scholarly journals Grouper Interferon-Induced Transmembrane Protein 1 Inhibits Iridovirus and Nodavirus Replication by Regulating Virus Entry and Host Lipid Metabolism

2021 ◽  
Vol 12 ◽  
Author(s):  
Ya Zhang ◽  
Liqun Wang ◽  
Jiaying Zheng ◽  
Liwei Huang ◽  
Shaowen Wang ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Viral Entry ◽  
Host Cells ◽  
Viral Gene ◽  
Target Cells ◽  
Epinephelus Coioides ◽  
Virus Infections ◽  
Fish Virus ◽  
Early Endosomes

Interferon-induced transmembrane proteins (IFITMs) are novel viral restriction factors which inhibit numerous virus infections by impeding viral entry into target cells. To investigate the roles of IFITMs during fish virus infection, we cloned and characterized an IFITM1 homolog from orange spotted grouper (Epinephelus coioides) (EcIFITM1) in this study. EcIFITM1 encodes a 131-amino-acid polypeptide, which shares 64 and 43% identity with Seriola dumerili and Homo sapiens, respectively. The multiple sequence alignment showed that EcIFITM1 contained five domains, including NTD (aa 1–45), IMD (aa 46–67), CIL (aa 68–93), TMD (aa 94–119), and CTD (aa 120–131). In vitro, the level of EcIFITM1 mRNA expression was significantly up-regulated in response to Singapore grouper iridovirus (SGIV), or red-spotted grouper nervous necrosis virus (RGNNV) infection. EcIFITM1 encoded a cytoplasmic protein, which was partly colocalized with early endosomes, late endosomes, and lysosomes. The ectopic expression of EcIFITM1 significantly inhibited the replication of SGIV or RGNNV, which was demonstrated by the reduced virus production, as well as the levels of viral gene transcription and protein expression. In contrast, knockdown of EcIFITM1 using small interfering RNAs (siRNAs) promoted the replication of both viruses. Notably, EcIFITM1 exerted its antiviral activity in the step of viral entry into the host cells. Furthermore, the results of non-targeted lipometabolomics showed that EcIFITM1 overexpression induced lipid metabolism remodeling in vitro. All of the detected ceramides were significantly increased following EcIFITM1 overexpression, suggesting that EcIFITM1 may suppress SGIV entry by regulating the level of ceramide in the lysosomal system. In addition, EcIFITM1 overexpression positively regulated both interferon-related molecules and ceramide synthesis-related genes. Taken together, our results demonstrated that EcIFITM1 exerted a bi-functional role, including immune regulation and lipid metabolism in response to fish virus infections.

scholarly journals Clathrin-Dependent Entry of Severe Acute Respiratory Syndrome Coronavirus into Target Cells Expressing ACE2 with the Cytoplasmic Tail Deleted

2007 ◽  
Vol 81 (16) ◽  
pp. 8722-8729 ◽  
Author(s):  
Yuuki Inoue ◽  
Nobuyuki Tanaka ◽  
Yoshinori Tanaka ◽  
Shingo Inoue ◽  
Kouichi Morita ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Viral Entry ◽  
Cytoplasmic Tail ◽  
Host Cells ◽  
Target Cells ◽  
Dependent Manner ◽  
Virus Attachment ◽  
Caveolin 1 ◽  
Early Endosomes ◽  
Interfering Rna

ABSTRACT The penetration of various viruses into host cells is accomplished by hijacking the host endocytosis machinery. In the case of severe acute respiratory syndrome coronavirus (SARS-CoV) infection, viral entry is reported to require a low pH in intracytoplasmic vesicles; however, little is known about how SARS-CoV invades such compartments. Here we demonstrate that SARS-CoV mainly utilizes the clathrin-mediated endocytosis pathway for its entry to target cells by using infectious SARS-CoV, as well as a SARS-CoV pseudovirus packaged in the SARS-CoV envelope. The SARS-CoV entered caveolin-1-negative HepG2 cells, and the entry was significantly inhibited by treatment with chlorpromazine, an inhibitor for clathrin-dependent endocytosis, and by small interfering RNA-mediated gene silencing for the clathrin heavy chain. Furthermore, the SARS-CoV entered COS7 cells transfected with the mutant of ACE2 with the cytoplasmic tail deleted, SARS-CoV receptor, as well as the wild-type ACE2, and their entries were significantly inhibited by treatment with chlorpromazine. In addition, ACE2 translocated into EEA1-positive early endosomes immediately after the virus attachment to ACE2. These results suggest that when SARS-CoV binds ACE2 it is internalized and penetrates early endosomes in a clathrin-dependent manner and that the cytoplasmic tail of ACE2 is not required for the penetration of SARS-CoV.

scholarly journals Molecular Signaling and Cellular Pathways for Virus Entry

ISRN Virology ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Pei-I Chi ◽  
Hung-Jen Liu
Keyword(s):  
Signaling Pathways ◽  
Viral Entry ◽  
Virus Entry ◽  
Host Cells ◽  
Target Cells ◽  
Molecular Signaling ◽  
Cellular Processes ◽  
Cellular Pathways ◽  
Host Life ◽  
Endocytic Vesicles

The cell signaling plays a pivotal role in regulating cellular processes and is often manipulated by viruses as they rely on the functions offered by cells for their propagation. The first stage of their host life is to pass the genetic materials into the cell. Although some viruses can directly penetrate into cytosol, in fact, most virus entry into their host cells is through endocytosis. This machinery initiates with cell type specific cellular signaling pathways, and the signaling compounds can be proteins, lipids, and carbohydrates. The activation can be triggered in a very short time after virus binds on target cells, such as receptors. The signaling pathways involved in regulation of viral entry are wide diversity that often cross-talk between different endocytosis results. Furthermore, some viruses have the ability to use the multiple internalization pathways which leads to the regulation being even more complex. In this paper, we discuss some recent advances in our understanding of cellular pathways for virus entry, molecular signaling during virus entry, formation of endocytic vesicles, and the traffic.

A screen of approved drugs and molecular probes identifies therapeutics with anti–Ebola virus activity

2015 ◽  
Vol 7 (290) ◽  
pp. 290ra89-290ra89 ◽  
Author(s):  
Lisa M. Johansen ◽  
Lisa Evans DeWald ◽  
Charles J. Shoemaker ◽  
Benjamin G. Hoffstrom ◽  
Calli M. Lear-Rooney ◽  
...  
Keyword(s):  
Viral Entry ◽  
Ebola Virus ◽  
Molecular Probes ◽  
Infection Model ◽  
Channel Blockers ◽  
Emerging Infections ◽  
Virus Infections ◽  
Approved Drugs

Currently, no approved therapeutics exist to treat or prevent infections induced by Ebola viruses, and recent events have demonstrated an urgent need for rapid discovery of new treatments. Repurposing approved drugs for emerging infections remains a critical resource for potential antiviral therapies. We tested ~2600 approved drugs and molecular probes in an in vitro infection assay using the type species, Zaire ebolavirus. Selective antiviral activity was found for 80 U.S. Food and Drug Administration–approved drugs spanning multiple mechanistic classes, including selective estrogen receptor modulators, antihistamines, calcium channel blockers, and antidepressants. Results using an in vivo murine Ebola virus infection model confirmed the protective ability of several drugs, such as bepridil and sertraline. Viral entry assays indicated that most of these antiviral drugs block a late stage of viral entry. By nature of their approved status, these drugs have the potential to be rapidly advanced to clinical settings and used as therapeutic countermeasures for Ebola virus infections.

Viral hemorrhagic fever – a vascular disease?

2003 ◽  
Vol 89 (06) ◽  
pp. 967-972 ◽  
Author(s):  
Heinz Feldmann ◽  
Hans Schnittler
Keyword(s):  
Ebola Virus ◽  
Vascular System ◽  
Current Knowledge ◽  
Hemorrhagic Fever ◽  
Host Cells ◽  
Fluid Distribution ◽  
Target Cells ◽  
Viral Hemorrhagic Fever ◽  
Virus Infections ◽  
Cytokines And Chemokines

SummaryThe syndrome of “viral hemorrhagic fever” in man caused by certain viruses, such as Ebola, Lassa, Dengue, and Crimean-Congo hemorrhagic fever viruses, is often associated with a shock syndrome of undetermined pathogenesis. However, the vascular system, particularly the vascular endothelium, seems to be directly and indirectly targeted by all these viruses. Here we briefly summarize the current knowledge on Marburg and Ebola virus infections, the prototype viral hemorrhagic fever agents, and formulate a working hypothesis for the pathogenesis of viral hemorrhagic fever. Infections with filoviruses show lethality up to 89% and in severe cases lead to a shock syndrome associated with hypotension, coagulation disorders and an imbalance of fluid distribution between the intravascular and extravascular tissue space. The primary target cells for filovi-ruses are mononuclear phagocytotic cells which are activated upon infection and release certain cytokines and chemokines. These mediators indirectly target the endothelium and are thought to play a key role in the pathogenesis of filoviral hemorrhagic fever. In addition, direct infection and subsequent destruction of endothelial cells might contribute to the pathogenesis. Filoviruses, particularly Ebola virus, encode nonstructural glycoproteins which are released from infected host cells. Their function as potential determinants in pathogenicity remains to be investigated.

scholarly journals Deubiquitinating Function of Adenovirus Proteinase

2002 ◽  
Vol 76 (12) ◽  
pp. 6323-6331 ◽  
Author(s):  
Maxim Y. Balakirev ◽  
Michel Jaquinod ◽  
Arthur L. Haas ◽  
Jadwiga Chroboczek
Keyword(s):  
Structural Model ◽  
Proteolytic Processing ◽  
Host Cells ◽  
Cellular Proteins ◽  
Viral Gene ◽  
Cellular Processes ◽  
Infected Cells ◽  
Substrate Binding Sites

ABSTRACT The invasion strategy of many viruses involves the synthesis of viral gene products that mimic the functions of the cellular proteins and thus interfere with the key cellular processes. Here we show that adenovirus infection is accompanied by an increased ubiquitin-cleaving (deubiquitinating) activity in the host cells. Affinity chromatography on ubiquitin aldehyde (Ubal), which was designed to identify the deubiquitinating proteases, revealed the presence of adenovirus L3 23K proteinase (Avp) in the eluate from adenovirus-infected cells. This proteinase is known to be necessary for the processing of viral precursor proteins during virion maturation. We show here that in vivo Avp deubiquitinates a number of cellular proteins. Analysis of the substrate specificity of Avp in vitro demonstrated that the protein deubiquitination by this enzyme could be as efficient as proteolytic processing of viral proteins. The structural model of the Ubal-Avp interaction revealed some similarity between S1-S4 substrate binding sites of Avp and ubiquitin hydrolases. These results may reflect the acquisition of an advantageous property by adenovirus and may indicate the importance of ubiquitin pathways in viral infection.

scholarly journals Signal-regulatory protein alpha is an anti-viral entry factor targeting viruses using endocytic pathways

2021 ◽  
Vol 17 (6) ◽  
pp. e1009662
Author(s):  
Nicolás Sarute ◽  
Han Cheng ◽  
Zhonghao Yan ◽  
Karen Salas-Briceno ◽  
Justin Richner ◽  
...  
Keyword(s):  
Viral Entry ◽  
New World ◽  
Ebola Virus ◽  
Regulatory Protein ◽  
Target Cells ◽  
Surface Receptors ◽  
Tacaribe Virus ◽  
Targeted Mutation ◽  
Pathogenic Viruses

Signal-regulatory protein alpha (SIRPA) is a well-known inhibitor of phagocytosis when it complexes with CD47 expressed on target cells. Here we show that SIRPA decreased in vitro infection by a number of pathogenic viruses, including New World and Old world arenaviruses, Zika virus, vesicular stomatitis virus and pseudoviruses bearing the Machupo virus, Ebola virus and SARS-CoV-2 glycoproteins, but not HSV-1, MLV or mNoV. Moreover, mice with targeted mutation of the Sirpa gene that renders it non-functional were more susceptible to infection with the New World arenaviruses Junín virus vaccine strain Candid 1 and Tacaribe virus, but not MLV or mNoV. All SIRPA-inhibited viruses have in common the requirement for trafficking to a low pH endosomal compartment. This was clearly demonstrated with SARS-CoV-2 pseudovirus, which was only inhibited by SIRPA in cells in which it required trafficking to the endosome. Similar to its role in phagocytosis inhibition, SIRPA decreased virus internalization but not binding to cell surface receptors. We also found that increasing SIRPA levels via treatment with IL-4 led to even greater anti-viral activity. These data suggest that enhancing SIRPA’s activity could be a target for anti-viral therapies.

scholarly journals In-vivo Protection from SARS-CoV-2 infection by ATN-161 in k18-hACE2 transgenic mice

2021 ◽  
Author(s):  
Amruta Narayanappa ◽  
Elizabeth B Engler-Chiurazzi ◽  
Isabel C Murray-Brown ◽  
Timothy E Gressett ◽  
Ifechukwude J Biose ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Viral Entry ◽  
Therapeutic Potential ◽  
Host Cells ◽  
Spike Protein ◽  
Cell Infection ◽  
Integrin Alpha5beta1 ◽  
Chemokine Ligand

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an infectious disease that has spread worldwide. Current treatments are limited in both availability and efficacy, such that improving our understanding of the factors that facilitate infection is urgently needed to more effectively treat infected individuals and to curb the pandemic. We and others have previously demonstrated the significance of interactions between the SARS-CoV-2 spike protein, integrin alpha5beta1 and human ACE2 to facilitate viral entry into host cells in vitro. We previously found that inhibition of integrin alpha5beta1 by the clinically validated small peptide ATN-161 inhibits these spike protein interactions and cell infection in vitro. In continuation with our previous findings, here we have further evaluated the therapeutic potential of ATN-161 on SARS-CoV-2 infection in k18-hACE2 transgenic (SARS-CoV-2 susceptible) mice in vivo. We discovered that treatment with single- or repeated intravenous doses of ATN-161 (1 mg/kg) within 48 hours after intranasal inoculation with SARS-CoV-2 lead to a reduction of lung viral load, viral immunofluorescence and improved lung histology in a majority of mice 72 hours post-infection. Furthermore, ATN-161 reduced SARS-CoV-2-induced increased expression of lung integrin alpha 5 and alpha v (an alpha 5-related integrin that has also been implicated in SARS-CoV-2 interactions) as well as the C-X-C motif chemokine ligand 10 (Cxcl10), further supporting the potential involvement of these integrins, and the anti-inflammatory potential of ATN-161, respectively, in SARS-CoV-2 infection. To the best of our knowledge, this is the first study demonstrating the potential therapeutic efficacy of targeting integrin alpha5beta1 in SARS-CoV-2 infection in vivo and supports the development of ATN-161 as a novel SARS-CoV-2 therapy.

scholarly journals Cryptosporidium parvum Subtilisin-Like Serine Protease (SUB1) Is Crucial for Parasite Egress from Host Cells

2019 ◽  
Vol 87 (5) ◽  
Author(s):  
Samantha Nava ◽  
A. Clinton White ◽  
Alejandro Castellanos-González
Keyword(s):  
Life Cycle ◽  
Serine Protease ◽  
Host Cells ◽  
Effective Vaccine ◽  
Infection Model ◽  
Target Cells ◽  
Calcium Dependent ◽  
Argonaute 2 ◽  
Parasite Egress

ABSTRACT Despite the severity and global burden of Cryptosporidium infection, treatments are less than optimal, and there is no effective vaccine. Egress from host cells is a key process for the completion of the life cycle of apicomplexan parasites. For Plasmodium species, subtilisin-like serine protease (SUB1) is a key mediator of egress. For Toxoplasma species, calcium-dependent protein kinases (CDPKs) are critical. In this study, we characterized Cryptosporidium SUB1 expression and evaluated its effect using an infection model. We found increased expression between 12 and 20 h after in vitro infection, prior to egress. We induced silencing of SUB1 (ΔSUB1) mRNA using SUB1 single-stranded antisense RNA coupled with human Argonaute 2. Silencing of SUB1 mRNA expression did not affect parasite viability, excystation, or invasion of target cells. However, knockdown led to a 95% decrease in the proportion of released merozoites in vitro (P < 0.0001). In contrast, silencing of CDPK5 had no effect on egress. Overall, our results indicate that SUB1 is a key mediator of Cryptosporidium egress and suggest that interruption of the life cycle at this stage may effectively inhibit the propagation of infection.

scholarly journals Antiviral protection by virus-immune cytotoxic T cells: infected target cells are lysed before infectious virus progeny is assembled.

1977 ◽  
Vol 145 (3) ◽  
pp. 644-651 ◽  
Author(s):  
R M Zinkernagel ◽  
A Althage
Keyword(s):  
T Cells ◽  
Adoptive Transfer ◽  
Infectious Virus ◽  
Cytotoxic T Cells ◽  
Target Cells ◽  
Virus Infections ◽  
Virus Growth ◽  
Virus Progeny

Virus-immune cytotoxic T cells can inhibit effectively growth of vaccinia virus in acutely infected target cells in vitro by destroying infected target cells before infectious virus progeny is assembled. Together with the fact that virus-specific T cells are demonstrable after 3 days, very early during infection, and with strong circumstantial evidence from adoptive transfer models in vivo, these data suggest that in some virus infections T cells may in fact act cytolytically in vivo to prevent virus growth and spread and be an important early antiviral effector mechanism.

scholarly journals Cell-in-cell phenomenon: leukocyte engulfment by non-tumorigenic cells and cancer cell lines

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Mareike F. Bauer ◽  
Michael Hader ◽  
Markus Hecht ◽  
Maike Büttner-Herold ◽  
Rainer Fietkau ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Mononuclear Cells ◽  
Cancer Cell Lines ◽  
Host Cells ◽  
Target Cells ◽  
Peripheral Blood Mononuclear ◽  
The Impact ◽  
Microwave Hyperthermia

Abstract Background Research on cell-in-cell (CIC) phenomena, including entosis, emperipolesis and cannibalism, and their biological implications has increased in recent years. Homotypic and heterotypic engulfment of various target cells by numerous types of host cells has been studied in vitro and in tissue sections. This work has identified proteins involved in the mechanism and uncovered evidence for CIC as a potential histopathologic predictive and prognostic marker in cancer. Our experimental study focused on non-professional phagocytosis of leukocytes. Results We studied the engulfment of peripheral blood mononuclear cells isolated from healthy donors by counting CIC structures. Two non-tumorigenic cell lines (BEAS-2B, SBLF-9) and two tumour cell lines (BxPC3, ICNI) served as host cells. Immune cells were live-stained and either directly co-incubated or treated with irradiation or with conventional or microwave hyperthermia. Prior to co-incubation, we determined leukocyte viability for each batch via Annexin V-FITC/propidium iodide staining. All host cells engulfed their targets, with uptake rates ranging from 1.0% ± 0.5% in BxPC3 to 8.1% ± 5.0% in BEAS-2B. Engulfment rates of the cancer cell lines BxPC3 and ICNI (1.6% ± 0.2%) were similar to those of the primary fibroblasts SBLF-9 (1.4% ± 0.2%). We found a significant negative correlation between leukocyte viability and cell-in-cell formation rates. The engulfment rate rose when we increased the dose of radiotherapy and prolonged the impact time. Further, microwave hyperthermia induced higher leukocyte uptake than conventional hyperthermia. Using fluorescent immunocytochemistry to descriptively study the proteins involved, we detected ring-like formations of diverse proteins around the leukocytes, consisting, among others, of α-tubulin, integrin, myosin, F-actin, and vinculin. These results suggest the involvement of actomyosin contraction, cell-cell adhesion, and the α-tubulin cytoskeleton in the engulfment process. Conclusions Both non-tumorigenic and cancer cells can form heterotypic CIC structures by engulfing leukocytes. Decreased viability and changes caused by microwave and X-ray irradiation trigger non-professional phagocytosis.

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