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Someya K, Okemoto-Nakamura Y, Kurata T, Kanbayashi D, Saito N, Itamochi M, Otsuki N, Hanada K, Takeda M. Establishment of measles virus receptor-expressing Vero cells lacking functional poliovirus receptors. Microbiol Immunol 2023; 67:166-170. [PMID: 36564197 DOI: 10.1111/1348-0421.13047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/20/2022] [Accepted: 12/21/2022] [Indexed: 12/25/2022]
Abstract
Global efforts are underway to eliminate measles and rubella, and active viral surveillance is the key to achieving this goal. In addition, the World Health Organization announced guidelines for handling materials potentially infectious for poliovirus (PV) to minimize the risk of PV reintroduction and to achieve PV eradication. To support global efforts, we established new PV-non-susceptible cell lines that are useful for the isolation of measles virus (MeV) and rubella virus (RuV) (Vero ΔPVR1/2 hSLAM+). In the cell lines, MeV and RuV replicated efficiently, with no concern regarding PV replication.
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Affiliation(s)
- Kenji Someya
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan.,Global Specialized Laboratory for Measles and Rubella, The World Health Organization, Tokyo, Japan
| | - Yuko Okemoto-Nakamura
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | | | | | - Noriko Saito
- Aichi Prefectural Institute of Public Health, Nagoya, Japan
| | | | - Noriyuki Otsuki
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan.,Global Specialized Laboratory for Measles and Rubella, The World Health Organization, Tokyo, Japan
| | - Kentaro Hanada
- Department of Quality Assurance and Radiological Protection, National Institute of Infectious Diseases, Tokyo, Japan
| | - Makoto Takeda
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan.,Global Specialized Laboratory for Measles and Rubella, The World Health Organization, Tokyo, Japan
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Membrane Sphingomyelin in Host Cells Is Essential for Nucleocapsid Penetration into the Cytoplasm after Hemifusion during Rubella Virus Entry. mBio 2022; 13:e0169822. [PMID: 36346228 PMCID: PMC9765692 DOI: 10.1128/mbio.01698-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The lipid composition of the host cell membrane is one of the key determinants of the entry of enveloped viruses into cells. To elucidate the detailed mechanisms behind the cell entry of rubella virus (RuV), one of the enveloped viruses, we searched for host factors involved in such entry by using CRISPR/Cas9 genome-wide knockout screening, and we found sphingomyelin synthase 1 (SMS1), encoded by the SGMS1 gene, as a candidate. RuV growth was strictly suppressed in SGMS1-knockout cells and was completely recovered by the overexpression of enzymatically active SMS1 and partially recovered by that of SMS2, another member of the SMS family, but not by that of enzymatically inactive SMS1. An entry assay using pseudotyped vesicular stomatitis virus possessing RuV envelope proteins revealed that sphingomyelin generated by SMSs is crucial for at least RuV entry. In SGMS1-knockout cells, lipid mixing between the RuV envelope membrane and the membrane of host cells occurred, but entry of the RuV genome from the viral particles into the cytoplasm was strongly inhibited. This indicates that sphingomyelin produced by SMSs is essential for the formation of membrane pores after hemifusion occurs during RuV entry. IMPORTANCE Infection with rubella virus during pregnancy causes congenital rubella syndrome in infants. Despite its importance in public health, the detailed mechanisms of rubella virus cell entry have only recently become somewhat clearer. The E1 protein of rubella virus is classified as a class II fusion protein based on its structural similarity, but it has the unique feature that its activity is dependent on calcium ion binding in the fusion loops. In this study, we found another unique feature, as cellular sphingomyelin plays a critical role in the penetration of the nucleocapsid into the cytoplasm after hemifusion by rubella virus. This provides important insight into the entry mechanism of rubella virus. This study also presents a model of hemifusion arrest during cell entry by an intact virus, providing a useful tool for analyzing membrane fusion, a biologically important phenomenon.
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Heat Shock Protein 90 Ensures the Integrity of Rubella Virus p150 Protein and Supports Viral Replication. J Virol 2019; 93:JVI.01142-19. [PMID: 31484751 DOI: 10.1128/jvi.01142-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 08/21/2019] [Indexed: 12/18/2022] Open
Abstract
Two viral nonstructural proteins, p150 and p90, are expressed in rubella virus (RUBV)-infected cells and mediate viral genome replication, presumably using various host machineries. Molecular chaperones are critical host factors for the maintenance of cellular proteostasis, and certain viral proteins use this chaperone system. The RUBV p150 and p90 proteins are generated from a precursor polyprotein, p200, via processing by the protease activity of its p150 region. This processing is essential for RUBV genome replication. Here we show that heat shock protein 90 (HSP90), a molecular chaperone, is an important host factor for RUBV genome replication. The treatment of RUBV-infected cells with the HSP90 inhibitors 17-allylamino-17-desmethoxygeldanamycin (17-AAG) and ganetespib suppressed RUBV genome replication. HSP90α physically interacted with p150, but not p90. Further analyses into the mechanism of action of the HSP90 inhibitors revealed that HSP90 activity contributes to p150 functional integrity and promotes p200 processing. Collectively, our data demonstrate that RUBV p150 is a client of the HSP90 molecular chaperone and that HSP90 functions as a key host factor for RUBV replication.IMPORTANCE Accumulating evidence indicates that RNA viruses use numerous host factors during replication of their genomes. However, the host factors involved in rubella virus (RUBV) genome replication are largely unknown. In this study, we demonstrate that the HSP90 molecular chaperone is needed for the efficient replication of the RUBV genome. Further, we reveal that HSP90 interacts with RUBV nonstructural protein p150 and its precursor polyprotein, p200. HSP90 contributes to the stability of p150 and the processing of p200 via its protease domain in the p150 region. We conclude that the cellular molecular chaperone HSP90 is a key host factor for functional maturation of nonstructural proteins for RUBV genome replication. These findings provide novel insight into this host-virus interaction.
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Kräter M, Sapudom J, Bilz NC, Pompe T, Guck J, Claus C. Alterations in Cell Mechanics by Actin Cytoskeletal Changes Correlate with Strain-Specific Rubella Virus Phenotypes for Cell Migration and Induction of Apoptosis. Cells 2018; 7:E136. [PMID: 30217036 PMCID: PMC6162683 DOI: 10.3390/cells7090136] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 09/07/2018] [Accepted: 09/10/2018] [Indexed: 02/06/2023] Open
Abstract
The cellular cytoskeleton is central for key cellular functions, and as such is a marker for diseased and infected cell states. Here we analyzed infection with rubella virus (RV) strains with respect to phenotypes in cellular mechanical properties, cell movement, and viral cytopathogenicity. Real-time deformability cytometry (RT-DC), as a high-throughput platform for the assessment of cell mechanics, revealed a correlation of an increase in cortical filamentous-actin (F-actin) with a higher cellular stiffness. The additional reduction of stress fibers noted for only some RV strains as the most severe actin rearrangement lowered cell stiffness. Furthermore, a reduced collective and single cell migration speed in a wound healing assay was detected in addition to severe changes in cell morphology. The latter was followed by activation of caspase 3/7 as a sign for induction of apoptosis. Our study emphasizes RT-DC technology as a sensitive means to characterize viral cell populations and to implicate alterations of cell mechanical properties with cell functions. These interdependent events are not only promising options to elucidate viral spread and to understand viral pathologies within the infected host. They also contribute to any diseased cell state, as exemplified by RV as a representative agent for cytoskeletal alterations involved in a cytopathological outcome.
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Affiliation(s)
- Martin Kräter
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany.
| | - Jiranuwat Sapudom
- Institute of Biochemistry, Leipzig University, 04103 Leipzig, Germany.
- Department of Dermatology, Venerology and Allergology, University Clinic of Leipzig, 04103 Leipzig, Germany.
| | | | - Tilo Pompe
- Institute of Biochemistry, Leipzig University, 04103 Leipzig, Germany.
| | - Jochen Guck
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany.
| | - Claudia Claus
- Institute of Virology, University of Leipzig, 04103 Leipzig, Germany.
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Otsuki N, Sakata M, Mori Y, Okamoto K, Takeda M. Analysis of the effect of Sphingomyelinase on rubellavirus infectivity in two cell lines. Bio Protoc 2018; 8:e2992. [PMID: 34395791 DOI: 10.21769/bioprotoc.2992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 08/09/2018] [Accepted: 08/15/2018] [Indexed: 11/02/2022] Open
Abstract
Rubella is a mildly contagious disease characterized by low-grade fever and a morbilliform rash caused by the rubella virus (RuV). Viruses often use cellular phospholipids for infection. We studied the roles of cellular sphingomyelin in RuV infection. Treatment of cells with sphingomyelinase (SMase) inhibited RuV infection in rabbit kidney-derived RK13 cells and African green monkey (Cercopithecus aethiops) kidney-derived Vero cells. Our data further demonstrated that RuV used cellular sphingomyelin and cholesterol for its binding to cells and membrane fusion at the step of virus entry. Detailed protocols of our assays, which assess the effects of SMase treatment on RuV infectivity in RK13 and Vero cells, are described.
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Affiliation(s)
- Noriyuki Otsuki
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
| | - Masafumi Sakata
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yoshio Mori
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kiyoko Okamoto
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
| | - Makoto Takeda
- Department of Virology III, National Institute of Infectious Diseases, Tokyo, Japan
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Both Sphingomyelin and Cholesterol in the Host Cell Membrane Are Essential for Rubella Virus Entry. J Virol 2017; 92:JVI.01130-17. [PMID: 29070689 DOI: 10.1128/jvi.01130-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 10/17/2017] [Indexed: 11/20/2022] Open
Abstract
Rubella virus (RuV) causes a systemic infection, and transplacental fetal infection causes congenital rubella syndrome. In this study, we showed that treatment of cells with sphingomyelinase inhibited RuV infection. Assays using inhibitors of serine palmitoyl transferase and ceramide transport protein demonstrated the contribution of sphingomyelin (SM) to RuV infection. Compelling evidence for direct binding of RuV to lipid membranes at neutral pH was obtained using liposome coflotation assays. The absence of either SM or cholesterol (Chol) abrogated the RuV-liposome interaction. SM and Chol (SM/Chol) were also critical for RuV binding to erythrocytes and lymphoid cells. Removal of Ca2+ from the assay buffer or mutation of RuV envelope E1 protein Ca2+-binding sites abrogated RuV binding to liposomes, erythrocytes, and lymphoid cells. However, RuV bound to various nonlymphoid adherent cell lines independently of extracellular Ca2+ or SM/Chol. Even in these adherent cell lines, both the E1 protein Ca2+-binding sites and cellular SM/Chol were essential for the early stage of RuV infection, possibly affecting envelope-membrane fusion in acidic compartments. Myelin oligodendrocyte glycoprotein (MOG) has recently been identified as a cellular receptor for RuV. However, RuV bound to MOG-negative cells in a Ca2+-independent manner. Collectively, our data demonstrate that RuV has two distinct binding mechanisms: one is Ca2+ dependent and the other is Ca2+ independent. Ca2+-dependent binding observed in lymphoid cells occurs by the direct interaction between E1 protein fusion loops and SM/Chol-enriched membranes. Clarification of the mechanism of Ca2+-independent RuV binding is an important next step in understanding the pathology of RuV infection.IMPORTANCE Rubella has a significant impact on public health as infection during early pregnancy can result in babies being born with congenital rubella syndrome. Even though effective rubella vaccines are available, rubella outbreaks still occur in many countries. We studied the entry mechanism of rubella virus (RuV) and found that RuV binds directly to the host plasma membrane in the presence of Ca2+ at neutral pH. This Ca2+-dependent binding is specifically directed to membranes enriched in sphingomyelin and cholesterol and is critical for RuV infection. Importantly, RuV also binds to many cell lines in a Ca2+-independent manner. An unidentified RuV receptor(s) is involved in this Ca2+-independent binding. We believe that the data presented here may aid the development of the first anti-RuV drug.
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Analysis of VSV pseudotype virus infection mediated by rubella virus envelope proteins. Sci Rep 2017; 7:11607. [PMID: 28912595 PMCID: PMC5599607 DOI: 10.1038/s41598-017-10865-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 08/16/2017] [Indexed: 01/20/2023] Open
Abstract
Rubella virus (RV) generally causes a systemic infection in humans. Viral cell tropism is a key determinant of viral pathogenesis, but the tropism of RV is currently poorly understood. We analyzed various human cell lines and determined that RV only establishes an infection efficiently in particular non-immune cell lines. To establish an infection the host cells must be susceptible and permissible. To assess the susceptibility of individual cell lines, we generated a pseudotype vesicular stomatitis virus bearing RV envelope proteins (VSV-RV/CE2E1). VSV-RV/CE2E1 entered cells in an RV envelope protein-dependent manner, and thus the infection was neutralized completely by an RV-specific antibody. The infection was Ca2+-dependent and inhibited by endosomal acidification inhibitors, further confirming the dependency on RV envelope proteins for the VSV-RV/CE2E1 infection. Human non-immune cell lines were mostly susceptible to VSV-RV/CE2E1, while immune cell lines were much less susceptible than non-immune cell lines. However, susceptibility of immune cells to VSV-RV/CE2E1 was increased upon stimulation of these cells. Our data therefore suggest that immune cells are generally less susceptible to RV infection than non-immune cells, but the susceptibility of immune cells is enhanced upon stimulation.
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Sivanandam V, Mathews D, Garmann R, Erdemci-Tandogan G, Zandi R, Rao ALN. Functional analysis of the N-terminal basic motif of a eukaryotic satellite RNA virus capsid protein in replication and packaging. Sci Rep 2016; 6:26328. [PMID: 27193742 PMCID: PMC4872054 DOI: 10.1038/srep26328] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 04/29/2016] [Indexed: 02/06/2023] Open
Abstract
Efficient replication and assembly of virus particles are integral to the establishment of infection. In addition to the primary role of the capsid protein (CP) in encapsidating the RNA progeny, experimental evidence on positive sense single-stranded RNA viruses suggests that the CP also regulates RNA synthesis. Here, we demonstrate that replication of Satellite tobacco mosaic virus (STMV) is controlled by the cooperative interaction between STMV CP and the helper virus (HV) Tobacco mosaic virus (TMV) replicase. We identified that the STMV CP-HV replicase interaction requires a positively charged residue at the third position (3R) in the N-terminal 13 amino acid (aa) motif. Far-Northwestern blotting showed that STMV CP promotes binding between HV-replicase and STMV RNA. An STMV CP variant having an arginine to alanine substitution at position 3 in the N-terminal 13aa motif abolished replicase-CP binding. The N-terminal 13aa motif of the CP bearing alanine substitutions for positively charged residues located at positions 5, 7, 10 and 11 are defective in packaging full-length STMV, but can package a truncated STMV RNA lacking the 3' terminal 150 nt region. These findings provide insights into the mechanism underlying the regulation of STMV replication and packaging.
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Affiliation(s)
- Venkatesh Sivanandam
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521, USA
| | - Deborah Mathews
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521, USA
| | - Rees Garmann
- Department of Chemistry & Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | | | - Roya Zandi
- Department of Physics & Astronomy, University of California, Riverside, CA 92521, USA
| | - A. L. N. Rao
- Department of Plant Pathology & Microbiology, University of California, Riverside, CA 92521, USA
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[The life cycle of Rubella Virus]. Uirusu 2014; 64:137-46. [PMID: 26437836 DOI: 10.2222/jsv.64.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Rubella virus (RV), an infectious agent of rubella, is the sole member of the genus Rubivirus in the family of Togaviridae. RV has a positive-stranded sense RNA as a genome. A natural host of RV is limited to human, and rubella is considered to be a childhood disease in general. When woman is infected with RV during early pregnancy, her fetus may develop severe birth defects known as congenital rubella syndrome. In this review, the RV life cycle from the virus entry to budding is illustrated in comparison with those of member viruses of the genus alphavirus in the same family. The multiple functions of the RV capsid protein are also introduced.
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