scholarly journals The Respiratory Syncytial Virus Matrix Protein Possesses a Crm1-Mediated Nuclear Export Mechanism

2009 ◽  
Vol 83 (11) ◽  
pp. 5353-5362 ◽  
Author(s):  
Reena Ghildyal ◽  
Adeline Ho ◽  
Manisha Dias ◽  
Lydia Soegiyono ◽  
Phillip G. Bardin ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Nuclear Export ◽  
Matrix Protein ◽  
Virus Assembly ◽  
Nuclear Export Signal ◽  
M Protein ◽  
Nuclear Accumulation ◽  
Infected Cells ◽  
Syncytial Virus ◽  
In Cells

ABSTRACT The respiratory syncytial virus (RSV) matrix (M) protein is localized in the nucleus of infected cells early in infection but is mostly cytoplasmic late in infection. We have previously shown that M localizes in the nucleus through the action of the importin β1 nuclear import receptor. Here, we establish for the first time that M's ability to shuttle to the cytoplasm is due to the action of the nuclear export receptor Crm1, as shown in infected cells, and in cells transfected to express green fluorescent protein (GFP)-M fusion proteins. Specific inhibition of Crm1-mediated nuclear export by leptomycin B increased M nuclear accumulation. Analysis of truncated and point-mutated M derivatives indicated that Crm1-dependent nuclear export of M is attributable to a nuclear export signal (NES) within residues 194 to 206. Importantly, inhibition of M nuclear export resulted in reduced virus production, and a recombinant RSV carrying a mutated NES could not be rescued by reverse genetics. That this is likely to be due to the inability of a nuclear export deficient M to localize to regions of virus assembly is indicated by the fact that a nuclear-export-deficient GFP-M fails to localize to regions of virus assembly when expressed in cells infected with wild-type RSV. Together, our data suggest that Crm1-dependent nuclear export of M is central to RSV infection, representing the first report of such a mechanism for a paramyxovirus M protein and with important implications for related paramyxoviruses.

Replication of a Nipah Virus Encoding a Nuclear-Retained Matrix Protein

2019 ◽  
Vol 221 (Supplement_4) ◽  
pp. S389-S394 ◽  
Author(s):  
Marc Ringel ◽  
Laura Behner ◽  
Anja Heiner ◽  
Lucie Sauerhering ◽  
Andrea Maisner
Keyword(s):  
Plasma Membrane ◽  
Nuclear Export ◽  
Matrix Protein ◽  
Virus Assembly ◽  
Nipah Virus ◽  
Nuclear Export Signal ◽  
Cell Types ◽  
Surface Transport ◽  
M Proteins ◽  
Infected Cells

Abstract Nipah virus (NiV) matrix protein (NiV M) plays a major role in virus assembly. It undergoes nuclear transit before accumulating at the plasma membrane and recruiting nucleocapsids to the budding sites. Because nuclear NiV M cannot be detected in all cell types, we wondered whether it can reach the cell surface by bypassing the nucleus. Using an M mutant with a defective nuclear export signal (MNESmut), however, we revealed that the nuclear import of M is ubiquitous, because MNESmut was retained in the nuclei of all cell types tested. Because a functional nuclear transit is a general prerequisite for M surface transport, we wanted to characterize the effect of nuclear-retained M protein in a full viral context and generated a recombinant NiV-MNESmut. Mutant NiV-MNESmut caused increased cell-cell fusion and produced lower virus titers. As expected for an assembly defective NiV, perinuclear inclusions (IBperi) were formed, but inclusions at the plasma membrane (IBPM), which probably represent the viral assembly platforms, were not found. It is interesting to note that the transport-defective MNESmut was recruited to IBperi. This probably prevents overaccumulation of nonfunctional M proteins in the cytoplasm and nuclei of NiV-infected cells and thus provides first evidence that IBperi are functionally relevant aggresome-like compartments.

scholarly journals Verdinexor (KPT-335), a Selective Inhibitor of Nuclear Export, Reduces Respiratory Syncytial Virus Replication In Vitro

2018 ◽  
Vol 93 (4) ◽  
Author(s):  
Patricia A. Jorquera ◽  
Cynthia Mathew ◽  
Jennifer Pickens ◽  
Colin Williams ◽  
Jasmina M. Luczo ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Young Children ◽  
Nuclear Export ◽  
Symptomatic Relief ◽  
Antiviral Drugs ◽  
M Protein ◽  
Nuclear Accumulation ◽  
Syncytial Virus ◽  
Infants And Young Children

ABSTRACT Respiratory syncytial virus (RSV) is a leading cause of hospitalization of infants and young children, causing considerable respiratory disease and repeat infections that may lead to chronic respiratory conditions such as asthma, wheezing, and bronchitis. RSV causes ∼34 million new episodes of lower respiratory tract illness (LRTI) in children younger than 5 years of age, with >3 million hospitalizations due to severe RSV-associated LRTI. The standard of care is limited to symptomatic relief as there are no approved vaccines and few effective antiviral drugs; thus, a safe and efficacious RSV therapeutic is needed. Therapeutic targeting of host proteins hijacked by RSV to facilitate replication is a promising antiviral strategy as targeting the host reduces the likelihood of developing drug resistance. The nuclear export of the RSV M protein, mediated by the nuclear export protein exportin 1 (XPO1), is crucial for RSV assembly and budding. Inhibition of RSV M protein export by leptomycin B correlated with reduced RSV replication in vitro. In this study, we evaluated the anti-RSV efficacy of Verdinexor (KPT-335), a small molecule designed to reversibly inhibit XPO1-mediated nuclear export. KPT-335 inhibited XPO1-mediated transport and reduced RSV replication in vitro. KPT-335 was effective against RSV A and B strains and reduced viral replication following prophylactic or therapeutic administration. Inhibition of RSV replication by KPT-335 was due to a combined effect of reduced XPO1 expression, disruption of the nuclear export of RSV M protein, and inactivation of the NF-κB signaling pathway. IMPORTANCE RSV is an important cause of LRTI in infants and young children for which there are no suitable antiviral drugs offered. We evaluated the efficacy of KPT-335 as an anti-RSV drug and show that KPT-335 inhibits XPO1-mediated nuclear export, leading to nuclear accumulation of RSV M protein and reduction in RSV levels. KPT-335 treatment also resulted in inhibition of proinflammatory pathways, which has important implications for its effectiveness in vivo.

scholarly journals Respiratory syncytial virus matrix protein associates with nucleocapsids in infected cells

2002 ◽  
Vol 83 (4) ◽  
pp. 753-757 ◽  
Author(s):  
R. Ghildyal ◽  
J. Mills ◽  
M. Murray ◽  
N. Vardaxis ◽  
J. Meanger
Keyword(s):  
Respiratory Syncytial Virus ◽  
Matrix Protein ◽  
Rna Viruses ◽  
M Protein ◽  
Dependent Manner ◽  
Cytoplasmic Inclusions ◽  
Negative Strand ◽  
The Matrix ◽  
Infected Cells ◽  
Syncytial Virus

Little is known about the functions of the matrix (M) protein of respiratory syncytial virus (RSV). By analogy with other negative-strand RNA viruses, the M protein should inhibit the viral polymerase prior to packaging and facilitate virion assembly. In this study, localization of the RSV M protein in infected cells and its association with the RSV nucleocapsid complex was investigated. RSV-infected cells were shown to contain characteristic cytoplasmic inclusions. Further analysis showed that these inclusions were localization sites of the M protein as well as the N, P, L and M2-1 proteins described previously. The M protein co-purified with viral ribonucleoproteins (RNPs) from RSV-infected cells. The transcriptase activity of purified RNPs was enhanced by treatment with antibodies to the M protein in a dose-dependent manner. These data suggest that the M protein is associated with RSV nucleocapsids and, like the matrix proteins of other negative-strand RNA viruses, can inhibit virus transcription.

scholarly journals Reversible disruption of XPO1-mediated nuclear export inhibits respiratory syncytial virus (RSV) replication

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cynthia Mathew ◽  
Sharon Tamir ◽  
Ralph A. Tripp ◽  
Reena Ghildyal
Keyword(s):  
Respiratory Syncytial Virus ◽  
Nuclear Export ◽  
Cell Cycle Progression ◽  
Virus Assembly ◽  
The Elderly ◽  
M Protein ◽  
Structural Protein ◽  
Syncytial Virus ◽  
Tract Disease ◽  
High Risk Infants

AbstractRespiratory syncytial virus (RSV) is the primary cause of serious lower respiratory tract disease in infants, young children, the elderly and immunocompromised individuals. Therapy for RSV infections is limited to high risk infants and there are no safe and efficacious vaccines. Matrix (M) protein is a major RSV structural protein with a key role in virus assembly. Interestingly, M is localised to the nucleus early in infection and its export into the cytoplasm by the nuclear exporter, exportin-1 (XPO1) is essential for RSV assembly. We have shown previously that chemical inhibition of XPO1 function results in reduced RSV replication. In this study, we have investigated the anti-RSV efficacy of Selective Inhibitor of Nuclear Export (SINE) compounds, KPT-335 and KPT-185. Our data shows that therapeutic administration of the SINE compounds results in reduced RSV titre in human respiratory epithelial cell culture. Within 24 h of treatment, RSV replication and XPO1 expression was reduced, M protein was partially retained in the nucleus, and cell cycle progression was delayed. Notably, the effect of SINE compounds was reversible within 24 h after their removal. Our data show that reversible inhibition of XPO1 can disrupt RSV replication by affecting downstream pathways regulated by the nuclear exporter.

scholarly journals Requirements for Human Respiratory Syncytial Virus Glycoproteins in Assembly and Egress from Infected Cells

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Melissa Batonick ◽  
Gail W. Wertz
Keyword(s):  
Plasma Membrane ◽  
Respiratory Syncytial Virus ◽  
G Proteins ◽  
Matrix Protein ◽  
Protein Localization ◽  
Viral Proteins ◽  
Human Respiratory Syncytial Virus ◽  
The Other ◽  
Infected Cells ◽  
Syncytial Virus

Human respiratory syncytial virus (HRSV) is an enveloped RNA virus that assembles and buds from the plasma membrane of infected cells. The ribonucleoprotein complex (RNP) must associate with the viral matrix protein and glycoproteins to form newly infectious particles prior to budding. The viral proteins involved in HRSV assembly and egress are mostly unexplored. We investigated whether the glycoproteins of HRSV were involved in the late stages of viral replication by utilizing recombinant viruses where each individual glycoprotein gene was deleted and replaced with a reporter gene to maintain wild-type levels of gene expression. These engineered viruses allowed us to study the roles of the glycoproteins in assembly and budding in the context of infectious virus. Microscopy data showed that the F glycoprotein was involved in the localization of the glycoproteins with the other viral proteins at the plasma membrane. Biochemical analyses showed that deletion of the F and G proteins affected incorporation of the other viral proteins into budded virions. However, efficient viral release was unaffected by the deletion of any of the glycoproteins individually or in concert. These studies attribute a novel role to the F and G proteins in viral protein localization and assembly.

scholarly journals Antibody-Induced Internalization of the Human Respiratory Syncytial Virus Fusion Protein

2017 ◽  
Vol 91 (14) ◽  
Author(s):  
A. Leemans ◽  
M. De Schryver ◽  
W. Van der Gucht ◽  
A. Heykers ◽  
I. Pintelon ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Virus Assembly ◽  
Natural Infection ◽  
Flow Cytometric Analysis ◽  
Surface Glycoprotein ◽  
Specific Antibodies ◽  
F Protein ◽  
Infected Cells ◽  
Syncytial Virus ◽  
Antigen Antibody

ABSTRACT Respiratory syncytial virus (RSV) infections remain a major cause of respiratory disease and hospitalizations among infants. Infection recurs frequently and establishes a weak and short-lived immunity. To date, RSV immunoprophylaxis and vaccine research is mainly focused on the RSV fusion (F) protein, but a vaccine remains elusive. The RSV F protein is a highly conserved surface glycoprotein and is the main target of neutralizing antibodies induced by natural infection. Here, we analyzed an internalization process of antigen-antibody complexes after binding of RSV-specific antibodies to RSV antigens expressed on the surface of infected cells. The RSV F protein and attachment (G) protein were found to be internalized in both infected and transfected cells after the addition of either RSV-specific polyclonal antibodies (PAbs) or RSV glycoprotein-specific monoclonal antibodies (MAbs), as determined by indirect immunofluorescence staining and flow-cytometric analysis. Internalization experiments with different cell lines, well-differentiated primary bronchial epithelial cells (WD-PBECs), and RSV isolates suggest that antibody internalization can be considered a general feature of RSV. More specifically for RSV F, the mechanism of internalization was shown to be clathrin dependent. All RSV F-targeted MAbs tested, regardless of their epitopes, induced internalization of RSV F. No differences could be observed between the different MAbs, indicating that RSV F internalization was epitope independent. Since this process can be either antiviral, by affecting virus assembly and production, or beneficial for the virus, by limiting the efficacy of antibodies and effector mechanism, further research is required to determine the extent to which this occurs in vivo and how this might impact RSV replication. IMPORTANCE Current research into the development of new immunoprophylaxis and vaccines is mainly focused on the RSV F protein since, among others, RSV F-specific antibodies are able to protect infants from severe disease, if administered prophylactically. However, antibody responses established after natural RSV infections are poorly protective against reinfection, and high levels of antibodies do not always correlate with protection. Therefore, RSV might be capable of interfering, at least partially, with antibody-induced neutralization. In this study, a process through which surface-expressed RSV F proteins are internalized after interaction with RSV-specific antibodies is described. One the one hand, this antigen-antibody complex internalization could result in an antiviral effect, since it may interfere with virus particle formation and virus production. On the other hand, this mechanism may also reduce the efficacy of antibody-mediated effector mechanisms toward infected cells.

scholarly journals Respiratory Syncytial Virus Matrix Protein-Chromatin Association Is Key to Transcriptional Inhibition in Infected Cells

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2786
Author(s):  
Hong-Mei Li ◽  
Reena Ghildyal ◽  
Mengjie Hu ◽  
Kim C. Tran ◽  
Lora M. Starrs ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Dna Binding ◽  
Host Cell ◽  
Rna Binding ◽  
M Protein ◽  
Free System ◽  
Transcriptional Inhibition ◽  
Infected Cells ◽  
Syncytial Virus

The morbidity and mortality caused by the globally prevalent human respiratory pathogen respiratory syncytial virus (RSV) approaches that world-wide of influenza. We previously demonstrated that the RSV matrix (M) protein shuttles, in signal-dependent fashion, between host cell nucleus and cytoplasm, and that this trafficking is central to RSV replication and assembly. Here we analyze in detail the nuclear role of M for the first time using a range of novel approaches, including quantitative analysis of de novo cell transcription in situ in the presence or absence of RSV infection or M ectopic expression, as well as in situ DNA binding. We show that M, dependent on amino acids 110–183, inhibits host cell transcription in RSV-infected cells as well as cells transfected to express M, with a clear correlation between nuclear levels of M and the degree of transcriptional inhibition. Analysis of bacterially expressed M protein and derivatives thereof mutated in key residues within M’s RNA binding domain indicates that M can bind to DNA as well as RNA in a cell-free system. Parallel results for point-mutated M derivatives implicate arginine 170 and lysine 172, in contrast to other basic residues such as lysine 121 and 130, as critically important residues for inhibition of transcription and DNA binding both in situ and in vitro. Importantly, recombinant RSV carrying arginine 170/lysine 172 mutations shows attenuated infectivity in cultured cells and in an animal model, concomitant with altered inflammatory responses. These findings define an RSV M-chromatin interface critical for host transcriptional inhibition in infection, with important implications for anti-RSV therapeutic development.

scholarly journals Interaction between the respiratory syncytial virus G glycoprotein cytoplasmic domain and the matrix protein

2005 ◽  
Vol 86 (7) ◽  
pp. 1879-1884 ◽  
Author(s):  
Reena Ghildyal ◽  
Dongsheng Li ◽  
Irene Peroulis ◽  
Benjamin Shields ◽  
Phillip G. Bardin ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Protein Interactions ◽  
Matrix Protein ◽  
Transmembrane Domain ◽  
Cytoplasmic Domain ◽  
Specific Protein ◽  
Glycoprotein G ◽  
The Matrix ◽  
Syncytial Virus ◽  
In Cells

Paramyxovirus assembly at the cell membrane requires the movement of viral components to budding sites and envelopment of nucleocapsids by cellular membranes containing viral glycoproteins, facilitated by interactions with the matrix protein. The specific protein interactions during assembly of respiratory syncytial virus (RSV) are unknown. Here, the postulated interaction between the RSV matrix protein (M) and G glycoprotein (G) was investigated. Partial co-localization of M with G was demonstrated, but not with a truncated variant lacking the cytoplasmic domain and one-third of the transmembrane domain, in cells infected with recombinant RSV or transfected to express G and M. A series of G mutants was constructed with progressively truncated or modified cytoplasmic domains. Data from co-expression in cells and a cell-free binding assay showed that the N-terminal aa 2–6 of G play a key role in G–M interaction, with serine at position 2 and aspartate at position 6 playing key roles.

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