protein of SARS-CoV-2, but not SARS-CoV-1, induced cell-cell fusion even in the absence of its receptor, angiotensin-converting enzyme 2 (ACE2). This poorly described ACE2-independent cell fusion activity of the spike protein was strictly dependent on the proteasomal cleavage of the spike by furin while TMPRSS2 was dispensable. Previous and current variants of concern (VOCs) differed significantly in their fusogenicity. The Delta spike was extremely potent compared to Alpha, Beta, Gamma and Kappa, while the Omicron spike was almost devoid of receptor-independent fusion activity. Nonetheless, for all analyzed variants, cell fusion was dependent on furin cleavage and could be pharmacologically inhibited with CMK. Mapping studies revealed that amino acids 652-1273 conferred the ACE2-independent fusion activity of the spike. Unexpectedly, residues proximal to the furin cleavage site were not of major relevance, whereas residue 655 critically regulated fusion. Finally, we found that the spike's fusion activity in the absence of ACE2 could be inhibited by antibodies directed against its N-terminal domain (NTD) but not by antibodies targeting its receptor-binding domain (RBD). In conclusion, our BSL-1-compatible DSP assay allowed us to screen for inhibitors or antibodies that interfere with the spike's fusogenic activity and may therefore contribute to both rational vaccine design and development of novel treatment options against SARS-CoV-2.
Collapse
Affiliation(s)
- Nina Reuter
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Xiaohan Chen
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Barbara Kropff
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Antonia Sophia Peter
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - William J Britt
- Departments of Pediatrics, Microbiology and Neurobiology, Children's Hospital of Alabama, School of Medicine, University of Alabama, Birmingham, AL 35233-1771, USA
| | - Michael Mach
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Klaus Überla
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Marco Thomas
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| |
Collapse
|
2
|
Häge S, Sonntag E, Svrlanska A, Borst EM, Stilp AC, Horsch D, Müller R, Kropff B, Milbradt J, Stamminger T, Schlötzer-Schrehardt U, Marschall M. Phenotypical Characterization of the Nuclear Egress of Recombinant Cytomegaloviruses Reveals Defective Replication upon ORF-UL50 Deletion but Not pUL50 Phosphosite Mutation. Viruses 2021; 13:v13020165. [PMID: 33499341 PMCID: PMC7911381 DOI: 10.3390/v13020165] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/19/2022] Open
Abstract
Nuclear egress is a common herpesviral process regulating nucleocytoplasmic capsid release. For human cytomegalovirus (HCMV), the nuclear egress complex (NEC) is determined by the pUL50-pUL53 core that regulates multicomponent assembly with NEC-associated proteins and capsids. Recently, NEC crystal structures were resolved for α-, β- and γ-herpesviruses, revealing profound structural conservation, which was not mirrored, however, by primary sequence and binding properties. The NEC binding principle is based on hook-into-groove interaction through an N-terminal hook-like pUL53 protrusion that embraces an α-helical pUL50 binding groove. So far, pUL50 has been considered as the major kinase-interacting determinant and massive phosphorylation of pUL50-pUL53 was assigned to NEC formation and functionality. Here, we addressed the question of phenotypical changes of ORF-UL50-mutated HCMVs. Surprisingly, our analyses did not detect a predominant replication defect for most of these viral mutants, concerning parameters of replication kinetics (qPCR), viral protein production (Western blot/CoIP) and capsid egress (confocal imaging/EM). Specifically, only the ORF-UL50 deletion rescue virus showed a block of genome synthesis during late stages of infection, whereas all phosphosite mutants exhibited marginal differences compared to wild-type or revertants. These results (i) emphasize a rate-limiting function of pUL50 for nuclear egress, and (ii) demonstrate that mutations in all mapped pUL50 phosphosites may be largely compensated. A refined mechanistic concept points to a multifaceted nuclear egress regulation, for which the dependence on the expression and phosphorylation of pUL50 is discussed.
Collapse
Affiliation(s)
- Sigrun Häge
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Eric Sonntag
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Adriana Svrlanska
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Eva Maria Borst
- Institute of Virology, Hannover Medical School (MHH), 30625 Hannover, Germany;
| | - Anne-Charlotte Stilp
- Institute for Virology, Ulm University Medical Center, 89081 Ulm, Germany; (A.-C.S.); (T.S.)
| | - Deborah Horsch
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Regina Müller
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Barbara Kropff
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Jens Milbradt
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
| | - Thomas Stamminger
- Institute for Virology, Ulm University Medical Center, 89081 Ulm, Germany; (A.-C.S.); (T.S.)
| | | | - Manfred Marschall
- Institute for Clinical and Molecular Virology, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; (S.H.); (E.S.); (A.S.); (D.H.); (R.M.); (B.K.); (J.M.)
- Correspondence: ; Tel.: +49-9131-8526089
| |
Collapse
|
3
|
Brait N, Stögerer T, Kalser J, Adler B, Kunz I, Benesch M, Kropff B, Mach M, Puchhammer-Stöckl E, Görzer I. Influence of Human Cytomegalovirus Glycoprotein O Polymorphism on the Inhibitory Effect of Soluble Forms of Trimer- and Pentamer-Specific Entry Receptors. J Virol 2020; 94:e00107-20. [PMID: 32350071 PMCID: PMC7343208 DOI: 10.1128/jvi.00107-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 04/21/2020] [Indexed: 01/24/2023] Open
Abstract
Human cytomegalovirus (HCMV) envelope glycoprotein complexes, gH/gL/gO trimer and gH/gL/UL128-131 pentamer, are important for cell-free HCMV entry. While soluble NRP2-Fc (sNRP2-Fc) interferes with epithelial/endothelial cell entry through UL128, soluble platelet-derived growth factor receptor α-Fc (sPDGFRα-Fc) interacts with gO, thereby inhibiting infection of all cell types. Since gO is the most variable subunit, we investigated the influence of gO polymorphism on the inhibitory capacities of sPDGFRα-Fc and sNRP2-Fc. Accordingly, gO genotype 1c (GT1c) sequence was fully or partially replaced by gO GT2b, GT3, and GT5 sequences in the bacterial artificial chromosome (BAC) TB40-BAC4-luc background (where luc is luciferase). All mutants were tested for fibroblast and epithelial cell infectivity, for virion content of gB, gH, and gO, and for infection inhibition by sPDGFRα-Fc and sNRP2-Fc. Full-length and partial gO GT swapping may increase epithelial-to-fibroblast ratios due to subtle alterations in fibroblast and/or epithelial infectivity but without substantial changes in gB and gH levels in mutant virions. All gO GT mutants except recombinant gO GT1c/3 displayed a nearly complete inhibition at 1.25 μg/ml sPDGFRα-Fc on epithelial cells (98% versus 91%), and all experienced complete inhibition on fibroblasts (≥99%). While gO GT replacement did not influence sNRP2-Fc inhibition at 1.25 μg/ml on epithelial cells (97% to 99%), it rendered recombinant mutant GT1c/3 moderately accessible to fibroblast inhibition (40%). In contrast to the steep sPDGFRα-Fc inhibition curves (slope of >1.0), sNRP2-Fc dose-response curves on epithelial cells displayed slopes of ∼1.0, suggesting functional differences between these entry inhibitors. Our findings demonstrate that artificially generated gO recombinants rather than the major gO genotypic forms may affect the inhibitory capacities of sPDGFRα and sNRP2 in a cell type-dependent manner.IMPORTANCE Human cytomegalovirus (HCMV) is known for its broad cell tropism, as reflected by the different organs and tissues affected by HCMV infection. Hence, inhibition of HCMV entry into distinct cell types could be considered a promising therapeutic option to limit cell-free HCMV infection. Soluble forms of cellular entry receptor PDGFRα rather than those of entry receptor neuropilin-2 inhibit infection of multiple cell types. sPDGFRα specifically interacts with gO of the trimeric gH/gL/gO envelope glycoprotein complex. HCMV strains may differ with respect to the amounts of trimer in virions and the highly polymorphic gO sequence. In this study, we show that the major gO genotypes of HCMV that are also found in vivo are similarly well inhibited by sPDGFRα. Novel gO genotypic forms potentially emerging through recombination, however, may evade sPDGFRα inhibition on epithelial cells. These findings provide useful additional information for the future development of anti-HCMV therapeutic compounds based on sPDGFRα.
Collapse
Affiliation(s)
- Nadja Brait
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Tanja Stögerer
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Julia Kalser
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Barbara Adler
- Max von Pettenkofer Institute for Virology, Ludwig Maximilians University Munich, Munich, Germany
| | - Ines Kunz
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Max Benesch
- Center for Virology, Medical University of Vienna, Vienna, Austria
| | - Barbara Kropff
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich Alexander Universität Erlangen Nürnberg, Erlangen, Germany
| | - Michael Mach
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich Alexander Universität Erlangen Nürnberg, Erlangen, Germany
| | | | - Irene Görzer
- Center for Virology, Medical University of Vienna, Vienna, Austria
| |
Collapse
|
4
|
Baraniak I, Kropff B, McLean GR, Pichon S, Piras-Douce F, Milne RSB, Smith C, Mach M, Griffiths PD, Reeves MB. Epitope-Specific Humoral Responses to Human Cytomegalovirus Glycoprotein-B Vaccine With MF59: Anti-AD2 Levels Correlate With Protection From Viremia. J Infect Dis 2019. [PMID: 29528415 PMCID: PMC5972559 DOI: 10.1093/infdis/jiy102] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
The human cytomegalovirus (HCMV) virion envelope protein glycoprotein B (gB) is essential for viral entry and represents a major target for humoral responses following infection. Previously, a phase 2 placebo-controlled clinical trial conducted in solid organ transplant candidates demonstrated that vaccination with gB plus MF59 adjuvant significantly increased gB enzyme-linked immunosorbent assay (ELISA) antibody levels whose titer correlated directly with protection against posttransplant viremia. The aim of the current study was to investigate in more detail this protective humoral response in vaccinated seropositive transplant recipients. We focused on 4 key antigenic domains (AD) of gB (AD1, AD2, AD4, and AD5), measuring antibody levels in patient sera and correlating these with posttransplant HCMV viremia. Vaccination of seropositive patients significantly boosted preexisting antibody levels against the immunodominant region AD1 as well as against AD2, AD4, and AD5. A decreased incidence of viremia correlated with higher antibody levels against AD2 but not with antibody levels against the other 3 ADs. Overall, these data support the hypothesis that antibodies against AD2 are a major component of the immune protection of seropositives seen following vaccination with gB/MF59 vaccine and identify a correlate of protective immunity in allograft patients.
Collapse
Affiliation(s)
- Ilona Baraniak
- Institute for Immunity and Transplantation, University College London, United Kingdom
| | - Barbara Kropff
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
| | - Gary R McLean
- Cellular and Molecular Immunology Research Centre, London Metropolitan University, United Kingdom
| | - Sylvie Pichon
- Clinical Development, Sanofi Pasteur, Marcy l'Etoile, France
| | | | - Richard S B Milne
- Institute for Immunity and Transplantation, University College London, United Kingdom
| | - Colette Smith
- Research Department of Infection and Population Health, University College London, United Kingdom
| | - Michael Mach
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
| | - Paul D Griffiths
- Institute for Immunity and Transplantation, University College London, United Kingdom
| | - Matthew B Reeves
- Institute for Immunity and Transplantation, University College London, United Kingdom
| |
Collapse
|
5
|
Alt M, Falk J, Eis-Hübinger AM, Kropff B, Sinzger C, Krawczyk A. Detection of antibody-secreting cells specific for the cytomegalovirus and herpes simplex virus surface antigens. J Immunol Methods 2018; 462:13-22. [PMID: 30056033 PMCID: PMC7094464 DOI: 10.1016/j.jim.2018.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 06/29/2018] [Accepted: 07/25/2018] [Indexed: 11/24/2022]
Abstract
Infections with the herpes simplex virus (HSV) and the human cytomegalovirus (HCMV) can lead to life-threatening diseases, particularly in immunosuppressed patients. Furthermore, HSV infections at birth (herpes neonatorum) can result in a disseminated disease associated with a fatal multiorgan failure. Congenital HCMV infections can result in miscarriage, serious birth defects or developmental disabilities. Antibody-based interventions with hyperimmunoglobulins showed encouraging results in clinical studies, but clearly need to be improved. The isolation of highly neutralizing monoclonal antibodies is a promising strategy to establish potent therapy options against HSV and HCMV infections. Monoclonal antibodies are commonly isolated from hybridomas or EBV-immortalized B-cell clones. The screening procedure to identify virus-specific cells from a cell mixture is a challenging step, since most of the highly neutralizing antibodies target complex conformational epitopes on the virus surface. Conventional assays such as ELISA are based on purified viral proteins and inappropriate to display complex epitopes. To overcome this obstacle, we have established two full-virus based methods that allow screening for cells and antibodies targeting complex conformational epitopes on viral surface antigens. The methods are suitable to detect surface antigen-specific cells from a cell mixture and may facilitate the isolation of highly neutralizing antibodies against HSV and HCMV.
Collapse
Affiliation(s)
- Mira Alt
- Institute for Virology, University Hospital of Essen, 45147 Essen, Germany
| | - Jessica Falk
- Institute for Virology, University Hospital of Ulm, 89081 Ulm, Germany
| | | | - Barbara Kropff
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-Nürnberg, Germany
| | - Christian Sinzger
- Institute for Virology, University Hospital of Ulm, 89081 Ulm, Germany
| | - Adalbert Krawczyk
- Institute for Virology, University Hospital of Essen, 45147 Essen, Germany.
| |
Collapse
|
6
|
Kalser J, Adler B, Mach M, Kropff B, Puchhammer-Stöckl E, Görzer I. Differences in Growth Properties among Two Human Cytomegalovirus Glycoprotein O Genotypes. Front Microbiol 2017; 8:1609. [PMID: 28878758 PMCID: PMC5572245 DOI: 10.3389/fmicb.2017.01609] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 08/07/2017] [Indexed: 11/22/2022] Open
Abstract
Glycoprotein O (gO) of the human cytomegalovirus (HCMV) is the critical subunit of the envelope trimer gH/gL/gO as it interacts with platelet-derived growth factor alpha receptor upon fibroblast entry, and triggers gB-mediated fusion for fibroblast and epithelial cell infection. Eight genotypes (GT) of the highly polymorphic gO gene are described, yet it is unclear whether the distinct GTs differ in their function. Thus, we aimed to elucidate potential functional differences between two highly diverse gO GTs in an otherwise genomically identical HCMV strain. Therefore, resident gO GT1c sequence of strain TB40-BAC4-luc was entirely replaced by gO GT4 of strain Towne and both, GT1c and GT4 viruses, were investigated for their growth properties in fibroblasts and epithelial cells. In addition, two conserved gO cysteines involved in gH/gL/gO stabilization were mutated to serine either in GT1c (C218S and C343S) or GT4 (C216S and C336S) and their effects on cell-free infectivity were assessed. GT4 viruses displayed a significantly enhanced epithelial cell tropism and this resulted in higher virus release upon replication in epithelial cells when compared to GT1c viruses. Further, when the two cysteines were individually mutated in gO GT1c no impairment in cell-free infectivity was observed. This, however, was in sharp contrast to gO GT4, in which both of the corresponding cysteine mutations led to a substantial reduction in cell-free infectivity which was even more pronounced upon mutation of GT4-C336 than of GT4-C216. In conclusion, these findings provide evidence that the two highly diverse gO genotypes, GT1c and GT4, differ in their functional properties as revealed by their different infection capacities for epithelial cells and by their different responsiveness to mutation of strictly conserved cysteine residues. Thus, it is likely that the gO heterogeneity influences cell-free infectivity of HCMV also in vivo which may have important implications for virus host transmission.
Collapse
Affiliation(s)
- Julia Kalser
- Center for Virology, Medical University of ViennaVienna, Austria
| | - Barbara Adler
- Max von Pettenkofer-Institute for Virology, Ludwig-Maximilians-University MunichMunich, Germany
| | - Michael Mach
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | - Barbara Kropff
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-NürnbergErlangen, Germany
| | | | - Irene Görzer
- Center for Virology, Medical University of ViennaVienna, Austria
| |
Collapse
|
7
|
Bootz A, Karbach A, Spindler J, Kropff B, Reuter N, Sticht H, Winkler TH, Britt WJ, Mach M. Protective capacity of neutralizing and non-neutralizing antibodies against glycoprotein B of cytomegalovirus. PLoS Pathog 2017; 13:e1006601. [PMID: 28854233 PMCID: PMC5595347 DOI: 10.1371/journal.ppat.1006601] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 09/12/2017] [Accepted: 08/22/2017] [Indexed: 01/19/2023] Open
Abstract
Human cytomegalovirus (HCMV) is an important, ubiquitous pathogen that causes severe clinical disease in immunocompromised individuals, such as organ transplant recipients and infants infected in utero. Antiviral chemotherapy remains problematic due to toxicity of the available compounds and the emergence of viruses resistant to available antiviral therapies. Antiviral antibodies could represent a valuable alternative strategy to limit the clinical consequences of viral disease in patients. The envelope glycoprotein B (gB) of HCMV is a major antigen for the induction of virus neutralizing antibodies. However, the role of anti-gB antibodies in the course of the infection in-vivo remains unknown. We have used a murine CMV (MCMV) model to generate and study a number of anti-gB monoclonal antibodies (mAbs) with differing virus-neutralizing capacities. The mAbs were found to bind to similar antigenic structures on MCMV gB that are represented in HCMV gB. When mAbs were used in immunodeficient RAG-/- hosts to limit an ongoing infection we observed a reduction in viral load both with mAbs having potent neutralizing capacity in-vitro as well as mAbs classified as non-neutralizing. In a therapeutic setting, neutralizing mAbs showed a greater capacity to reduce the viral burden compared to non-neutralizing antibodies. Efficacy was correlated with sustained concentration of virus neutralizing mAbs in-vivo rather than their in-vitro neutralizing capacity. Combinations of neutralizing mAbs further augmented the antiviral effect and were found to be as potent in protection as polyvalent serum from immune animals. Prophylactic administration of mAbs before infection was also protective and both neutralizing and non-neutralizing mAbs were equally effective in preventing lethal infection of immunodeficient mice. In summary, our data argue that therapeutic application of potently neutralizing mAbs against gB represent a strategy to modify the outcome of CMV infection in immunodeficient hosts. When present before infection, both neutralizing and non-neutralizing anti-gB exhibited protective capacity.
Collapse
Affiliation(s)
- Anna Bootz
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Astrid Karbach
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Johannes Spindler
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Kropff
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Nina Reuter
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Heinrich Sticht
- Institut für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Thomas H. Winkler
- Nikolaus-Fiebiger-Zentrum für Molekulare Medizin, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - William J. Britt
- Departments of Pediatrics, Microbiology and Neurobiology, Children's Hospital of Alabama, University of Alabama, School of Medicine, Birmingham, Alabama, United States of America
| | - Michael Mach
- Virologisches Institut, Klinische und Molekulare Virologie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| |
Collapse
|
8
|
Kropff B, Petersilka G, Flemmig T, Ehmke B, Heuft G, Schneider G. Success of a smoking cessation programme in smoking behaviour of chronic periodontitis patients and identification of predictors of motivation for smoking cessation - a pilot study. Int J Dent Hyg 2015; 14:168-77. [DOI: 10.1111/idh.12124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2014] [Indexed: 11/28/2022]
Affiliation(s)
- B Kropff
- Department of Psychosomatics and Psychotherapy; University of Münster; Münster Germany
| | - G Petersilka
- Department of Periodontology; University of Münster; Münster Germany
- Private Practice; Würzburg Germany
| | - T Flemmig
- Prince Philip Dental Hospital; Sai Ying Pun Hong Kong
| | - B Ehmke
- Department of Periodontology; University of Münster; Münster Germany
| | - G Heuft
- Department of Psychosomatics and Psychotherapy; University of Münster; Münster Germany
| | - G Schneider
- Department of Psychosomatics and Psychotherapy; University of Münster; Münster Germany
| |
Collapse
|
9
|
Kropff B, Burkhardt C, Schott J, Nentwich J, Fisch T, Britt W, Mach M. Glycoprotein N of human cytomegalovirus protects the virus from neutralizing antibodies. PLoS Pathog 2012; 8:e1002999. [PMID: 23133379 PMCID: PMC3486915 DOI: 10.1371/journal.ppat.1002999] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 09/11/2012] [Indexed: 11/19/2022] Open
Abstract
Herpes viruses persist in the infected host and are transmitted between hosts in the presence of a fully functional humoral immune response, suggesting that they can evade neutralization by antiviral antibodies. Human cytomegalovirus (HCMV) encodes a number of polymorphic highly glycosylated virion glycoproteins (g), including the essential envelope glycoprotein, gN. We have tested the hypothesis that glycosylation of gN contributes to resistance of the virus to neutralizing antibodies. Recombinant viruses carrying deletions in serine/threonine rich sequences within the glycosylated surface domain of gN were constructed in the genetic background of HCMV strain AD169. The deletions had no influence on the formation of the gM/gN complex and in vitro replication of the respective viruses compared to the parent virus. The gN-truncated viruses were significantly more susceptible to neutralization by a gN-specific monoclonal antibody and in addition by a number of gB- and gH-specific monoclonal antibodies. Sera from individuals previously infected with HCMV also more efficiently neutralized gN-truncated viruses. Immunization of mice with viruses that expressed the truncated forms of gN resulted in significantly higher serum neutralizing antibody titers against the homologous strain that was accompanied by increased antibody titers against known neutralizing epitopes on gB and gH. Importantly, neutralization activity of sera from animals immunized with gN-truncated virus did not exhibit enhanced neutralizing activity against the parental wild type virus carrying the fully glycosylated wild type gN. Our results indicate that the extensive glycosylation of gN could represent a potentially important mechanism by which HCMV neutralization by a number of different antibody reactivities can be inhibited. Herpes viruses are transmitted between individuals in cell free form and successful spread benefits from mechanisms that limit the loss of infectivity by the activity of virus neutralizing antibodies. Human cytomegalovirus (HCMV) is an important pathogen and understanding how the virus can evade antiviral antibodies may be clinically relevant. HCMV particles contain a number of highly polymorphic, extensively glycosylated envelope proteins, one of which is glycoprotein N (gN). This protein is essential for replication of HCMV. We have hypothesized that the extensive glycosylation of gN may serve as a tool to evade neutralization by antiviral antibodies. Recombinant viruses were generated expressing gN proteins with reduced glycan modification. The loss of glycan modification had no detectable influence on the in vitro replication of the respective viruses. However, the recombinant viruses containing under-glycosylated forms of gN were significantly more susceptible to neutralization by a diverse array of antibody reactivities. Immunization of mice with viruses carrying fewer glycan modification induced significantly higher antibody titers against the homologous virus; however, the neutralization titers against the fully glycosylated virions, were not enhanced. Our results indicate that glycosylation of gN of HCMV represents a potentially important mechanism for evasion of antibody-mediated neutralization by a number of different antibody specificities.
Collapse
Affiliation(s)
- Barbara Kropff
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Germany
| | - Christiane Burkhardt
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Germany
| | - Juliane Schott
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Germany
| | - Jens Nentwich
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Germany
| | - Tanja Fisch
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Germany
| | - William Britt
- Department of Pediatrics, University of Alabama Birmingham, Birmingham, Alabama, United States of America
| | - Michael Mach
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Germany
- * E-mail:
| |
Collapse
|
10
|
Mach M, Osinski K, Kropff B, Schloetzer-Schrehardt U, Krzyzaniak M, Britt W. The carboxy-terminal domain of glycoprotein N of human cytomegalovirus is required for virion morphogenesis. J Virol 2007; 81:5212-24. [PMID: 17229708 PMCID: PMC1900226 DOI: 10.1128/jvi.01463-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycoproteins M and N (gM and gN, respectively) are among the few proteins that are conserved across the herpesvirus family. The function of the complex is largely unknown. Whereas deletion from most alphaherpesviruses has marginal effects on the replication of the respective viruses, both proteins are essential for replication of human cytomegalovirus (HCMV). We have constructed a series of mutants in gN to study the function of this protein. gN of HCMV is a type I glycoprotein containing a short carboxy-terminal domain of 14 amino acids, including two cysteine residues directly adjacent to the predicted transmembrane anchor at positions 125 and 126. Deletion of the entire carboxy-terminal domain as well as substitution with the corresponding region from alpha herpesviruses or mutations of both cysteine residues resulted in a replication-incompetent virus. Recombinant viruses containing point mutations of either cysteine residue could be generated. These viruses were profoundly defective for replication. Complex formation of the mutant gNs with gM and transport of the complex to the viral assembly compartment appeared unaltered compared to the wild type. However, in infected cells, large numbers of capsids accumulated in the cytoplasm that failed to acquire an envelope. Transiently expressed gN was shown to be modified by palmitic acid at both cysteine residues. In summary, our data suggest that the carboxy-terminal domain of gN plays a critical role in secondary envelopment of HCMV and that palmitoylation of gN appears to be essential for function in secondary envelopment of HCMV and virus replication.
Collapse
Affiliation(s)
- Michael Mach
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
| | | | | | | | | | | |
Collapse
|
11
|
Spaderna S, Kropff B, Ködel Y, Shen S, Coley S, Lu S, Britt W, Mach M. Deletion of gpUL132, a structural component of human cytomegalovirus, results in impaired virus replication in fibroblasts. J Virol 2005; 79:11837-47. [PMID: 16140760 PMCID: PMC1212622 DOI: 10.1128/jvi.79.18.11837-11847.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The coding capacity of human cytomegalovirus (HCMV) for glycoproteins by far exceeds that of other herpesviruses. Few of these proteins have been characterized so far. We have investigated the gene product of reading frame UL132. The putative protein product of UL132 is a glycoprotein with a theoretical mass of 29.8 kDa. Transcription analysis revealed that the gene is transcribed with a true late kinetics from the laboratory-adapted strain AD169 and the low-passage isolate TB40E. Two proteins of 22 to 28 kDa and 45 to 60 kDa were detected in virus-infected cells as well as in extracellular virions. The larger protein carried N-linked carbohydrates. Both protein forms were present in laboratory-adapted strains as well as in low-passage isolates of HCMV. Recombinant viruses with the UL132 gene deleted were constructed in the low-passage HCMV isolate PAN as well as the high-passage isolate AD169. Deletion of UL132 from either genome resulted in a pronounced replication deficit with a reduction of approximately 100-fold for HCMV strain AD169. Thus, the protein product of the UL132 reading frame represents a structural viral glycoprotein of HCMV that has an important function for viral replication in tissue culture.
Collapse
Affiliation(s)
- Simone Spaderna
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
The genomes of herpesviruses contain a number of genes which are conserved throughout the family of Herpesviridae, indicating that the proteins may serve important functions in the replication of these viruses. Among these are several envelope glycoproteins, including glycoprotein M (gM) and gN, which form a complex that is covalently linked via disulfide bonds in some herpesviruses. However, deletion of gM and/or gN from most alphaherpesviruses has limited effects on replication of the respective viruses in vitro. In contrast, insertional inactivation of the gM gene of the betaherpesvirus human cytomegalovirus (HCMV) results in a replication-incompetent virus. We have started to analyze the structural and functional aspects of the interaction between gM and gN of HCMV. We show that large parts of gM are dispensable for the formation of a gM/gN complex that is transported to distal parts of the cellular secretory pathway. In addition, we demonstrate that the disulfide bond is between the cysteine at position 44 in gM and cysteine 90 in gN. However, disulfide linkage is not a prerequisite for modification and transport of the gM/gN complex. Moreover, mutant viruses that lack a disulfide bridge between gM and gN replicate with efficiencies similar to that of wild-type viruses.
Collapse
Affiliation(s)
- Michael Mach
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
| | | | | | | |
Collapse
|
13
|
Abstract
CD40 has been identified as an important molecule for a number of processes, such as immune responses, inflammation, and the activation of endothelia. We investigated CD40 in endothelial cells (EC) following infection with an endotheliotropic strain of human cytomegalovirus (HCMV). Between 8 and 72 h postinfection, we observed a significant increase in CD40 levels on the surface of infected EC, as measured by fluorescence-activated cell sorting analysis. As a consequence of CD40 upregulation, increased levels of E-selectin were found on infected EC after stimulation with CD154-expressing T cells. Enhanced expression of CD40 was specific for EC, since infection of fibroblasts did not result in the upregulation of CD40. The addition of neutralizing antibodies as well as UV inactivation of virus completely prevented the upregulation of CD40 on EC. Also, laboratory-adapted HCMV strain AD169 was not able to induce CD40 on EC. De novo protein synthesis was necessary for the increased surface expression. At early times (4 to 24 h) postinfection, this change was not accompanied by increased levels of CD40 protein or mRNA. At late times (48 to 96 h) postinfection, increased amounts of CD40 protein and mRNA were detected. Immunohistochemical analysis of infected tissues demonstrated elevated levels of CD40 on HCMV-infected EC in vivo. Thus, infection of EC by HCMV may result in the activation of endothelia and in the augmentation of inflammatory processes.
Collapse
Affiliation(s)
- Tim Maisch
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany
| | | | | | | |
Collapse
|
14
|
Abstract
The envelope glycoproteins of human cytomegalovirus (HCMV) virions are incompletely characterized. We have analyzed complex formation between glycoprotein M (gM or gpUL100) and a second glycoprotein. gM-homologous proteins are conserved throughout the herpesvirus family and represent type III membrane proteins containing multiple hydrophobic sequences. In extracellular HCMV particles, gM was found to be complexed through disulfide bonds to a second protein with an apparent molecular mass of 50 to 60 kDa. The 50- to 60-kDa protein was found to be derived from reading frame UL73 of HCMV strain AD169. UL73-homologous genes are also conserved within herpesviruses. When transiently expressed by itself, the UL73 gene product consisted of a protein of 18 kDa. However, in the presence of gM, the UL73 gene product was posttranslationally modified to the 50- to 60-kDa species. Thus, gM and the UL73 gene product, which represents the gN homolog of herpesviruses, form a disulfide-linked complex in HCMV virions. Transient expression of gM and gN followed by fluorescence imaging with monoclonal antibodies against either protein demonstrated that complex formation was required for transport of the proteins from the endoplasmic reticulum to the Golgi and trans-Golgi compartments. Finally, we tested the gM-gN complex for reactivity with sera from HCMV-seropositive donors. Whereas most sera failed to react with either gM or gN when expressed alone, 62% of sera were positive for the gM-gN complex. Because a murine monoclonal antibody reactive with gN in the gM-gN complex efficiently neutralizes infectious virus, the gM-gN complex may represent a major antigenic target of antiviral antibody responses.
Collapse
Affiliation(s)
- M Mach
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Erlangen, Germany.
| | | | | | | |
Collapse
|
15
|
Abstract
Glycoprotein B (gB, gpUL55) is the major antigen recognized by the neutralizing humoral immune response against human cytomegalovirus (HCMV). The immunodominant region on gB is the antigenic domain 1 (AD-1), a complex structure that requires a minimal continuous sequence of more than 75 amino acids (aa 552-635) for antibody binding. In this study, the structural requirements for antibody binding to AD-1 have been determined. The domain was expressed in prokaryotic and eukaryotic systems and analysed in immunoblots under reducing and non-reducing conditions. In addition, AD-1 was purified in an immunologically active form and the concentration of sulphydryl groups was determined. The data clearly show that the only form that is recognized by antibodies is a disulphide-linked monomer of AD-1. The disulphide bond is formed between cysteines at amino acid positions 573 and 610 of gB.
Collapse
Affiliation(s)
- Andrea Speckner
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schloßgarten 4, 91054 Erlangen, Germany1
| | - Barbara Kropff
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schloßgarten 4, 91054 Erlangen, Germany1
| | - Susanne Knör
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schloßgarten 4, 91054 Erlangen, Germany1
| | - Michael Mach
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Schloßgarten 4, 91054 Erlangen, Germany1
| |
Collapse
|
16
|
Kropff B, Mach M. Identification of the gene coding for rhesus cytomegalovirus glycoprotein B and immunological analysis of the protein. J Gen Virol 1997; 78 ( Pt 8):1999-2007. [PMID: 9267000 DOI: 10.1099/0022-1317-78-8-1999] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The nucleotide sequence of the gene encoding glycoprotein B (gB) of rhesus cytomegalovirus (RhCMV) was determined and the protein characterized. The open reading frame of gB encoded a protein of 854 amino acids with 60% identity and 75% similarity at the amino acid level to human cytomegalovirus (HCMV) gB. Cysteine residues in the extraluminal part of the protein are perfectly conserved. Out of the 16 potential N-linked glycosylation sites present in HCMV gB, 15 are conserved in RhCMV gB. Immunoblot analyses with antisera detected three bands of 150 kDa, 90-110 kDa and 55 kDa representing the full-length gB as well as the proteolytic cleavage products. Cross-reactivity and cross-neutralization of a number of HCMV gB-specific monoclonal antibodies with RhCMV gB indicated sharing of immunogenic epitopes between the two molecules. The RhCMV gB regions corresponding to antigenic domains AD-1, 2 and 3 of HCMV gB were immunogenic during natural RhCMV infection with the AD-1 region being the immunodominant domain. The data indicate that RhCMV might represent a useful model to investigate pathogenesis and immune surveillance of cytomegaloviruses.
Collapse
Affiliation(s)
- B Kropff
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Erlangen, Germany
| | | |
Collapse
|
17
|
Schoppel K, Kropff B, Schmidt C, Vornhagen R, Mach M. The humoral immune response against human cytomegalovirus is characterized by a delayed synthesis of glycoprotein-specific antibodies. J Infect Dis 1997; 175:533-44. [PMID: 9041323 DOI: 10.1093/infdis/175.3.533] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
An individual analysis of IgG antibodies against 12 known antigenic domains of human cytomegalovirus (HCMV)-derived structural phospho- and glycoproteins and nonstructural polypeptides was performed. In HCMV-seropositive healthy persons, the separate determination of antibody titers against the various antigens resulted in an antibody profile that was characteristic for each individual. Profiles were qualitatively stable over a period of >4 years. However, quantitative changes were observed in some persons. During primary HCMV infection, a delay of 50-100 days in the appearance of glycoprotein-specific antibodies was observed, whereas immunoglobulins directed against other HCMV-specific antigens were promptly synthesized. In contrast, during reactivation or reinfection, a synchronized production of antibodies was found. Levels of glycoprotein-specific antibodies and detection of viral DNA in peripheral blood inversely correlated. Precursor B cell analyses showed no significant differences between glycoprotein-specific and phosphoprotein-specific B cells.
Collapse
Affiliation(s)
- K Schoppel
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
| | | | | | | | | |
Collapse
|
18
|
Abstract
The potential of selected proteins of human cytomegalovirus (HCMV) to induce a helper T (Th) cell immune response was investigated in healthy HCMV-seropositive donors. Recombinant derived glycoproteins B (gpUL55), H (gpUL75), integral membrane protein (pUL100), the US6-US11 glycoprotein family (pUS6-US11), the matrix proteins pp65 (ppUL83), pp28 (ppUL99) and the immediate early proteins IE1 (pUL123), IE2 (pUL122) and UL69 (pUL69) were used as stimulating antigens in a lymphocyte proliferation assay. The antigen-specific proliferative response was measured in HCMV-specific T cell lines (phenotype CD4+ CD8-) generated from five donors by stimulation of peripheral blood mononuclear cells with purified HCMV or HCMV-infected fibroblasts. A proliferative T cell response was induced by pp65, gB, gH, IE1, IE2 and UL69, with a dominant response to pp65 in all donors. Three T cell lines responded to gB and gH, respectively. For IE1, IE2 and UL69 a T cell stimulation could be demonstrated in single cell lines generated with lysate of HCMV-infected fibroblasts.
Collapse
Affiliation(s)
- J Beninga
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Germany
| | | | | |
Collapse
|
19
|
Abstract
Two prokaryotically expressed fusion proteins encompassing amino acids 484-650 (AD-1) and 27-100 (AD-2) of glycoprotein gp58/116 of human cytomegalovirus (HCMV) were purified from E. coli lysates and used in ELISA to determine antibody levels in human sera. The specificity of the test was established by comparison of 116 randomly selected sera with commercially available HCMV-ELISA tests. The recombinant polypeptides were then used for the analysis of antibody titers in 112 human sera and were compared to the capacity to neutralize HCMV. A strong correlation between the neutralization titer and antibody levels against AD-1 and a weaker correlation for AD-2 was observed. Of 29 sera with a high neutralization titer (> 1:128), 96% and 62% were positive for AD-1 and AD-2, respectively, while 44% and 19% were positive in sera with low neutralization titer (< 1:8). Serum pools prepared from human sera selected on the basis of recognition of the recombinant antigens had a 10-fold higher neutralization capacity than pools prepared from sera with a high titer in commercially available HCMV tests. A synchronous increase in neutralization capacity and titer against recombinant antigens was observed in transplant patients.
Collapse
Affiliation(s)
- B Kropff
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Germany
| | | | | |
Collapse
|
20
|
Wagner B, Kropff B, Kalbacher H, Britt W, Sundqvist VA, Ostberg L, Mach M. A continuous sequence of more than 70 amino acids is essential for antibody binding to the dominant antigenic site of glycoprotein gp58 of human cytomegalovirus. J Virol 1992; 66:5290-7. [PMID: 1323695 PMCID: PMC289083 DOI: 10.1128/jvi.66.9.5290-5297.1992] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Antigenic domain 1 (AD-1) on glycoprotein gp58 of human cytomegalovirus was characterized in detail, using mouse and human monoclonal antibodies as well as human convalescent sera. Series of procaryotically expressed fusion proteins and synthetic peptides of various lengths were used as sources of antigen. Binding of antibodies was found to depend on a continuous sequence of more than 70 amino acids between residues 552 and 635 of gp58. The fine specificities for sequences involved in antibody binding were (i) amino acids 557 to 635 for neutralizing as well as nonneutralizing mouse monoclonal antibodies, (ii) amino acids 552 to 630 for a neutralizing human monoclonal antibody, and (iii) amino acids 557 to 630 for antibodies present in human sera. Experiments involving fragments of AD-1, presented either as procaryotically expressed fusion protein or as synthetic peptides, indicated that the intact structure was required for recognition of AD-1 by antibodies.
Collapse
Affiliation(s)
- B Wagner
- Institut für Klinische und Molekulare Virologie, Universität Erlangen-Nürnberg, Germany
| | | | | | | | | | | | | |
Collapse
|