scholarly journals Ebola Virus Uptake into Polarized Cells from the Apical Surface

Viruses ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1117 ◽  
Author(s):  
Meng Hu ◽  
Fei Wang ◽  
Wei Li ◽  
Xiaowei Zhang ◽  
Zhiping Zhang ◽  
...  
Keyword(s):  
Viral Entry ◽  
Ebola Virus ◽  
Apical Cell ◽  
Hemorrhagic Fever ◽  
Vero Cells ◽  
Cell Polarization ◽  
Apical Surface ◽  
Intracellular Receptor ◽  
Ebov Infection ◽  
Niemann Pick

Ebola virus (EBOV) causes severe hemorrhagic fever with high mortality rates. EBOV can infect many types of cells. During severe EBOV infection, polarized epithelial and endothelial cells are damaged, which promotes vascular instability and dysregulation. However, the mechanism causing these symptoms is largely unknown. Here, we studied virus infection in polarized Vero C1008 cells grown on semipermeable Transwell by using EGFP-labeled Ebola virus-like particles (VLPs). Our results showed that Ebola VLPs preferred to enter polarized Vero cells from the apical cell surface. Furthermore, we showed that the EBOV receptors TIM-1 and Axl were distributed apically, which could be responsible for mediating efficient apical viral entry. Macropinocytosis and intracellular receptor Niemann–Pick type C1 (NPC1) had no polarized distribution, although they played roles in virus entry. This study provides a new view of EBOV uptake and cell polarization, which facilitates a further understanding of EBOV infection and pathogenesis.

scholarly journals Structure of the Ebola virus envelope protein MPER/TM domain and its interaction with the fusion loop explains their fusion activity

2017 ◽  
Vol 114 (38) ◽  
pp. E7987-E7996 ◽  
Author(s):  
Jinwoo Lee ◽  
David A. Nyenhuis ◽  
Elizabeth A. Nelson ◽  
David S. Cafiso ◽  
Judith M. White ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Viral Entry ◽  
Ebola Virus ◽  
Rna Virus ◽  
Hemorrhagic Fever ◽  
Virus Envelope ◽  
Tm Domain ◽  
Virus Envelope Protein ◽  
Niemann Pick ◽  
Fusion Loop

Ebolavirus (EBOV), an enveloped filamentous RNA virus causing severe hemorrhagic fever, enters cells by macropinocytosis and membrane fusion in a late endosomal compartment. Fusion is mediated by the EBOV envelope glycoprotein GP, which consists of subunits GP1 and GP2. GP1 binds to cellular receptors, including Niemann-Pick C1 (NPC1) protein, and GP2 is responsible for low pH-induced membrane fusion. Proteolytic cleavage and NPC1 binding at endosomal pH lead to conformational rearrangements of GP2 that include exposing the hydrophobic fusion loop (FL) for insertion into the cellular target membrane and forming a six-helix bundle structure. Although major portions of the GP2 structure have been solved in pre- and postfusion states and although current models place the transmembrane (TM) and FL domains of GP2 in close proximity at critical steps of membrane fusion, their structures in membrane environments, and especially interactions between them, have not yet been characterized. Here, we present the structure of the membrane proximal external region (MPER) connected to the TM domain: i.e., the missing parts of the EBOV GP2 structure. The structure, solved by solution NMR and EPR spectroscopy in membrane-mimetic environments, consists of a helix-turn-helix architecture that is independent of pH. Moreover, the MPER region is shown to interact in the membrane interface with the previously determined structure of the EBOV FL through several critical aromatic residues. Mutation of aromatic and neighboring residues in both binding partners decreases fusion and viral entry, highlighting the functional importance of the MPER/TM–FL interaction in EBOV entry and fusion.

scholarly journals Analysis of Resistance of Ebola Virus Glycoprotein-Driven Entry Against MDL28170, An Inhibitor of Cysteine Cathepsins

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 192 ◽  
Author(s):  
Markus Hoffmann ◽  
Svenja Victoria Kaufmann ◽  
Carina Fischer ◽  
Wiebke Maurer ◽  
Anna-Sophie Moldenhauer ◽  
...  
Keyword(s):  
Viral Entry ◽  
Ebola Virus ◽  
Mutational Analysis ◽  
Cathepsin L ◽  
Cysteine Proteases ◽  
Host Cells ◽  
Single Amino Acid ◽  
Limited Information ◽  
Cysteine Cathepsins ◽  
Ebov Infection

Ebola virus (EBOV) infection can cause severe and frequently fatal disease in human patients. The EBOV glycoprotein (GP) mediates viral entry into host cells. For this, GP depends on priming by the pH-dependent endolysosomal cysteine proteases cathepsin B (CatB) and, to a lesser degree, cathepsin L (CatL), at least in most cell culture systems. However, there is limited information on whether and how EBOV-GP can acquire resistance to CatB/L inhibitors. Here, we addressed this question using replication-competent vesicular stomatitis virus bearing EBOV-GP. Five passages of this virus in the presence of the CatB/CatL inhibitor MDL28170 were sufficient to select resistant viral variants and sequencing revealed that all GP sequences contained a V37A mutation, which, in the context of native GP, is located in the base of the GP surface unit. In addition, some GP sequences harbored mutation S195R in the receptor-binding domain. Finally, mutational analysis demonstrated that V37A but not S195R conferred resistance against MDL28170 and other CatB/CatL inhibitors. Collectively, a single amino acid substitution in GP is sufficient to confer resistance against CatB/CatL inhibitors, suggesting that usage of CatB/CatL inhibitors for antiviral therapy may rapidly select for resistant viral variants.

scholarly journals A Single Intranasal Inoculation with a Paramyxovirus-Vectored Vaccine Protects Guinea Pigs against a Lethal-Dose Ebola Virus Challenge

2006 ◽  
Vol 80 (5) ◽  
pp. 2267-2279 ◽  
Author(s):  
Alexander Bukreyev ◽  
Lijuan Yang ◽  
Sherif R. Zaki ◽  
Wun-Ju Shieh ◽  
Pierre E. Rollin ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Ebola Virus ◽  
Lethal Dose ◽  
Vaccine Dose ◽  
Humoral Response ◽  
Hemorrhagic Fever ◽  
Vero Cells ◽  
Intranasal Inoculation ◽  
Virus Challenge ◽  
Vectored Vaccine

ABSTRACT To determine whether intranasal inoculation with a paramyxovirus-vectored vaccine can induce protective immunity against Ebola virus (EV), recombinant human parainfluenza virus type 3 (HPIV3) was modified to express either the EV structural glycoprotein (GP) by itself (HPIV3/EboGP) or together with the EV nucleoprotein (NP) (HPIV3/EboGP-NP). Expression of EV GP by these recombinant viruses resulted in its efficient incorporation into virus particles and increased cytopathic effect in Vero cells. HPIV3/EboGP was 100-fold more efficiently neutralized by antibodies to EV than by antibodies to HPIV3. Guinea pigs infected with a single intranasal inoculation of 105.3 PFU of HPIV3/EboGP or HPIV3/EboGP-NP showed no apparent signs of disease yet developed a strong humoral response specific to the EV proteins. When these animals were challenged with an intraperitoneal injection of 103 PFU of EV, there were no outward signs of disease, no viremia or detectable EV antigen in the blood, and no evidence of infection in the spleen, liver, and lungs. In contrast, all of the control animals died or developed severe EV disease following challenge. The highly effective immunity achieved with a single vaccine dose suggests that intranasal immunization with live vectored vaccines based on recombinant respiratory viruses may be an advantageous approach to inducing protective responses against severe systemic infections, such as those caused by hemorrhagic fever agents.

scholarly journals Altered microRNA Transcriptome in Cultured Human Liver Cells upon Infection with Ebola Virus

2021 ◽  
Vol 22 (7) ◽  
pp. 3792
Author(s):  
Idrissa Diallo ◽  
Jeffrey Ho ◽  
Benoit Laffont ◽  
Jonathan Laugier ◽  
Abderrahim Benmoussa ◽  
...  
Keyword(s):  
Human Liver ◽  
Ebola Virus ◽  
Hemorrhagic Fever ◽  
Regulatory Elements ◽  
Liver Cells ◽  
Molecular Signature ◽  
Small Rna Sequencing ◽  
Human Liver Cell ◽  
Ebov Infection ◽  
The Impact

Ebola virus (EBOV) is a virulent pathogen, notorious for inducing life-threatening hemorrhagic fever, that has been responsible for several outbreaks in Africa and remains a public health threat. Yet, its pathogenesis is still not completely understood. Although there have been numerous studies on host transcriptional response to EBOV, with an emphasis on the clinical features, the impact of EBOV infection on post-transcriptional regulatory elements, such as microRNAs (miRNAs), remains largely unexplored. MiRNAs are involved in inflammation and immunity and are believed to be important modulators of the host response to viral infection. Here, we have used small RNA sequencing (sRNA-Seq), qPCR and functional analyses to obtain the first comparative miRNA transcriptome (miRNome) of a human liver cell line (Huh7) infected with one of the following three EBOV strains: Mayinga (responsible for the first Zaire outbreak in 1976), Makona (responsible for the West Africa outbreak in 2013–2016) and the epizootic Reston (presumably innocuous to humans). Our results highlight specific miRNA-based immunity pathways and substantial differences between the strains beyond their clinical manifestation and pathogenicity. These analyses shed new light into the molecular signature of liver cells upon EBOV infection and reveal new insights into miRNA-based virus attack and host defense strategy.

scholarly journals The Host E3-Ubiquitin Ligase TRIM6 Ubiquitinates the Ebola Virus VP35 Protein and Promotes Virus Replication

2017 ◽  
Vol 91 (18) ◽  
Author(s):  
Preeti Bharaj ◽  
Colm Atkins ◽  
Priya Luthra ◽  
Maria Isabel Giraldo ◽  
Brian E. Dawes ◽  
...  
Keyword(s):  
Virus Replication ◽  
Ubiquitin Ligase ◽  
Ebola Virus ◽  
E3 Ubiquitin Ligase ◽  
Hemorrhagic Fever ◽  
Viral Polymerase ◽  
Highly Pathogenic ◽  
Polyubiquitin Chains ◽  
Ebov Infection ◽  
Potent Antagonist

ABSTRACT Ebola virus (EBOV), a member of the Filoviridae family, is a highly pathogenic virus that causes severe hemorrhagic fever in humans and is responsible for epidemics throughout sub-Saharan, central, and West Africa. The EBOV genome encodes VP35, an important viral protein involved in virus replication by acting as an essential cofactor of the viral polymerase as well as a potent antagonist of the host antiviral type I interferon (IFN-I) system. By using mass spectrometry analysis and coimmunoprecipitation assays, we show here that VP35 is ubiquitinated on lysine 309 (K309), a residue located on its IFN antagonist domain. We also found that VP35 interacts with TRIM6, a member of the E3-ubiquitin ligase tripartite motif (TRIM) family. We recently reported that TRIM6 promotes the synthesis of unanchored K48-linked polyubiquitin chains, which are not covalently attached to any protein, to induce efficient antiviral IFN-I-mediated responses. Consistent with this notion, VP35 also associated noncovalently with polyubiquitin chains and inhibited TRIM6-mediated IFN-I induction. Intriguingly, we also found that TRIM6 enhances EBOV polymerase activity in a minigenome assay and TRIM6 knockout cells have reduced replication of infectious EBOV, suggesting that VP35 hijacks TRIM6 to promote EBOV replication through ubiquitination. Our work provides evidence that TRIM6 is an important host cellular factor that promotes EBOV replication, and future studies will focus on whether TRIM6 could be targeted for therapeutic intervention against EBOV infection. IMPORTANCE EBOV belongs to a family of highly pathogenic viruses that cause severe hemorrhagic fever in humans and other mammals with high mortality rates (40 to 90%). Because of its high pathogenicity and lack of licensed antivirals and vaccines, EBOV is listed as a tier 1 select-agent risk group 4 pathogen. An important mechanism for the severity of EBOV infection is its suppression of innate immune responses. The EBOV VP35 protein contributes to pathogenesis, because it serves as an essential cofactor of the viral polymerase as well as a potent antagonist of innate immunity. However, how VP35 function is regulated by host cellular factors is poorly understood. Here, we report that the host E3-ubiquitin ligase TRIM6 promotes VP35 ubiquitination and is important for efficient virus replication. Therefore, our study identifies a new host factor, TRIM6, as a potential target in the development of antiviral drugs against EBOV.

scholarly journals Early Transcriptional Changes within Liver, Adrenal Gland, and Lymphoid Tissues Significantly Contribute to Ebola Virus Pathogenesis in Cynomolgus Macaques

2020 ◽  
Vol 94 (11) ◽  
Author(s):  
Allen Jankeel ◽  
Andrea R. Menicucci ◽  
Courtney Woolsey ◽  
Karla A. Fenton ◽  
Norma Mendoza ◽  
...  
Keyword(s):  
Ebola Virus ◽  
Adrenal Glands ◽  
Case Fatality ◽  
Hemorrhagic Fever ◽  
Organ Damage ◽  
Host Responses ◽  
Lymphoid Tissues ◽  
Cynomolgus Macaques ◽  
Ebov Infection ◽  
Transcriptional Changes

ABSTRACT Ebola virus (EBOV) continues to pose a significant threat to human health, as evidenced by the 2013–2016 epidemic in West Africa and the ongoing outbreak in the Democratic Republic of the Congo. EBOV causes hemorrhagic fever, organ damage, and shock culminating in death, with case fatality rates as high as 90%. This high lethality combined with the paucity of licensed medical countermeasures makes EBOV a critical human pathogen. Although EBOV infection results in significant damage to the liver and the adrenal glands, little is known about the molecular signatures of injury in these organs. Moreover, while changes in peripheral blood cells are becoming increasingly understood, the host responses within organs and lymphoid tissues remain poorly characterized. To address this knowledge gap, we tracked longitudinal transcriptional changes in tissues collected from EBOV-Makona-infected cynomolgus macaques. Following infection, both liver and adrenal glands exhibited significant and early downregulation of genes involved in metabolism, coagulation, hormone synthesis, and angiogenesis; upregulated genes were associated with inflammation. Analysis of lymphoid tissues showed early upregulation of genes that play a role in innate immunity and inflammation and downregulation of genes associated with cell cycle and adaptive immunity. Moreover, transient activation of innate immune responses and downregulation of humoral immune responses in lymphoid tissues were confirmed with flow cytometry. Together, these data suggest that the liver, adrenal gland, and lymphatic organs are important sites of EBOV infection and that dysregulating the function of these vital organs contributes to the development of Ebola virus disease. IMPORTANCE Ebola virus (EBOV) remains a high-priority pathogen since it continues to cause outbreaks with high case fatality rates. Although it is well established that EBOV results in severe organ damage, our understanding of tissue injury in the liver, adrenal glands, and lymphoid tissues remains limited. We begin to address this knowledge gap by conducting longitudinal gene expression studies in these tissues, which were collected from EBOV-infected cynomolgus macaques. We report robust and early gene expression changes within these tissues, indicating they are primary sites of EBOV infection. Furthermore, genes involved in metabolism, coagulation, and adaptive immunity were downregulated, while inflammation-related genes were upregulated. These results indicate significant tissue damage consistent with the development of hemorrhagic fever and lymphopenia. Our study provides novel insight into EBOV-host interactions and elucidates how host responses within the liver, adrenal glands, and lymphoid tissues contribute to EBOV pathogenesis.

scholarly journals Quercetin Blocks Ebola Virus Infection by Counteracting the VP24 Interferon-Inhibitory Function

2020 ◽  
Vol 64 (7) ◽  
Author(s):  
Elisa Fanunza ◽  
Mathieu Iampietro ◽  
Simona Distinto ◽  
Angela Corona ◽  
Marina Quartu ◽  
...  
Keyword(s):  
Ebola Virus ◽  
Hemorrhagic Fever ◽  
Type I ◽  
Virulence Determinants ◽  
Inhibitory Function ◽  
Viral Binding ◽  
Ebov Infection ◽  
Small Set ◽  
Tight Correlation ◽  
Ebola Virus Infection

ABSTRACT Ebola virus (EBOV) is among the most devastating pathogens causing fatal hemorrhagic fever in humans. The epidemics from 2013 to 2016 resulted in more than 11,000 deaths, and another outbreak is currently ongoing. Since there is no FDA-approved drug so far to fight EBOV infection, there is an urgent need to focus on drug discovery. Considering the tight correlation between the high EBOV virulence and its ability to suppress the type I interferon (IFN-I) system, identifying molecules targeting viral protein VP24, one of the main virulence determinants blocking the IFN response, is a promising novel anti-EBOV therapy approach. Hence, in the effort to find novel EBOV inhibitors, a screening of a small set of flavonoids was performed; it showed that quercetin and wogonin can suppress the VP24 effect on IFN-I signaling inhibition. The mechanism of action of the most active compound, quercetin, showing a half-maximal inhibitory concentration (IC50) of 7.4 μM, was characterized to significantly restore the IFN-I signaling cascade, blocked by VP24, by directly interfering with the VP24 binding to karyopherin-α and thus restoring P-STAT1 nuclear transport and IFN gene transcription. Quercetin significantly blocked viral infection, specifically targeting EBOV VP24 anti-IFN-I function. Overall, quercetin is the first identified inhibitor of the EBOV VP24 anti-IFN function, representing a molecule interacting with a viral binding site that is very promising for further drug development aiming to block EBOV infection at the early steps.

scholarly journals The Roles of Ebola Virus Soluble Glycoprotein in Replication, Pathogenesis, and Countermeasure Development

Viruses ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 999 ◽  
Author(s):  
Wenjun Zhu ◽  
Logan Banadyga ◽  
Karla Emeterio ◽  
Gary Wong ◽  
Xiangguo Qiu
Keyword(s):  
Immune Response ◽  
Envelope Protein ◽  
Ebola Virus ◽  
Hemorrhagic Fever ◽  
Antiviral Drugs ◽  
Viral Envelope ◽  
Multiple Roles ◽  
Its Sequence ◽  
Viral Envelope Protein ◽  
Ebov Infection

Ebola virus (EBOV) is a highly lethal pathogen that has caused several outbreaks of severe hemorrhagic fever in humans since its emergence in 1976. The EBOV glycoprotein (GP1,2) is the sole viral envelope protein and a major component of immunogenicity; it is encoded by the GP gene along with two truncated versions: soluble GP (sGP) and small soluble GP (ssGP). sGP is, in fact, the primary product of the GP gene, and it is secreted in abundance during EBOV infection. Since sGP shares large portions of its sequence with GP1,2, it has been hypothesized that sGP may subvert the host immune response by inducing antibodies against sGP rather than GP1,2. Several reports have shown that sGP plays multiple roles that contribute to the complex pathogenesis of EBOV. In this review, we focus on sGP and discuss its possible roles with regards to the pathogenesis of EBOV and the development of specific antiviral drugs.

scholarly journals A Single Residue in Ebola Virus Receptor NPC1 Influences Cellular Host Range in Reptiles

mSphere ◽  
2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Esther Ndungo ◽  
Andrew S. Herbert ◽  
Matthijs Raaben ◽  
Gregor Obernosterer ◽  
Rohan Biswas ◽  
...  
Keyword(s):  
Amino Acid ◽  
Host Range ◽  
Amino Acid Residue ◽  
Ebola Virus ◽  
Single Amino Acid ◽  
Binding Interface ◽  
Single Amino Acid Residue ◽  
Ebov Infection ◽  
Russell’S Viper ◽  
Niemann Pick

ABSTRACT Identifying cellular factors that determine susceptibility to infection can help us understand how Ebola virus is transmitted. We asked if the EBOV receptor Niemann-Pick C1 (NPC1) could explain why reptiles are resistant to EBOV infection. We demonstrate that cells derived from the Russell’s viper are not susceptible to infection because EBOV cannot bind to viper NPC1. This resistance to infection can be mapped to a single amino acid residue in viper NPC1 that renders it unable to bind to EBOV GP. The newly solved structure of EBOV GP bound to NPC1 confirms our findings, revealing that this residue dips into the GP receptor-binding pocket and is therefore critical to the binding interface. Consequently, this otherwise well-conserved residue in vertebrate species influences the ability of reptilian NPC1 proteins to bind to EBOV GP, thereby affecting viral host range in reptilian cells. Filoviruses are the causative agents of an increasing number of disease outbreaks in human populations, including the current unprecedented Ebola virus disease (EVD) outbreak in western Africa. One obstacle to controlling these epidemics is our poor understanding of the host range of filoviruses and their natural reservoirs. Here, we investigated the role of the intracellular filovirus receptor, Niemann-Pick C1 (NPC1) as a molecular determinant of Ebola virus (EBOV) host range at the cellular level. Whereas human cells can be infected by EBOV, a cell line derived from a Russell’s viper (Daboia russellii) (VH-2) is resistant to infection in an NPC1-dependent manner. We found that VH-2 cells are resistant to EBOV infection because the Russell’s viper NPC1 ortholog bound poorly to the EBOV spike glycoprotein (GP). Analysis of panels of viper-human NPC1 chimeras and point mutants allowed us to identify a single amino acid residue in NPC1, at position 503, that bidirectionally influenced both its binding to EBOV GP and its viral receptor activity in cells. Significantly, this single residue change perturbed neither NPC1’s endosomal localization nor its housekeeping role in cellular cholesterol trafficking. Together with other recent work, these findings identify sequences in NPC1 that are important for viral receptor activity by virtue of their direct interaction with EBOV GP and suggest that they may influence filovirus host range in nature. Broader surveys of NPC1 orthologs from vertebrates may delineate additional sequence polymorphisms in this gene that control susceptibility to filovirus infection. IMPORTANCE Identifying cellular factors that determine susceptibility to infection can help us understand how Ebola virus is transmitted. We asked if the EBOV receptor Niemann-Pick C1 (NPC1) could explain why reptiles are resistant to EBOV infection. We demonstrate that cells derived from the Russell’s viper are not susceptible to infection because EBOV cannot bind to viper NPC1. This resistance to infection can be mapped to a single amino acid residue in viper NPC1 that renders it unable to bind to EBOV GP. The newly solved structure of EBOV GP bound to NPC1 confirms our findings, revealing that this residue dips into the GP receptor-binding pocket and is therefore critical to the binding interface. Consequently, this otherwise well-conserved residue in vertebrate species influences the ability of reptilian NPC1 proteins to bind to EBOV GP, thereby affecting viral host range in reptilian cells.

scholarly journals Inhibition of Ebola Virus Entry by a C-peptide Targeted to Endosomes

2011 ◽  
Vol 286 (18) ◽  
pp. 15854-15861 ◽  
Author(s):  
Emily Happy Miller ◽  
Joseph S. Harrison ◽  
Sheli R. Radoshitzky ◽  
Chelsea D. Higgins ◽  
Xiaoli Chi ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Viral Entry ◽  
Ebola Virus ◽  
Hemorrhagic Fever ◽  
Marburg Virus ◽  
Viral Envelope ◽  
Heptad Repeat ◽  
Fusion Event ◽  
C Peptide ◽  
Hiv 1

Ebola virus (EboV) and Marburg virus (MarV) (filoviruses) are the causative agents of severe hemorrhagic fever. Infection begins with uptake of particles into cellular endosomes, where the viral envelope glycoprotein (GP) catalyzes fusion between the viral and host cell membranes. This fusion event is thought to involve conformational rearrangements of the transmembrane subunit (GP2) of the envelope spike that ultimately result in formation of a six-helix bundle by the N- and C-terminal heptad repeat (NHR and CHR, respectively) regions of GP2. Infection by other viruses employing similar viral entry mechanisms (such as HIV-1 and severe acute respiratory syndrome coronavirus) can be inhibited with synthetic peptides corresponding to the native CHR sequence (“C-peptides”). However, previously reported EboV C-peptides have shown weak or insignificant antiviral activity. To determine whether the activity of a C-peptide could be improved by increasing its intracellular concentration, we prepared an EboV C-peptide conjugated to the arginine-rich sequence from HIV-1 Tat, which is known to accumulate in endosomes. We found that this peptide specifically inhibited viral entry mediated by filovirus GP proteins and infection by authentic filoviruses. We determined that antiviral activity was dependent on both the Tat sequence and the native EboV CHR sequence. Mechanistic studies suggested that the peptide acts by blocking a membrane fusion intermediate.

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