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Abstract
Infectious diseases pose two main compelling issues. First, the identification of the molecular factors that allow chronic infections, that is, the often completely asymptomatic coexistence of infectious agents with the human host. Second, the definition of the mechanisms that allow the switch from pathogen dormancy to pathologic (re)activation. Furthering previous studies, the present study (1) analyzed the frequency of occurrence of synonymous codons in coding DNA, that is, codon usage, as a genetic tool that rules protein expression; (2) described how human codon usage can inhibit protein expression of infectious agents during latency, so that pathogen genes the codon usage of which does not conform to the human codon usage cannot be translated; and (3) framed human codon usage among the front-line instruments of the innate immunity against infections. In parallel, it was shown that, while genetics can account for the molecular basis of pathogen latency, the changes of the quantitative relationship between codon frequencies and isoaccepting tRNAs during cell proliferation offer a biochemical mechanism that explains the pathogen switching to (re)activation. Immunologically, this study warns that using codon optimization methodologies can (re)activate, potentiate, and immortalize otherwise quiescent, asymptomatic pathogens, thus leading to uncontrollable pandemics.
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Affiliation(s)
- Darja Kanduc
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
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2
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New Insights Into the Molecular Mechanisms and Immune Control of Cytomegalovirus Reactivation. Transplantation 2020; 104:e118-e124. [PMID: 31996662 PMCID: PMC7790173 DOI: 10.1097/tp.0000000000003138] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cytomegalovirus (CMV) is a β-herpesvirus that establishes lifelong latency in infected hosts. Following transplantation of a latently infected organ, reactivation can occur and consists of a spectrum of clinically apparent syndromes from mild symptoms to tissue-invasive, resulting in both direct and indirect sequelae. Before the advent of effective antiviral agents, the primary treatment was reduction in immunosuppression (IS). While antiviral agents provide effective prophylaxis, there are several important caveats associated with their use, including drug toxicity and resistance. The traditional view attributes CMV reactivation and the ensuing clinical disease primarily to IS, either intrinsic to disease-related immune compromise or from the extrinsic administration of IS agents. However, previous data from both animal models and human subjects showed that inflammatory signals could induce upregulation of latent viral gene expression. New data demonstrate that ischemia/reperfusion is necessary and sufficient to induce CMV reactivation following murine transplantation of a latently infected graft. In this article, we review a growing body of evidence that suggests that reactivation of both human CMV and murine CMV is first triggered by molecular events that activate CMV gene expression and lytic infection and viral dissemination are then facilitated by IS. The initial activation of viral gene expression may be mediated by oxidative stress, DNA damage, or inflammatory cytokines, and these factors may act synergistically. New therapeutic approaches are needed to capture this complex array of targets.
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3
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Lyon SM, Yetming KD, Paulus C, Nevels M, Kalejta RF. Human Cytomegalovirus Genomes Survive Mitosis via the IE19 Chromatin-Tethering Domain. mBio 2020; 11:e02410-20. [PMID: 32994332 PMCID: PMC7527735 DOI: 10.1128/mbio.02410-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 08/26/2020] [Indexed: 12/12/2022] Open
Abstract
The genomes of DNA tumor viruses regain nuclear localization after nuclear envelope breakdown during mitosis through the action of a viral protein with a chromatin-tethering domain (CTD). Here, we report that the human cytomegalovirus (HCMV) genome is maintained during mitosis by the CTD of the viral IE19 protein. Deletion of the IE19 CTD or disruption of the IE19 splice acceptor site reduced viral genome maintenance and progeny virion formation during infection of dividing fibroblasts, both of which were rescued by IE19 ectopic expression. The discovery of a viral genome maintenance factor during productive infection provides new insight into the mode of HCMV infection implicated in birth defects, organ transplant failure, and cancer.IMPORTANCE Human cytomegalovirus (HCMV) is the leading infectious cause of birth defects, represents a serious complication for immunocompromised HIV/AIDS and organ transplant patients, and contributes to both immunosenescence and cardiovascular diseases. HCMV is also implicated in cancers such as glioblastoma multiforme (GBM) and infects ex vivo-cultured GBM tumor cells. In dividing tumor cells, the genomes of DNA tumor viruses regain nuclear localization after nuclear envelope breakdown during mitosis. This mitotic survival is mediated by a viral protein with a chromatin-tethering domain (CTD). Here, we report that the HCMV genome is maintained in dividing fibroblasts by the CTD of the viral IE19 protein. The discovery of a viral genome maintenance factor during productive infection could help explain viral genome dynamics within HCMV-positive tumors as well as during latency.
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Affiliation(s)
- Shelby M Lyon
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kristen D Yetming
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Christina Paulus
- Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, United Kingdom
| | - Michael Nevels
- Biomedical Sciences Research Complex, University of St. Andrews, St. Andrews, United Kingdom
| | - Robert F Kalejta
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, USA
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4
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Lee JH, Pasquarella JR, Kalejta RF. Cell Line Models for Human Cytomegalovirus Latency Faithfully Mimic Viral Entry by Macropinocytosis and Endocytosis. J Virol 2019; 93:e01021-19. [PMID: 31391271 PMCID: PMC6803280 DOI: 10.1128/jvi.01021-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 08/05/2019] [Indexed: 02/06/2023] Open
Abstract
Human cytomegalovirus (HCMV) enters primary CD34+ hematopoietic progenitor cells by macropinocytosis, where it establishes latency in part because its tegument-transactivating protein, pp71, remains associated with endosomes and is therefore unable to initiate productive, lytic replication. Here we show that multiple HCMV strains also enter cell line models used to study latency by macropinocytosis and endocytosis. In all latency models tested, tegument-delivered pp71 was found to be colocalized with endosomal markers and was not associated with the seven other cytoplasmic localization markers tested. Like the capsid-associated pp150 tegument protein, we initially detected capsid proteins in association with endosomes but later detected them in the nucleus. Inhibitors of macropinocytosis and endocytosis reduced latent viral gene expression and precluded reactivation. Importantly, we utilized electron microscopy to observe entry by macropinocytosis and endocytosis, providing additional visual corroboration of the findings of our functional studies. Our demonstration that HCMV enters cell line models for latency in a manner indistinguishable from that of its entry into primary cells illustrates the utility of these cell lines for probing the mechanisms, host genetics, and small-molecule-mediated inhibition of HCMV entry into the cell types where it establishes latency.IMPORTANCE Primary cells cultured in vitro currently provide the highest available relevance for examining molecular and genetic requirements for the establishment, maintenance, and reactivation of HCMV latency. However, their expense, heterogeneity, and intransigence to both long-term culture and molecular or genetic modification create rigor and reproducibility challenges for HCMV latency studies. There are several cell line models for latency not obstructed by deficiencies inherent in primary cells. However, many researchers view cell line studies of latency to be physiologically irrelevant because of the perception that these models display numerous and significant differences from primary cells. Here, we show that the very first step in a latent HCMV infection, entry of the virus into cells, occurs in cell line models in a manner indistinguishable from that in which it occurs in primary CD34+ hematopoietic progenitor cells. Our data argue that experimental HCMV latency is much more similar than it is different in cell lines and primary cells.
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Affiliation(s)
- Jeong-Hee Lee
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Joseph R Pasquarella
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Robert F Kalejta
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, Wisconsin, USA
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5
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Piekarowicz K, Bertrand AT, Azibani F, Beuvin M, Julien L, Machowska M, Bonne G, Rzepecki R. A Muscle Hybrid Promoter as a Novel Tool for Gene Therapy. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2019; 15:157-169. [PMID: 31660418 PMCID: PMC6807297 DOI: 10.1016/j.omtm.2019.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 09/03/2019] [Indexed: 01/29/2023]
Abstract
Gene therapy is a promising strategy to cure rare diseases. The lack of regulatory sequences ensuring specific and robust expression in skeletal and cardiac muscle is a substantial limitation of gene therapy efficiency targeting the muscle tissue. Here we describe a novel muscle hybrid (MH) promoter that is highly active in both skeletal and cardiac muscle cells. It has an easily exchangeable modular structure, including an intronic module that highly enhances the expression of the gene driven by it. In cultured myoblasts, myotubes, and cardiomyocytes, the MH promoter gives relatively stable expression as well as higher activity and protein levels than the standard CMV and desmin gene promoters or the previously developed synthetic or CKM-based promoters. Combined with AAV2/9, the MH promoter also provides a high in vivo expression level in skeletal muscle and the heart after both intramuscular and systemic delivery. It is much more efficient than the desmin-encoding gene promoter, and it maintains the same specificity. This novel promoter has potential for gene therapy in muscle cells. It can provide stable transgene expression, ensuring high levels of therapeutic protein, and limited side effects because of its specificity. This constitutes an improvement in the efficiency of genetic disease therapy.
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Affiliation(s)
- Katarzyna Piekarowicz
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Wroclaw 50-383, Poland
| | - Anne T Bertrand
- Sorbonne Université, INSERM UMRS974, Center of Research in Myology, Institute of Myology, Paris 75 651, France
| | - Feriel Azibani
- Sorbonne Université, INSERM UMRS974, Center of Research in Myology, Institute of Myology, Paris 75 651, France
| | - Maud Beuvin
- Sorbonne Université, INSERM UMRS974, Center of Research in Myology, Institute of Myology, Paris 75 651, France
| | - Laura Julien
- Sorbonne Université, INSERM UMRS974, Center of Research in Myology, Institute of Myology, Paris 75 651, France
| | - Magdalena Machowska
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Wroclaw 50-383, Poland
| | - Gisèle Bonne
- Sorbonne Université, INSERM UMRS974, Center of Research in Myology, Institute of Myology, Paris 75 651, France
| | - Ryszard Rzepecki
- Laboratory of Nuclear Proteins, Faculty of Biotechnology, University of Wroclaw, Wroclaw 50-383, Poland
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6
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Gelbmann CB, Kalejta RF. The Golgi sorting motifs of human cytomegalovirus UL138 are not required for latency maintenance. Virus Res 2019; 270:197646. [PMID: 31260705 PMCID: PMC6697590 DOI: 10.1016/j.virusres.2019.197646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 02/07/2023]
Abstract
Human cytomegalovirus (HCMV) establishes latency within incompletely differentiated cells of the myeloid lineage. The viral protein UL138 participates in establishing and maintaining this latent state. UL138 has multiple functions during latency that include silencing productive phase viral gene transcription and modulating intracellular protein trafficking. Trafficking and subsequent downregulation of the multidrug resistance-associated protein 1 (MRP1) by UL138 is mediated by one of four Golgi sorting motifs within UL138. Here we investigate whether any of the Golgi sorting motifs of UL138 are required for the establishment and/or maintenance of HCMV latency in model cell systems in vitro. We determined that a mutant UL138 protein lacking an acidic cluster dileucine sorting motif unable to downregulate MRP1, as well as another mutant lacking all four Golgi sorting motifs still silenced viral immediate early (IE) gene expression and prevented progeny virion formation during latency. We conclude that the Golgi sorting motifs are not required for latency establishment or maintenance in model cell systems in vitro.
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Affiliation(s)
- Christopher B Gelbmann
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI, 53706, USA
| | - Robert F Kalejta
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI, 53706, USA.
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7
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Marshall EE, Malouli D, Hansen SG, Gilbride RM, Hughes CM, Ventura AB, Ainslie E, Selseth AN, Ford JC, Burke D, Kreklywich CN, Womack J, Legasse AW, Axthelm MK, Kahl C, Streblow D, Edlefsen PT, Picker LJ, Früh K. Enhancing safety of cytomegalovirus-based vaccine vectors by engaging host intrinsic immunity. Sci Transl Med 2019; 11:eaaw2603. [PMID: 31316006 PMCID: PMC6830438 DOI: 10.1126/scitranslmed.aaw2603] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 03/14/2019] [Accepted: 06/13/2019] [Indexed: 12/29/2022]
Abstract
Rhesus cytomegalovirus (RhCMV)-based vaccines maintain effector memory T cell responses (TEM) that protect ~50% of rhesus monkeys (RMs) challenged with simian immunodeficiency virus (SIV). Because human CMV (HCMV) causes disease in immunodeficient subjects, clinical translation will depend upon attenuation strategies that reduce pathogenic potential without sacrificing CMV's unique immunological properties. We demonstrate that "intrinsic" immunity can be used to attenuate strain 68-1 RhCMV vectors without impairment of immunogenicity. The tegument proteins pp71 and UL35 encoded by UL82 and UL35 of HCMV counteract cell-intrinsic restriction via degradation of host transcriptional repressors. When the corresponding RhCMV genes, Rh110 and Rh59, were deleted from 68-1 RhCMV (ΔRh110 and ΔRh59), we observed only a modest growth defect in vitro, but in vivo, these modified vectors manifested little to no amplification at the injection site and dissemination to distant sites, in contrast to parental 68-1 RhCMV. ΔRh110 was not shed at any time after infection and was not transmitted to naïve hosts either by close contact (mother to infant) or by leukocyte transfusion. In contrast, ΔRh59 was both shed and transmitted by leukocyte transfusion, indicating less effective attenuation than pp71 deletion. The T cell immunogenicity of ΔRh110 was essentially identical to 68-1 RhCMV with respect to magnitude, TEM phenotype, epitope targeting, and durability. Thus, pp71 deletion preserves CMV vector immunogenicity while stringently limiting vector spread, making pp71 deletion an attractive attenuation strategy for HCMV vectors.
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Affiliation(s)
- Emily E Marshall
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Daniel Malouli
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Scott G Hansen
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Roxanne M Gilbride
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Colette M Hughes
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Abigail B Ventura
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Emily Ainslie
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Andrea N Selseth
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Julia C Ford
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - David Burke
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Craig N Kreklywich
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Jennie Womack
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Alfred W Legasse
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Michael K Axthelm
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Christoph Kahl
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Daniel Streblow
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Paul T Edlefsen
- Statistical Center for HIV/AIDS Research and Prevention, Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Louis J Picker
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA.
| | - Klaus Früh
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA.
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Tumor Necrosis Factor Alpha Induces Reactivation of Human Cytomegalovirus Independently of Myeloid Cell Differentiation following Posttranscriptional Establishment of Latency. mBio 2018; 9:mBio.01560-18. [PMID: 30206173 PMCID: PMC6134100 DOI: 10.1128/mbio.01560-18] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
HCMV is an important human pathogen that establishes lifelong latent infection in myeloid progenitor cells and reactivates frequently to cause significant disease in immunocompromised people. Our observation that viral gene expression is first turned on and then turned off to establish latency suggests that there is a host defense, which may be myeloid cell specific, responsible for transcriptional silencing of viral gene expression. Our observation that TNF-α induces reactivation independently of differentiation provides insight into molecular mechanisms that control reactivation. We used the Kasumi-3 model to study human cytomegalovirus (HCMV) latency and reactivation in myeloid progenitor cells. Kasumi-3 cells were infected with HCMV strain TB40/Ewt-GFP, flow sorted for green fluorescent protein-positive (GFP+) cells, and cultured for various times to monitor establishment of latency, as judged by repression of viral gene expression (RNA/DNA ratio) and loss of virus production. We found that, in the vast majority of cells, latency was established posttranscriptionally in the GFP+ infected cells: transcription was initially turned on and then turned off. We also found that some of the GFP− cells were infected, suggesting that latency might be established in these cells at the outset of infection. We were not able to test this hypothesis because some GFP− cells expressed lytic genes and thus it was not possible to separate them from GFP− quiescent cells. In addition, we found that the pattern of expression of lytic genes that have been associated with latency, including UL138, US28, and RNA2.7, was the same as that of other lytic genes, indicating that there was no preferential expression of these genes once latency was established. We confirmed previous studies showing that tumor necrosis factor alpha (TNF-α) induced reactivation of infectious virus, and by analyzing expression of the progenitor cell marker CD34 as well as myeloid cell differentiation markers in IE+ cells after treatment with TNF-α, we showed that TNF-α induced transcriptional reactivation of IE gene expression independently of differentiation. TNF-α-mediated reactivation in Kasumi-3 cells was correlated with activation of NF-κB, KAP-1, and ATM.
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9
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Abstract
Viral latency can be considered a metastable, nonproductive infection state that is capable of subsequent reactivation to repeat the infection cycle. Viral latent infections have numerous associated pathologies, including cancer, birth defects, neuropathy, cardiovascular disease, chronic inflammation, and immunological dysfunctions. The mechanisms controlling the establishment, maintenance, and reactivation from latency are complex and diversified among virus families, species, and strains. Yet, as examined in this review, common properties of latent viral infections can be defined. Eradicating latent virus has become an important but elusive challenge and will require a more complete understanding of the mechanisms controlling these processes.
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10
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Human Cytomegalovirus-Infected Glioblastoma Cells Display Stem Cell-Like Phenotypes. mSphere 2017; 2:mSphere00137-17. [PMID: 28656174 PMCID: PMC5480031 DOI: 10.1128/msphere.00137-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/07/2017] [Indexed: 12/27/2022] Open
Abstract
A role for HCMV in GBMs remains controversial for several reasons. Some studies find HCMV in GBM tumors, while others do not. Few cells within a GBM may harbor HCMV, making it unclear how the virus could be contributing to the tumor phenotype without infecting every cell. Finally, HCMV does not overtly transform cells in vitro. However, tumors induced by other viruses can be treated with antiviral remedies, and initial results indicate that this may be true for anti-HCMV therapies and GBMs. With such a poor prognosis for GBM patients, any potential new intervention deserves exploration. Our work here describes an evidence-based model for how HCMV could contribute to GBM biology while infecting very few cells and without transforming them. It also illuminates why anti-HCMV treatments may be beneficial to GBM patients. Our observations provide blueprints for future in vitro studies examining how HCMV manipulates stem cell-specific pathways and future clinical studies of anti-HCMV measures as GBM therapeutics. Glioblastoma multiforme (GBM) is the most common brain tumor in adults. Human cytomegalovirus (HCMV) genomes are present in GBM tumors, yielding hope that antiviral treatments could prove therapeutic and improve the poor prognosis of GBM patients. We discovered that GBM cells infected in vitro with HCMV display properties of cancer stem cells. HCMV-infected GBM cells grow more slowly than mock-infected controls, demonstrate a higher capacity for self-renewal determined by a sphere formation assay, and display resistance to the chemotherapeutic drug temozolomide. Our data suggest that HCMV, while present in only a minority of the cells within a tumor, could contribute to the pathogenesis of GBMs by promoting or prolonging stem cell-like phenotypes, thereby perpetuating tumors in the face of chemotherapy. Importantly, we show that temozolomide sensitivity is restored by the antiviral drug ganciclovir, indicating a potential mechanism underlying the positive effects observed in GBM patients treated with antiviral therapy. IMPORTANCE A role for HCMV in GBMs remains controversial for several reasons. Some studies find HCMV in GBM tumors, while others do not. Few cells within a GBM may harbor HCMV, making it unclear how the virus could be contributing to the tumor phenotype without infecting every cell. Finally, HCMV does not overtly transform cells in vitro. However, tumors induced by other viruses can be treated with antiviral remedies, and initial results indicate that this may be true for anti-HCMV therapies and GBMs. With such a poor prognosis for GBM patients, any potential new intervention deserves exploration. Our work here describes an evidence-based model for how HCMV could contribute to GBM biology while infecting very few cells and without transforming them. It also illuminates why anti-HCMV treatments may be beneficial to GBM patients. Our observations provide blueprints for future in vitro studies examining how HCMV manipulates stem cell-specific pathways and future clinical studies of anti-HCMV measures as GBM therapeutics.
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11
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Lee SH, Albright ER, Lee JH, Jacobs D, Kalejta RF. Cellular defense against latent colonization foiled by human cytomegalovirus UL138 protein. SCIENCE ADVANCES 2015; 1:e1501164. [PMID: 26702450 PMCID: PMC4681346 DOI: 10.1126/sciadv.1501164] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/08/2015] [Indexed: 05/10/2023]
Abstract
Intrinsic immune defenses mediated by restriction factors inhibit productive viral infections. Select viruses rapidly establish latent infections and, with gene expression profiles that imply cell-autonomous intrinsic defenses, may be the most effective immune control measure against latent reservoirs. We illustrate that lysine-specific demethylases (KDMs) are restriction factors that prevent human cytomegalovirus from establishing latency by removing repressive epigenetic modifications from histones associated with the viral major immediate early promoter (MIEP), stimulating the expression of a viral lytic phase target of cell-mediated adaptive immunity. The viral UL138 protein negates this defense by preventing KDM association with the MIEP. The presence of an intrinsic defense against latency and the emergence of a cognate neutralizing viral factor indicate that "arms races" between hosts and viruses over lifelong colonization exist at the cellular level.
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12
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Zhang H, Niu X, Qian Z, Qian J, Xuan B. The c-Jun N-terminal kinase inhibitor SP600125 inhibits human cytomegalovirus replication. J Med Virol 2015; 87:2135-44. [PMID: 26058558 DOI: 10.1002/jmv.24286] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2015] [Indexed: 12/19/2022]
Abstract
Human cytomegalovirus (HCMV) is an opportunistic pathogen that causes severe diseases in congenitally infected newborns and immunocompromised patients. Currently, no vaccine is available to prevent HCMV infection. Anti-viral drugs are limited by their side effects and drug resistance. In this study, by performing a medium-sized, anti-HCMV chemical screening, we identified SP600125, CC-401, and the c-Jun N-terminal kinase (JNK) inhibitor VIII, three structurally different small molecule JNK inhibitors that effectively inhibited HCMV replication in cultured human fibroblasts (HFs). SP600125 showed its potential by inhibiting the viral replication of a HCMV laboratory strain in HFs and a HCMV clinical strain in human retinal pigment epithelial cells. Knockdown of JNK expression by RNA interference significantly impaired HCMV replication, mimicking the effect of the chemical inhibitors on virus infection. Mechanistically, SP600125 affects a very early step of the viral life cycle. Viral binding, entry, and the delivery of viral DNA into the cells were not inhibited by the compound. Instead, it suppressed the transcription of the immediate-early viral genes IE1/2 and the accumulation of their gene products. IE1/2 are among the first genes expressed after viral entry, and they are the master regulators of late phase viral gene expression. Consistent with this notion, the expression of other viral genes was also reduced after SP600125 treatment. We propose that JNK inhibitors have the potential to become a new class of anti-HCMV drug candidates, and JNK is a feasible target for the development of anti-HCMV drugs.
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Affiliation(s)
- Huiping Zhang
- Department of Neonatology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Xiaofeng Niu
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhikang Qian
- Unit of Herpesvirus and Molecular Virology, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Jihong Qian
- Department of Neonatology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Baoqin Xuan
- Unit of Herpesvirus and Molecular Virology, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
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13
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Wu SE, Miller WE. The human cytomegalovirus lytic cycle is induced by 1,25-dihydroxyvitamin D3 in peripheral blood monocytes and in the THP-1 monocytic cell line. Virology 2015; 483:83-95. [PMID: 25965798 DOI: 10.1016/j.virol.2015.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 01/12/2015] [Accepted: 04/02/2015] [Indexed: 12/11/2022]
Abstract
Human cytomegalovirus (HCMV) resides in a latent form in hematopoietic progenitors and undifferentiated cells within the myeloid lineage. Maturation and differentiation along the myeloid lineage triggers lytic replication. Here, we used peripheral blood monocytes and the monocytic cell line THP-1 to investigate the effects of 1,25-dihydroxyvitamin D3 on HCMV replication. Interestingly, 1,25-dihydroxyvitamin D3 induces lytic replication marked by upregulation of HCMV gene expression and production of infectious virus. Moreover, we demonstrate that the effects of 1,25-dihydroxyvitamin D3 correlate with maturation/differentiation of the monocytes and not by directly stimulating the MIEP. These results are somewhat surprising as 1,25-dihydroxyvitamin D3 typically boosts immunity to bacteria and viruses rather than driving the infectious life cycle as it does for HCMV. Defining the signaling pathways kindled by 1,25-dihydroxyvitamin D3 will lead to a better understanding of the underlying molecular mechanisms that determine the fate of HCMV once it infects cells in the myeloid lineage.
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Affiliation(s)
- Shu-En Wu
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0524, United States
| | - William E Miller
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0524, United States.
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Sinclair J, Poole E. Human cytomegalovirus latency and reactivation in and beyond the myeloid lineage. Future Virol 2014. [DOI: 10.2217/fvl.14.34] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
ABSTRACT: After primary infection with human cytomegalovirus (HCMV), which rarely causes any serious clinical problems in the immune competent, the virus persists subclinically for the lifetime of the host due, at least in part, to its ability to undergo latent infection. By contrast, HCMV can be a serious cause of morbidity, and in some cases mortality, upon primary infection of, or reactivation in, immune suppressed individuals. While current antivirals that target its lytic lifecycle have helped enormously in managing HCMV disease, to date, there are no available antivirals that target latent infection. In this review, we discuss research using natural and experimental models of latency that has led to some understanding of how HCMV latency is maintained, and reactivation controlled, in the myeloid lineage. Such analyses are now beginning to inform us of novel rationales that could allow the development of novel antivirals to target latency, itself.
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Affiliation(s)
- John Sinclair
- Department of Medicine, Box 157, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Emma Poole
- Department of Medicine, Box 157, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
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Shen ZZ, Pan X, Miao LF, Ye HQ, Chavanas S, Davrinche C, McVoy M, Luo MH. Comprehensive analysis of human cytomegalovirus microRNA expression during lytic and quiescent infection. PLoS One 2014; 9:e88531. [PMID: 24533100 PMCID: PMC3922878 DOI: 10.1371/journal.pone.0088531] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 01/06/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Human cytomegalovirus (HCMV) encodes microRNAs (miRNAs) that function as post-transcriptional regulators of gene expression during lytic infection in permissive cells. Some miRNAs have been shown to suppress virus replication, which could help HCMV to establish or maintain latent infection. However, HCMV miRNA expression has not been comprehensively examined and compared using cell culture systems representing permissive (lytic) and semi-permissive vs. non-permissive (latent-like) infection. METHODS Viral miRNAs levels and expression kinetics during HCMV infection were determined by miRNA-specific stem-loop RT-PCR. HCMV infected THP-1 (non-permissive), differentiated THP-1 (d-THP-1, semi-permissive) and human embryo lung fibroblasts (HELs, fully-permissive) were examined. The impact of selected miRNAs on HCMV infection (gene expression, genome replication and virus release) was determined by Western blotting, RT-PCR, qPCR, and plaque assay. RESULTS Abundant expression of 15 HCMV miRNAs was observed during lytic infection in HELs; highest peak inductions (11- to 1502-fold) occurred at 48 hpi. In d-THP-1s, fourteen mRNAs were detected with moderate induction (3- to 288-fold), but kinetics of expression was generally delayed for 24 h relative to HELs. In contrast, only three miRNAs were induced to low levels (3- to 4-fold) during quiescent infection in THP-1s. Interestingly, miR-UL70-3p was poorly induced in HEL (1.5-fold), moderately in THP-1s (4-fold), and strongly (58-fold) in d-THP-1s, suggesting a potentially specific role for miR-UL70-3p in THP-1s and d-THP-1s. MiR-US33, -UL22A and -UL70 were further evaluated for their impact on HCMV replication in HELs. Ectopic expression of miR-UL22A and miR-UL70 did not affect HCMV replication in HELs, whereas miR-US33 inhibited HCMV replication and reduced levels of HCMV US29 mRNA, confirming that US29 is a target of miR-US33. CONCLUSIONS Viral miRNA expression kinetics differs between permissive, semi-permissive and quiescent infections, and miR-US33 down-regulates HCMV replication. These results suggest that miR-US33 may function to impair entry into lytic replication and hence promote establishment of latency.
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Affiliation(s)
- Zhang-Zhou Shen
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Xing Pan
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Ling-Feng Miao
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Han-Qing Ye
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
| | | | | | - Michael McVoy
- Department of Pediatrics, Virginia Commonwealth University, School of Medicine, Richmond, Virginia, United States of America
| | - Min-Hua Luo
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, China
- * E-mail:
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Abstract
Human cytomegalovirus (HCMV) genome replication requires host DNA damage responses (DDRs) and raises the possibility that DNA repair pathways may influence viral replication. We report here that a nucleotide excision repair (NER)-associated-factor is required for efficient HCMV DNA replication. Mutations in genes encoding NER factors are associated with xeroderma pigmentosum (XP). One of the XP complementation groups, XPE, involves mutation in ddb2, which encodes DNA damage binding protein 2 (DDB2). Infectious progeny virus production was reduced by >2 logs in XPE fibroblasts compared to levels in normal fibroblasts. The levels of immediate early (IE) (IE2), early (E) (pp65), and early/late (E/L) (gB55) proteins were decreased in XPE cells. These replication defects were rescued by infection with a retrovirus expressing DDB2 cDNA. Similar patterns of reduced viral gene expression and progeny virus production were also observed in normal fibroblasts that were depleted for DDB2 by RNA interference (RNAi). Mature replication compartments (RCs) were nearly absent in XPE cells, and there were 1.5- to 2.0-log reductions in viral DNA loads in infected XPE cells relative to those in normal fibroblasts. The expression of viral genes (UL122, UL44, UL54, UL55, and UL84) affected by DDB2 status was also sensitive to a viral DNA replication inhibitor, phosphonoacetic acid (PAA), suggesting that DDB2 affects gene expression upstream of or events associated with the initiation of DNA replication. Finally, a novel, infection-associated feedback loop between DDB2 and ataxia telangiectasia mutated (ATM) was observed in infected cells. Together, these results demonstrate that DDB2 and a DDB2-ATM feedback loop influence HCMV replication.
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Qin Q, Lee SH, Liang R, Kalejta RF. Insertion of myeloid-active elements into the human cytomegalovirus major immediate early promoter is not sufficient to drive its activation upon infection of undifferentiated myeloid cells. Virology 2013; 448:125-32. [PMID: 24314643 DOI: 10.1016/j.virol.2013.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 07/29/2013] [Accepted: 10/07/2013] [Indexed: 12/13/2022]
Abstract
The Major Immediate Early Promoter (MIEP) of human cytomegalovirus (HCMV) controls viral Immediate Early (IE) gene expression, which must be activated to initiate productive infection and repressed to establish latency. Regulation of the MIEP is critical for both viral spread and persistence. In addition to the Daxx-mediated intrinsic cellular defense that regulates the MIEP, the cell-type specific balance between cellular activators and repressors of the promoter may help dictate whether viral IE genes will be expressed or silenced. For example, in undifferentiated myeloid cells, transcriptional repressors of the MIEP may outnumber transcriptional activators, leading to promoter silencing and latency establishment. We created a recombinant viral genome in which a myeloid-active promoter replaced part of the MIEP. The viable virus generated failed to express the viral IE genes in an undifferentiated myeloid cell line. These observations have mechanistic implications regarding how viral IE gene expression is regulated during latency.
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Affiliation(s)
- Qingsong Qin
- Institute for Molecular Virology and McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, Madison, WI 53706, USA
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