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 Ebola virus infection induces a type I interferon response and the shutdown of key liver functions in human iPSC-derived hepatocytes

2021 ◽  
Author(s):  
Whitney Manhart ◽  
Liliana Mancio ◽  
Ellen Suder ◽  
Carlos Villacorta-Martin ◽  
Jonathan Lindstrom-Vautrin ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Ebola Virus ◽  
Interferon Response ◽  
Type I ◽  
Interferon Signaling ◽  
Liver Functions ◽  
Ebov Infection ◽  
Transcriptomic Changes ◽  
Human Ipsc ◽  
Ebola Virus Infection

Abstract Liver damage and an exacerbated inflammatory response are hallmarks of Ebola virus (EBOV) infection. Little is known about the intrinsic response to infection in human hepatocytes and their contribution to the observed inflammatory response. Here, we present an iPSC-derived hepatocyte platform to define the hepato-intrinsic response to EBOV infection. Transcriptomics analysis revealed a delayed host response with minimal transcriptomic changes at one day post infection (dpi) followed by a general downregulation of genes associated with hepatic functions and upregulation of interferon signaling at two and three dpi. Using RNA-FISH, we showed at single cell resolution that IFNβ and CXCL10 were mainly expressed in bystander cells or cells with weak EBOV mRNA signal intensity. We did not observe an inflammatory signature at any timepoint. In conclusion, iPSC-derived hepatocytes are an immune competent platform to study intrinsic responses to EBOV infection that have not been observed in EBOV-infected hepatocarcinoma cell lines.

scholarly journals Functional Importance of Hydrophobic Patches on the Ebola Virus VP35 IFN-Inhibitory Domain

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2316
Author(s):  
Nodoka Kasajima ◽  
Keita Matsuno ◽  
Hiroko Miyamoto ◽  
Masahiro Kajihara ◽  
Manabu Igarashi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Ebola Virus ◽  
Structural Information ◽  
Site Directed Mutagenesis ◽  
Genome Replication ◽  
Type I ◽  
Multifunctional Protein ◽  
Functional Sites ◽  
Inhibitory Function ◽  
Inhibitory Domain

Viral protein 35 (VP35) of Ebola virus (EBOV) is a multifunctional protein that mainly acts as a viral polymerase cofactor and an interferon antagonist. VP35 interacts with the viral nucleoprotein (NP) and double-stranded RNA for viral RNA transcription/replication and inhibition of type I interferon (IFN) production, respectively. The C-terminal portion of VP35, which is termed the IFN-inhibitory domain (IID), is important for both functions. To further identify critical regions in this domain, we analyzed the physical properties of the surface of VP35 IID, focusing on hydrophobic patches, which are expected to be functional sites that are involved in interactions with other molecules. Based on the known structural information of VP35 IID, three hydrophobic patches were identified on its surface and their biological importance was investigated using minigenome and IFN-β promoter-reporter assays. Site-directed mutagenesis revealed that some of the amino acid substitutions that were predicted to disrupt the hydrophobicity of the patches significantly decreased the efficiency of viral genome replication/transcription due to reduced interaction with NP, suggesting that the hydrophobic patches might be critical for the formation of a replication complex through the interaction with NP. It was also found that the hydrophobic patches were involved in the IFN-inhibitory function of VP35. These results highlight the importance of hydrophobic patches on the surface of EBOV VP35 IID and also indicate that patch analysis is useful for the identification of amino acid residues that directly contribute to protein functions.

scholarly journals Reverse Genetic Generation of Recombinant Zaire Ebola Viruses Containing Disrupted IRF-3 Inhibitory Domains Results in Attenuated Virus Growth In Vitro and Higher Levels of IRF-3 Activation without Inhibiting Viral Transcription or Replication

2006 ◽  
Vol 80 (13) ◽  
pp. 6430-6440 ◽  
Author(s):  
Amy L. Hartman ◽  
Jason E. Dover ◽  
Jonathan S. Towner ◽  
Stuart T. Nichol
Keyword(s):  
Reverse Genetics ◽  
Ebola Virus ◽  
Viral Transcription ◽  
Type I ◽  
Virus Growth ◽  
Recombinant Viruses ◽  
Inhibitory Function ◽  
C Terminus ◽  
Inhibitory Domain

ABSTRACT The VP35 protein of Zaire Ebola virus is an essential component of the viral RNA polymerase complex and also functions to antagonize the cellular type I interferon (IFN) response by blocking activation of the transcription factor IRF-3. We previously mapped the IRF-3 inhibitory domain within the C terminus of VP35. In the present study, we show that mutations that disrupt the IRF-3 inhibitory function of VP35 do not disrupt viral transcription/replication, suggesting that the two functions of VP35 are separable. Second, using reverse genetics, we successfully recovered recombinant Ebola viruses containing mutations within the IRF-3 inhibitory domain. Importantly, we show that the recombinant viruses were attenuated for growth in cell culture and that they activated IRF-3 and IRF-3-inducible gene expression at levels higher than that for Ebola virus containing wild-type VP35. In the context of Ebola virus pathogenesis, VP35 may function to limit early IFN-β production and other antiviral signals generated from cells at the primary site of infection, thereby slowing down the host's ability to curb virus replication and induce adaptive immunity.

scholarly journals Mannosyl Glycodendritic Structure Inhibits DC-SIGN-Mediated Ebola Virus Infection in cis and in trans

2003 ◽  
Vol 47 (12) ◽  
pp. 3970-3972 ◽  
Author(s):  
Fátima Lasala ◽  
Eva Arce ◽  
Joaquín R. Otero ◽  
Javier Rojo ◽  
Rafael Delgado
Keyword(s):  
Dendritic Cell ◽  
Virus Infection ◽  
Adhesion Molecule ◽  
Ebola Virus ◽  
Cell Entry ◽  
Intercellular Adhesion Molecule ◽  
Ebov Infection ◽  
In Trans ◽  
In Cis ◽  
Ebola Virus Infection

ABSTRACT We have designed a glycodendritic structure, BH30sucMan, that blocks the interaction between dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) and Ebola virus (EBOV) envelope. BH30sucMan inhibits DC-SIGN-mediated EBOV infection at nanomolar concentrations. BH30sucMan may counteract important steps of the infective process of EBOV and, potentially, of microorganisms shown to exploit DC-SIGN for cell entry and infection.

scholarly journals Reverse Genetics Demonstrates that Proteolytic Processing of the Ebola Virus Glycoprotein Is Not Essential for Replication in Cell Culture

2002 ◽  
Vol 76 (1) ◽  
pp. 406-410 ◽  
Author(s):  
Gabriele Neumann ◽  
Heinz Feldmann ◽  
Shinji Watanabe ◽  
Igor Lukashevich ◽  
Yoshihiro Kawaoka
Keyword(s):  
Cell Culture ◽  
Reverse Genetics ◽  
Ebola Virus ◽  
Hemorrhagic Fever ◽  
Proteolytic Processing ◽  
Wild Type ◽  
Effective Strategies ◽  
Recognition Motif ◽  
Cloned Cdna ◽  
Ebola Virus Infection

ABSTRACT Ebola virus, a prime example of an emerging pathogen, causes fatal hemorrhagic fever in humans and in nonhuman primates. Identification of major determinants of Ebola virus pathogenicity has been hampered by the lack of effective strategies for experimental mutagenesis. Here we exploit a reverse genetics system that allows the generation of Ebola virus from cloned cDNA to engineer a mutant Ebola virus with an altered furin recognition motif in the glycoprotein (GP). When expressed in cells, the GP of the wild type, but not of the mutant, virus was cleaved into GP1 and GP2. Although posttranslational furin-mediated cleavage of GP was thought to be an essential step in Ebola virus infection, generation of a viable mutant Ebola virus lacking a furin recognition motif in the GP cleavage site demonstrates that GP cleavage is not essential for replication of Ebola virus in cell culture.

scholarly journals Ebolaviruses Associated with Differential Pathogenicity Induce Distinct Host Responses in Human Macrophages

2017 ◽  
Vol 91 (11) ◽  
Author(s):  
Judith Olejnik ◽  
Adriana Forero ◽  
Laure R. Deflubé ◽  
Adam J. Hume ◽  
Whitney A. Manhart ◽  
...  
Keyword(s):  
Host Response ◽  
Ebola Virus ◽  
Severe Disease ◽  
Health Concern ◽  
Type I ◽  
Proinflammatory Response ◽  
Tlr4 Signaling ◽  
Human Macrophages ◽  
Ebov Infection ◽  
Reston Virus

ABSTRACT Ebola virus (EBOV) and Reston virus (RESTV) are members of the Ebolavirus genus which greatly differ in their pathogenicity. While EBOV causes a severe disease in humans characterized by a dysregulated inflammatory response and elevated cytokine and chemokine production, there are no reported disease-associated human cases of RESTV infection, suggesting that RESTV is nonpathogenic for humans. The underlying mechanisms determining the pathogenicity of different ebolavirus species are not yet known. In this study, we dissected the host response to EBOV and RESTV infection in primary human monocyte-derived macrophages (MDMs). As expected, EBOV infection led to a profound proinflammatory response, including strong induction of type I and type III interferons (IFNs). In contrast, RESTV-infected macrophages remained surprisingly silent. Early activation of IFN regulatory factor 3 (IRF3) and NF-κB was observed in EBOV-infected, but not in RESTV-infected, MDMs. In concordance with previous results, MDMs treated with inactivated EBOV and Ebola virus-like particles (VLPs) induced NF-κB activation mediated by Toll-like receptor 4 (TLR4) in a glycoprotein (GP)-dependent manner. This was not the case in cells exposed to live RESTV, inactivated RESTV, or VLPs containing RESTV GP, indicating that RESTV GP does not trigger TLR4 signaling. Our results suggest that the lack of immune activation in RESTV-infected MDMs contributes to lower pathogenicity by preventing the cytokine storm observed in EBOV infection. We further demonstrate that inhibition of TLR4 signaling abolishes EBOV GP-mediated NF-κB activation. This finding indicates that limiting the excessive TLR4-mediated proinflammatory response in EBOV infection should be considered as a potential supportive treatment option for EBOV disease. IMPORTANCE Emerging infectious diseases are a major public health concern, as exemplified by the recent devastating Ebola virus (EBOV) outbreak. Different ebolavirus species are associated with widely varying pathogenicity in humans, ranging from asymptomatic infections for Reston virus (RESTV) to severe disease with fatal outcomes for EBOV. In this comparative study of EBOV- and RESTV-infected human macrophages, we identified key differences in host cell responses. Consistent with previous data, EBOV infection is associated with a proinflammatory signature triggered by the surface glycoprotein (GP), which can be inhibited by blocking TLR4 signaling. In contrast, infection with RESTV failed to stimulate a strong host response in infected macrophages due to the inability of RESTV GP to stimulate TLR4. We propose that disparate proinflammatory host signatures contribute to the differences in pathogenicity reported for ebolavirus species and suggest that proinflammatory pathways represent an intriguing target for the development of novel therapeutics.

scholarly journals Passive Transfer of Antibodies Protects Immunocompetent and Immunodeficient Mice against Lethal Ebola Virus Infection without Complete Inhibition of Viral Replication

2001 ◽  
Vol 75 (10) ◽  
pp. 4649-4654 ◽  
Author(s):  
Manisha Gupta ◽  
Siddhartha Mahanty ◽  
Mike Bray ◽  
Rafi Ahmed ◽  
Pierre E. Rollin
Keyword(s):  
Virus Infection ◽  
Viral Replication ◽  
Ebola Virus ◽  
Protective Efficacy ◽  
Hemorrhagic Fever ◽  
Passive Transfer ◽  
Immune Serum ◽  
Immunodeficient Mice ◽  
Ebola Hemorrhagic Fever ◽  
Ebola Virus Infection

ABSTRACT Ebola hemorrhagic fever is a severe, usually fatal illness caused by Ebola virus, a member of the filovirus family. The use of nonhomologous immune serum in animal studies and blood from survivors in two anecdotal reports of Ebola hemorrhagic fever in humans has shown promise, but the efficacy of these treatments has not been demonstrated definitively. We have evaluated the protective efficacy of polyclonal immune serum in a mouse model of Ebola virus infection. Our results demonstrate that mice infected subcutaneously with live Ebola virus survive infection and generate high levels of anti-Ebola virus immunoglobulin G (IgG). Passive transfer of immune serum from these mice before challenge protected upto 100% of naive mice against lethal Ebola virus infection. Protection correlated with the level of anti-Ebola virus IgG titers, and passive treatment with high-titer antiserum was associated with a delay in the peak of viral replication. Transfer of immune serum to SCID mice resulted in 100% survival after lethal challenge with Ebola virus, indicating that antibodies alone can protect from lethal disease. Thus antibodies suppress or delay viral growth, provide protection against lethal Ebola virus infection, and may not require participation of other immune components for protection.

scholarly journals A THEORETICAL STUDY ON FRACTIONAL EBOLA HEMORRHAGIC FEVER MODEL

Fractals ◽  
2021 ◽  
Author(s):  
SHAHER MOMANI ◽  
R. P. CHAUHAN ◽  
SUNIL KUMAR ◽  
SAMIR HADID
Keyword(s):  
Virus Infection ◽  
Ebola Virus ◽  
Virus Disease ◽  
Numerical Technique ◽  
Disease Model ◽  
Hemorrhagic Fever ◽  
Health Concern ◽  
Ebola Hemorrhagic Fever ◽  
Conformable Derivatives ◽  
Ebola Virus Infection

The Ebola virus infection (EVI), generally known as Ebola hemorrhagic fever, is a major health concern. The occasional outbreaks of virus occur primarily in certain parts of Africa. Many researches have been devoted to the study of the Ebola virus disease. In this paper, we have taken susceptible-infected-recovered-deceased-environment (SIRDP) system to investigate the dynamics of Ebola virus infection. We adopted fractional operators for a better illustration of model dynamics and memory effects. Initially, the Ebola disease model is modified with Caputo–Fabrizio arbitrary operator in Caputo sense (CFC) and we employed the fixed-point results for the existence and uniqueness of the solution of the fractional system. Further, we adopted the arbitrary fractional conformable and [Formula: see text]-conformable derivatives to the alternative representation of the model. For the numerical approximation of the system, we show a numerical technique based on the fundamental theorem of fractional calculus for CFC derivative and a numerical scheme called the Adams–Moulton for conformable derivatives. Finally, for the validation of theoretical results, the numerical simulations are displayed.

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 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.

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