scholarly journals Manipulation of Host Cell Organelles by Intracellular Pathogens

2021 ◽  
Vol 22 (12) ◽  
pp. 6484
Author(s):  
Malte Kellermann ◽  
Felix Scharte ◽  
Michael Hensel
Keyword(s):  
Legionella Pneumophila ◽  
Influenza A ◽  
Brome Mosaic Virus ◽  
Host Cells ◽  
Respiratory Syndrome Virus ◽  
Mammalian Host ◽  
Cell Organelles ◽  
Barr Virus ◽  
Epstein Barr ◽  
Virus Zika

Pathogenic intracellular bacteria, parasites and viruses have evolved sophisticated mechanisms to manipulate mammalian host cells to serve as niches for persistence and proliferation. The intracellular lifestyles of pathogens involve the manipulation of membrane-bound organellar compartments of host cells. In this review, we described how normal structural organization and cellular functions of endosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, or lipid droplets are targeted by microbial virulence mechanisms. We focus on the specific interactions of Salmonella, Legionella pneumophila, Rickettsia rickettsii, Chlamydia spp. and Mycobacterium tuberculosis representing intracellular bacterial pathogens, and of Plasmodium spp. and Toxoplasma gondii representing intracellular parasites. The replication strategies of various viruses, i.e., Influenza A virus, Poliovirus, Brome mosaic virus, Epstein-Barr Virus, Hepatitis C virus, severe acute respiratory syndrome virus (SARS), Dengue virus, Zika virus, and others are presented with focus on the specific manipulation of the organelle compartments. We compare the specific features of intracellular lifestyle and replication cycles, and highlight the communalities in mechanisms of manipulation deployed.

Acute Pharyngitis: Etiology and Diagnosis

PEDIATRICS ◽  
1996 ◽  
Vol 97 (6) ◽  
pp. 949-954
Author(s):  
Alan L. Bisno
Keyword(s):  
Herpes Simplex ◽  
Influenza A ◽  
Epstein Barr Virus ◽  
Viral Infections ◽  
Clinical Manifestations ◽  
Acute Pharyngitis ◽  
Herpesvirus Type ◽  
Barr Virus ◽  
Epstein Barr

Acute pharyngitis may be caused by a wide variety of microbial agents (Table 1). The relative importance of each of these agents varies greatly depending on a number of epidemiologic factors, including age of the patient, season of the year, and geographic locale. Viruses Most cases of acute pharyngitis are viral in etiology and involve the pharynx as well as other portions of the respiratory tract as manifestations of the common cold, influenza, or croup. Examples include the rhinoviruses, coronaviruses, influenza A and B, and the parainfluenza viruses. Certain viral infections causing sore throat may exhibit clinical manifestations that are rather distinctive. Examples include enteroviruses (herpangina due to Coxsackie A), Epstein-Barr virus (infectious mononucleosis), cytomegalovirus (cytomegalovirus mononucleosis), adenovirus (pharyngoconjunctival fever, acute respiratory disease of military recruits), and herpes simplex virus (pharyngitis, gingivitis, and stomatitis). In many instances, however, the illnesses caused by these agents may overlap so broadly with that of streptococcal pharyngitis as to be clinically indistinguishable. Thus, Epstein-Barr virus, adenovirus, and herpes virus may all cause fever, exudative pharyngitis, and cervical adenitis. Several studies have documented the role of primary herpesvirus type 1 infection as a cause of acute pharyngitis in college students.1-4 Herpesvirus type 2 can occasionally cause a similar illness as a consequence of oral-genital sexual contact.5 Although herpesvirus infections may involve the anterior oral cavity (vesicular or ulcerative gingivostomatitis) as well as the posterior pharynx, they do not routinely do so. Only about one-fourth of students with culturally and serologically proven primary herpes simplex type 1 pharyngitis studied by Glezen et al,2 for example, had gingivostomatitis.

scholarly journals Identification of Three gp350/220 Regions Involved in Epstein-Barr Virus Invasion of Host Cells

2005 ◽  
Vol 280 (42) ◽  
pp. 35598-35605 ◽  
Author(s):  
Mauricio Urquiza ◽  
Ramses Lopez ◽  
Helena Patiño ◽  
Jaiver E. Rosas ◽  
Manuel E. Patarroyo
Keyword(s):  
Epstein Barr Virus ◽  
Host Cells ◽  
Barr Virus ◽  
Epstein Barr

scholarly journals Tumour viruses and innate immunity

2017 ◽  
Vol 372 (1732) ◽  
pp. 20160267 ◽  
Author(s):  
Sharon E. Hopcraft ◽  
Blossom Damania
Keyword(s):  
Immune Response ◽  
Inflammatory Response ◽  
Viral Infection ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Host Cells ◽  
Oncogenic Viruses ◽  
Barr Virus ◽  
Human T Cell ◽  
Epstein Barr

Host cells sense viral infection through pattern recognition receptors (PRRs), which detect pathogen-associated molecular patterns (PAMPs) and stimulate an innate immune response. PRRs are localized to several different cellular compartments and are stimulated by viral proteins and nucleic acids. PRR activation initiates signal transduction events that ultimately result in an inflammatory response. Human tumour viruses, which include Kaposi's sarcoma-associated herpesvirus, Epstein–Barr virus, human papillomavirus, hepatitis C virus, hepatitis B virus, human T-cell lymphotropic virus type 1 and Merkel cell polyomavirus, are detected by several different PRRs. These viruses engage in a variety of mechanisms to evade the innate immune response, including downregulating PRRs, inhibiting PRR signalling, and disrupting the activation of transcription factors critical for mediating the inflammatory response, among others. This review will describe tumour virus PAMPs and the PRRs responsible for detecting viral infection, PRR signalling pathways, and the mechanisms by which tumour viruses evade the host innate immune system. This article is part of the themed issue ‘Human oncogenic viruses’.

scholarly journals PB2 Residue 271 Plays a Key Role in Enhanced Polymerase Activity of Influenza A Viruses in Mammalian Host Cells

2010 ◽  
Vol 84 (9) ◽  
pp. 4395-4406 ◽  
Author(s):  
Kendra A. Bussey ◽  
Tatiana L. Bousse ◽  
Emily A. Desmet ◽  
Baek Kim ◽  
Toru Takimoto
Keyword(s):  
Mammalian Cells ◽  
Influenza A ◽  
Virus Titer ◽  
Polymerase Activity ◽  
Influenza Viruses ◽  
Host Cells ◽  
Mammalian Host ◽  
Influenza A Viruses ◽  
H5n1 Influenza ◽  
Avian Viruses

ABSTRACT The direct infection of humans with highly pathogenic avian H5N1 influenza viruses has suggested viral mutation as one mechanism for the emergence of novel human influenza A viruses. Although the polymerase complex is known to be a key component in host adaptation, mutations that enhance the polymerase activity of avian viruses in mammalian hosts are not fully characterized. The genomic comparison of influenza A virus isolates has identified highly conserved residues in influenza proteins that are specific to either human or avian viruses, including 10 residues in PB2. We characterized the activity of avian polymerase complexes containing avian-to-human mutations at these conserved PB2 residues and found that, in addition to the E627K mutation, the PB2 mutation T271A enhances polymerase activity in human cells. We confirmed the effects of the T271A mutation using recombinant WSN viruses containing avian NP and polymerase genes with wild-type (WT) or mutant PB2. The 271A virus showed enhanced growth compared to that of the WT in mammalian cells in vitro. The 271A mutant did not increase viral pathogenicity significantly in mice compared to that of the 627K mutant, but it did enhance the lung virus titer. Also, cell infiltration was more evident in lungs of 271A-infected mice than in those of the WT. Interestingly, the avian-derived PB2 of the 2009 pandemic H1N1 influenza virus has 271A. The characterization of the polymerase activity of A/California/04/2009 (H1N1) and corresponding PB2 mutants indicates that the high polymerase activity of the pandemic strain in mammalian cells is, in part, dependent on 271A. Our results clearly indicate the contribution of PB2 amino acid 271 to enhanced polymerase activity and viral growth in mammalian hosts.

scholarly journals Interferon Antagonism of Epstein–Barr Virus Tegument Proteins

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 74
Author(s):  
Wai-Yan Lui ◽  
Sonia Jangra ◽  
Kit-San Yuen ◽  
Michael George Botelho ◽  
Dong-Yan Jin
Keyword(s):  
Epstein Barr Virus ◽  
Tyrosine Phosphatase ◽  
Host Cells ◽  
Tegument Protein ◽  
Small Subset ◽  
Type I ◽  
Type I Ifn ◽  
Tegument Proteins ◽  
Barr Virus ◽  
Epstein Barr

The Epstein–Barr virus (EBV) successfully infects 95% of all adults but causes Burkitt’s lymphoma, Hodgkin’s lymphoma, gastric carcinoma, nasopharyngeal carcinoma or other malignancies in only a small subset of infected individuals. The virus must have developed effective viral countermeasures to evade host innate immunity. In this study, we performed functional screens to identify EBV-encoded interferon (IFN) antagonists. Several tegument proteins were found to be potent suppressors of IFN production and/or signaling. The large tegument protein and deubiquitinase BPLF1 antagonized type I IFN production induced by DNA sensors cGAS and STING or RNA sensors RIG-I and MAVS. BPLF1’s ability to suppress innate immune signaling required its deubiquitinase activity. BPLF1 functioned as a catalytically active deubiquitinase for both K63- and K48-linked ubiquitin chains on STING and TBK1, with no ubiquitin linkage specificity. Induced expression of BPLF1 in EBV-infected cells through CRISPRa led to effective suppression of innate DNA and RNA sensing. Another EBV tegument protein, BGLF2, was found to suppress JAK-STAT signaling. This suppression was ascribed to more pronounced K48-linked polyubiquitination and proteasomal degradation of BGLF2-associated STAT2. In addition, BGLF2 also recruited tyrosine phosphatase SHP1 to inhibit tyrosine phosphorylation of JAK1 and STAT1. A BGLF2-deficient EBV activated type I IFN signaling more robustly. Taken together, we characterized the IFN antagonism of EBV tegument proteins BPLF1 and BGLF2, which modulate ubiquitination of key transducer proteins to counteract type I IFN production and signaling in host cells. Supported by HMRF 17160822, HMRF 18170942, and RGC C7027-16G.

scholarly journals Elucidation of the c-Jun N-Terminal Kinase Pathway Mediated by Epstein-Barr Virus-Encoded Latent Membrane Protein 1

2004 ◽  
Vol 24 (1) ◽  
pp. 192-199 ◽  
Author(s):  
Jun Wan ◽  
Luguo Sun ◽  
Jennifer Woo Mendoza ◽  
Yiu Loon Chui ◽  
Dolly P. Huang ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Epstein Barr Virus ◽  
Cellular Transformation ◽  
Latent Membrane Protein ◽  
Host Cells ◽  
Latent Membrane Protein 1 ◽  
Tnf Receptor ◽  
Jnk Pathway ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) is associated with several human diseases including infectious mononucleosis and nasopharyngeal carcinoma. EBV-encoded latent membrane protein 1 (LMP1) is oncogenic and indispensable for cellular transformation caused by EBV. Expression of LMP1 in host cells constitutively activates both the c-Jun N-terminal kinase (JNK) and NF-κB pathways, which contributes to the oncogenic effect of LMP1. However, the underlying signaling mechanisms are not very well understood. Based mainly on overexpression studies with various dominant-negative constructs, LMP1 was generally thought to functionally mimic members of the tumor necrosis factor (TNF) receptor superfamily in signaling. In contrast to the prevailing paradigm, using embryonic fibroblasts from different knockout mice and the small interfering RNA technique, we find that the LMP1-mediated JNK pathway is distinct from those mediated by either TNF-α or interleukin-1. Moreover, we have further elucidated the LMP1-mediated JNK pathway by demonstrating that LMP1 selectively utilizes TNF receptor-associated factor 6, TAK1/TAB1, and c-Jun N-terminal kinase kinases 1 and 2 to activate JNK.

scholarly journals Modulation of Epstein-Barr Virus Glycoprotein B (gB) Fusion Activity by the gB Cytoplasmic Tail Domain

mBio ◽  
2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Nicholas J. Garcia ◽  
Jia Chen ◽  
Richard Longnecker
Keyword(s):  
Membrane Fusion ◽  
Epstein Barr Virus ◽  
Cytoplasmic Tail ◽  
Host Cells ◽  
Glycoprotein B ◽  
Tail Domain ◽  
Induced Membrane ◽  
Barr Virus ◽  
Cellular Expression ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus (EBV), along with other members of the herpesvirus family, requires a set of viral glycoproteins to mediate host cell attachment and entry. Viral glycoprotein B (gB), a highly conserved glycoprotein within the herpesvirus family, is thought to be the viral fusogen based on structural comparison of EBV gB and herpes simplex virus (HSV) gB with the postfusion crystal structure of vesicular stomatitis virus fusion protein glycoprotein G (VSV-G). In addition, mutational studies indicate that gB plays an important role in fusion function. In the current study, we constructed a comprehensive library of mutants with truncations of the C-terminal cytoplasmic tail domain (CTD) of EBV gB. Our studies indicate that the gB CTD is important in the cellular localization, expression, and fusion function of EBV gB. However, in line with observations from other studies, we conclude that the degree of cell surface expression of gB is not directly proportional to observed fusion phenotypes. Rather, we conclude that other biochemical or biophysical properties of EBV gB must be altered to explain the different fusion phenotypes observed.IMPORTANCEEpstein-Barr virus (EBV), like all enveloped viruses, fuses the virion envelope to a cellular membrane to allow release of the capsid, resulting in virus infection. To further characterize the function of EBV glycoprotein B (gB) in fusion, a comprehensive library of mutants with truncations in the gB C-terminal cytoplasmic tail domain (CTD) were made. These studies indicate that the CTD of gB is important for the cellular expression and localization of gB, as well as for the function of gB in fusion. These studies will lead to a better understanding of the mechanism of EBV-induced membrane fusion and herpesvirus-induced membrane fusion in general, which will ultimately lead to focused therapies guided at preventing viral entry into host cells.

scholarly journals Epstein-Barr Virus MicroRNA miR-BART20-5p Suppresses Lytic Induction by InhibitingBAD-Mediatedcaspase-3-Dependent Apoptosis

2015 ◽  
Vol 90 (3) ◽  
pp. 1359-1368 ◽  
Author(s):  
Hyoji Kim ◽  
Hoyun Choi ◽  
Suk Kyeong Lee
Keyword(s):  
Epstein Barr Virus ◽  
Caspase 3 ◽  
Immune Surveillance ◽  
Virus Production ◽  
Lytic Cycle ◽  
Host Cells ◽  
Immediate Early ◽  
Progeny Virus ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACTEpstein-Barr virus (EBV) is a human gammaherpesvirus associated with a variety of tumor types. EBV can establish latency or undergo lytic replication in host cells. In general, EBV remains latent in tumors and expresses a limited repertoire of latent proteins to avoid host immune surveillance. When the lytic cycle is triggered by some as-yet-unknown form of stimulation, lytic gene expression and progeny virus production commence. Thus far, the exact mechanism of EBV latency maintenance and thein vivotriggering signal for lytic induction have yet to be elucidated. Previously, we have shown that the EBV microRNA miR-BART20-5p directly targets the immediate early genesBRLF1andBZLF1as well asBcl-2-associated death promoter (BAD) in EBV-associated gastric carcinoma. In this study, we found that both mRNA and protein levels ofBRLF1andBZLF1were suppressed in cells followingBADknockdown and increased afterBADoverexpression. Progeny virus production was also downregulated by specific knockdown ofBAD. Our results demonstrated thatcaspase-3-dependent apoptosis is a prerequisite forBAD-mediated EBV lytic cycle induction. Therefore, our data suggest that miR-BART20-5p plays an important role in latency maintenance and tumor persistence of EBV-associated gastric carcinoma by inhibitingBAD-mediatedcaspase-3-dependent apoptosis, which would trigger immediate early gene expression.IMPORTANCEEBV has an ability to remain latent in host cells, including EBV-associated tumor cells hiding from immune surveillance. However, the exact molecular mechanisms of EBV latency maintenance remain poorly understood. Here, we demonstrated that miR-BART20-5p inhibited the expression of EBV immediate early genes indirectly, by suppressingBAD-inducedcaspase-3-dependent apoptosis, in addition to directly, as we previously reported. Our study suggests that EBV-associated tumor cells might endure apoptotic stress to some extent and remain latent with the aid of miR-BART20-5p. Blocking the expression or function of BART20-5p may expedite EBV-associated tumor cell death via immune attack and apoptosis.

Suppression of JAK-STAT signaling by Epstein-Barr virus tegument protein BGLF2 through recruitment of SHP1 phosphatase and promotion of STAT2 degradation

2021 ◽  
Author(s):  
Sonia Jangra ◽  
Aradhana Bharti ◽  
Wai-Yin Lui ◽  
Vidyanath Chaudhary ◽  
Michael George Botelho ◽  
...  
Keyword(s):  
Epstein Barr Virus ◽  
Suppressive Effect ◽  
Host Cells ◽  
Interferon Response ◽  
Tegument Protein ◽  
Type Ii ◽  
Barr Virus ◽  
Stat Signaling ◽  
Epstein Barr ◽  
Type Iii Ifn

Some lytic proteins encoded by Epstein-Barr virus (EBV) suppress host interferon (IFN) signaling to facilitate viral replication. In this study we sought to identify and characterize EBV proteins antagonizing IFN signaling. The induction of IFN-stimulated genes (ISGs) by IFN-β was effectively suppressed by EBV. A functional screen was therefore performed to identify IFN-antagonizing proteins encoded by EBV. EBV tegument protein BGLF2 was identified as a potent suppressor of JAK-STAT signaling. This activity was found to be independent of its stimulatory effect on p38 and JNK pathways. Association of BGLF2 with STAT2 resulted in more pronounced K48-linked polyubiquitination and proteasomal degradation of the latter. Mechanistically, BGLF2 promoted the recruitment of SHP1 phosphatase to STAT1 to inhibit its tyrosine phosphorylation. In addition, BGLF2 associated with cullin 1 E3 ubiquitin ligase to facilitate its recruitment to STAT2. Consequently, BGLF2 suppressed ISG induction by IFN-β. Furthermore, BGLF2 also suppressed type II and type III IFN signaling, although the suppressive effect on type II IFN response was milder. When pre-treated with IFN-β, host cells became less susceptible to primary infection of EBV. This phenotype was reversed when expression of BGLF2 was enforced. Finally, genetic disruption of BGLF2 in EBV led to more pronounced induction of ISGs. Taken together, our study unveils the roles of BGLF2 not only in the subversion of innate IFN response but also in lytic infection and reactivation of EBV. Importance Epstein-Barr virus (EBV) is an oncogenic virus associated with the development of lymphoid and epithelial malignancies. EBV has to subvert interferon-mediated host antiviral response to replicate and cause diseases. It is therefore of great interest to identify and characterize interferon-antagonizing proteins produced by EBV. In this study we perform a screen to search for EBV proteins that suppress the action of interferons. We further show that BGLF2 protein of EBV is particularly strong in this suppression. This is achieved by inhibiting two key proteins STAT1 and STAT2 that mediate the antiviral activity of interferons. BGLF2 recruits a host enzyme to remove the phosphate group from STAT1 thereby inactivating its activity. BGLF2 also redirects STAT2 for degradation. A recombinant virus in which BGLF2 gene has been disrupted can activate host interferon response more robustly. Our findings reveal a novel mechanism by which EBV BGLF2 protein suppresses interferon signaling.

scholarly journals Mapping the N-Terminal Residues of Epstein-Barr Virus gp42 That Bind gH/gL by Using Fluorescence Polarization and Cell-Based Fusion Assays

2010 ◽  
Vol 84 (19) ◽  
pp. 10375-10385 ◽  
Author(s):  
Fengling Liu ◽  
Gaby Marquardt ◽  
Austin N. Kirschner ◽  
Richard Longnecker ◽  
Theodore S. Jardetzky
Keyword(s):  
Epithelial Cell ◽  
Viral Infection ◽  
B Cell ◽  
Cell Fusion ◽  
Viral Entry ◽  
Fluorescence Polarization ◽  
Epstein Barr Virus ◽  
Host Cells ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) requires at a minimum membrane-associated glycoproteins gB, gH, and gL for entry into host cells. B-cell entry additionally requires gp42, which binds to gH/gL and triggers viral entry into B cells. The presence of soluble gp42 inhibits membrane fusion with epithelial cells by forming a stable heterotrimer of gH/gL/gp42. The interaction of gp42 with gH/gL has been previously mapped to residues 36 to 81 at the N-terminal region of gp42. In this study, we further mapped this region to identify essential features for binding to gH/gL by use of synthetic peptides. Data from fluorescence polarization, cell-cell fusion, and viral infection assays demonstrated that 33 residues corresponding to 44 to 61 and 67 to 81 of gp42 were indispensable for maintaining low-nanomolar-concentration gH/gL binding affinity and inhibiting B-cell fusion and epithelial cell fusion as well as viral infection. Overall, specific, large hydrophobic side chain residues of gp42 appeared to provide critical interactions, determining the binding strength. Mutations of these residues also diminished the inhibition of B-cell and epithelial cell fusions as well as EBV infection. A linker region (residues 62 to 66) between two gH/gL binding regions served as an important spacer, but individual amino acids were not critical for gH/gL binding. Probing the binding site of gH/gL and gp42 with gp42 peptides is critical for a better understanding of the interaction of gH/gL with gp42 as well as for the design of novel entry inhibitors of EBV and related human herpesviruses.

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