1
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Bootz A, Reuter N, Nimmerjahn F, Britt WJ, Mach M, Winkler TH. Functional Fc receptors are crucial in antibody-mediated protection against cytomegalovirus. Eur J Immunol 2024; 54:e2451044. [PMID: 39014923 DOI: 10.1002/eji.202451044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 07/07/2024] [Accepted: 07/09/2024] [Indexed: 07/18/2024]
Abstract
Human cytomegalovirus is a medically important pathogen. Previously, using murine CMV (MCMV), we provided evidence that both neutralizing and nonneutralizing antibodies can confer protection from viral infection in vivo. In this study, we report that serum derived from infected animals had a greater protective capacity in MCMV-infected RAG-/- mice than serum from animals immunized with purified virus. The protective activity of immune serum was strictly dependent on functional Fcγ receptors (FcγR). Deletion of individual FcγRs or combined deletion of FcγRI and FcγRIV had little impact on the protection afforded by serum. Adoptive transfer of CD115-positive cells from noninfected donors demonstrated that monocytes represent important cellular mediators of the protective activity provided by immune serum. Our studies suggest that Fc-FcγR interactions and monocytic cells are critical for antibody-mediated protection against MCMV infection in vivo. These findings may provide new avenues for the development of novel strategies for more effective CMV vaccines or antiviral immunotherapies.
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Affiliation(s)
- Anna Bootz
- Institute of Clinical and Molecular Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Nina Reuter
- Institute of Clinical and Molecular Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Falk Nimmerjahn
- Division of Genetics, Department Biology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - William J Britt
- Departments of Pediatrics, Microbiology and Neurobiology, Children's Hospital of Alabama, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Michael Mach
- Institute of Clinical and Molecular Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Thomas H Winkler
- Division of Genetics, Department Biology, Nikolaus-Fiebiger-Center of Molecular Medicine, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
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2
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Ebert S, Böhm V, Büttner JK, Brune W, Brinkmann MM, Holtappels R, Reddehase MJ, Lemmermann NAW. Cytomegalovirus inhibitors of programmed cell death restrict antigen cross-presentation in the priming of antiviral CD8 T cells. PLoS Pathog 2024; 20:e1012173. [PMID: 39146364 PMCID: PMC11349235 DOI: 10.1371/journal.ppat.1012173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 08/27/2024] [Accepted: 08/02/2024] [Indexed: 08/17/2024] Open
Abstract
CD8 T cells are the predominant effector cells of adaptive immunity in preventing cytomegalovirus (CMV) multiple-organ disease caused by cytopathogenic tissue infection. The mechanism by which CMV-specific, naïve CD8 T cells become primed and clonally expand is of fundamental importance for our understanding of CMV immune control. For CD8 T-cell priming, two pathways have been identified: direct antigen presentation by infected professional antigen-presenting cells (pAPCs) and antigen cross-presentation by uninfected pAPCs that take up antigenic material derived from infected tissue cells. Studies in mouse models using murine CMV (mCMV) and precluding either pathway genetically or experimentally have shown that, in principle, both pathways can congruently generate the mouse MHC/H-2 class-I-determined epitope-specificity repertoire of the CD8 T-cell response. Recent studies, however, have shown that direct antigen presentation is the canonical pathway when both are accessible. This raised the question of why antigen cross-presentation is ineffective even under conditions of high virus replication thought to provide high amounts of antigenic material for feeding cross-presenting pAPCs. As delivery of antigenic material for cross-presentation is associated with programmed cell death, and as CMVs encode inhibitors of different cell death pathways, we pursued the idea that these inhibitors restrict antigen delivery and thus CD8 T-cell priming by cross-presentation. To test this hypothesis, we compared the CD8 T-cell responses to recombinant mCMVs lacking expression of the apoptosis-inhibiting protein M36 or the necroptosis-inhibiting protein M45 with responses to wild-type mCMV and revertant viruses expressing the respective cell death inhibitors. The data reveal that increased programmed cell death improves CD8 T-cell priming in mice capable of antigen cross-presentation but not in a mutant mouse strain unable to cross-present. These findings strongly support the conclusion that CMV cell death inhibitors restrict the priming of CD8 T cells by antigen cross-presentation.
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Affiliation(s)
- Stefan Ebert
- Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Verena Böhm
- Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Julia K. Büttner
- Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Wolfram Brune
- Leibniz Institute of Virology (LIV), Hamburg, Germany
| | - Melanie M. Brinkmann
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
- Virology and Innate Immunity Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Rafaela Holtappels
- Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- Research Center for Immunotherapy (FZI), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Matthias J. Reddehase
- Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- Research Center for Immunotherapy (FZI), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Niels A. W. Lemmermann
- Institute for Virology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- Research Center for Immunotherapy (FZI), University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- Institute of Virology, Medical Faculty, University of Bonn, Bonn, Germany
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3
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Kobayashi R, Hashida N. Overview of Cytomegalovirus Ocular Diseases: Retinitis, Corneal Endotheliitis, and Iridocyclitis. Viruses 2024; 16:1110. [PMID: 39066272 PMCID: PMC11281654 DOI: 10.3390/v16071110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/24/2024] [Accepted: 06/29/2024] [Indexed: 07/28/2024] Open
Abstract
Cytomegalovirus (CMV) infection is a significant clinical concern in newborns, immunocompromised patients with acquired immunodeficiency syndrome (AIDS), and patients undergoing immunosuppressive therapy or chemotherapy. CMV infection affects many organs, such as the lungs, digestive organs, the central nerve system, and eyes. In addition, CMV infection sometimes occurs in immunocompetent individuals. CMV ocular diseases includes retinitis, corneal endotheliitis, and iridocyclitis. CMV retinitis often develops in infected newborns and immunocompromised patients. CMV corneal endotheliitis and iridocyclitis sometimes develop in immunocompetent individuals. Systemic infections and CMV ocular diseases often require systemic treatment in addition to topical treatment.
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Affiliation(s)
| | - Noriyasu Hashida
- Department of Ophthalmology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
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4
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Li R, Galindo CC, Davidson D, Guo H, Zhong MC, Qian J, Li B, Ruzsics Z, Lau CM, O'Sullivan TE, Vidal SM, Sun JC, Veillette A. Suppression of adaptive NK cell expansion by macrophage-mediated phagocytosis inhibited by 2B4-CD48. Cell Rep 2024; 43:113800. [PMID: 38386559 DOI: 10.1016/j.celrep.2024.113800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 12/21/2023] [Accepted: 01/31/2024] [Indexed: 02/24/2024] Open
Abstract
Infection of mice by mouse cytomegalovirus (MCMV) triggers activation and expansion of Ly49H+ natural killer (NK) cells, which are virus specific and considered to be "adaptive" or "memory" NK cells. Here, we find that signaling lymphocytic activation molecule family receptors (SFRs), a group of hematopoietic cell-restricted receptors, are essential for the expansion of Ly49H+ NK cells after MCMV infection. This activity is largely mediated by CD48, an SFR broadly expressed on NK cells and displaying augmented expression after MCMV infection. It is also dependent on the CD48 counter-receptor, 2B4, expressed on host macrophages. The 2B4-CD48 axis promotes expansion of Ly49H+ NK cells by repressing their phagocytosis by virus-activated macrophages through inhibition of the pro-phagocytic integrin lymphocyte function-associated antigen-1 (LFA-1) on macrophages. These data identify key roles of macrophages and the 2B4-CD48 pathway in controlling the expansion of adaptive NK cells following MCMV infection. Stimulation of the 2B4-CD48 axis may be helpful in enhancing adaptive NK cell responses for therapeutic purposes.
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Affiliation(s)
- Rui Li
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada; Department of Medicine, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Cristian Camilo Galindo
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada; Department of Medicine, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Dominique Davidson
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Huaijian Guo
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada; Department of Medicine, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Ming-Chao Zhong
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Jin Qian
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Bin Li
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada; Molecular Biology Program, University of Montréal, Montréal, QC H3T 1J4, Canada
| | - Zsolt Ruzsics
- Institute of Virology, University Medical Center, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Colleen M Lau
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Timothy E O'Sullivan
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Silvia M Vidal
- Department of Human Genetics, McGill University, Montréal, QC H3A 0C7, Canada; Dahdaleh Institute of Genomic Medicine, McGill University, Montréal, QC H3A 0G1, Canada
| | - Joseph C Sun
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Department of Immunology and Microbial Pathogenesis, Weill Cornell Medical College, New York, NY 10065, USA
| | - André Veillette
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada; Department of Medicine, McGill University, Montréal, QC H3G 1Y6, Canada; Molecular Biology Program, University of Montréal, Montréal, QC H3T 1J4, Canada.
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5
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Annis JL, Duncan JBW, Billcheck HO, Kuzma AG, Crittenden RB, Brown MG. Multiple Immune and Genetic Mechanisms Contribute to Cmv5s-Driven Susceptibility and Tissue Damage during Acute Murine Cytomegalovirus Infection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2024; 212:813-824. [PMID: 38224204 PMCID: PMC10922835 DOI: 10.4049/jimmunol.2300648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 12/31/2023] [Indexed: 01/16/2024]
Abstract
The MHC class I molecule H-2Dk conveys resistance to acute murine CMV infection in both C57L (H-2Dk transgenic) and MA/My mice. M.H2k/b mice are on an MA/My background aside from a C57L-derived region spanning the MHC (Cmv5s), which diminishes this resistance and causes significant spleen histopathology. To hone in on the effector elements within the Cmv5s interval, we generated several Cmv5-recombinant congenic mouse strains and screened them in vivo, allowing us to narrow the phenotype-associated interval >6-fold and segment the genetic mechanism to at least two independent loci within the MHC region. In addition, we sought to further characterize the Cmv5s-associated phenotypes in their temporal appearance and potential direct relationship to viral load. To this end, we found that Cmv5s histopathology and NK cell activation could not be fully mirrored in the MA/My mice with increased viral dose, and that marginal zone destruction was the first apparent Cmv5s phenotype, being reliably quantified as early as 2 d postinfection in the M.H2k/b mice, prior to divergence in viral load, weight loss, or NK cell phenotype. Finally, we further dissect NK cell involvement, finding no intrinsic differences in NK cell function, despite increased upregulation of activation markers and checkpoint receptors. In conclusion, these data dissect the genetic and immunologic underpinnings of Cmv5 and reveal a model in which polymorphism within the MHC region of the genome leads to the development of tissue damage and corrupts protective NK cell immunity during acute viral infection.
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Affiliation(s)
- Jessica L. Annis
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville Virginia, USA
- Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, USA
| | - John Benjamin W. Duncan
- Biomedical Sciences Graduate Program, School of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Helen O. Billcheck
- Center for Comparative Medicine, School of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Anna G. Kuzma
- Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, USA
- Department of Medicine, Division of Nephrology, University of Virginia, Charlottesville, Virginia, USA
| | - Rowena B. Crittenden
- Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, USA
- Department of Medicine, Division of Nephrology, University of Virginia, Charlottesville, Virginia, USA
| | - Michael G. Brown
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville Virginia, USA
- Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, USA
- Department of Medicine, Division of Nephrology, University of Virginia, Charlottesville, Virginia, USA
- Center for Immunity, Inflammation, and Regenerative Medicine, University of Virginia, Charlottesville, Virginia, USA
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6
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Kandalla PK, Subburayalu J, Cocita C, de Laval B, Tomasello E, Iacono J, Nitsche J, Canali MM, Cathou W, Bessou G, Mossadegh‐Keller N, Huber C, Mouchiroud G, Bourette RP, Grasset M, Bornhäuser M, Sarrazin S, Dalod M, Sieweke MH. M-CSF directs myeloid and NK cell differentiation to protect from CMV after hematopoietic cell transplantation. EMBO Mol Med 2023; 15:e17694. [PMID: 37635627 PMCID: PMC10630876 DOI: 10.15252/emmm.202317694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 07/25/2023] [Accepted: 07/25/2023] [Indexed: 08/29/2023] Open
Abstract
Therapies reconstituting autologous antiviral immunocompetence may represent an important prophylaxis and treatment for immunosuppressed individuals. Following hematopoietic cell transplantation (HCT), patients are susceptible to Herpesviridae including cytomegalovirus (CMV). We show in a murine model of HCT that macrophage colony-stimulating factor (M-CSF) promoted rapid antiviral activity and protection from viremia caused by murine CMV. M-CSF given at transplantation stimulated sequential myeloid and natural killer (NK) cell differentiation culminating in increased NK cell numbers, production of granzyme B and interferon-γ. This depended upon M-CSF-induced myelopoiesis leading to IL15Rα-mediated presentation of IL-15 on monocytes, augmented by type I interferons from plasmacytoid dendritic cells. Demonstrating relevance to human HCT, M-CSF induced myelomonocytic IL15Rα expression and numbers of functional NK cells in G-CSF-mobilized hematopoietic stem and progenitor cells. Together, M-CSF-induced myelopoiesis triggered an integrated differentiation of myeloid and NK cells to protect HCT recipients from CMV. Thus, our results identify a rationale for the therapeutic use of M-CSF to rapidly reconstitute antiviral activity in immunocompromised individuals, which may provide a general paradigm to boost innate antiviral immunocompetence using host-directed therapies.
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Affiliation(s)
- Prashanth K Kandalla
- Center for Regenerative Therapies Dresden (CRTD)Technical University DresdenDresdenGermany
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
| | - Julien Subburayalu
- Center for Regenerative Therapies Dresden (CRTD)Technical University DresdenDresdenGermany
- Department of Internal Medicine IUniversity Hospital Carl Gustav Carus DresdenDresdenGermany
| | - Clément Cocita
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
- Aix‐Marseille University, CNRS, INSERMCIML, Turing Center for Living SystemsMarseilleFrance
| | | | - Elena Tomasello
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
- Aix‐Marseille University, CNRS, INSERMCIML, Turing Center for Living SystemsMarseilleFrance
| | - Johanna Iacono
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
| | - Jessica Nitsche
- Center for Regenerative Therapies Dresden (CRTD)Technical University DresdenDresdenGermany
| | - Maria M Canali
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
| | | | - Gilles Bessou
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
- Aix‐Marseille University, CNRS, INSERMCIML, Turing Center for Living SystemsMarseilleFrance
| | | | - Caroline Huber
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
| | | | - Roland P Bourette
- CNRS, INSERM, CHU Lille, University LilleUMR9020‐U1277 ‐ CANTHER – Cancer Heterogeneity Plasticity and Resistance to TherapiesLilleFrance
| | | | - Martin Bornhäuser
- Center for Regenerative Therapies Dresden (CRTD)Technical University DresdenDresdenGermany
- Department of Internal Medicine IUniversity Hospital Carl Gustav Carus DresdenDresdenGermany
- National Center for Tumor Diseases (NCT), DresdenDresdenGermany
| | - Sandrine Sarrazin
- Center for Regenerative Therapies Dresden (CRTD)Technical University DresdenDresdenGermany
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
| | - Marc Dalod
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
- Aix‐Marseille University, CNRS, INSERMCIML, Turing Center for Living SystemsMarseilleFrance
| | - Michael H Sieweke
- Center for Regenerative Therapies Dresden (CRTD)Technical University DresdenDresdenGermany
- Aix Marseille University, CNRS, INSERMCIMLMarseilleFrance
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7
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Mody PH, Marvin KN, Hynds DL, Hanson LK. Cytomegalovirus infection induces Alzheimer's disease-associated alterations in tau. J Neurovirol 2023; 29:400-415. [PMID: 37436577 DOI: 10.1007/s13365-022-01109-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/21/2022] [Accepted: 12/01/2022] [Indexed: 07/13/2023]
Abstract
Alzheimer's disease (AD) manifests with loss of neurons correlated with intercellular deposition of amyloid (amyloid plaques) and intracellular neurofibrillary tangles of hyperphosphorylated tau. However, targeting AD hallmarks has not as yet led to development of an effective treatment despite numerous clinical trials. A better understanding of the early stages of neurodegeneration may lead to development of more effective treatments. One underexplored area is the clinical correlation between infection with herpesviruses and increased risk of AD. We hypothesized that similar to work performed with herpes simplex virus 1 (HSV1), infection with the cytomegalovirus (CMV) herpesvirus increases levels and phosphorylation of tau, similar to AD tauopathy. We used murine CMV (MCMV) to infect mouse fibroblasts and rat neuronal cells to test our hypothesis. MCMV infection increased steady-state levels of primarily high molecular weight forms of tau and altered the patterns of tau phosphorylation. Both changes required viral late gene products. Glycogen synthase kinase 3 beta (GSK3β) was upregulated in the HSVI model, but inhibition with lithium chloride suggested that this enzyme is unlikely to be involved in MCMV infection mediated tau phosphorylation. Thus, we confirm that MCMV, a beta herpes virus, like alpha herpes viruses (e.g., HSV1), can promote tau pathology. This suggests that CMV infection can be useful as another model system to study mechanisms leading to neurodegeneration. Since MCMV infects both mice and rats as permissive hosts, our findings from tissue culture can likely be applied to a variety of AD models to study development of abnormal tau pathology.
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Affiliation(s)
- Prapti H Mody
- Division of Biology, Texas Woman's University, 304 Administration Drive, Denton, TX, 76204, USA
- Current affiliation: University of Texas Southwestern Medical Center, Dallas, USA
| | - Kelsey N Marvin
- Division of Biology, Texas Woman's University, 304 Administration Drive, Denton, TX, 76204, USA
| | - DiAnna L Hynds
- Division of Biology, Texas Woman's University, 304 Administration Drive, Denton, TX, 76204, USA
| | - Laura K Hanson
- Division of Biology, Texas Woman's University, 304 Administration Drive, Denton, TX, 76204, USA.
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8
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Khalil M, Mei A, Hashemi E, Wang D, Schumacher M, Terhune S, Malarkannan S. Method to Study Adaptive NK Cells Following MCMV Infections. Methods Mol Biol 2022; 2463:195-204. [PMID: 35344176 DOI: 10.1007/978-1-0716-2160-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Immunological memory is a fundamental feature of the adaptive immune system that protects the host from recurrent infections from pathogens. Natural killer (NK) cells are a predominant member of the innate immune system that lack clonotypic receptors, which are essential for memory formation. However, evidence demonstrates that a unique subpopulation of NK cells develops adaptive-like features using germline-encoded receptors. Recent studies have shown that infection of cytomegalovirus (CMV) leads to clonal expansion of NKG2C+ and Ly49H+ NK cells, in humans and mouse, respectively. These activation receptors have the capability to recognize CMV-encoded proteins and facilitate a recall response upon reinfection. Although NK cells do not rearrange genes encoding their activating receptors as seen in B and T cells, they possess a selective process to generate memory features and a long-lived progeny. Here, we describe an established in vivo protocol for infecting mice with mouse cytomegalovirus (MCMV) to study an adaptive NK cell response.
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Affiliation(s)
- Mohamed Khalil
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Ao Mei
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Elaheh Hashemi
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Dandan Wang
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Megan Schumacher
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Scott Terhune
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Subramaniam Malarkannan
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA.
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA.
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA.
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA.
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9
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Bellomo A, Gentek R, Golub R, Bajénoff M. Macrophage-fibroblast circuits in the spleen. Immunol Rev 2021; 302:104-125. [PMID: 34028841 DOI: 10.1111/imr.12979] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/30/2021] [Accepted: 04/30/2021] [Indexed: 12/22/2022]
Abstract
Macrophages are an integral part of all organs in the body, where they contribute to immune surveillance, protection, and tissue-specific homeostatic functions. This is facilitated by so-called niches composed of macrophages and their surrounding stroma. These niches structurally anchor macrophages and provide them with survival factors and tissue-specific signals that imprint their functional identity. In turn, macrophages ensure appropriate functioning of the niches they reside in. Macrophages thus form reciprocal, mutually beneficial circuits with their cellular niches. In this review, we explore how this concept applies to the spleen, a large secondary lymphoid organ whose primary functions are to filter the blood and regulate immunity. We first outline the splenic micro-anatomy, the different populations of splenic fibroblasts and macrophages and their respective contribution to protection of and key physiological processes occurring in the spleen. We then discuss firmly established and potential cellular circuits formed by splenic macrophages and fibroblasts, with an emphasis on the molecular cues underlying their crosstalk and their relevance to splenic functionality. Lastly, we conclude by considering how these macrophage-fibroblast circuits might be impaired by aging, and how understanding these changes might help identify novel therapeutic avenues with the potential of restoring splenic functions in the elderly.
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Affiliation(s)
- Alicia Bellomo
- CIRI, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, École Normale Supérieure de Lyon, Univ Lyon, Lyon, France
| | - Rebecca Gentek
- Centre for Inflammation Research & Centre for Reproductive Health, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Rachel Golub
- Inserm U1223, Institut Pasteur, Paris, France.,Lymphopoiesis Unit, Institut Pasteur, Paris, France
| | - Marc Bajénoff
- Aix Marseille Univ, CNRS, INSERM, CIML, Marseille, France
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10
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Murine cytomegaloviruses m139 targets DDX3 to curtail interferon production and promote viral replication. PLoS Pathog 2020; 16:e1008546. [PMID: 33031466 PMCID: PMC7575108 DOI: 10.1371/journal.ppat.1008546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 10/20/2020] [Accepted: 09/09/2020] [Indexed: 12/13/2022] Open
Abstract
Cytomegaloviruses (CMV) infect many different cell types and tissues in their respective hosts. Monocytes and macrophages play an important role in CMV dissemination from the site of infection to target organs. Moreover, macrophages are specialized in pathogen sensing and respond to infection by secreting cytokines and interferons. In murine cytomegalovirus (MCMV), a model for human cytomegalovirus, several genes required for efficient replication in macrophages have been identified, but their specific functions remain poorly understood. Here we show that MCMV m139, a gene of the conserved US22 gene family, encodes a protein that interacts with the DEAD box helicase DDX3, a protein involved in pathogen sensing and interferon (IFN) induction, and the E3 ubiquitin ligase UBR5. DDX3 and UBR5 also participate in the transcription, processing, and translation of a subset of cellular mRNAs. We show that m139 inhibits DDX3-mediated IFN-α and IFN-β induction and is necessary for efficient viral replication in bone-marrow derived macrophages. In vivo, m139 is crucial for viral dissemination to local lymph nodes and to the salivary glands. An m139-deficient MCMV also replicated to lower titers in SVEC4-10 endothelial cells. This replication defect was not accompanied by increased IFN-β transcription, but was rescued by knockout of either DDX3 or UBR5. Moreover, m139 co-localized with DDX3 and UBR5 in viral replication compartments in the cell nucleus. These results suggest that m139 inhibits DDX3-mediated IFN production in macrophages and antagonizes DDX3 and UBR5-dependent functions related to RNA metabolism in endothelial cells. Human cytomegalovirus is an opportunistic pathogen that causes severe infections in immunocompromised individuals. The virus infects certain cell types, such as macrophages and endothelial cells, to ensure its dissemination within the body. Little is known about the viral factors that promote a productive infection of these cell types. The identification of critical viral factors and the molecular pathways they target can lead to the development of novel antiviral treatment strategies. Using the mouse cytomegalovirus as a model, we studied the viral m139 gene, which is important for virus replication in macrophages and endothelial cells and for dissemination in the mouse. This gene encodes a protein that interacts with the host proteins DDX3 and UBR5. Both proteins are involved in gene expression, and the RNA helicase DDX3 also participates in mounting an innate antiviral response. By interacting with DDX3 and UBR5, m139 ensures efficient viral replication in endothelial cells. Importantly, we identify m139 as a new viral DDX3 inhibitor, which curtails the production of interferon by macrophages.
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Gawish R, Bulat T, Biaggio M, Lassnig C, Bago-Horvath Z, Macho-Maschler S, Poelzl A, Simonović N, Prchal-Murphy M, Rom R, Amenitsch L, Ferrarese L, Kornhoff J, Lederer T, Svinka J, Eferl R, Bosmann M, Kalinke U, Stoiber D, Sexl V, Krmpotić A, Jonjić S, Müller M, Strobl B. Myeloid Cells Restrict MCMV and Drive Stress-Induced Extramedullary Hematopoiesis through STAT1. Cell Rep 2020; 26:2394-2406.e5. [PMID: 30811989 DOI: 10.1016/j.celrep.2019.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 12/13/2018] [Accepted: 02/05/2019] [Indexed: 12/11/2022] Open
Abstract
Cytomegalovirus (CMV) has a high prevalence worldwide, is often fatal for immunocompromised patients, and causes bone marrow suppression. Deficiency of signal transducer and activator of transcription 1 (STAT1) results in severely impaired antiviral immunity. We have used cell-type restricted deletion of Stat1 to determine the importance of myeloid cell activity for the defense against murine CMV (MCMV). We show that myeloid STAT1 limits MCMV burden and infection-associated pathology in the spleen but does not affect ultimate clearance of infection. Unexpectedly, we found an essential role of myeloid STAT1 in the induction of extramedullary hematopoiesis (EMH). The EMH-promoting function of STAT1 was not restricted to MCMV infection but was also observed during CpG oligodeoxynucleotide-induced sterile inflammation. Collectively, we provide genetic evidence that signaling through STAT1 in myeloid cells is required to restrict MCMV at early time points post-infection and to induce compensatory hematopoiesis in the spleen.
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Affiliation(s)
- Riem Gawish
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Tanja Bulat
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Mario Biaggio
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Caroline Lassnig
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; Biomodels Austria, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | | | - Sabine Macho-Maschler
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; Biomodels Austria, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Andrea Poelzl
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Natalija Simonović
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Michaela Prchal-Murphy
- Institute of Pharmacology and Toxicology, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Rita Rom
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Lena Amenitsch
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Luca Ferrarese
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Juliana Kornhoff
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Therese Lederer
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Jasmin Svinka
- Institute of Cancer Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Robert Eferl
- Institute of Cancer Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Markus Bosmann
- Pulmonary Center, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA; Center for Thrombosis and Hemostasis, University Medical Center, Johannes Gutenberg University Mainz, 55131 Mainz, Germany
| | - Ulrich Kalinke
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Hanover Medical School and the Helmholtz Centre for Infection Research, 30625 Hannover, Germany
| | - Dagmar Stoiber
- Ludwig Boltzmann Institute for Cancer Research, Vienna and Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Veronika Sexl
- Institute of Pharmacology and Toxicology, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Astrid Krmpotić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia
| | - Stipan Jonjić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia
| | - Mathias Müller
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; Biomodels Austria, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
| | - Birgit Strobl
- Institute of Animal Breeding and Genetics, Department of Biomedical Science, University of Veterinary Medicine Vienna, 1210 Vienna, Austria.
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Alston CI, Dix RD. SOCS and Herpesviruses, With Emphasis on Cytomegalovirus Retinitis. Front Immunol 2019; 10:732. [PMID: 31031749 PMCID: PMC6470272 DOI: 10.3389/fimmu.2019.00732] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 03/19/2019] [Indexed: 01/08/2023] Open
Abstract
Suppressor of cytokine signaling (SOCS) proteins provide selective negative feedback to prevent pathogeneses caused by overstimulation of the immune system. Of the eight known SOCS proteins, SOCS1 and SOCS3 are the best studied, and systemic deletion of either gene causes early lethality in mice. Many viruses, including herpesviruses such as herpes simplex virus and cytomegalovirus, can manipulate expression of these host proteins, with overstimulation of SOCS1 and/or SOCS3 putatively facilitating viral evasion of immune surveillance, and SOCS suppression generally exacerbating immunopathogenesis. This is particularly poignant within the eye, which contains a diverse assortment of specialized cell types working together in a tightly controlled microenvironment of immune privilege. When the immune privilege of the ocular compartment fails, inflammation causing severe immunopathogenesis and permanent, sight-threatening damage may occur, as in the case of AIDS-related human cytomegalovirus (HCMV) retinitis. Herein we review how SOCS1 and SOCS3 impact the virologic, immunologic, and/or pathologic outcomes of herpesvirus infection with particular emphasis on retinitis caused by HCMV or its mouse model experimental counterpart, murine cytomegalovirus (MCMV). The accumulated data suggests that SOCS1 and/or SOCS3 can differentially affect the severity of viral diseases in a highly cell-type-specific manner, reflecting the diversity and complexity of herpesvirus infection and the ocular compartment.
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Affiliation(s)
- Christine I Alston
- Department of Biology, Viral Immunology Center, Georgia State University, Atlanta, GA, United States.,Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, United States
| | - Richard D Dix
- Department of Biology, Viral Immunology Center, Georgia State University, Atlanta, GA, United States.,Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA, United States
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Suppressor of Cytokine Signaling 1 (SOCS1) and SOCS3 Are Stimulated within the Eye during Experimental Murine Cytomegalovirus Retinitis in Mice with Retrovirus-Induced Immunosuppression. J Virol 2018; 92:JVI.00526-18. [PMID: 29976680 DOI: 10.1128/jvi.00526-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 06/15/2018] [Indexed: 11/20/2022] Open
Abstract
AIDS-related human cytomegalovirus retinitis remains the leading cause of blindness among untreated HIV/AIDS patients worldwide. To study mechanisms of this disease, we used a clinically relevant animal model of murine cytomegalovirus (MCMV) retinitis with retrovirus-induced murine AIDS (MAIDS) that mimics the progression of AIDS in humans. We found in this model that MCMV infection significantly stimulates ocular suppressor of cytokine signaling 1 (SOCS1) and SOCS3, host proteins which hinder immune-related signaling by cytokines, including antiviral type I and type II interferons. The present study demonstrates that in the absence of retinal disease, systemic MCMV infection of mice without MAIDS, but not in mice with MAIDS, leads to mild stimulation of splenic SOCS1 mRNA. In sharp contrast, when MCMV is directly inoculated into the eyes of retinitis-susceptible MAIDS mice, high levels of intraocular SOCS1 and SOCS3 mRNA and protein are produced which are associated with significant intraocular upregulation of gamma interferon (IFN-γ) and interleukin-6 (IL-6) mRNA expression. We also show that infiltrating macrophages, granulocytes, and resident retinal cells are sources of intraocular SOCS1 and SOCS3 protein production during development of MAIDS-related MCMV retinitis, and SOCS1 and SOCS3 mRNA transcripts are detected in retinal areas histologically characteristic of MCMV retinitis. Furthermore, SOCS1 and SOCS3 are found in both MCMV-infected cells and uninfected cells, suggesting that these SOCS proteins are stimulated via a bystander mechanism during MCMV retinitis. Taken together, our findings suggest a role for MCMV-related stimulation of SOCS1 and SOCS3 in the progression of retinal disease during ocular, but not systemic, MCMV infection.IMPORTANCE Cytomegalovirus infection frequently causes blindness in untreated HIV/AIDS patients. This virus manipulates host cells to dysregulate immune functions and drive disease. Here, we use an animal model of this disease to demonstrate that cytomegalovirus infection within eyes during retinitis causes massive upregulation of immunosuppressive host proteins called SOCS. As viral overexpression of SOCS proteins exacerbates infection with other viruses, they may also enhance cytomegalovirus infection. Alternatively, the immunosuppressive effect of SOCS proteins may be protective against immunopathology during cytomegalovirus retinitis, and in such a case SOCS mimetics or overexpression treatment strategies might be used to combat this disease. The results of this work therefore provide crucial basic knowledge that contributes to our understanding of the mechanisms of AIDS-related cytomegalovirus retinitis and, together with future studies, may contribute to the development of novel therapeutic targets that could improve the treatment or management of this sight-threatening disease.
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Alston CI, Dix RD. Murine cytomegalovirus infection of mouse macrophages stimulates early expression of suppressor of cytokine signaling (SOCS)1 and SOCS3. PLoS One 2017; 12:e0171812. [PMID: 28182772 PMCID: PMC5300177 DOI: 10.1371/journal.pone.0171812] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 01/26/2017] [Indexed: 12/13/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a species-specific β-herpesvirus that infects for life up to 80% of the world’s population and causes severe morbidity in at-risk immunocompromised populations. Suppressors of cytokine signaling (SOCS)1 and SOCS3 are host proteins that act as inducible negative feedback regulators of cytokine signaling and have been implicated in several ocular diseases and viral infections. We recently found in our mouse model of experimental cytomegalovirus retinitis that subretinally-injected murine cytomegalovirus (MCMV) stimulates ocular SOCS1 and SOCS3 during retrovirus-induced immune suppression of murine AIDS (MAIDS), and that infiltrating macrophages are prominent cellular sources of retinal SOCS1 and SOCS3 expression. Herein we investigate possible virologic mechanisms whereby MCMV infection may stimulate SOCS1 and/or SOCS3 expression in cell culture. We report that infection of IC-21 mouse macrophages with MCMV propagated through the salivary glands of BALB/c mice, but not from tissue culture in C57BL/6 fibroblasts, transiently stimulates SOCS1 and SOCS3 mRNA transcripts, but not SOCS5 mRNA. Viral tegument proteins are insufficient for this stimulation, as replication-deficient UV-inactivated MCMV fails to stimulate SOCS1 or SOCS3 in IC-21 macrophages. By contrast, infection of murine embryonic fibroblasts (MEFs) with either productive MCMV or UV-inactivated MCMV significantly stimulates SOCS1 and SOCS3 mRNA expression early after infection. Treatment of MCMV-infected IC-21 mouse macrophages with the antiviral drug ganciclovir significantly decreases MCMV-stimulated SOCS3 expression at 3 days post-infection. These data suggest cell type-specific, different roles for viral immediate early or early gene expression and/or viral tegument proteins in the early stimulation of SOCS1 and SOCS3 during MCMV infection. Furthermore, putative biphasic stimulation of SOCS3 during late MCMV infection of IC-21 mouse macrophages may occur by divergent virologic mechanisms.
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Affiliation(s)
- Christine I. Alston
- Viral Immunology Center, Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Richard D. Dix
- Viral Immunology Center, Department of Biology, Georgia State University, Atlanta, Georgia, United States of America
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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Al-Ali AT, Sweet C. Further studies on the role of the residue 890 cysteine to tyrosine mutation in the M70 primase ORF of the temperature-sensitive mutant (tsm5) of murine cytomegalovirus. J Med Virol 2016; 88:1613-21. [PMID: 26919386 DOI: 10.1002/jmv.24507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2016] [Indexed: 11/06/2022]
Abstract
A mutation (C890Y) introduced into the M70 primase gene of murine cytomegalovirus (MCMV) resulted in reduced viral replication in murine embryo fibroblasts at 40°C and the mutant was severely attenuated in vivo. The attenuated replication of the M70 mutant was also observed in Raw 264.7 macrophages at 37°C, demonstrating that the mutation produced a defective rather than an unstable protein possibly reducing the amount of functional protein under different environmental conditions. Many synonymous mutations were introduced into this ORF by changing codon preferences that should reduce the efficiency of gene translation, but not change protein sequence or structure. Two Bacterial Artificial Chromosome (BAC) constructs were produced with 155 codons (at the distal third of the M70 gene) changed to MCMV less preferred codons and with either cysteine (BAC70(155Cys) ) or tyrosine (BAC70(155Tyr) ) at residue 890. Upon transfection of these BACs into NIH 3T3 cells, only BAC70(155Cys) produced virus and this mutant Mt70(155Cys) replicated similarly to its revertant and the wt MCMV K181 (Perth) variant. A metagenomic analysis of the protein structure of the primase using PredictProtein showed that the change from cysteine (M70Cys) to tyrosine (M70Tyr) has a marked effect on protein structure. However, when the cysteine residue was replaced by serine (M70Ser) or methionine (M70Met), which produced mutant viruses with a wild-type phenotype, the predicted structure was similar to the wild-type structure. J. Med. Virol. 88:1613-1621, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
| | - Clive Sweet
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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Alveolar Macrophages Are a Prominent but Nonessential Target for Murine Cytomegalovirus Infecting the Lungs. J Virol 2015; 90:2756-66. [PMID: 26719275 DOI: 10.1128/jvi.02856-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/11/2015] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Cytomegaloviruses (CMVs) infect the lungs and cause pathological damage there in immunocompromised hosts. How lung infection starts is unknown. Inhaled murine CMV (MCMV) directly infected alveolar macrophages (AMs) and type 2 alveolar epithelial cells (AEC2s) but not type 1 alveolar epithelial cells (AEC1s). In contrast, herpes simplex virus 1 infected AEC1s and murid herpesvirus 4 (MuHV-4) infected AEC1s via AMs. MCMV-infected AMs prominently expressed viral reporter genes from a human CMV IE1 promoter; but most IE1-positive cells were AEC2s, and CD11c-cre mice, which express cre in AMs, switched the fluorochrome expression of <5% of floxed MCMV in the lungs. In contrast, CD11C-cre mice exhibited fluorochrome switching in >90% of floxed MuHV-4 in the lungs and 50% of floxed MCMV in the blood. AM depletion increased MCMV titers in the lung during the acute phase of infection. Thus, the influence of AMs was more restrictive than permissive. Circulating monocytes entered infected lungs in large numbers and became infected, but not directly; infection occurred mainly via AEC2s. Mice infected with an MCMV mutant lacking its m131/m129 chemokine homolog, which promotes macrophage infection, showed levels of lung infection equivalent to those of wild-type MCMV-infected mice. The level of lung infiltration by Gr-1-positive cells infected with the MCMV m131/m129-null mutant was modestly different from that for wild-type MCMV-infected lungs. These results are consistent with myeloid cells mainly disseminating MCMV from the lungs, whereas AEC2s provide local amplification. IMPORTANCE Cytomegaloviruses (CMVs) chronically and systemically infect most mammals. Human CMV infection is usually asymptomatic but causes lung disease in people with poor immune function. As human infection is hard to analyze, studies with related animal viruses provide important insights. We show that murine CMV has two targets in the lungs: macrophages and surfactant-secreting epithelial cells. Acute virus replication occurred largely in epithelial cells. Macrophages had an important defensive role, as their removal increased the level of infection. These results establish the dual nature of lung infection, with local virus replication occurring in epithelial cells and spread occurring via quiescently infected macrophages. Distinct therapies may be needed to target these contrasting events.
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Lymph Node Macrophages Restrict Murine Cytomegalovirus Dissemination. J Virol 2015; 89:7147-58. [PMID: 25926638 DOI: 10.1128/jvi.00480-15] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 04/23/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Cytomegaloviruses (CMVs) establish chronic infections that spread from a primary entry site to secondary vascular sites, such as the spleen, and then to tertiary shedding sites, such as the salivary glands. Human CMV (HCMV) is difficult to analyze, because its spread precedes clinical presentation. Murine CMV (MCMV) offers a tractable model. It is hypothesized to spread from peripheral sites via vascular endothelial cells and associated monocytes. However, viral luciferase imaging showed footpad-inoculated MCMV first reaching the popliteal lymph nodes (PLN). PLN colonization was rapid and further spread was slow, implying that LN infection can be a significant bottleneck. Most acutely infected PLN cells were CD169(+) subcapsular sinus macrophages (SSM). Replication-deficient MCMV also reached them, indicating direct infection. Many SSM expressed viral reporter genes, but few expressed lytic genes. SSM expressed CD11c, and MCMV with a cre-sensitive fluorochrome switch showed switched infected cells in PLN of CD11c-cre mice but yielded little switched virus. SSM depletion with liposomal clodronate or via a CD169-diphtheria toxin receptor transgene shifted infection to ER-TR7(+) stromal cells, increased virus production, and accelerated its spread to the spleen. Therefore, MCMV disseminated via LN, and SSM slowed this spread by shielding permissive fibroblasts and poorly supporting viral lytic replication. IMPORTANCE HCMV chronically infects most people, and it can cause congenital disability and harm the immunocompromised. A major goal of vaccination is to prevent systemic infection. How this is established is unclear. Restriction to humans makes HCMV difficult to analyze. We show that peripheral MCMV infection spreads via lymph nodes. Here, MCMV infected filtering macrophages, which supported virus replication poorly. When these macrophages were depleted, MCMV infected susceptible fibroblasts and spread faster. The capacity of filtering macrophages to limit MCMV spread argued that their infection is an important bottleneck in host colonization and might be a good vaccine target.
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Biron CA, Tarrio ML. Immunoregulatory cytokine networks: 60 years of learning from murine cytomegalovirus. Med Microbiol Immunol 2015; 204:345-54. [PMID: 25850988 DOI: 10.1007/s00430-015-0412-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 03/23/2015] [Indexed: 10/23/2022]
Abstract
Innate immunity defends against infection but also mediates immunoregulatory effects shaping innate and adaptive responses. Studies of murine cytomegalovirus (MCMV) infections have helped elucidate the mechanisms inducing, as well as the elicited soluble and cellular networks contributing to, innate immunity. Specialized receptors are engaged by infection-induced structures to stimulate production of key innate cytokines. These then stimulate cytokine and cellular responses such as activation of natural killer (NK) cells to mediate elevated killing by type 1 interferon (IFN) and/or to produce the pro-inflammatory and antiviral cytokine IFN-γ by interleukin 12 (IL-12). An inter-systemic loop, with IL-6 inducing glucocorticoid release, negatively regulates these early cytokine responses. As infections advance into periods of overlapping innate and adaptive responses, however, the cells are intrinsically conditioned to modify the biological effects of exposure to individual cytokines. Some pathways are turned off to inhibit an existing, whereas others are broadened for acquisition of a new, response function. Remarkably, extended NK cell proliferation during MCMV infection is associated with epigenetic modifications shifting the state of the inhibitory cytokine IL-10 gene from closed to open and results in their becoming equipped to produce this cytokine. When induced, NK cell IL-10 negatively regulates the magnitude of adaptive responses to protect against immune pathology. Thus, innate immunoregulatory cytokine networks are integral to pro-inflammatory and defense functions, but responding cells have the flexibility to undergo cell intrinsic conditioning with changing network characteristics to result in a new negative immunoregulatory function, and consequently, both promote beneficial and limit detrimental immune responses.
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Affiliation(s)
- Christine A Biron
- Department of Molecular Microbiology and Immunology, The Division of Biology and Medicine and The Warren Alpert Medical School, Brown University, 171 Meeting Street, Providence, RI, 02912, USA,
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Drori A, Messerle M, Brune W, Tirosh B. Lack of XBP-1 impedes murine cytomegalovirus gene expression. PLoS One 2014; 9:e110942. [PMID: 25333725 PMCID: PMC4205010 DOI: 10.1371/journal.pone.0110942] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 09/26/2014] [Indexed: 11/17/2022] Open
Abstract
The unfolded protein response (UPR) is an endoplasmic reticulum (ER)-to-nucleus signaling cascade induced in response to ER stress. The UPR aims at restoring homeostasis, but can also induce apoptosis if stress persists. Infection by human and murine cytomegaloviruses (CMVs) provokes ER stress and induces the UPR. However, both CMVs manipulate the UPR to promote its prosurvival activity and delay apoptosis. The underlying mechanisms remain largely unknown. Recently, we demonstrated that MCMV and HCMV encode a late protein to target IRE1 for degradation. However, the importance of its downstream effector, X Box binding protein 1 (XBP-1), has not been directly studied. Here we show that deletion of XBP-1 prior to or early after infection confers a transient delay in viral propagation in fibroblasts that can be overcome by increasing the viral dose. A similar phenotype was demonstrated in peritoneal macrophages. In vivo, acute infection by MCMV is reduced in the absence of XBP-1. Our data indicate that removal of XBP-1 confers a kinetic delay in early stages of MCMV infection and suggest that the late targeting of IRE1 is aimed at inhibiting activities other than the splicing of XBP-1 mRNA.
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Affiliation(s)
- Adi Drori
- Institute for Drug Research, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Martin Messerle
- Department of Virology, Hannover Medical School, Hannover, Germany
| | - Wolfram Brune
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Boaz Tirosh
- Institute for Drug Research, The Hebrew University of Jerusalem, Jerusalem, Israel
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Zarama A, Pérez-Carmona N, Farré D, Tomic A, Borst EM, Messerle M, Jonjic S, Engel P, Angulo A. Cytomegalovirus m154 hinders CD48 cell-surface expression and promotes viral escape from host natural killer cell control. PLoS Pathog 2014; 10:e1004000. [PMID: 24626474 PMCID: PMC3953435 DOI: 10.1371/journal.ppat.1004000] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 01/31/2014] [Indexed: 11/19/2022] Open
Abstract
Receptors of the signalling lymphocyte-activation molecules (SLAM) family are involved in the functional regulation of a variety of immune cells upon engagement through homotypic or heterotypic interactions amongst them. Here we show that murine cytomegalovirus (MCMV) dampens the surface expression of several SLAM receptors during the course of the infection of macrophages. By screening a panel of MCMV deletion mutants, we identified m154 as an immunoevasin that effectively reduces the cell-surface expression of the SLAM family member CD48, a high-affinity ligand for natural killer (NK) and cytotoxic T cell receptor CD244. m154 is a mucin-like protein, expressed with early kinetics, which can be found at the cell surface of the infected cell. During infection, m154 leads to proteolytic degradation of CD48. This viral protein interferes with the NK cell cytotoxicity triggered by MCMV-infected macrophages. In addition, we demonstrate that an MCMV mutant virus lacking m154 expression results in an attenuated phenotype in vivo, which can be substantially restored after NK cell depletion in mice. This is the first description of a viral gene capable of downregulating CD48. Our novel findings define m154 as an important player in MCMV innate immune regulation.
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Affiliation(s)
- Angela Zarama
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | | | - Domènec Farré
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Adriana Tomic
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Eva Maria Borst
- Department of Virology, Hannover Medical School, Hannover, Germany
| | - Martin Messerle
- Department of Virology, Hannover Medical School, Hannover, Germany
| | - Stipan Jonjic
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Pablo Engel
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
- Immunology Unit, Department of Cell Biology, Immunology, and Neurosciences, Medical School, University of Barcelona, Barcelona, Spain
| | - Ana Angulo
- Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
- Immunology Unit, Department of Cell Biology, Immunology, and Neurosciences, Medical School, University of Barcelona, Barcelona, Spain
- * E-mail:
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Ebermann L, Ruzsics Z, Guzmán CA, van Rooijen N, Casalegno-Garduño R, Koszinowski U, Čičin-Šain L. Block of death-receptor apoptosis protects mouse cytomegalovirus from macrophages and is a determinant of virulence in immunodeficient hosts. PLoS Pathog 2012; 8:e1003062. [PMID: 23271968 PMCID: PMC3521658 DOI: 10.1371/journal.ppat.1003062] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 10/16/2012] [Indexed: 01/26/2023] Open
Abstract
The inhibition of death-receptor apoptosis is a conserved viral function. The murine cytomegalovirus (MCMV) gene M36 is a sequence and functional homologue of the human cytomegalovirus gene UL36, and it encodes an inhibitor of apoptosis that binds to caspase-8, blocks downstream signaling and thus contributes to viral fitness in macrophages and in vivo. Here we show a direct link between the inability of mutants lacking the M36 gene (ΔM36) to inhibit apoptosis, poor viral growth in macrophage cell cultures and viral in vivo fitness and virulence. ΔM36 grew poorly in RAG1 knockout mice and in RAG/IL-2-receptor common gamma chain double knockout mice (RAGγC−/−), but the depletion of macrophages in either mouse strain rescued the growth of ΔM36 to almost wild-type levels. This was consistent with the observation that activated macrophages were sufficient to impair ΔM36 growth in vitro. Namely, spiking fibroblast cell cultures with activated macrophages had a suppressive effect on ΔM36 growth, which could be reverted by z-VAD-fmk, a chemical apoptosis inhibitor. TNFα from activated macrophages synergized with IFNγ in target cells to inhibit ΔM36 growth. Hence, our data show that poor ΔM36 growth in macrophages does not reflect a defect in tropism, but rather a defect in the suppression of antiviral mediators secreted by macrophages. To the best of our knowledge, this shows for the first time an immune evasion mechanism that protects MCMV selectively from the antiviral activity of macrophages, and thus critically contributes to viral pathogenicity in the immunocompromised host devoid of the adaptive immune system. The majority of adult people are infected with human cytomegalovirus (CMV), but in hosts with a healthy immune system it is kept in check and does not cause disease. On the other hand, in patients suffering from innate or acquired immune deficiencies, CMV can cause severe disease or death. Infection of mice with the mouse CMV (MCMV) is an experimental model to study the biology of CMV infection, and mice that lack all of their lymphocytes are very susceptible to MCMV and die typically within three weeks of infection. In this article we show that MCMV causes disease and death in mice lacking lymphocytes because its gene M36 blocks programmed cell death, or apoptosis. MCMV lacking the M36 gene grew thousand folds less well in these mice, which significantly improved survival. This was because M36 deletion made MCMV susceptible to the action of macrophages, cells that secrete soluble factors that induce apoptosis. Importantly, viral growth and virulence of the M36-deficient MCMV could be restored by blocking apoptosis by other means, showing that the block of apoptosis was critical for viral replication. Therefore, our data imply that viral inhibition of apoptosis may be a key molecular target for antiviral strategies in immunodeficient hosts.
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Affiliation(s)
- Linda Ebermann
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Zsolt Ruzsics
- Max von Pettenkofer Institute, Ludwig Maximilians University, Munich, Germany
| | - Carlos A. Guzmán
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Nico van Rooijen
- Department of Molecular Cell Biology, Faculty of Medicine, Vrije University, Amsterdam, The Netherlands
| | - Rosaely Casalegno-Garduño
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Ulrich Koszinowski
- Max von Pettenkofer Institute, Ludwig Maximilians University, Munich, Germany
| | - Luka Čičin-Šain
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Department of Virology, Hannover School of Medicine, Hannover, Germany
- * E-mail:
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22
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Abstract
As intracellular parasites, viruses rely on many host cell functions to ensure their replication. The early induction of programmed cell death (PCD) in infected cells constitutes an effective antiviral host mechanism to restrict viral spread within an organism. As a countermeasure, viruses have evolved numerous strategies to interfere with the induction or execution of PCD. Slowly replicating viruses such as the cytomegaloviruses (CMVs) are particularly dependent on sustained cell viability. To preserve viability, the CMVs encode several viral cell death inhibitors that target different key regulators of the extrinsic and intrinsic apoptosis pathways. The best-characterized CMV-encoded inhibitors are the viral inhibitor of caspase-8-induced apoptosis (vICA), viral mitochondrial inhibitor of apoptosis (vMIA), and viral inhibitor of Bak oligomerization (vIBO). Moreover, a viral inhibitor of RIP-mediated signaling (vIRS) that blocks programmed necrosis has been identified in the genome of murine CMV (MCMV), indicating that this cell death mode is a particularly important part of the antiviral host response. This review provides an overview of the known cell death suppressors encoded by CMVs and their mechanisms of action.
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23
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Rodríguez-Martín S, Kropp KA, Wilhelmi V, Lisnic VJ, Hsieh WY, Blanc M, Livingston A, Busche A, Tekotte H, Messerle M, Auer M, Fraser I, Jonjic S, Angulo A, Reddehase MJ, Ghazal P. Ablation of the regulatory IE1 protein of murine cytomegalovirus alters in vivo pro-inflammatory TNF-alpha production during acute infection. PLoS Pathog 2012; 8:e1002901. [PMID: 22952450 PMCID: PMC3431344 DOI: 10.1371/journal.ppat.1002901] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 07/27/2012] [Indexed: 12/24/2022] Open
Abstract
Little is known about the role of viral genes in modulating host cytokine responses. Here we report a new functional role of the viral encoded IE1 protein of the murine cytomegalovirus in sculpting the inflammatory response in an acute infection. In time course experiments of infected primary macrophages (MΦs) measuring cytokine production levels, genetic ablation of the immediate-early 1 (ie1) gene results in a significant increase in TNFα production. Intracellular staining for cytokine production and viral early gene expression shows that TNFα production is highly associated with the productively infected MΦ population of cells. The ie1- dependent phenotype of enhanced MΦ TNFα production occurs at both protein and RNA levels. Noticeably, we show in a series of in vivo infection experiments that in multiple organs the presence of ie1 potently inhibits the pro-inflammatory cytokine response. From these experiments, levels of TNFα, and to a lesser extent IFNβ, but not the anti-inflammatory cytokine IL10, are moderated in the presence of ie1. The ie1- mediated inhibition of TNFα production has a similar quantitative phenotype profile in infection of susceptible (BALB/c) and resistant (C57BL/6) mouse strains as well as in a severe immuno-ablative model of infection. In vitro experiments with infected macrophages reveal that deletion of ie1 results in increased sensitivity of viral replication to TNFα inhibition. However, in vivo infection studies show that genetic ablation of TNFα or TNFRp55 receptor is not sufficient to rescue the restricted replication phenotype of the ie1 mutant virus. These results provide, for the first time, evidence for a role of IE1 as a regulator of the pro-inflammatory response and demonstrate a specific pathogen gene capable of moderating the host production of TNFα in vivo. The suppression of the production rather than the blockage of action of the potent inflammatory mediator TNFα is a particular hallmark of anti-TNFα mechanisms associated with microbial and parasitic infections. Whether this mode of counter-regulation is an important feature of infection by viruses is not clear. Also, it remains to be determined whether a specific pathogen gene in the context of an infection in vivo is capable of modulating levels of TNFα production. In this study we disclose a virus-mediated moderation of TNFα production, dependent on the ie1 gene of murine cytomegalovirus (MCMV). The ie1 gene product IE1 is a well-characterized nuclear protein capable of altering levels of host and viral gene expression although its biological role in the context of a natural infection is to date unknown. We provide evidence showing that ie1 is associated with a moderated pro-inflammatory cytokine response, in particular with TNFα production. Further, we show that the viral moderation of this cytokine is not only readily apparent in vitro but also in the natural host. The identification of a viral gene responsible for this mode of regulation in vivo may have therapeutic potential in the future in both anti-viral and anti-inflammatory strategies.
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Affiliation(s)
- Sara Rodríguez-Martín
- Division of Pathway Medicine and Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom
| | - Kai Alexander Kropp
- Division of Pathway Medicine and Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom
| | - Vanessa Wilhelmi
- Institute for Virology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Vanda Juranic Lisnic
- Department of Histology and Embryology/Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Wei Yuan Hsieh
- Division of Pathway Medicine and Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom
| | - Mathieu Blanc
- Division of Pathway Medicine and Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew Livingston
- Division of Pathway Medicine and Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom
| | - Andreas Busche
- Department of Virology, Hannover Medical School, Hannover, Germany
| | - Hille Tekotte
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Martin Messerle
- Department of Virology, Hannover Medical School, Hannover, Germany
| | - Manfred Auer
- University of Edinburgh, School of Biological Sciences (CSE) and School of Biomedical Sciences (CMVM), Edinburgh, United Kingdom
| | - Iain Fraser
- Laboratory of Systems Biology, National Institution of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Stipan Jonjic
- Department of Histology and Embryology/Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Ana Angulo
- Institut d'Investigacions Biomediques August Pi i Sunyer, Barcelona, Spain
| | - Matthias J. Reddehase
- Institute for Virology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Peter Ghazal
- Division of Pathway Medicine and Centre for Infectious Diseases, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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24
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Cousins SW, Espinosa-Heidmann DG, Miller DM, Pereira-Simon S, Hernandez EP, Chien H, Meier-Jewett C, Dix RD. Macrophage activation associated with chronic murine cytomegalovirus infection results in more severe experimental choroidal neovascularization. PLoS Pathog 2012; 8:e1002671. [PMID: 22570607 PMCID: PMC3343109 DOI: 10.1371/journal.ppat.1002671] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 03/14/2012] [Indexed: 02/05/2023] Open
Abstract
The neovascular (wet) form of age-related macular degeneration (AMD) leads to vision loss due to choroidal neovascularization (CNV). Since macrophages are important in CNV development, and cytomegalovirus (CMV)-specific IgG serum titers in patients with wet AMD are elevated, we hypothesized that chronic CMV infection contributes to wet AMD, possibly by pro-angiogenic macrophage activation. This hypothesis was tested using an established mouse model of experimental CNV. At 6 days, 6 weeks, or 12 weeks after infection with murine CMV (MCMV), laser-induced CNV was performed, and CNV severity was determined 4 weeks later by analysis of choroidal flatmounts. Although all MCMV-infected mice exhibited more severe CNV when compared with control mice, the most severe CNV developed in mice with chronic infection, a time when MCMV-specific gene sequences could not be detected within choroidal tissues. Splenic macrophages collected from mice with chronic MCMV infection, however, expressed significantly greater levels of TNF-α, COX-2, MMP-9, and, most significantly, VEGF transcripts by quantitative RT-PCR assay when compared to splenic macrophages from control mice. Direct MCMV infection of monolayers of IC-21 mouse macrophages confirmed significant stimulation of VEGF mRNA and VEGF protein as determined by quantitative RT-PCR assay, ELISA, and immunostaining. Stimulation of VEGF production in vivo and in vitro was sensitive to the antiviral ganciclovir. These studies suggest that chronic CMV infection may serve as a heretofore unrecognized risk factor in the pathogenesis of wet AMD. One mechanism by which chronic CMV infection might promote increased CNV severity is via stimulation of macrophages to make pro-angiogenic factors (VEGF), an outcome that requires active virus replication.
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Affiliation(s)
- Scott W. Cousins
- Duke University Eye Center, Duke Center for Macular Diseases, Department of Ophthalmology, Duke University, Durham, North Carolina, United States of America
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Diego G. Espinosa-Heidmann
- Duke University Eye Center, Duke Center for Macular Diseases, Department of Ophthalmology, Duke University, Durham, North Carolina, United States of America
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Daniel M. Miller
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Simone Pereira-Simon
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Eleut P. Hernandez
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Hsin Chien
- Department of Biology, Viral Immunology Center, Georgia State University, Atlanta, Georgia, United States of America
| | - Courtney Meier-Jewett
- Department of Biology, Viral Immunology Center, Georgia State University, Atlanta, Georgia, United States of America
| | - Richard D. Dix
- Department of Biology, Viral Immunology Center, Georgia State University, Atlanta, Georgia, United States of America
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States of America
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25
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Al-Ali A, Timoshenko O, Martin BA, Sweet C. Role of mutations identified in ORFs M27, M36, m139, m141, and m143 in the temperature-sensitive phenotype of murine cytomegalovirus mutanttsm5. J Med Virol 2012; 84:912-22. [DOI: 10.1002/jmv.23273] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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26
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The role of cell types in cytomegalovirus infection in vivo. Eur J Cell Biol 2011; 91:70-7. [PMID: 21492952 DOI: 10.1016/j.ejcb.2011.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 02/09/2011] [Accepted: 02/14/2011] [Indexed: 11/20/2022] Open
Abstract
Human cytomegalovirus (HCMV) is the major viral cause of morbidity in immune compromised patients and of pre- and perinatal pathology in newborns. The clinical manifestations are highly variable and the principles which govern these differences cannot be understood without detailed knowledge on tissue specific aspects of HCMV infection. For decades the role of individual cell types during cytomegalovirus infection and disease has been discussed. The pathogenesis of mouse cytomegalovirus (MCMV) mirrors the human infection in many aspects. Although only MCMV infection is studied extensively at the level of organs, the relative contribution of specific cell types to viral pathogenesis in vivo has remained enigmatic. Here we discuss new approaches based on the cre/loxP-system to label nascent virus progeny or to lift a replication block. The salient aspect of this technique is the change of viral genome properties selectively in cells that express cre during infection in vivo. This allowed us to study the role of endothelial cells and hepatocytes for virus dissemination and will permit detailed studies on innate and adaptive immune responses to CMV.
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27
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Inhibition of programmed cell death by cytomegaloviruses. Virus Res 2010; 157:144-50. [PMID: 20969904 DOI: 10.1016/j.virusres.2010.10.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 10/07/2010] [Accepted: 10/11/2010] [Indexed: 12/24/2022]
Abstract
The elimination of infected cells by programmed cell death (PCD) is one of the most ancestral defense mechanisms against infectious agents. This mechanism should be most effective against intracellular parasites, such as viruses, which depend on the host cell for their replication. However, even large and slowly replicating viruses like the cytomegaloviruses (CMVs) can prevail and persist in face of cellular suicide programs and other innate defense mechanisms. During evolution, these viruses have developed an impressive set of countermeasures against premature demise of the host cell. In the last decade, several genes encoding suppressors of apoptosis and necrosis have been identified in the genomes of human and murine CMV (HCMV and MCMV). Curiously, most of the gene products are not homologous to cellular antiapoptotic proteins, suggesting that the CMVs did not capture the genes from the host cell genome. This review summarizes our current understanding of how the CMVs suppress PCD and which signaling pathways they target.
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28
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Investigation of the impact of the common animal facility contaminant murine norovirus on experimental murine cytomegalovirus infection. Virology 2009; 392:153-61. [PMID: 19647849 DOI: 10.1016/j.virol.2009.05.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 03/20/2009] [Accepted: 05/28/2009] [Indexed: 11/23/2022]
Abstract
Murine norovirus (MNV) is a recently discovered pathogen that has become a common contaminant of specific pathogen-free mouse colonies. MNV-1 induces a robust interferon-beta response and causes histopathology in some mouse strains, suggesting that it may impact other mouse models of infection. Despite many concerns about MNV-1 contamination, there is little information about its impact on immune responses to other infections. This study addresses whether MNV-1 infection has an effect on a model of murine cytomegalovirus (MCMV) infection. Exposure to MNV-1 resulted in a decreased CD8 T cell response to immunodominant MCMV epitopes in both BALB/c and C57BL/6 mice. However, MNV-1 did not impact MCMV titers in either mouse strain, nor did it stimulate reactivation of latent MCMV. These data suggest that while MNV-1 has a mild impact on the immune response to MCMV, it is not likely to affect most experimental outcomes in immunocompetent mice in the MCMV model.
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29
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Ashley SL, Welton AR, Harwood KM, Van Rooijen N, Spindler KR. Mouse adenovirus type 1 infection of macrophages. Virology 2009; 390:307-14. [PMID: 19540545 DOI: 10.1016/j.virol.2009.05.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 04/28/2009] [Accepted: 05/26/2009] [Indexed: 12/29/2022]
Abstract
Mouse adenovirus type 1 (MAV-1) causes acute and persistent infections in mice, with high levels of virus found in the brain, spinal cord and spleen in acute infections. MAV-1 infects endothelial cells throughout the mouse, and monocytes/macrophages have also been implicated as targets of the virus. Here we determined the extent and functional importance of macrophage infection by MAV-1. Bone marrow-derived macrophages expressed MAV-1 mRNAs and proteins upon ex vivo infection. Adherent peritoneal macrophages from infected mice expressed viral mRNAs and produced infectious virus. Infected chemokine (C-C motif) receptor 2 (CCR2) knockout mice, which are defective for macrophage recruitment, did not show differences in survival or MAV-1 load compared to controls. In contrast, macrophage depletion using clodronate-loaded liposomes resulted in increased virus replication in spleens of a MAV-1-resistant mouse strain, BALB/cJ. Thus macrophages serve both as targets of infection and as effectors of the host response.
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Affiliation(s)
- Shanna L Ashley
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA
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30
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Murine cytomegalovirus capsid assembly is dependent on US22 family gene M140 in infected macrophages. J Virol 2009; 83:7449-56. [PMID: 19458005 DOI: 10.1128/jvi.00325-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Macrophages are an important target cell for infection with cytomegalovirus (CMV). A number of viral genes that either are expressed specifically in this cell type or function to optimize CMV replication in this host cell have now been identified. Among these is the murine CMV (MCMV) US22 gene family member M140, a nonessential early gene whose deletion (RVDelta140) leads to significant impairment in virus replication in differentiated macrophages. We have now determined that the defect in replication is at the stage of viral DNA encapsidation. Although the rate of RVDelta140 genome replication and extent of DNA cleavage were comparable to those for revertant virus, deletion of M140 resulted in a significant reduction in the number of viral capsids in the nucleus, and the viral DNA remained sensitive to DNase treatment. These data are indicative of incomplete virion assembly. Steady-state levels of both the major capsid protein (M86) and tegument protein M25 were reduced in the absence of the M140 protein (pM140). This effect may be related to the localization of pM140 to an aggresome-like, microtubule organizing center-associated structure that is known to target misfolded and overexpressed proteins for degradation. It appears, therefore, that pM140 indirectly influences MCMV capsid formation in differentiated macrophages by regulating the stability of viral structural proteins.
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31
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Wesley JD, Tessmer MS, Chaukos D, Brossay L. NK cell-like behavior of Valpha14i NK T cells during MCMV infection. PLoS Pathog 2008; 4:e1000106. [PMID: 18636102 PMCID: PMC2442879 DOI: 10.1371/journal.ppat.1000106] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Accepted: 06/19/2008] [Indexed: 01/12/2023] Open
Abstract
Immunity to the murine cytomegalovirus (MCMV) is critically dependent on the innate response for initial containment of viral replication, resolution of active infection, and proper induction of the adaptive phase of the anti-viral response. In contrast to NK cells, the Valpha14 invariant natural killer T cell response to MCMV has not been examined. We found that Valpha14i NK T cells become activated and produce significant levels of IFN-gamma, but do not proliferate or produce IL-4 following MCMV infection. In vivo treatment with an anti-CD1d mAb and adoptive transfer of Valpha14i NK T cells into MCMV-infected CD1d(-/-) mice demonstrate that CD1d is dispensable for Valpha14i NK T cell activation. In contrast, both IFN-alpha/beta and IL-12 are required for optimal activation. Valpha14i NK T cell-derived IFN-gamma is partially dependent on IFN-alpha/beta but highly dependent on IL-12. Valpha14i NK T cells contribute to the immune response to MCMV and amplify NK cell-derived IFN-gamma. Importantly, mortality is increased in CD1d(-/-) mice in response to high dose MCMV infection when compared to heterozygote littermate controls. Collectively, these findings illustrate the plasticity of Valpha14i NK T cells that act as effector T cells during bacterial infection, but have NK cell-like behavior during the innate immune response to MCMV infection.
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Affiliation(s)
- Johnna D. Wesley
- Department of Molecular Microbiology and Immunology and Graduate Program in Pathobiology, Division of Biology and Medicine, Brown University, Providence, Rhode Island, United States of America
| | - Marlowe S. Tessmer
- Department of Molecular Microbiology and Immunology and Graduate Program in Pathobiology, Division of Biology and Medicine, Brown University, Providence, Rhode Island, United States of America
| | - Deanna Chaukos
- Department of Molecular Microbiology and Immunology and Graduate Program in Pathobiology, Division of Biology and Medicine, Brown University, Providence, Rhode Island, United States of America
| | - Laurent Brossay
- Department of Molecular Microbiology and Immunology and Graduate Program in Pathobiology, Division of Biology and Medicine, Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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32
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Boelen E, Steinbusch HWM, van der Ven AJAM, Grauls G, Bruggeman CA, Stassen FRM. Chlamydia pneumoniae infection of brain cells: An in vitro study. Neurobiol Aging 2007; 28:524-32. [PMID: 16621171 DOI: 10.1016/j.neurobiolaging.2006.02.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 02/14/2006] [Accepted: 02/16/2006] [Indexed: 10/24/2022]
Abstract
Inspired by the suggested associations between neurological diseases and infections, we determined the susceptibility of brain cells to Chlamydia pneumoniae (Cpn). Murine astrocyte (C8D1A), neuronal (NB41A3) and microglial (BV-2) cell lines were inoculated with Cpn. Infection was established by immunofluorescence and real-time PCR at various time points. Productive infection was assessed by transferring medium of infected cells to a detection layer. Finally, apoptosis and necrosis post-infection was determined. Our data demonstrate that the neuronal cell line is highly sensitive to Cpn, produces viable progeny and is prone to die after infection by necrosis. Cpn tropism was similar in an astrocyte cell line, apart from the higher production of extracellular Cpn and less pronounced necrosis. In contrast, the microglial cell line is highly resistant to Cpn as the immunohistochemical signs almost completely disappeared after 24 h. Nevertheless, significant Cpn DNA amounts could be detected, suggesting Cpn persistence. Low viable progeny and hardly any necrotic microglial cells were observed. Further research is warranted to determine whether these cell types show the same sensitivity to Cpn in an in vivo setting.
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Affiliation(s)
- Ellen Boelen
- Department of Medical Microbiology, CARIM (Cardiovascular Research Institute Maastricht), Maastricht University, Maastricht, The Netherlands
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33
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Roback JD, Su L, Zimring JC, Hillyer CD. Transfusion-Transmitted Cytomegalovirus: Lessons From a Murine Model. Transfus Med Rev 2007; 21:26-36. [PMID: 17174218 DOI: 10.1016/j.tmrv.2006.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Transfusion-transmitted cytomegalovirus (CMV) infection (TT-CMV) continues to complicate blood transfusion therapy, which can lead to severe morbidity or mortality in immunocompromised or immuno-immature recipients. The biological mechanisms that underlie TT-CMV (eg, viral latency in donor monocytes or stimulatory signals in the transfusion recipient leading to cytomegalovirus reactivation) are difficult to study in humans, but can be addressed in animal models. In this review, we discuss a mouse blood transfusion model, which can be used to investigate these issues as well as to validate methods to prevent TT-CMV in at-risk patients.
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Affiliation(s)
- John D Roback
- Department of Pathology and Laboratory Medicine, Transfusion Medicine Program, Emory University School of Medicine, Atlanta, GA 30322, USA
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34
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Dutt K, Ezeonu I. Human retinal and brain cell lines: A model of HCMV retinitis and encephalitis. DNA Cell Biol 2006; 25:581-96. [PMID: 17132089 DOI: 10.1089/dna.2006.25.581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although HIV is accepted as the etiologic agent in AIDS, other factors have been implicated in accelerating the disease. Human cytomegalovirus (HCMV) in particular has been implicated as a cofactor in the progression from AIDS-related complex (ARC) to AIDS. HCMV infection of the central nervous system (CNS) (brain, retina) has been reported in at least 50% of AIDS patients, and has been implicated in producing encephalitis and sight-threatening retinitis. HCMV exhibits strict species specificity and animal models for human HCMV are conspicuous by their absence. We have developed a human brain cell line (mixed glial/neuronal) and a multipotential human retinal precursor cell line (neuronal in nature). We have tested the suitability of these cell lines as models for the study of HCMV infectibility. In this study, we report that these cell lines are optimal for the study of HCMV infectibility and pathogenesis in tissues of neural origin and appropriate to study HIV-HCMV interaction. Immortalized human brain and retinal cell lines were infected with a laboratory strain of HCMV (AD 169, Towne) at a multiplicity of infection moi (1-5) and viral infectibility and cell specificity monitored by: (a) phenotypic analysis (multinucleate cells, syncytium formation, etc.), (b) antigen expression (IE, E, late) by immunohistochemistry, Western blot analysis, (c) presence of viral particles by TEM, and (d) expression of indicator plasmids (HIV-LTR-CAT). We report that both human retinal and brain cell lines are permissive for HCMV infectibility. Cell specificity was not seen; both cells expressing glial/neuronal cell markers were positive for the presence of HCMV early/late antigens. Formation of multinucleate giant cells with nuclear inclusion bodies and syncytia were seen. Productive viral infection was confirmed by the ability of cell-free supernatant from the third passage of infected cells to produce pathogenicity and express viral particles, when added to fresh cultures. Using indicator plasmids, HIV-LTR, and CAT, we have shown that HIV and HCMV interact at the cellular level. We have also shown that HIV production in retinal and brain cell lines transfected with cloned HIV was enhanced by HCMV-IE genes. We did not see any differences in HCMV. AD 169, Towne isolate, and data from both strains is presented in this paper. This model could prove extremely useful for the study of cell specificity/cellular and molecular interaction between HIV/HCMV and to test antiviral therapies.
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Affiliation(s)
- Kamla Dutt
- Department of Pathology, Morehouse School of Medicine, Atlanta, Georgia 30310, USA.
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Visalli RJ, Nicolosi DM, Irven K, Khan T, Visalli MA. Characterization of the murine cytomegalovirus m136 gene. Virus Genes 2006; 34:117-26. [PMID: 17143724 DOI: 10.1007/s11262-006-0047-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 10/10/2006] [Indexed: 11/25/2022]
Abstract
The 230-kbp murine cytomegalovirus (MCMV) genome is predicted to encode 182 open reading frames (orfs). One gene whose functional role is not known is encoded by the 762-bp m136 orf. Sequence analysis of rat cytomegalovirus (RCMV) strains Maastricht and English revealed homologous orfs, pr136, and ORF HJ4, respectively. Conservation of these orfs suggested that m136 and the RCMV homologs might play a role during virus replication. Expression of an epitope tagged form of m136 (m136-V5) yielded a polypeptide of 34 kDa that localized to the perinuclear region of transfected mouse 3T3 fibroblasts. Three independently generated MCMV m136 mutants were isolated and characterized. Mutations were introduced into the m136 orf by inserting either a beta-glucuronidase (m136-beta-gluc) or a guanosine phosphoribosyl transferase (m136-gpt) expression cassette into a unique BglII site, or by inserting a gpt cassette into a deleted region (Deltam136) of m136. No differences were observed in viral yield, plaque size, and plaque morphology between the parental strain and any of the m136 mutant viruses. In vivo analysis using a SCID mouse virulence model showed a consistently measurable attenuated phenotype for all three m136 mutants. The results showed that although the m136 gene was not essential for replication in vitro or in vivo, an intact m136 gene was necessary to yield wild type virulence during infection of the host.
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Affiliation(s)
- Robert J Visalli
- Department of Biology, Indiana University Purdue University Fort Wayne, 2101 E. Coliseum Blvd., Fort Wayne, IN 46805, USA.
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36
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van Dommelen SLH, Sumaria N, Schreiber RD, Scalzo AA, Smyth MJ, Degli-Esposti MA. Perforin and Granzymes Have Distinct Roles in Defensive Immunity and Immunopathology. Immunity 2006; 25:835-48. [PMID: 17088087 DOI: 10.1016/j.immuni.2006.09.010] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 08/11/2006] [Accepted: 09/06/2006] [Indexed: 01/12/2023]
Abstract
Successful control of viral infection requires the host to eliminate the infecting pathogen without causing overt immunopathology. Here we showed that perforin (Prf1) and granzymes (Gzms) have distinct roles in defensive immunity and immunopathology in a well-established model of viral infection. Both Prf1 and Gzms drastically affected the outcome of murine cytomegalovirus (MCMV) infection. Viral titres increased markedly in both Prf1(-/-) and Gzma(-/-)Gzmb(-/-) mice, but Gzma(-/-)Gzmb(-/-) mice recovered and survived infection, whereas Prf1(-/-) mice did not. Indeed, infected Prf1-deficient hosts developed a fatal hemophagocytic lymphohistiocytosis (HLH)-like syndrome. This distinction in outcome depended on accumulation of mononuclear cells and T cells in infected Prf1(-/-) mice. Importantly, blocking experiments that clearly identified tumor necrosis factor-alpha (TNF-alpha) as the principal contributor to the lethality observed in infected Prf1(-/-) mice provided support for the clinical potential of such an approach in HLH patients whose disease is triggered by viral infection.
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Affiliation(s)
- Serani L H van Dommelen
- Immunology and Virology Program, Centre for Ophthalmology and Visual Science, The University of Western Australia, Western Australia, Australia
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Louten J, van Rooijen N, Biron CA. Type 1 IFN deficiency in the absence of normal splenic architecture during lymphocytic choriomeningitis virus infection. THE JOURNAL OF IMMUNOLOGY 2006; 177:3266-72. [PMID: 16920967 DOI: 10.4049/jimmunol.177.5.3266] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The innate immune system uses different mechanisms to respond to infectious pathogens. Experiments evaluating the requirements for a type 1 IFN (IFN-alphabeta) response to lymphocytic choriomeningitis virus (LCMV) resulted in the surprising discovery that mice deficient in B and T cell development, i.e., RAG-deficient and SCID, had profoundly reduced levels of IFN-alphabeta in serum and spleen, despite high viral replication. In addition to lacking an adaptive immune system, these strains exhibit aberrant splenic architecture, and the defect in type 1 IFN production was also observed in mice lacking normal splenic marginal zone (MZ) organization due to genetic deficiencies in B cell development or in cytokine functions required for development of the MZ, i.e., muMT, lymphotoxin-alpha, and TNFR1. Interestingly, the IFN-alphabeta reduction was not observed after murine CMV infection. Depletion of phagocytic cells from normally developed spleens by treatment with clodronate-containing liposomes demonstrated that these populations were required for the type 1 IFN response to LCMV, but not to murine CMV, and for control of viral replication. Complete repopulation of the MZ was necessary to restore normal IFN-alphabeta production. In contrast, control of LCMV replication correlated with the return of CD11c+ cells. Taken together, these results demonstrate the complexity and sophistication of the splenic MZ in sensing and responding to particular pathogens and reveal the importance of organ architecture in the production of type 1 IFN.
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Affiliation(s)
- Jennifer Louten
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI 02912, USA
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Pinto AK, Munks MW, Koszinowski UH, Hill AB. Coordinated function of murine cytomegalovirus genes completely inhibits CTL lysis. THE JOURNAL OF IMMUNOLOGY 2006; 177:3225-34. [PMID: 16920962 DOI: 10.4049/jimmunol.177.5.3225] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Murine CMV (MCMV) encodes three viral genes that interfere with Ag presentation (VIPRs) to CD8 T cells, m04, m06, and m152. Because the functional impact of these genes during normal infection of C57BL/6 mice is surprisingly modest, we wanted to determine whether the VIPRs are equally effective against the entire spectrum of H-2(b)-restricted CD8 T cell epitopes. We also wanted to understand how the VIPRs interact at a functional level. To address these questions, we used a panel of MCMV mutants lacking each VIPR in all possible combinations, and CTL specific for 15 H-2(b)-restricted MCMV epitopes. Only expression of all three MCMV VIPRs completely inhibited killing by CTL specific for all 15 epitopes, but removal of any one VIPR enabled lysis by at least some CTL. The dominant interaction between the VIPRs was cooperation: m06 increased the inhibition of lysis achieved by either m152 or m04. However, for 1 of 15 epitopes m04 functionally antagonized m152. There was little differential impact of any of the VIPRs on K(b) vs D(b), but a surprising degree of differential impact of the three VIPRs for different epitopes. These epitope-specific differences did not correlate with functional avidity, or with timing of VIPR expression in relation to Ag expression in the virus replication cycle. Although questions remain about the molecular mechanism and in vivo role of these genes, we conclude that the coordinated function of MCMV's three VIPRs results in a powerful inhibition of lysis of infected cells by CD8 T cells.
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Affiliation(s)
- Amelia K Pinto
- Oregon Health and Science University, Molecular Microbiology and Immunology, Portland, OR 97239, USA
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39
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Valchanova RS, Picard-Maureau M, Budt M, Brune W. Murine cytomegalovirus m142 and m143 are both required to block protein kinase R-mediated shutdown of protein synthesis. J Virol 2006; 80:10181-90. [PMID: 17005695 PMCID: PMC1617306 DOI: 10.1128/jvi.00908-06] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Accepted: 07/21/2006] [Indexed: 11/20/2022] Open
Abstract
Cytomegaloviruses carry the US22 family of genes, which have common sequence motifs but diverse functions. Only two of the 12 US22 family genes of murine cytomegalovirus (MCMV) are essential for virus replication, but their functions have remained unknown. In the present study, we deleted the essential US22 family genes, m142 and m143, from the MCMV genome and propagated the mutant viruses on complementing cells. The m142 and the m143 deletion mutants were both unable to replicate in noncomplementing cells at low and high multiplicities of infection. In cells infected with the deletion mutants, viral immediate-early and early proteins were expressed, but viral DNA replication and synthesis of the late-gene product glycoprotein B were inhibited, even though mRNAs of late genes were present. Global protein synthesis was impaired in these cells, which correlated with phosphorylation of the double-stranded RNA-dependent protein kinase R (PKR) and its target protein, the eukaryotic translation initiation factor 2alpha, suggesting that m142 and m143 are necessary to block the PKR-mediated shutdown of protein synthesis. Replication of the m142 and m143 knockout mutants was partially restored by expression of the human cytomegalovirus TRS1 gene, a known double-stranded-RNA-binding protein that inhibits PKR activation. These results indicate that m142 and m143 are both required for inhibition of the PKR-mediated host antiviral response.
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Affiliation(s)
- Ralitsa S Valchanova
- Robert Koch-Institut, Fachgebiet Virale Infektionen, Nordufer 20, 13353 Berlin, Germany
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40
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Munks MW, Cho KS, Pinto AK, Sierro S, Klenerman P, Hill AB. Four distinct patterns of memory CD8 T cell responses to chronic murine cytomegalovirus infection. THE JOURNAL OF IMMUNOLOGY 2006; 177:450-8. [PMID: 16785542 DOI: 10.4049/jimmunol.177.1.450] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
CMVs are beta herpesviruses that establish lifelong latent infection of their hosts. Acute infection of C57BL/6 mice with murine CMV elicits a very broad CD8 T cell response, comprising at least 24 epitopes from 18 viral proteins. In contrast, we show here that the CD8 T cell response in chronically infected mice was dominated by only five epitopes. Altogether, four distinct CD8 T cell kinetic patterns were evident. Responses to some epitopes, including M45, which dominates the acute response, contracted sharply after day 7 and developed into stable long-term memory. The response to m139 underwent rapid expansion and contraction, followed by a phase of memory inflation, whereas the response to an M38 epitope did not display any contraction phase. Finally, responses against two epitopes encoded by the immediate early gene IE3 were readily detectable in chronically infected mice but near the limit of detection during acute infection. CD8 T cells specific for the noninflationary M45 epitope displayed a classic central memory phenotype, re-expressing the lymph node homing receptor CD62L and homeostatic cytokine receptors for IL-7 and IL-15, and produced low levels of IL-2. Responses to two inflationary epitopes, m139 and IE3, retained an effector memory surface phenotype (CD62L(low), IL-7Ralpha(-), IL-15Rbeta(-)) and were unable to produce IL-2. We suggest that immunological choices are superimposed on altered viral gene expression profiles to determine immunodominance during chronic murine CMV infection.
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Affiliation(s)
- Michael W Munks
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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41
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Roback JD, Su L, Newman JL, Saakadze N, Lezhava LJ, Hillyer CD. Transfusion-transmitted cytomegalovirus (CMV) infections in a murine model: characterization of CMV-infected donor mice. Transfusion 2006; 46:889-95. [PMID: 16734804 DOI: 10.1111/j.1537-2995.2006.00820.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Donor and recipient mechanisms that modulate the incidence and severity of transfusion-transmitted cytomegalovirus (TT-CMV) are unclear. The kinetics of murine CMV (MCMV) infection in the peripheral blood of donor mice were investigated to determine the utility of this model for studying TT-CMV. STUDY DESIGN AND METHODS BALB/cByJ mice, experimentally infected with Smith strain MCMV, were killed at serial time points up to 28 days after infection. Peritoneal exudate cells (PECs), peripheral blood white blood cells (WBCs), plasma, and marrow were tested for MCMV DNA with quantitative polymerase chain reaction (PCR), replication-competent virus with quantitative culture, and transcription of viral genes with reverse transcription (RT)-PCR targeted at the immediate-early 1 (ie1) gene. RESULTS PECs, macrophages infected by MCMV shortly after intraperitoneal inoculation, demonstrated high mean levels of MCMV DNA (10(5)-10(7) genome equivalents [geqs]/10(5) PECs), virus production (10(1)-10(4) infectious virions/10(5) PECs), and ie1 gene transcription, demonstrating productive infection. In contrast, while MCMV loads averaged 10(4) to 10(6) geqs per 10(5) peripheral WBCs, all WBC samples were uniformly negative for MCMV ie1 expression by RT-PCR and for culturable virus, consistent with latent MCMV infection. Plasma and marrow showed lower viral loads than WBCs and PECs and were all negative by culture and RT-PCR analysis. CONCLUSIONS Following experimental MCMV infection, murine peripheral blood WBCs appear to be latently infected with virus (MCMV DNA-positive; MCMV RNA-negative; MCMV culture-negative), similar to the latently infected human monocytes in peripheral blood of CMV-seropositive donors. These donor kinetics suggest that the experimental MCMV system can be used to effectively model the mechanisms of TT-CMV infections in humans.
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Affiliation(s)
- John D Roback
- Transfusion Medicine Program, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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42
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He R, Ruan Q, Qi Y, Ma YP, Huang YJ, Sun ZR, Ji YH. Sequence variability of human cytomegalovirus UL146 and UL147 genes in low-passage clinical isolates. Intervirology 2006; 49:215-23. [PMID: 16491016 DOI: 10.1159/000091468] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Accepted: 07/21/2005] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVES Human cytomegalovirus (HCMV) infects a number of organs and cell types in vivo. The different symptoms and tissue tropisms of HCMV infection perhaps result from the genetic polymorphism. A new region of DNA containing at least 19 open reading frames (ORFs - denoted UL133-151) was found in the low-passage HCMV clinical strain Toledo and several other low-passage clinical isolates, but not present in the HCMV laboratory strain AD169. Two of these genes, UL146 and UL147, encode proteins with sequence characteristics of CXC (alpha) chemokines, suggesting that they might influence the behavior of neutrophils during infection. This research was to study the sequence variability of UL146 and UL147 ORFs in HCMV clinical isolates and examine the possible associations between gene variability and the outcome of HCMV infection. METHODS UL146 and UL147 genes from strains obtained from suspected congenitally HCMV-infected infants were PCR amplified and sequenced. RESULTS High variability was found in UL146 and UL147 gene among HCMV clinical strains. However, the alpha chemokine motif in UL146 and UL147 genes was conserved in almost all sequences. According to the phylogenetic analysis, all sequences of UL146 in clinical isolates could be divided into three groups. All strains from congenital megacolon infants existed in G2A only, and all from asymptomatic infants existed in G2B peculiarly. CONCLUSIONS Sequence variability among HCMV clinical strains may affect the ability of UL146 and UL147 to attract human neutrophils and influence viral dissemination. No obvious linkage was observed between UL146 polymorphisms and outcome of suspected congenital HCMV infection.
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Affiliation(s)
- Rong He
- Virus Laboratory, 2nd Affiliated Hospital, China Medical University, Shenyang, China
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43
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Strobl B, Bubic I, Bruns U, Steinborn R, Lajko R, Kolbe T, Karaghiosoff M, Kalinke U, Jonjic S, Müller M. Novel Functions of Tyrosine Kinase 2 in the Antiviral Defense against Murine Cytomegalovirus. THE JOURNAL OF IMMUNOLOGY 2005; 175:4000-8. [PMID: 16148148 DOI: 10.4049/jimmunol.175.6.4000] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have recently reported that tyrosine kinase 2 (Tyk2)-deficient mice have a selective defect in the in vivo defense against certain viruses. In our current study we show that Tyk2 is essential for the defense against murine CMV (MCMV). In vivo challenges with MCMV revealed impaired clearance of virus from organs and decreased survival of mice in the absence of Tyk2. Our in vitro studies demonstrate that MCMV replicates to dramatically higher titers in Tyk2-deficient macrophages compared with wild-type cells. We show an essential role of type I IFN (IFN-alphabeta) in the control of MCMV replication, with a prominent role of IFN-beta. MCMV infection leads to the activation of STAT1 and STAT2 in an IFN-alphabeta receptor 1-dependent manner. Consistent with the role of Tyk2 in IFN-alphabeta signaling, activation of STAT1 and STAT2 is reduced in Tyk2-deficient cells. However, lack of Tyk2 results in impaired MCMV-mediated gene induction of only a subset of MCMV-induced IFN-alphabeta-responsive genes. Taken together, our data demonstrate a requirement for Tyk2 in the in vitro and in vivo antiviral defense against MCMV infection. In addition to the established role of Tyk2 as an amplifier of Jak/Stat signaling upon IFN-alphabeta stimulation, we provide evidence for a novel role of Tyk2 as a modifier of host responses.
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Affiliation(s)
- Birgit Strobl
- Institute of Animal Breeding and Genetics, Veterinary University of Vienna, Vienna, Austria.
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44
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Noda S, Aguirre SA, Bitmansour A, Brown JM, Sparer TE, Huang J, Mocarski ES. Cytomegalovirus MCK-2 controls mobilization and recruitment of myeloid progenitor cells to facilitate dissemination. Blood 2005; 107:30-8. [PMID: 16046529 PMCID: PMC1895360 DOI: 10.1182/blood-2005-05-1833] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Murine cytomegalovirus encodes a secreted, pro-inflammatory chemokine-like protein, MCK-2, that recruits leukocytes and facilitates viral dissemination. We have shown that MCK-2-enhanced recruitment of myelomonocytic leukocytes with an immature phenotype occurs early during infection and is associated with efficient viral dissemination. Expression of MCK-2 drives the mobilization of a population of leukocytes from bone marrow that express myeloid marker Mac-1 (CD11b), intermediate levels of Gr-1 (Ly6 G/C), platelet-endothelial-cell adhesion molecule-1 (PECAM-1, CD31), together with heterogeneous levels of stem-cell antigen-1 (Sca-1, Ly-6 A /E). Recombinant MCK-2 mediates recruitment of this population even in the absence of viral infection. Recruitment of this cell population and viral dissemination via the bloodstream to salivary glands proceeds normally in mice that lack CCR2 and MCP-1 (CCL2), suggesting that recruitment of macrophages is not a requisite component of pathogenesis. Thus, a systemic impact of MCK-2 enhances the normal host response and causes a marked increase in myelomonocytic recruitment with an immature phenotype to initial sites of infection. Mobilization influences levels of virus dissemination via the bloodstream to salivary glands and is dependent on a myelomonocytic cell type other than mature macrophages.
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Affiliation(s)
- Satoshi Noda
- Department of Microbiology and Immunology, Stanford University School of Medicine, Fairchild Science Bldg, 299 Campus Dr, Stanford, CA 94305-5124, USA
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Hanson LK, Dalton BL, Cageao LF, Brock RE, Slater JS, Kerry JA, Campbell AE. Characterization and regulation of essential murine cytomegalovirus genes m142 and m143. Virology 2005; 334:166-77. [PMID: 15780867 DOI: 10.1016/j.virol.2005.01.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Revised: 10/13/2004] [Accepted: 01/27/2005] [Indexed: 10/25/2022]
Abstract
US22 gene family members m142 and m143 are essential for replication of murine cytomegalovirus (MCMV). Their transcripts are produced with immediate-early kinetics, but little else is known about these viral genes. Unlike their transcripts, the m142 and m143 gene products (pm142, pm143) were not expressed until early times post-infection, with levels increasing over the course of infection. Both pm142 and pm143 were predominantly cytoplasmic, but cellular fractionation studies confirmed that the proteins were present in the nucleus as well. In addition, pm142 was detected within the virion. Both the m142 and m143 promoters were strongly upregulated by viral infection or by MCMV IE1. However, UV-inactivated virus and IE3 upregulated only the m142 promoter. When tested for transcriptional transactivating activity, neither m142 nor m143 demonstrated significant activity, either alone or in combination with the major immediate-early gene products. This failure to transactivate, along with their essential nature, makes m142 and m143 unique among the immediate-early genes of the US22 gene family.
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Affiliation(s)
- Laura K Hanson
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA 23501, USA.
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46
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Karabekian Z, Hanson LK, Slater JS, Krishna NK, Bolin LL, Kerry JA, Campbell AE. Complex formation among murine cytomegalovirus US22 proteins encoded by genes M139, M140, and M141. J Virol 2005; 79:3525-35. [PMID: 15731247 PMCID: PMC1075738 DOI: 10.1128/jvi.79.6.3525-3535.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The murine cytomegalovirus (MCMV) proteins encoded by US22 genes M139, M140, and M141 function, at least in part, to regulate replication of this virus in macrophages. Mutant MCMV having one or more of these genes deleted replicates poorly in macrophages in culture and in the macrophage-dense environment of the spleen. In this report, we demonstrate the existence of stable complexes formed by the products of all three of these US22 genes, as well as a complex composed of the products of M140 and M141. These complexes form in the absence of other viral proteins; however, the pM140/pM141 complex serves as a requisite binding partner for the M139 gene products. Products from all three genes colocalize to a perinuclear region of the cell juxtaposed to or within the cis-Golgi region but excluded from the trans-Golgi region. Interestingly, expression of pM141 redirects pM140 from its predominantly nuclear residence to the perinuclear, cytoplasmic locale where these US22 proteins apparently exist in complex. Thus, complexing of these nonessential, early MCMV proteins likely confers a function(s) independent of each individual protein and important for optimal replication of MCMV in its natural host.
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Affiliation(s)
- Zaruhi Karabekian
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, 700 W. Olney Rd., Norfolk, VA 23507, USA
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Dix RD, Cousins SW. Susceptibility to murine cytomegalovirus retinitis during progression of MAIDS: correlation with intraocular levels of tumor necrosis factor-alpha and interferon-gamma. Curr Eye Res 2005; 29:173-80. [PMID: 15512964 DOI: 10.1080/02713680490504876] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE To correlate tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) synthesis with histopathologic disease and virus replication within murine cytomegalovirus (MCMV)-infected eyes during progression of murine acquired immunodeficiency syndrome (MAIDS). MATERIALS AND METHODS Groups of normal mice and mice with MAIDS of 2-weeks (MAIDS-2), 4-weeks (MAIDS-4), and 12-weeks (MAIDS-12) duration were infected uniocularly with MCMV by subretinal MCMV injection. MCMV-inoculated eyes from all mice were subjected to histopathologic analysis, quantitative plaque assay, or cytometric bead array analysis for quantification of TNF-alpha and IFN-gamma. RESULTS Whereas MCMV-inoculated eyes of normal, MAIDS-2, and MAIDS-4 mice were resistant to MCMV retinitis, all MCMV-inoculated eyes of MAIDS-12 mice developed retinitis. Surprisingly, MCMV-inoculated eyes of MAIDS-4 mice without retinitis harbored high amounts of infectious virus at a level equivalent to that of MCMV-inoculated eyes of MAIDS-12 mice that developed retinitis. Intraocular TNF-alpha levels were consistently approximately 50% greater in MCMV-inoculated eyes of MAIDS-12 mice when compared with TNF-alpha levels of normal, MAIDS-2, and MAIDS-4 mice. In contrast, intraocular INF-gamma levels within MCMV-inoculated eyes progressively declined as animals became susceptible to retinitis. CONCLUSIONS An inverse relationship exists between TNF-alpha and INF-gamma production within MCMV-inoculated eyes during MAIDS evolution that is characterized by an increase in intraocular TNF-alpha levels and a concomitant decrease in intraocular INF-gamma levels. Susceptibility of MCMV-inoculated eyes to virus replication and development of necrotizing retinitis are independent events with susceptibility to MCMV replication preceding susceptibility to MCMV retinitis by several weeks. Time of Th1/Th2 shift in cytokine profile appears to be a crucial event in the pathogenesis of MAIDS-related MCMV retinitis.
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Affiliation(s)
- Richard D Dix
- Department of Ophthalmology, Jones Eye Institute, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
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48
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Loewendorf A, Krüger C, Borst EM, Wagner M, Just U, Messerle M. Identification of a mouse cytomegalovirus gene selectively targeting CD86 expression on antigen-presenting cells. J Virol 2004; 78:13062-71. [PMID: 15542658 PMCID: PMC524971 DOI: 10.1128/jvi.78.23.13062-13071.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 07/22/2004] [Indexed: 02/03/2023] Open
Abstract
We and others have shown that infection of dendritic cells with murine cytomegalovirus (MCMV) leads to severe functional impairment of these antigen-presenting cells (D. M. Andrews, C. E. Andoniou, F. Granucci, P. Ricciardi-Castagnoli, and M. A. Degli-Esposti, Nat. Immunol. 2:1077-1084, 2001; S. Mathys, T. Schroeder, J. Ellwart, U. H. Koszinowski, M. Messerle, and U. Just, J. Infect. Dis. 187:988-999, 2003). Phenotypically, reduced surface expression of costimulatory molecules and major histocompatibility complex molecules was detected. In order to identify the molecular basis for the observed effects, we generated MCMV mutants with large deletions of nonessential genes. The study was facilitated by the finding that a monocyte-macrophage cell line displayed similar phenotypic alterations after MCMV infection. By analyzing the expression of cell surface molecules on infected cells, we identified a mutant virus which is no longer able to downmodulate the expression of the costimulatory molecule CD86. Additional mutants with smaller deletions allowed us to pin down the responsible gene to a certain genomic region. RNA analysis led to the identification of the spliced gene m147.5, encoding a protein with 145 amino acids. Experiments with an m147.5 mutant revealed that the protein affects CD86 expression only, suggesting that additional MCMV genes are responsible for downmodulation of the other surface molecules. Identification of viral gene products interfering with functionally important proteins of antigen-presenting cells will provide the basis to dissect the complex interaction of CMV with these important cells and to evaluate the biological importance of these viral genes in vivo.
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Affiliation(s)
- Andrea Loewendorf
- Virus-Cell Interaction Group, Medical Faculty, Martin Luther University of Halle-Wittenberg, Heinrich-Damerow-Str. 1, 06120 Halle (Saale), Germany
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49
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Lembo D, Donalisio M, Hofer A, Cornaglia M, Brune W, Koszinowski U, Thelander L, Landolfo S. The ribonucleotide reductase R1 homolog of murine cytomegalovirus is not a functional enzyme subunit but is required for pathogenesis. J Virol 2004; 78:4278-88. [PMID: 15047841 PMCID: PMC374293 DOI: 10.1128/jvi.78.8.4278-4288.2004] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ribonucleotide reductase (RNR) is the key enzyme in the biosynthesis of deoxyribonucleotides. Alpha- and gammaherpesviruses express a functional enzyme, since they code for both the R1 and the R2 subunits. By contrast, betaherpesviruses contain an open reading frame (ORF) with homology to R1, but an ORF for R2 is absent, suggesting that they do not express a functional RNR. The M45 protein of murine cytomegalovirus (MCMV) exhibits the sequence features of a class Ia RNR R1 subunit but lacks certain amino acid residues believed to be critical for enzymatic function. It starts to be expressed independently upon the onset of viral DNA synthesis at 12 h after infection and accumulates at later times in the cytoplasm of the infected cells. Moreover, it is associated with the virion particle. To investigate direct involvement of the virally encoded R1 subunit in ribonucleotide reduction, recombinant M45 was tested in enzyme activity assays together with cellular R1 and R2. The results indicate that M45 neither is a functional equivalent of an R1 subunit nor affects the activity or the allosteric control of the mouse enzyme. To replicate in quiescent cells, MCMV induces the expression and activity of the cellular RNR. Mutant viruses in which the M45 gene has been inactivated are avirulent in immunodeficient SCID mice and fail to replicate in their target organs. These results suggest that M45 has evolved a new function that is indispensable for virus replication and pathogenesis in vivo.
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Affiliation(s)
- David Lembo
- Department of Public Health and Microbiology, University of Turin, Turin, Italy.
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Pereira L, Maidji E, McDonagh S, Genbacev O, Fisher S. Human cytomegalovirus transmission from the uterus to the placenta correlates with the presence of pathogenic bacteria and maternal immunity. J Virol 2004; 77:13301-14. [PMID: 14645586 PMCID: PMC296088 DOI: 10.1128/jvi.77.24.13301-13314.2003] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prenatal cytomegalovirus infection may cause pregnancy complications such as intrauterine growth restriction and birth defects. How virus from the mother traverses the placenta is unknown. PCR analysis of biopsy specimens of the maternal-fetal interface revealed that DNA sequences from cytomegalovirus were commonly found with those of herpes simplex viruses and pathogenic bacteria. Cytomegalovirus DNA and infected cell proteins were found more often in the decidua than in the placenta, suggesting that the uterus functions as a reservoir for infection. In women with low neutralizing titers, cytomegalovirus replicated in diverse decidual cells and placental trophoblasts and capillaries. In women with intermediate to high neutralizing titers, decidual infection was suppressed and the placenta was spared. Overall, cytomegalovirus virions and maternal immunoglobulin G were detected in syncytiotrophoblasts, villus core macrophages, and dendritic cells. These results suggest that the outcome of cytomegalovirus infection depends on the presence of other pathogens and coordinated immune responses to viral replication at the maternal-fetal interface.
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Affiliation(s)
- Lenore Pereira
- Departments of Stomatology, University of California-San Francisco, San Francisco, California 94143-0512, USA.
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