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Lu J, Gullett JM, Kanneganti TD. Filoviruses: Innate Immunity, Inflammatory Cell Death, and Cytokines. Pathogens 2022; 11:1400. [PMID: 36558734 PMCID: PMC9785368 DOI: 10.3390/pathogens11121400] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/17/2022] [Accepted: 11/19/2022] [Indexed: 11/24/2022] Open
Abstract
Filoviruses are a group of single-stranded negative sense RNA viruses. The most well-known filoviruses that affect humans are ebolaviruses and marburgviruses. During infection, they can cause life-threatening symptoms such as inflammation, tissue damage, and hemorrhagic fever, with case fatality rates as high as 90%. The innate immune system is the first line of defense against pathogenic insults such as filoviruses. Pattern recognition receptors (PRRs), including toll-like receptors, retinoic acid-inducible gene-I-like receptors, C-type lectin receptors, AIM2-like receptors, and NOD-like receptors, detect pathogens and activate downstream signaling to induce the production of proinflammatory cytokines and interferons, alert the surrounding cells to the threat, and clear infected and damaged cells through innate immune cell death. However, filoviruses can modulate the host inflammatory response and innate immune cell death, causing an aberrant immune reaction. Here, we discuss how the innate immune system senses invading filoviruses and how these deadly pathogens interfere with the immune response. Furthermore, we highlight the experimental difficulties of studying filoviruses as well as the current state of filovirus-targeting therapeutics.
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2
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Shah S, Sinharay S, Patel R, Solomon J, Lee JH, Schreiber-Stainthorp W, Basuli F, Zhang X, Hagen KR, Reeder R, Wakim P, Huzella LM, Maric D, Johnson RF, Hammoud DA. PET imaging of TSPO expression in immune cells can assess organ-level pathophysiology in high-consequence viral infections. Proc Natl Acad Sci U S A 2022; 119:e2110846119. [PMID: 35385353 PMCID: PMC9169664 DOI: 10.1073/pnas.2110846119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 02/10/2022] [Indexed: 01/08/2023] Open
Abstract
Ebola virus (EBOV) disease is characterized by lymphopenia, breach in vascular integrity, cytokine storm, and multiorgan failure. The pathophysiology of organ involvement, however, is incompletely understood. Using [18F]-DPA-714 positron emission tomography (PET) imaging targeting the translocator protein (TSPO), an immune cell marker, we sought to characterize the progression of EBOV-associated organ-level pathophysiology in the EBOV Rhesus macaque model. Dynamic [18F]-DPA-714 PET/computed tomography imaging was performed longitudinally at baseline and at multiple time points after EBOV inoculation, and distribution volumes (Vt) were calculated as a measure of peripheral TSPO binding. Using a mixed-effect linear regression model, spleen and lung Vt decreased, while the bone marrow Vt increased over time after infection. No clear trend was found for liver Vt. Multiple plasma cytokines correlated negatively with lung/spleen Vt and positively with bone marrow Vt. Multiplex immunofluorescence staining in spleen and lung sections confirmed organ-level lymphoid and monocytic loss/apoptosis, thus validating the imaging results. Our findings are consistent with EBOV-induced progressive monocytic and lymphocytic depletion in the spleen, rather than immune activation, as well as depletion of alveolar macrophages in the lungs, with inefficient reactive neutrophilic activation. Increased bone marrow Vt, on the other hand, suggests hematopoietic activation in response to systemic immune cell depletion and leukocytosis and could have prognostic relevance. In vivo PET imaging provided better understanding of organ-level pathophysiology during EBOV infection. A similar approach can be used to delineate the pathophysiology of other systemic infections and to evaluate the effectiveness of newly developed treatment and vaccine strategies.
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Affiliation(s)
- Swati Shah
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD 20892
| | - Sanhita Sinharay
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD 20892
| | - Reema Patel
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD 20892
| | - Jeffrey Solomon
- Clinical Monitoring Research Program Directorate, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702
| | - Ji Hyun Lee
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, NIH, Frederick, MD 21702
| | | | - Falguni Basuli
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, NIH, Rockville, MD 20824
| | - Xiang Zhang
- Chemistry and Synthesis Center, National Heart, Lung, and Blood Institute, NIH, Rockville, MD 20824
| | - Katie R. Hagen
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, NIH, Frederick, MD 21702
| | - Rebecca Reeder
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, NIH, Frederick, MD 21702
| | - Paul Wakim
- Biostatistics and Clinical Epidemiology Service, Clinical Center, NIH, Bethesda, MD 20892
| | - Louis M. Huzella
- Integrated Research Facility, National Institute of Allergy and Infectious Diseases, NIH, Frederick, MD 21702
| | - Dragan Maric
- Flow and Imaging Cytometry Core Facility, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892
| | - Reed F. Johnson
- Emerging Viral Pathogens Section, National Institute of Allergy and Infectious Diseases, NIH, Frederick, MD 21702
| | - Dima A. Hammoud
- Center for Infectious Disease Imaging, Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD 20892
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3
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Ebola virus requires phosphatidylserine scrambling activity for efficient budding and optimal infectivity. J Virol 2021; 95:e0116521. [PMID: 34319156 DOI: 10.1128/jvi.01165-21] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ebola virus (EBOV) attaches to target cells using two categories of cell surface receptors, C-type lectins and phosphatidylserine (PS) receptors. PS receptors typically bind to apoptotic cell membrane PS and orchestrate the uptake and clearance of apoptotic debris. Many enveloped viruses also contain exposed PS and can therefore exploit these receptors for cell entry. Viral infection can induce PS externalization in host cells, resulting in increased outer PS levels on budding virions. Scramblase enzymes carry out cellular PS externalization, thus, we targeted these proteins in order to manipulate viral envelope PS levels. We investigated two scramblases previously identified to be involved in EBOV PS levels, transmembrane protein 16F and Xk-related protein 8 (XKR8), as possible mediators of cellular and viral envelope surface PS levels during the replication of recombinant vesicular stomatitis virus containing its native glycoprotein (rVSV/G) or the EBOV glycoprotein (rVSV/EBOV-GP). We found that rVSV/G and rVSV/EBOV-GP virions produced in XKR8 knockout cells contain decreased levels of PS on their surfaces, and the PS-deficient rVSV/EBOV-GP virions are 70% less efficient at infecting cells through PS receptors. We also observed reduced rVSV and EBOV virus-like particle (VLP) budding in ΔXKR8 cells. Deleting XKR8 in HAP1 cells reduced rVSV/G and rVSV/EBOV-GP budding by 60% and 65% respectively, and reduced Ebola VLP budding more than 60%. We further demonstrated that caspase cleavage of XKR8 is required to promote budding. This suggests that XKR8, in addition to mediating virion PS levels, may also be critical for enveloped virus budding at the plasma membrane. Importance Within the last decade, countries in western and central Africa have experienced the most widespread and deadly Ebola outbreaks since the virus was identified in 1976. While outbreaks are primarily attributed to zoonotic transfer events, new evidence is emerging that outbreaks may be caused by a combination of spillover events and viral latency or persistence in survivors. The possibility that Ebola can remain dormant then re-emerge in survivors highlights the critical need to prevent the virus from entering and establishing infection in human cells. Thus far, host-cell scramblases TMEM16F and XKR8 have been implicated in Ebola envelope surface phosphatidylserine (PS) and cell entry using PS receptors. We assessed the contributions of these proteins using CRISPR knockout cells and two EBOV models: rVSV/EBOV-GP and EBOV VLPs. We observed that XKR8 is required for optimal EBOV envelope PS levels and infectivity, and particle budding across all viral models.
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Imre G, Krähling V, Eichler M, Trautmann S, Ferreirós N, Aman MJ, Kashanchi F, Rajalingam K, Pöhlmann S, Becker S, Meyer Zu Heringdorf D, Pfeilschifter J. The sphingosine kinase 1 activator, K6PC-5, attenuates Ebola virus infection. iScience 2021; 24:102266. [PMID: 33817572 PMCID: PMC8005759 DOI: 10.1016/j.isci.2021.102266] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 02/08/2021] [Accepted: 03/01/2021] [Indexed: 12/18/2022] Open
Abstract
Ebola virus (EBOV) is responsible for outbreaks with case fatality rates of up to 90% and for an epidemic in West Africa with more than ten thousand deaths. EBOV glycoprotein (EBOV-GP) is the only viral surface protein and is responsible for viral entry into cells. Here, by employing pseudotyped EBOV-GP viral particles, we uncover a critical role for sphingolipids in inhibiting viral entry. Sphingosine kinase 1 (SphK1) catalyzes the phosphorylation of sphingosine to sphingosine 1-phosphate (S1P). The administration of the SphK1 activator, K6PC-5, or S1P, or the overexpression of SphK1 consistently exhibited striking inhibitory effects in EBOV-GP-driven entry in diverse cell lines. Finally, K6PC-5 markedly reduced the EBOV titer in infected cells and the de novo production of viral proteins. These data present K6PC-5 as an efficient tool to inhibit EBOV infection in endothelial cells and suggest further studies to evaluate its systemic effects. K6PC-5, a sphingosine kinase 1 activator, inhibits Ebola virus infection Sphingosine 1-phosphate, the product of SphK1, attenuates the viral entry Inhibiton/activation of S1P receptors has no influence on Ebola virus entry These data support the endogen effect of S1P in Ebola virus infection
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Affiliation(s)
- Gergely Imre
- Institute of General Pharmacology and Toxicology, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main 60590, Germany
| | - Verena Krähling
- Institute of Virology, Philipps University Marburg, Marburg, Germany.,German Center for Infection Research (DZIF), partner site Gießen-Marburg-Langen, Marburg, Germany
| | - Madeleine Eichler
- Institute of General Pharmacology and Toxicology, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main 60590, Germany
| | - Sandra Trautmann
- Institute of Clinical Pharmacology, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main 60590, Germany
| | - Nerea Ferreirós
- Institute of Clinical Pharmacology, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main 60590, Germany
| | - M Javad Aman
- Integrated BioTherapeutics, Inc., Gaithersburg, MD 20850, USA
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, George Mason University Manassas, VA 20110, USA
| | - Krishnaraj Rajalingam
- Cell Biology Unit, University Medical Center of the Johannes Gutenberg University Mainz, 55131 Mainz, Germany
| | - Stefan Pöhlmann
- Infection Biology Unit, German Primate Center - Leibniz Institute for Primate Research, 37077 Göttingen, Germany.,Faculty of Biology and Psychology, University Göttingen, 37077 Göttingen, Germany
| | - Stephan Becker
- Institute of Virology, Philipps University Marburg, Marburg, Germany.,German Center for Infection Research (DZIF), partner site Gießen-Marburg-Langen, Marburg, Germany
| | - Dagmar Meyer Zu Heringdorf
- Institute of General Pharmacology and Toxicology, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main 60590, Germany
| | - Josef Pfeilschifter
- Institute of General Pharmacology and Toxicology, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main 60590, Germany
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5
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Kuroda M, Halfmann P, Kawaoka Y. HER2-mediated enhancement of Ebola virus entry. PLoS Pathog 2020; 16:e1008900. [PMID: 33052961 PMCID: PMC7556532 DOI: 10.1371/journal.ppat.1008900] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 08/17/2020] [Indexed: 11/29/2022] Open
Abstract
Multiple cell surface molecules including TAM receptors (TYRO3, AXL, and MERTK), a family of tyrosine kinase receptors, can serve as attachment receptors for Ebola virus (EBOV) entry into cells. The interaction of these receptors with EBOV particles is believed to trigger the initial internalization events that lead to macropinocytosis. However, the details of how these interactions lead to EBOV internalization have yet to be elucidated. Here, we screened receptor tyrosine kinase (RTK) inhibitors for anti-EBOV activity by using our previously established biologically contained Ebola virus that lacks the VP30 gene (EBOVΔVP30) and identified several RTKs, including human epidermal growth factor receptor 2 (HER2), as potential targets of anti-EBOV inhibitors and as novel host factors that have a role in EBOV infection. Of these identified RTKs, it was only HER2 whose knockdown by siRNAs impaired EBOVΔVP30-induced AKT1 phosphorylation, an event that is required for AKT1 activation and subsequent macropinocytosis. Stable expression of HER2 resulted in constitutive activation of AKT1, resulting in the enhancement of EBOVΔVP30 growth, EBOV GP-mediated entry, and macropinocytosis. Moreover, we found that HER2 interacts with the TAM receptors, and in particular forms a complex with TYRO3 and EBOVΔVP30 particles on the cell surface. Interestingly, HER2 was required for EBOVΔVP30-induced TYRO3 and AKT1 activation, but the other TAM receptors (TYRO3 and MERTK) were not essential for EBOVΔVP30-induced HER2 and AKT1 activation. Our findings demonstrate that HER2 plays an important role in EBOV entry and provide novel insights for the development of therapeutics against the virus.
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Affiliation(s)
- Makoto Kuroda
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
| | - Peter Halfmann
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
| | - Yoshihiro Kawaoka
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin–Madison, Madison, Wisconsin, United States of America
- Department of Microbiology and Immunology, Division of Virology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
- Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo, Japan
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6
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Investigating the Cellular Transcriptomic Response Induced by the Makona Variant of Ebola Virus in Differentiated THP-1 Cells. Viruses 2019; 11:v11111023. [PMID: 31689981 PMCID: PMC6893830 DOI: 10.3390/v11111023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 11/17/2022] Open
Abstract
Recent studies have shown that transcriptomic analysis of blood samples taken from patients with acute Ebola virus disease (EVD) during the 2013–2016 West African outbreak was suggestive that a severe inflammatory response took place in acutely ill patients. The significant knowledge gained from studying the Makona variant, a cause of the largest known EVD outbreak, may be applicable to other species of ebolavirus, and other variants of the Ebola virus (EBOV) species. To investigate the ability of Makona to initiate an inflammatory response in human macrophages and characterise the host response in a similar manner to previously characterised EBOV variants, the human monocytic cell line THP-1 was differentiated into macrophage-like cells and infected with Makona. RNA-Seq and quantitative proteomics were used to identify and quantify host mRNA and protein abundance during infection. Data from infection with Reston virus (RESTV) were used as comparators to investigate changes that may be specific to, or enhanced in, Makona infection in relation to a less pathogenic species of ebolavirus.. This study found demonstrable induction of the inflammatory response, and increase in the activation state of THP-1 macrophages infected with Makona. NFκB and inflammation-associated transcripts displayed significant changes in abundance, reflective of what was observed in human patients during the 2013–2016 EBOV outbreak in West Africa, and demonstrated that transcriptomic changes found in Makona-infected cells were similar to that observed in Reston virus infection and that have been described in previous studies of other variants of EBOV.
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7
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Younan P, Iampietro M, Santos RI, Ramanathan P, Popov VL, Bukreyev A. Role of Transmembrane Protein 16F in the Incorporation of Phosphatidylserine Into Budding Ebola Virus Virions. J Infect Dis 2019; 218:S335-S345. [PMID: 30289531 DOI: 10.1093/infdis/jiy485] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Viral apoptotic mimicry, which is defined by exposure of phosphatidylserine (PtdSer) into the outer leaflet of budding enveloped viruses, increases viral tropism, infectivity and promotes immune evasion. Here, we report that the calcium (Ca2+)-dependent scramblase, transmembrane protein 16F (TMEM16F), is responsible for the incorporation of PtdSer into virion membranes during Ebola virus infection. Infection of Huh7 cells with Ebola virus resulted in a pronounced increase in plasma membrane-associated PtdSer, which was demonstrated to be dependent on TMEM16F function. Analysis of virions using imaging flow cytometry revealed that short hairpin RNA-mediated down-regulation of TMEM16F function directly reduced virion-associated PtdSer. Taken together, these studies demonstrate that TMEM16F is a central cellular factor in the exposure of PtdSer in the outer leaflet of viral membranes.
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Affiliation(s)
- Patrick Younan
- Departments of Pathology, University of Texas Medical Branch, Galveston.,Departments of Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Departments of University of Texas Medical Branch, Galveston
| | - Mathieu Iampietro
- Departments of Pathology, University of Texas Medical Branch, Galveston.,Departments of Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Departments of University of Texas Medical Branch, Galveston
| | - Rodrigo I Santos
- Departments of Pathology, University of Texas Medical Branch, Galveston.,Departments of Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Departments of University of Texas Medical Branch, Galveston
| | - Palaniappan Ramanathan
- Departments of Pathology, University of Texas Medical Branch, Galveston.,Departments of Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Departments of University of Texas Medical Branch, Galveston
| | - Vsevolod L Popov
- Departments of Pathology, University of Texas Medical Branch, Galveston.,Departments of University of Texas Medical Branch, Galveston
| | - Alexander Bukreyev
- Departments of Pathology, University of Texas Medical Branch, Galveston.,Departments of Microbiology and Immunology, University of Texas Medical Branch, Galveston.,Departments of Galveston National Laboratory, University of Texas Medical Branch, Galveston.,Departments of University of Texas Medical Branch, Galveston
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8
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Olejnik J, Hume AJ, Leung DW, Amarasinghe GK, Basler CF, Mühlberger E. Filovirus Strategies to Escape Antiviral Responses. Curr Top Microbiol Immunol 2019; 411:293-322. [PMID: 28685291 PMCID: PMC5973841 DOI: 10.1007/82_2017_13] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This chapter describes the various strategies filoviruses use to escape host immune responses with a focus on innate immune and cell death pathways. Since filovirus replication can be efficiently blocked by interferon (IFN), filoviruses have evolved mechanisms to counteract both type I IFN induction and IFN response signaling pathways. Intriguingly, marburg- and ebolaviruses use different strategies to inhibit IFN signaling. This chapter also summarizes what is known about the role of IFN-stimulated genes (ISGs) in filovirus infection. These fall into three categories: those that restrict filovirus replication, those whose activation is inhibited by filoviruses, and those that have no measurable effect on viral replication. In addition to innate immunity, mammalian cells have evolved strategies to counter viral infections, including the induction of cell death and stress response pathways, and we summarize our current knowledge of how filoviruses interact with these pathways. Finally, this chapter delves into the interaction of EBOV with myeloid dendritic cells and macrophages and the associated inflammatory response, which differs dramatically between these cell types when they are infected with EBOV. In summary, we highlight the multifaceted nature of the host-viral interactions during filoviral infections.
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Affiliation(s)
- Judith Olejnik
- Department of Microbiology and National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, 620 Albany Street, Boston, MA, 02118, USA
| | - Adam J Hume
- Department of Microbiology and National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, 620 Albany Street, Boston, MA, 02118, USA
| | - Daisy W Leung
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Gaya K Amarasinghe
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - Christopher F Basler
- Microbial Pathogenesis, Georgia State University, Institute for Biomedical Sciences, Atlanta, GA, 30303, USA
| | - Elke Mühlberger
- Department of Microbiology and National Emerging Infectious Diseases Laboratories, Boston University School of Medicine, 620 Albany Street, Boston, MA, 02118, USA.
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9
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Nanbo A, Kawaoka Y. Molecular Mechanism of Externalization of Phosphatidylserine on the Surface of Ebola Virus Particles. DNA Cell Biol 2019; 38:115-120. [PMID: 30615471 DOI: 10.1089/dna.2018.4485] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Ebola virus (EBOV) is an enveloped filamentous virus that causes severe hemorrhagic fever in humans and nonhuman primates with up to 90% fatality. Accumulating evidence indicates that various viruses, including EBOV, exploit the host apoptotic clearance machinery to enhance their entry into host cells by externalizing phosphatidylserine (PS) in the viral envelope. PS is typically distributed in the inner layer of the plasma membrane (PM) in normal cells. Progeny EBOV virions bud from the PM of infected cells, suggesting that PS is likely flipped to the outer leaflet of the envelope of Ebola virions. Currently, the intracellular dynamics of PS during EBOV infection are poorly understood. This review summarizes recent progress in determining the molecular mechanism of externalization of PS in the envelope of EBOV particles. We also discuss future directions and how viral apoptotic mimicry could be targeted for therapeutics.
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Affiliation(s)
- Asuka Nanbo
- 1 Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yoshihiro Kawaoka
- 2 Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.,3 Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin.,4 Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo, Japan
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10
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Pleet ML, Erickson J, DeMarino C, Barclay RA, Cowen M, Lepene B, Liang J, Kuhn JH, Prugar L, Stonier SW, Dye JM, Zhou W, Liotta LA, Aman MJ, Kashanchi F. Ebola Virus VP40 Modulates Cell Cycle and Biogenesis of Extracellular Vesicles. J Infect Dis 2018; 218:S365-S387. [PMID: 30169850 PMCID: PMC6249571 DOI: 10.1093/infdis/jiy472] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Background Ebola virus (EBOV) mainly targets myeloid cells; however, extensive death of T cells is often observed in lethal infections. We have previously shown that EBOV VP40 in exosomes causes recipient immune cell death. Methods Using VP40-producing clones, we analyzed donor cell cycle, extracellular vesicle (EV) biogenesis, and recipient immune cell death. Transcription of cyclin D1 and nuclear localization of VP40 were examined via kinase and chromatin immunoprecipitation assays. Extracellular vesicle contents were characterized by mass spectrometry, cytokine array, and western blot. Biosafety level-4 facilities were used for wild-type Ebola virus infection studies. Results VP40 EVs induced apoptosis in recipient T cells and monocytes. VP40 clones were accelerated in growth due to cyclin D1 upregulation, and nuclear VP40 was found bound to the cyclin D1 promoter. Accelerated cell cycling was related to EV biogenesis, resulting in fewer but larger EVs. VP40 EV contents were enriched in ribonucleic acid-binding proteins and cytokines (interleukin-15, transforming growth factor-β1, and interferon-γ). Finally, EBOV-infected cell and animal EVs contained VP40, nucleoprotein, and glycoprotein. Conclusions Nuclear VP40 upregulates cyclin D1 levels, resulting in dysregulated cell cycle and EV biogenesis. Packaging of cytokines and EBOV proteins into EVs from infected cells may be responsible for the decimation of immune cells during EBOV pathogenesis.
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Affiliation(s)
- Michelle L Pleet
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, Virginia
| | - James Erickson
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, Virginia
| | - Catherine DeMarino
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, Virginia
| | - Robert A Barclay
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, Virginia
| | - Maria Cowen
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, Virginia
| | | | - Janie Liang
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Frederick, Maryland
| | - Jens H Kuhn
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Frederick, Maryland
| | - Laura Prugar
- Virology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland
| | - Spencer W Stonier
- Virology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland
| | - John M Dye
- Virology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland
| | - Weidong Zhou
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, Virginia
| | - Lance A Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, Virginia
| | - M Javad Aman
- Integrated BioTherapeutics, Inc., Gaithersburg, Maryland
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, Virginia
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11
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Abstract
In this chapter, we describe a Western blot assay for the successful detection of apoptosis in Ebola virus (EBOV)-infected cells. The protocol includes all steps from cell culture, infection of cells, generation of lysates, and analysis using Western blot to detect caspase cleavage as marker of apoptosis.
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12
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Nanbo A, Maruyama J, Imai M, Ujie M, Fujioka Y, Nishide S, Takada A, Ohba Y, Kawaoka Y. Ebola virus requires a host scramblase for externalization of phosphatidylserine on the surface of viral particles. PLoS Pathog 2018; 14:e1006848. [PMID: 29338048 PMCID: PMC5786336 DOI: 10.1371/journal.ppat.1006848] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 01/26/2018] [Accepted: 01/02/2018] [Indexed: 11/30/2022] Open
Abstract
Cell surface receptors for phosphatidylserine contribute to the entry of Ebola virus (EBOV) particles, indicating that the presence of phosphatidylserine in the envelope of EBOV is important for the internalization of EBOV particles. Phosphatidylserine is typically distributed in the inner layer of the plasma membrane in normal cells. Progeny virions bud from the plasma membrane of infected cells, suggesting that phosphatidylserine is likely flipped to the outer leaflet of the plasma membrane in infected cells for EBOV virions to acquire it. Currently, the intracellular dynamics of phosphatidylserine during EBOV infection are poorly understood. Here, we explored the role of XK-related protein (Xkr) 8, which is a scramblase responsible for exposure of phosphatidylserine in the plasma membrane of apoptotic cells, to understand its significance in phosphatidylserine-dependent entry of EBOV. We found that Xkr8 and transiently expressed EBOV glycoprotein GP often co-localized in intracellular vesicles and the plasma membrane. We also found that co-expression of GP and viral major matrix protein VP40 promoted incorporation of Xkr8 into ebolavirus-like particles (VLPs) and exposure of phosphatidylserine on their surface, although only a limited amount of phosphatidylserine was exposed on the surface of the cells expressing GP and/or VP40. Downregulating Xkr8 or blocking caspase-mediated Xkr8 activation did not affect VLP production, but they reduced the amount of phosphatidylserine on the VLPs and their uptake in recipient cells. Taken together, our findings indicate that Xkr8 is trafficked to budding sites via GP-containing vesicles, is incorporated into VLPs, and then promote the entry of the released EBOV to cells in a phosphatidylserine-dependent manner. Although Ebola virus causes severe hemorrhagic fever with a high mortality rate, there are no approved therapeutics. The viral entry process is one of the targets for antiviral development. Previous studies suggest that binding of phosphatidylserine, a component of the viral envelop, to the receptors promotes the entry of Ebola virus. Ebola virus is released from the surface membrane of infected cells. However, phosphatidylserine normally distributes in the inner layer of the cell surface membrane, suggesting that phosphatidylserine is likely flipped to the outer leaflet of the membrane in infected cells for Ebola virus to acquire it. Because the mechanism by which phosphatidylserine changes its orientation in Ebola virus-infected cells is poorly understood, we studied and identified a cellular enzyme, XK-related protein 8 (Xkr8), as a responsible factor involved in this process. We demonstrated that the Ebola virus glycoprotein promoted the incorporation of Xkr8 in viral particles, which flips phosphatidylserine on their surface, enhancing their entry to cells. Our findings provide new insights into the mechanism of Ebola virus infection, which may be exploited for the development of therapeutics against Ebola virus infection.
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Affiliation(s)
- Asuka Nanbo
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
- * E-mail: (AN); (YK)
| | - Junki Maruyama
- Division of Global Epidemiology, Hokkaido University Research Center for Zoonosis Control, Sapporo, Hokkaido, Japan
| | - Masaki Imai
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Michiko Ujie
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Yoichiro Fujioka
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Shinya Nishide
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Ayato Takada
- Division of Global Epidemiology, Hokkaido University Research Center for Zoonosis Control, Sapporo, Hokkaido, Japan
- Global Station for Zoonosis Control, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yusuke Ohba
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yoshihiro Kawaoka
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo, Japan
- * E-mail: (AN); (YK)
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13
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A comparison of host gene expression signatures associated with infection in vitro by the Makona and Ecran (Mayinga) variants of Ebola virus. Sci Rep 2017; 7:43144. [PMID: 28240256 PMCID: PMC5327407 DOI: 10.1038/srep43144] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 01/18/2017] [Indexed: 11/08/2022] Open
Abstract
The Ebola virus (EBOV) variant Makona (which emerged in 2013) was the causative agent of the largest outbreak of Ebola Virus Disease recorded. Differences in virus-host interactions between viral variants have potential consequences for transmission, disease severity and mortality. A detailed profile of the cellular changes induced by the Makona variant compared with other Ebola virus variants was lacking. In this study, A549 cells, a human cell line with a robust innate response, were infected with the Makona variant or with the Ecran variant originating from the 1976 outbreak in Central Africa. The abundance of viral and cellular mRNA transcripts was profiled using RNASeq and differential gene expression analysis performed. Differences in effects of each virus on the expression of interferon-stimulated genes were also investigated in A549 NPro cells where the type 1 interferon response had been attenuated. Cellular transcriptomic changes were compared with those induced by human respiratory syncytial virus (HRSV), a virus with a similar genome organisation and replication strategy to EBOV. Pathway and gene ontology analysis revealed differential expression of functionally important genes; including genes involved in the inflammatory response, cell proliferation, leukocyte extravasation and cholesterol biosynthesis. Whilst there was overlap with HRSV, there was unique commonality to the EBOV variants.
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14
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Pleet ML, Mathiesen A, DeMarino C, Akpamagbo YA, Barclay RA, Schwab A, Iordanskiy S, Sampey GC, Lepene B, Nekhai S, Aman MJ, Kashanchi F. Ebola VP40 in Exosomes Can Cause Immune Cell Dysfunction. Front Microbiol 2016; 7:1765. [PMID: 27872619 PMCID: PMC5098130 DOI: 10.3389/fmicb.2016.01765] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/20/2016] [Indexed: 12/14/2022] Open
Abstract
Ebola virus (EBOV) is an enveloped, ssRNA virus from the family Filoviridae capable of causing severe hemorrhagic fever with up to 80–90% mortality rates. The most recent outbreak of EBOV in West Africa starting in 2014 resulted in over 11,300 deaths; however, long-lasting persistence and recurrence in survivors has been documented, potentially leading to further transmission of the virus. We have previously shown that exosomes from cells infected with HIV-1, HTLV-1 and Rift Valley Fever virus are able to transfer viral proteins and non-coding RNAs to naïve recipient cells, resulting in an altered cellular activity. In the current manuscript, we examined the effect of Ebola structural proteins VP40, GP, NP and VLPs on recipient immune cells, as well as the effect of exosomes containing these proteins on naïve immune cells. We found that VP40-transfected cells packaged VP40 into exosomes, and that these exosomes were capable of inducing apoptosis in recipient immune cells. Additionally, we show that presence of VP40 within parental cells or in exosomes delivered to naïve cells could result in the regulation of RNAi machinery including Dicer, Drosha, and Ago 1, which may play a role in the induction of cell death in recipient immune cells. Exosome biogenesis was regulated by VP40 in transfected cells by increasing levels of ESCRT-II proteins EAP20 and EAP45, and exosomal marker proteins CD63 and Alix. VP40 was phosphorylated by Cdk2/Cyclin complexes at Serine 233 which could be reversed with r-Roscovitine treatment. The level of VP40-containing exosomes could also be regulated by treated cells with FDA-approved Oxytetracycline. Additionally, we utilized novel nanoparticles to safely capture VP40 and other viral proteins from Ebola VLPs spiked into human samples using SDS/reducing agents, thus minimizing the need for BSL-4 conditions for most downstream assays. Collectively, our data indicates that VP40 packaged into exosomes may be responsible for the deregulation and eventual destruction of the T-cell and myeloid arms of the immune system (bystander lymphocyte apoptosis), allowing the virus to replicate to high titers in the immunocompromised host. Moreover, our results suggest that the use of drugs such as Oxytetracycline to modulate the levels of exosomes exiting EBOV-infected cells may be able to prevent the devastation of the adaptive immune system and allow for an improved rate of survival.
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Affiliation(s)
- Michelle L Pleet
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas VA, USA
| | - Allison Mathiesen
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk VA, USA
| | - Catherine DeMarino
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas VA, USA
| | - Yao A Akpamagbo
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas VA, USA
| | - Robert A Barclay
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas VA, USA
| | - Angela Schwab
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas VA, USA
| | - Sergey Iordanskiy
- Research Center for Neglected Diseases of Poverty, Department of Microbiology, Immunology and Tropical Medicine, George Washington University School of Medicine and Health Sciences, Washington DC, USA
| | - Gavin C Sampey
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, ManassasVA, USA; University of North Carolina HIV Cure Center, Department of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel HillNC, USA
| | | | - Sergei Nekhai
- Center for Sickle Cell Disease, Department of Medicine, Howard University, Washington DC, USA
| | - M J Aman
- Integrated BioTherapeutics, Inc., Gaithersburg MD, USA
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas VA, USA
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15
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Differential transcriptional responses to Ebola and Marburg virus infection in bat and human cells. Sci Rep 2016; 6:34589. [PMID: 27713552 PMCID: PMC5054393 DOI: 10.1038/srep34589] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/15/2016] [Indexed: 01/04/2023] Open
Abstract
The unprecedented outbreak of Ebola in West Africa resulted in over 28,000 cases and 11,000 deaths, underlining the need for a better understanding of the biology of this highly pathogenic virus to develop specific counter strategies. Two filoviruses, the Ebola and Marburg viruses, result in a severe and often fatal infection in humans. However, bats are natural hosts and survive filovirus infections without obvious symptoms. The molecular basis of this striking difference in the response to filovirus infections is not well understood. We report a systematic overview of differentially expressed genes, activity motifs and pathways in human and bat cells infected with the Ebola and Marburg viruses, and we demonstrate that the replication of filoviruses is more rapid in human cells than in bat cells. We also found that the most strongly regulated genes upon filovirus infection are chemokine ligands and transcription factors. We observed a strong induction of the JAK/STAT pathway, of several genes encoding inhibitors of MAP kinases (DUSP genes) and of PPP1R15A, which is involved in ER stress-induced cell death. We used comparative transcriptomics to provide a data resource that can be used to identify cellular responses that might allow bats to survive filovirus infections.
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16
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Ebola Virus Does Not Induce Stress Granule Formation during Infection and Sequesters Stress Granule Proteins within Viral Inclusions. J Virol 2016; 90:7268-7284. [PMID: 27252530 DOI: 10.1128/jvi.00459-16] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/25/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED A hallmark of Ebola virus (EBOV) infection is the formation of viral inclusions in the cytoplasm of infected cells. These viral inclusions contain the EBOV nucleocapsids and are sites of viral replication and nucleocapsid maturation. Although there is growing evidence that viral inclusions create a protected environment that fosters EBOV replication, little is known about their role in the host response to infection. The cellular stress response is an effective antiviral strategy that leads to stress granule (SG) formation and translational arrest mediated by the phosphorylation of a translation initiation factor, the α subunit of eukaryotic initiation factor 2 (eIF2α). Here, we show that selected SG proteins are sequestered within EBOV inclusions, where they form distinct granules that colocalize with viral RNA. These inclusion-bound (IB) granules are functionally and structurally different from canonical SGs. Formation of IB granules does not indicate translational arrest in the infected cells. We further show that EBOV does not induce formation of canonical SGs or eIF2α phosphorylation at any time postinfection but is unable to fully inhibit SG formation induced by different exogenous stressors, including sodium arsenite, heat, and hippuristanol. Despite the sequestration of SG marker proteins into IB granules, canonical SGs are unable to form within inclusions, which we propose might be mediated by a novel function of VP35, which disrupts SG formation. This function is independent of VP35's RNA binding activity. Further studies aim to reveal the mechanism for SG protein sequestration and precise function within inclusions. IMPORTANCE Although progress has been made developing antiviral therapeutics and vaccines against the highly pathogenic Ebola virus (EBOV), the cellular mechanisms involved in EBOV infection are still largely unknown. To better understand these intracellular events, we investigated the cellular stress response, an antiviral pathway manipulated by many viruses. We show that EBOV does not induce formation of stress granules (SGs) in infected cells and is therefore unrestricted by their concomitant translational arrest. We identified SG proteins sequestered within viral inclusions, which did not impair protein translation. We further show that EBOV is unable to block SG formation triggered by exogenous stress early in infection. These findings provide insight into potential targets of therapeutic intervention. Additionally, we identified a novel function of the interferon antagonist VP35, which is able to disrupt SG formation.
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17
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Wang W, Wang WH, Azadzoi KM, Su N, Dai P, Sun J, Wang Q, Liang P, Zhang W, Lei X, Yan Z, Yang JH. Activation of innate antiviral immune response via double-stranded RNA-dependent RLR receptor-mediated necroptosis. Sci Rep 2016; 6:22550. [PMID: 26935990 PMCID: PMC4776105 DOI: 10.1038/srep22550] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/16/2016] [Indexed: 12/14/2022] Open
Abstract
Viruses induce double-stranded RNA (dsRNA) in the host cells. The mammalian system has developed dsRNA-dependent recognition receptors such as RLRs that recognize the long stretches of dsRNA as PAMPs to activate interferon-mediated antiviral pathways and apoptosis in severe infection. Here we report an efficient antiviral immune response through dsRNA-dependent RLR receptor-mediated necroptosis against infections from different classes of viruses. We demonstrated that virus-infected A549 cells were efficiently killed in the presence of a chimeric RLR receptor, dsCARE. It measurably suppressed the interferon antiviral pathway but promoted IL-1β production. Canonical cell death analysis by morphologic assessment, phosphatidylserine exposure, caspase cleavage and chemical inhibition excluded the involvement of apoptosis and consistently suggested RLR receptor-mediated necroptosis as the underlying mechanism of infected cell death. The necroptotic pathway was augmented by the formation of RIP1-RIP3 necrosome, recruitment of MLKL protein and the activation of cathepsin D. Contributing roles of RIP1 and RIP3 were confirmed by gene knockdown. Furthermore, the necroptosis inhibitor necrostatin-1 but not the pan-caspase inhibitor zVAD impeded dsCARE-dependent infected cell death. Our data provides compelling evidence that the chimeric RLR receptor shifts the common interferon antiviral responses of infected cells to necroptosis and leads to rapid death of the virus-infected cells. This mechanism could be targeted as an efficient antiviral strategy.
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Affiliation(s)
- Wei Wang
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Wei-Hua Wang
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Kazem M Azadzoi
- Departments of Surgery and Urology, VA Boston Healthcare System, Boston University School of Medicine, Boston 510660, MA, USA
| | - Ning Su
- Departments of Neurosurgery and Oncology, Xijing and Tangdu Hospital, Xi'an, China.,Cancer Research Center, Shandong University School of Medicine, Jinan, 250012, China
| | - Peng Dai
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Jianbin Sun
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Qin Wang
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Ping Liang
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Wentao Zhang
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Xiaoying Lei
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Zhen Yan
- The State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, 710032, China
| | - Jing-Hua Yang
- Departments of Surgery and Urology, VA Boston Healthcare System, Boston University School of Medicine, Boston 510660, MA, USA.,Cancer Research Center, Shandong University School of Medicine, Jinan, 250012, China
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18
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de La Vega MA, Wong G, Kobinger GP, Qiu X. The multiple roles of sGP in Ebola pathogenesis. Viral Immunol 2015; 28:3-9. [PMID: 25354393 DOI: 10.1089/vim.2014.0068] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Ebola causes severe hemorrhagic fever in humans and nonhuman primates, and there are currently no approved therapeutic countermeasures. The virulence of Ebola virus (EBOV) may be partially attributed to the secreted glycoprotein (sGP), which is the main product transcribed from its GP gene. sGP is secreted from infected cells and can be readily detected in the serum of EBOV-infected hosts. This review summarizes the multiple roles that sGP may play during infection and highlights the implications for the future design of vaccines and treatments.
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Affiliation(s)
- Marc-Antoine de La Vega
- 1 Special Pathogens Program, National Microbiology Laboratory, Public Health Agency of Canada , Winnipeg, Manitoba, Canada
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19
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Falasca L, Agrati C, Petrosillo N, Di Caro A, Capobianchi MR, Ippolito G, Piacentini M. Molecular mechanisms of Ebola virus pathogenesis: focus on cell death. Cell Death Differ 2015; 22:1250-9. [PMID: 26024394 PMCID: PMC4495366 DOI: 10.1038/cdd.2015.67] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/31/2015] [Accepted: 04/20/2015] [Indexed: 12/28/2022] Open
Abstract
Ebola virus (EBOV) belongs to the Filoviridae family and is responsible for a severe disease characterized by the sudden onset of fever and malaise accompanied by other non-specific signs and symptoms; in 30–50% of cases hemorrhagic symptoms are present. Multiorgan dysfunction occurs in severe forms with a mortality up to 90%. The EBOV first attacks macrophages and dendritic immune cells. The innate immune reaction is characterized by a cytokine storm, with secretion of numerous pro-inflammatory cytokines, which induces a huge number of contradictory signals and hurts the immune cells, as well as other tissues. Other highly pathogenic viruses also trigger cytokine storms, but Filoviruses are thought to be particularly lethal because they affect a wide array of tissues. In addition to the immune system, EBOV attacks the spleen and kidneys, where it kills cells that help the body to regulate its fluid and chemical balance and that make proteins that help the blood to clot. In addition, EBOV causes liver, lungs and kidneys to shut down their functions and the blood vessels to leak fluid into surrounding tissues. In this review, we analyze the molecular mechanisms at the basis of Ebola pathogenesis with a particular focus on the cell death pathways induced by the virus. We also discuss how the treatment of the infection can benefit from the recent experience of blocking/modulating cell death in human degenerative diseases.
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Affiliation(s)
- L Falasca
- National Institute for Infectious Diseases, Lazzaro Spallanzani, Rome, Italy
| | - C Agrati
- National Institute for Infectious Diseases, Lazzaro Spallanzani, Rome, Italy
| | - N Petrosillo
- National Institute for Infectious Diseases, Lazzaro Spallanzani, Rome, Italy
| | - A Di Caro
- National Institute for Infectious Diseases, Lazzaro Spallanzani, Rome, Italy
| | - M R Capobianchi
- National Institute for Infectious Diseases, Lazzaro Spallanzani, Rome, Italy
| | - G Ippolito
- National Institute for Infectious Diseases, Lazzaro Spallanzani, Rome, Italy
| | - M Piacentini
- 1] National Institute for Infectious Diseases, Lazzaro Spallanzani, Rome, Italy [2] Department of Biology, University of Rome Tor Vergata, Rome, Italy
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20
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Lai KY, Ng WYG, Cheng FF. Human Ebola virus infection in West Africa: a review of available therapeutic agents that target different steps of the life cycle of Ebola virus. Infect Dis Poverty 2014; 3:43. [PMID: 25699183 PMCID: PMC4334593 DOI: 10.1186/2049-9957-3-43] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 11/13/2014] [Indexed: 12/21/2022] Open
Abstract
The recent outbreak of the human Zaire ebolavirus (EBOV) epidemic is spiraling out of control in West Africa. Human EBOV hemorrhagic fever has a case fatality rate of up to 90%. The EBOV is classified as a biosafety level 4 pathogen and is considered a category A agent of bioterrorism by Centers for Disease Control and Prevention, with no approved therapies and vaccines available for its treatment apart from supportive care. Although several promising therapeutic agents and vaccines against EBOV are undergoing the Phase I human trial, the current epidemic might be outpacing the speed at which drugs and vaccines can be produced. Like all viruses, the EBOV largely relies on host cell factors and physiological processes for its entry, replication, and egress. We have reviewed currently available therapeutic agents that have been shown to be effective in suppressing the proliferation of the EBOV in cell cultures or animal studies. Most of the therapeutic agents in this review are directed against non-mutable targets of the host, which is independent of viral mutation. These medications are approved by the Food and Drug Administration (FDA) for the treatment of other diseases. They are available and stockpileable for immediate use. They may also have a complementary role to those therapeutic agents under development that are directed against the mutable targets of the EBOV.
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Affiliation(s)
- Kang Yiu Lai
- />Department of Intensive Care, Queen Elizabeth Hospital, HKSAR, B6, 30 Gascoigne Rd, Kowloon, Hong Kong SAR China
| | - Wing Yiu George Ng
- />Department of Intensive Care, Queen Elizabeth Hospital, HKSAR, B6, 30 Gascoigne Rd, Kowloon, Hong Kong SAR China
| | - Fan Fanny Cheng
- />Department of Medicine, Queen Elizabeth Hospital, HKSAR, Kowloon, Hong Kong SARChina
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21
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Moller-Tank S, Maury W. Phosphatidylserine receptors: enhancers of enveloped virus entry and infection. Virology 2014; 468-470:565-580. [PMID: 25277499 PMCID: PMC4252826 DOI: 10.1016/j.virol.2014.09.009] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 07/15/2014] [Accepted: 09/08/2014] [Indexed: 12/23/2022]
Abstract
A variety of both RNA and DNA viruses envelop their capsids in a lipid bilayer. One of the more recently appreciated benefits this envelope is incorporation of phosphatidylserine (PtdSer). Surface exposure of PtdSer disguises viruses as apoptotic bodies; tricking cells into engulfing virions. This mechanism is termed apoptotic mimicry. Several PtdSer receptors have been identified to enhance virus entry and we have termed this group of proteins PtdSer-mediated virus entry enhancing receptors or PVEERs. These receptors enhance entry of a range of enveloped viruses. Internalization of virions by PVEERs provides a broad mechanism of entry with little investment by the virus itself. PVEERs may allow some viruses to attach to cells, thereby making viral glycoprotein/cellular receptor interactions more probable. Alternatively, other viruses may rely entirely on PVEERs for internalization into endosomes. This review provides an overview of PtdSer receptors that serve as PVEERs and the biology behind virion/PVEER interaction. Phosphatidylserine (PtdSer) receptors can mediate entry of enveloped viruses. PtdSer is present on the outer leaflet of the virion envelope. PtdSer receptors are expressed on a variety of primary cells and cell lines. Characteristics of PtdSer receptors that mediate virus entry are defined.
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Affiliation(s)
- Sven Moller-Tank
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
| | - Wendy Maury
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA.
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22
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Noyori O, Nakayama E, Maruyama J, Yoshida R, Takada A. Suppression of Fas-mediated apoptosis via steric shielding by filovirus glycoproteins. Biochem Biophys Res Commun 2013; 441:994-8. [PMID: 24239546 DOI: 10.1016/j.bbrc.2013.11.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 11/03/2013] [Indexed: 10/26/2022]
Abstract
Apoptotic death of virus-infected cells is generally thought to be a defense mechanism to limit the spread of infectious virions by eliminating virus-producing cells in host animals. On the other hand, several viruses have been shown to have anti-apoptotic mechanisms to facilitate efficient viral replication and transmission. In this study, we found that the filovirus glycoprotein (GP) expressed on cell surfaces formed a steric shield over the Fas molecule and that GP-expressing cells showed resistance to cell death induced by a Fas agonistic antibody. These results suggest that filovirus GP-mediated steric shielding may interfere with the Fas-induced apoptotic signal transduction in infected cells and serve as an immune evasion mechanism for filoviruses.
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Affiliation(s)
- Osamu Noyori
- Division of Global Epidemiology, Hokkaido University Research Center for Zoonosis Control, Sapporo 001-0020, Japan
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