scholarly journals IFITMs Inhibit Cell Fusion Mediated by Trophoblast Syncytins

2019 ◽  
Author(s):  
Ashley Zani ◽  
Lizhi Zhang ◽  
Adam Kenney ◽  
Temet M. McMichael ◽  
Jesse J. Kwiek ◽  
...  
Keyword(s):  
Virus Infection ◽  
Fetal Development ◽  
Type I Interferon ◽  
Cell Structure ◽  
Transmembrane Proteins ◽  
Type I ◽  
Multinucleated Cell ◽  
Virus Infections ◽  
Infected Cells ◽  
Inhibit Cell Fusion

AbstractType I interferon (IFN) induced by virus infections during pregnancy causes placental damage, though the mechanisms and identities of IFN-stimulated genes that are involved remain under investigation. The IFN-induced transmembrane proteins (IFITMs) inhibit virus infections by preventing virus membrane fusion with cells and by inhibiting fusion of infected cells (syncytialization). Fusion of placental trophoblasts via expression of endogenous retroviral fusogens known as Syncytins forms the syncytiotrophoblast, a multinucleated cell structure essential for fetal development. We found that IFN blocks fusion of BeWo human placental trophoblasts. Stably-expressed IFITMs 1, 2, and 3 also blocked fusion of these trophoblasts, while making them more resistant to virus infections. Conversely, stable knockdown of IFITMs in BeWo trophoblasts increased their spontaneous fusion and allowed fusion in the presence of IFN, while also making the cells more susceptible to virus infection. Overall, our data demonstrate that IFITMs are anti-viral and anti-fusogenic in trophoblasts.

scholarly journals Epstein-Barr Virus (EBV) Tegument Protein BGLF2 Suppresses Type I Interferon Signaling To Promote EBV Reactivation

2020 ◽  
Vol 94 (11) ◽  
Author(s):  
XueQiao Liu ◽  
Tomohiko Sadaoka ◽  
Tammy Krogmann ◽  
Jeffrey I. Cohen
Keyword(s):  
Virus Infection ◽  
Type I Interferon ◽  
Tegument Protein ◽  
Type I ◽  
Type I Ifn ◽  
Virus Reactivation ◽  
Ebv Infection ◽  
Ebv Reactivation ◽  
Stat3 Phosphorylation ◽  
Infected Cells

ABSTRACT Interferon alpha (IFN-α) and IFN-β are type I IFNs that are induced by virus infection and are important in the host’s innate antiviral response. EBV infection activates multiple cell signaling pathways, resulting in the production of type I IFN which inhibits EBV infection and virus-induced B-cell transformation. We reported previously that EBV tegument protein BGLF2 activates p38 and enhances EBV reactivation. To further understand the role of BGLF2 in EBV infection, we used mass spectrometry to identify cellular proteins that interact with BGLF2. We found that BGLF2 binds to Tyk2 and confirmed this interaction by coimmunoprecipitation. BGLF2 blocked type I IFN-induced Tyk2, STAT1, and STAT3 phosphorylation and the expression of IFN-stimulated genes (ISGs) IRF1, IRF7, and MxA. In contrast, BGLF2 did not inhibit STAT1 phosphorylation induced by IFN-γ. Deletion of the carboxyl-terminal 66 amino acids of BGLF2 reduced the ability of the protein to repress type I IFN signaling. Treatment of gastric carcinoma and Raji cells with IFN-α blocked BZLF1 expression and EBV reactivation; however, expression of BGLF2 reduced the ability of IFN-α to inhibit BZLF1 expression and enhanced EBV reactivation. In summary, EBV BGLF2 interacts with Tyk2, inhibiting Tyk2, STAT1, and STAT3 phosphorylation and impairs type I IFN signaling; BGLF2 also counteracts the ability of IFN-α to suppress EBV reactivation. IMPORTANCE Type I interferons are important for controlling virus infection. We have found that the Epstein-Barr virus (EBV) BGLF2 tegument protein binds to a protein in the type I interferon signaling pathway Tyk2 and inhibits the expression of genes induced by type I interferons. Treatment of EBV-infected cells with type I interferon inhibits reactivation of the virus, while expression of EBV BGLF2 reduces the ability of type I interferon to inhibit virus reactivation. Thus, a tegument protein delivered to cells during virus infection inhibits the host’s antiviral response and promotes virus reactivation of latently infected cells. Therefore, EBV BGLF2 might protect virus-infected cells from the type I interferon response in cells undergoing lytic virus replication.

scholarly journals Influenza Virus Infection Enhances Antibody-Mediated NK Cell Functions via Type I Interferon-Dependent Pathways

2018 ◽  
Vol 93 (5) ◽  
Author(s):  
Sinthujan Jegaskanda ◽  
Hillary A. Vanderven ◽  
Hyon-Xhi Tan ◽  
Sheilajen Alcantara ◽  
Kathleen M. Wragg ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Nk Cells ◽  
Nk Cell ◽  
Type I Interferon ◽  
A549 Cells ◽  
Influenza Virus Infection ◽  
Type I ◽  
Cell Functions ◽  
Infected Cells

ABSTRACT Natural killer (NK) cells are an important component in the control of influenza virus infection, acting to both clear virus-infected cells and release antiviral cytokines. Engagement of CD16 on NK cells by antibody-coated influenza virus-infected cells results in antibody-dependent cellular cytotoxicity (ADCC). Increasing the potency of antibody-mediated NK cell activity could ultimately lead to improved control of influenza virus infection. To understand if NK cells can be functionally enhanced following exposure to influenza virus-infected cells, we cocultured human peripheral blood mononuclear cells (PBMCs) with influenza virus-infected human alveolar epithelial (A549) cells and evaluated the capacity of NK cells to mediate antibody-dependent functions. Preincubation of PBMCs with influenza virus-infected cells markedly enhanced the ability of NK cells to respond to immune complexes containing hemagglutinin (HA) and anti-HA antibodies or transformed allogeneic cells in the presence or absence of a therapeutic monoclonal antibody. Cytokine multiplex, RNA sequencing, supernatant transfer, Transwell, and cytokine-blocking/cytokine supplementation experiments showed that type I interferons released from PBMCs were primarily responsible for the influenza virus-induced enhancement of antibody-mediated NK cell functions. Importantly, the influenza virus-mediated increase in antibody-dependent NK cell functionality was mimicked by the type I interferon agonist poly(I·C). We conclude that the type I interferon secretion induced by influenza virus infection enhances the capacity of NK cells to mediate ADCC and that this pathway could be manipulated to alter the potency of anti-influenza virus therapies and vaccines. IMPORTANCE Protection from severe influenza may be assisted by antibodies that engage NK cells to kill infected cells through ADCC. Studies have primarily focused on antibodies that have ADCC activity, rather than the capacity of NK cells to become activated and mediate ADCC during an influenza virus infection. We found that type I interferon released in response to influenza virus infection primes NK cells to become highly reactive to anti-influenza virus ADCC antibodies. Enhancing the capacity of NK cells to mediate ADCC could assist in controlling influenza virus infections.

scholarly journals B.1.1.7 and B.1.351 SARS-CoV-2 variants display enhanced Spike-mediated fusion

2021 ◽  
Author(s):  
Maaran Michael Rajah ◽  
Mathieu Hubert ◽  
Elodie Bishop ◽  
Nell Saunders ◽  
Rémy Robinot ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Monoclonal Antibodies ◽  
Reference Strain ◽  
Type I Interferon ◽  
Transmembrane Proteins ◽  
Viral Proteins ◽  
Type I ◽  
Cytopathic Effects ◽  
Lung Abnormalities ◽  
Infected Cells

SARS-CoV-2 B.1.1.7 (variant Alpha) and B.1.351 (variant Beta) have supplanted pre-existing strains in many countries. Severe COVID-19 is characterized by lung abnormalities, including the presence of syncytial pneumocytes. Syncytia form when infected cells fuse with adjacent cells. The fitness, cytopathic effects and type-I interferon (IFN) sensitivity of the variants remain poorly characterized. Here, we assessed B.1.1.7 and B.1.351 spread and fusion in cell cultures. B.1.1.7 and B.1.351 replicated similarly to D614G reference strain in Vero, Caco-2, Calu-3 and primary airway cells and were similarly sensitive to IFN. The variants formed larger and more numerous syncytia. Variant Spikes, in the absence of any other viral proteins, resulted in faster fusion relative to D614G. B.1.1.7 and B.1.351 fusion was similarly inhibited by interferon induced transmembrane proteins (IFITMs). Individual mutations present in the variant Spikes modified fusogenicity, binding to ACE2 and recognition by monoclonal antibodies. Also, B.1.1.7 and B.1.351 variants remain sensitive to innate immunity components. The mutations present in the two variants globally enhance viral fusogenicity and allow for antibody evasion.

scholarly journals Whole-brain fluorescence-MRI coregistration for precise anatomical mapping of virus infection

2021 ◽  
Author(s):  
Nunya Chotiwan ◽  
Stefanie M.A. Willekens ◽  
Erin Schexnaydre ◽  
Max Hahn ◽  
Federico Morini ◽  
...  
Keyword(s):  
Virus Infection ◽  
Type I Interferon ◽  
Ex Vivo ◽  
Interferon Response ◽  
Type I ◽  
Virus Infections ◽  
Whole Brain ◽  
Neurotropic Virus ◽  
Langat Virus ◽  
The Brain

Neurotropic virus infections cause tremendous disease burden. Methods visualizing infection in the whole brain remain unavailable which greatly impedes understanding of viral neurotropism and pathogenesis. We devised an approach to visualize the distribution of neurotropic virus infection in whole mouse brain ex vivo. Optical projection tomography (OPT) signal was coregistered with a unique magnetic resonance imaging (MRI) brain template, enabling precise anatomical mapping of viral distribution, and the effect of type I interferon on distribution of infection was analyzed. Guided by OPT-MR, we show that Langat virus specifically targets sensory brain systems and the lack of type I interferon response results in an anatomical shift in infection patterns in the brain. We confirm this regional tropism, observed with whole brain OPT-MRI, by confocal and electron microscopy to provide unprecedented insight into viral neurotropism. This approach can be applied to any fluorescently labeled target in the brain.

scholarly journals Novel Mode of ISG15-Mediated Protection against Influenza A Virus and Sendai Virus in Mice

2014 ◽  
Vol 89 (1) ◽  
pp. 337-349 ◽  
Author(s):  
David J. Morales ◽  
Kristen Monte ◽  
Lulu Sun ◽  
Jessica J. Struckhoff ◽  
Eugene Agapov ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Virus Infection ◽  
Influenza A Virus ◽  
Virus Replication ◽  
Influenza A ◽  
Type I Interferon ◽  
Sendai Virus ◽  
Type I ◽  
Induced Genes

ABSTRACTISG15 is a diubiquitin-like modifier and one of the most rapidly induced genes upon type I interferon stimulation. Hundreds of host proteins and a number of viral proteins have been shown to be ISGylated, and understanding how these modifications affect the interferon response and virus replication has been of considerable interest. ISG15−/−mice exhibit increased susceptibility to viral infection, and in the case of influenza B virus and vaccinia virus, ISG15 conjugation has been shown to restrict virus replicationin vivo. A number of studies have also found that ISG15 is capable of antagonizing replication of some viruses in tissue culture. However, recent findings have demonstrated that ISG15 can protect mice from Chikungunya virus infection without affecting the virus burden. In order to better understand the function of ISG15in vivo, we characterized the pathogenesis of influenza A virus and Sendai virus in ISG15−/−mice. We found that ISG15 protects mice from virus induced lethality by a conjugation-dependent mechanism in both of these models. However, surprisingly, we found that ISG15 had minimal effect on virus replication and did not have an obvious role in the modulation of the acute immune response to infection. Instead, we observed an increase in the number of diseased small airways in mice lacking ISG15. This ability of ISG15 to protect mice in a conjugation-dependent, but nonantiviral, manner from respiratory virus infection represents a previously undescribed role for ISG15 and demonstrates the importance of further characterization of ISG15in vivo.IMPORTANCEIt has previously been demonstrated that ISG15−/−mice are more susceptible to a number of viral infections. Since ISG15 is one of the most strongly induced genes after type I interferon stimulation, analysis of ISG15 function has largely focused on its role as an antiviral molecule during acute infection. Although a number of studies have shown that ISG15 does have a small effect on virus replication in tissue culture, few studies have confirmed this mechanism of protectionin vivo. In these studies we have found that while ISG15−/−mice are more susceptible to influenza A virus and Sendai virus infections, ISGylation does not appear to mediate this protection through the direct inhibition of virus replication or the modulation of the acute immune response. Thus, in addition to showing a novel mode of ISG15 mediated protection from virus infection, this study demonstrates the importance of studying the role of ISG15in vivo.

AXL promotes Zika virus infection in astrocytes by antagonizing type I interferon signalling

2018 ◽  
Vol 3 (3) ◽  
pp. 302-309 ◽  
Author(s):  
Jian Chen ◽  
Yi-feng Yang ◽  
Yu Yang ◽  
Peng Zou ◽  
Jun Chen ◽  
...  
Keyword(s):  
Virus Infection ◽  
Zika Virus ◽  
Type I Interferon ◽  
Type I ◽  
Zika Virus Infection ◽  
Interferon Signalling

scholarly journals Mitochondrial Import of Dengue Virus NS3 Protease and Cleavage of GrpEL1, a Cochaperone of Mitochondrial Hsp70

2020 ◽  
Vol 94 (17) ◽  
Author(s):  
Chaitanya Gandikota ◽  
Fareed Mohammed ◽  
Lekha Gandhi ◽  
Deepti Maisnam ◽  
Ushodaya Mattam ◽  
...  
Keyword(s):  
Virus Infection ◽  
Dengue Virus ◽  
Severe Dengue ◽  
Clinical Samples ◽  
Mitochondrial Matrix ◽  
Virus Infections ◽  
Mitochondrial Import ◽  
Mitochondrial Transport ◽  
Infected Cells ◽  
Mitochondrial Hsp70

ABSTRACT Dengue virus infections, which have been reported in nearly 140 countries, pose a significant threat to human health. The genome of dengue virus encodes three structural and seven nonstructural (NS) proteins along with two untranslated regions, one each on both ends. Among them, dengue protease (NS3) plays a pivotal role in polyprotein processing and virus multiplication. NS3 is also known to regulate several host proteins to induce and maintain pathogenesis. Certain viral proteins are known to interact with mitochondrial membrane proteins and interfere with their functions, but the association of a virus-coded protein with the mitochondrial matrix is not known. In this report, by using in silico analysis, we show that NS3pro alone is capable of mitochondrial import; however, this is dependent on its innate mitochondrial transport signal (MTS). Transient-transfection and protein import studies confirm the import of NS3pro to the mitochondrial matrix. Similarly, NS3pro-helicase (amino acids 1 to 464 of NS3) also targets the mitochondria. Intriguingly, reduced levels of matrix-localized GrpE protein homolog 1 (GrpEL1), a cochaperone of mitochondrial Hsp70 (mtHsp70), were noticed in NS3pro-expressing, NS3pro-helicase-expressing, and virus-infected cells. Upon the use of purified components, GrpEL1 undergoes cleavage, and the cleavage sites have been mapped to KR81A and QR92S. Importantly, GrpEL1 levels are seriously compromised in severe dengue virus-infected clinical samples. Our studies provide novel insights into the import of NS3 into host mitochondria and identify a hitherto unknown factor, GrpEL1, as a cleavage target, thereby providing new avenues for dengue virus research and the design of potential therapeutics. IMPORTANCE Approximately 40% of the world’s population is at risk of dengue virus infection. There is currently no specific drug or potential vaccine for these infections. Lack of complete understanding of the pathogenesis of the virus is one of the hurdles that must be overcome in developing antivirals for this virus infection. In the present study, we observed that the dengue virus-coded protease imports to the mitochondrial matrix, and our report is the first ever of a virus-coded protein, either animal or human, importing to the mitochondrial matrix. Our analysis indicates that the observed mitochondrial import is due to an inherited mitochondrial transport signal. We also show that matrix-localized GrpE protein homolog 1 (GrpEL1), a cochaperone of mitochondrial Hsp70 (mtHsp70), is also the substrate of dengue virus protease, as observed in vitro and ex vivo in virus-infected cells and dengue virus-infected clinical samples. Hence, our studies reveal an essential aspect of the pathogenesis of dengue virus infections, which may aid in developing antidengue therapeutics.

Obesity worsens the outcome of influenza virus infection associated with impaired type I interferon induction in mice

2019 ◽  
Vol 513 (2) ◽  
pp. 405-411 ◽  
Author(s):  
Ho Namkoong ◽  
Makoto Ishii ◽  
Hideki Fujii ◽  
Takahiro Asami ◽  
Kazuma Yagi ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Type I Interferon ◽  
Influenza Virus Infection ◽  
Type I ◽  
Interferon Induction
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