scholarly journals Establishment and Maintenance of Gammaherpesvirus Latency Are Independent of Infective Dose and Route of Infection

2003 ◽  
Vol 77 (13) ◽  
pp. 7696-7701 ◽  
Author(s):  
Scott A. Tibbetts ◽  
Joy Loh ◽  
Victor van Berkel ◽  
James S. McClellan ◽  
Meagan A. Jacoby ◽  
...  
Keyword(s):  
Acute Phase ◽  
Latent Infection ◽  
Ex Vivo ◽  
Latent Infections ◽  
Human Pathogens ◽  
Infectious Dose ◽  
Murine Gammaherpesvirus ◽  
Barr Virus ◽  
Route Of Infection ◽  
Epstein Barr

ABSTRACT Gammaherpesviruses such as Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus are important human pathogens that establish long-term latent infections. Understanding of the initiation and maintenance of latent infections has important implications for the prevention and treatment of gammaherpesvirus-related diseases. Although much is known about gammaherpesvirus pathogenesis, it is unclear how the infectious dose of a virus influences its ability to establish latent infection. To examine the relationship between the infectious dose and gammaherpesvirus latency, we inoculated wild-type mice with 0.01 to 106 PFU of murine gammaherpesvirus 68 (γHV68) and quantitatively measured latency and acute-phase replication. Surprisingly, during latency, the frequencies of ex vivo reactivation were similar over a 107-fold range of doses for i.p. infection and over a 104-fold range of doses for intranasal infection. Further, the frequencies of cells harboring viral genome during latency did not differ substantially over similar dose ranges. Although the kinetics of acute-phase replication were delayed at small doses of virus, the peak titer did not differ significantly between mice infected with a large dose of virus and those infected with a small dose of virus. The results presented here indicate that any initiation of infection leads to substantial acute-phase replication and subsequent establishment of a maximal level of latency. Thus, infections with doses as small as 0.1 PFU of γHV68 result in stable levels of acute-phase replication and latent infection. These results demonstrate that the equilibrium level of establishment of gammaherpesvirus latency is independent of the infectious dose and route of infection.

scholarly journals Granzymes and Caspase 3 Play Important Roles in Control of Gammaherpesvirus Latency

2004 ◽  
Vol 78 (22) ◽  
pp. 12519-12528 ◽  
Author(s):  
Joy Loh ◽  
Dori A. Thomas ◽  
Paula A. Revell ◽  
Timothy J. Ley ◽  
Herbert W. Virgin
Keyword(s):  
Caspase 3 ◽  
Latent Infection ◽  
Granzyme B ◽  
Critical Role ◽  
Small Animal ◽  
Lymphoid Cells ◽  
Epstein Barr Virus Infection ◽  
Murine Gammaherpesvirus ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Gammaherpesviruses can establish lifelong latent infections in lymphoid cells of their hosts despite active antiviral immunity. Identification of the immune mechanisms which regulate gammaherpesvirus latent infection is therefore essential for understanding how gammaherpesviruses persist for the lifetime of their host. Recently, an individual with chronic active Epstein-Barr virus infection was found to have mutations in perforin, and studies using murine gammaherpesvirus 68 (γHV68) as a small-animal model for gammaherpesvirus infection have similarly revealed a critical role for perforin in regulating latent infection. These results suggest involvement of the perforin/granzyme granule exocytosis pathway in immune regulation of gammaherpesvirus latent infection. In this study, we examined γHV68 infection of knockout mice to identify specific molecules within the perforin/granzyme pathway which are essential for regulating gammaherpesvirus latent infection. We show that granzymes A and B and the granzyme B substrate, caspase 3, are important for regulating γHV68 latent infection. Interestingly, we show for the first time that orphan granzymes encoded in the granzyme B gene cluster are also critical for regulating viral infection. The requirement for specific granzymes differs for early versus late forms of latent infection. These data indicate that different granzymes play important and distinct roles in regulating latent gammaherpesvirus infection.

scholarly journals A Gammaherpesvirus MicroRNA Targets EWSR1 (Ewing Sarcoma Breakpoint Region 1) In Vivo To Promote Latent Infection of Germinal Center B Cells

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Yiping Wang ◽  
Emily R. Feldman ◽  
Whitney L. Bullard ◽  
Scott A. Tibbetts
Keyword(s):  
B Cells ◽  
B Cell ◽  
Ewing Sarcoma ◽  
Cell Biology ◽  
Breakpoint Region ◽  
Human Pathogens ◽  
Murine Gammaherpesvirus ◽  
Barr Virus ◽  
Epstein Barr

ABSTRACT Gammaherpesviruses, including the human pathogens Epstein-Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV), directly contribute to the genesis of multiple types of malignancies, including B cell lymphomas. In vivo, these viruses infect B cells and manipulate B cell biology to establish lifelong latent infection. To accomplish this, gammaherpesviruses employ an array of gene products, including microRNAs (miRNAs). Although numerous host mRNA targets of gammaherpesvirus miRNAs have been identified, the in vivo relevance of repression of these targets remains elusive due to species restriction. Murine gammaherpesvirus 68 (MHV68) provides a robust virus-host system to dissect the in vivo function of conserved gammaherpesvirus genetic elements. We identified here MHV68 mghv-miR-M1-7-5p as critical for in vivo infection and then validated host EWSR1 (Ewing sarcoma breakpoint region 1) as the predominant target for this miRNA. Using novel, target-specific shRNA-expressing viruses, we determined that EWSR1 repression in vivo was essential for germinal center B cell infection. These findings provide the first in vivo demonstration of the biological significance of repression of a specific host mRNA by a gammaherpesvirus miRNA. IMPORTANCE Gammaherpesviruses, including the human pathogens Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV), directly contribute to the genesis of multiple types of malignancies. In vivo, these viruses infect B cells and manipulate B cell biology to establish lifelong infection. To accomplish this, gammaherpesviruses employ an array of gene products, including miRNAs, short noncoding RNAs that bind to and repress protein synthesis from specific target mRNAs. The in vivo relevance of repression of targets of gammaherpesvirus miRNAs remains highly elusive. Here, we identified a murine gammaherpesvirus miRNA as critical for in vivo infection and validated the host mRNA EWSR1 (Ewing sarcoma breakpoint region 1) as the predominant target for this miRNA. Using a novel technology, we demonstrated that repression of EWSR1 was essential for in vivo infection of the critical B cell reservoir. These findings provide the first in vivo demonstration of the significance of repression of a specific host mRNA by a gammaherpesvirus miRNA.

scholarly journals TRAF1 Is a Critical Regulator of JNK Signaling by the TRAF-Binding Domain of the Epstein-Barr Virus-Encoded Latent Infection Membrane Protein 1 but Not CD40

2003 ◽  
Vol 77 (2) ◽  
pp. 1316-1328 ◽  
Author(s):  
Aristides G. Eliopoulos ◽  
Elyse R. Waites ◽  
Sarah M. S. Blake ◽  
Clare Davies ◽  
Paul Murray ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Epstein Barr Virus ◽  
Latent Infection ◽  
Binding Domain ◽  
Cell Phenotype ◽  
Tnf Receptor ◽  
Jnk Signaling ◽  
Barr Virus ◽  
Epstein Barr ◽  
Jnk Activation

ABSTRACT The oncogenic Epstein-Barr virus (EBV)-encoded latent infection membrane protein 1 (LMP1) mimics a constitutive active tumor necrosis factor (TNF) family receptor in its ability to recruit TNF receptor-associated factors (TRAFs) and TNF receptor-associated death domain protein (TRADD) in a ligand-independent manner. As a result, LMP1 constitutively engages signaling pathways, such as the JNK and p38 mitogen-activated protein kinases (MAPK), the transcription factor NF-κB, and the JAK/STAT cascade, and these activities may explain many of its pleiotropic effects on cell phenotype, growth, and transformation. In this study we demonstrate the ability of the TRAF-binding domain of LMP1 to signal on the JNK/AP-1 axis in a cell type- dependent manner that critically involves TRAF1 and TRAF2. Thus, expression of this LMP1 domain in TRAF1-positive lymphoma cells promotes significant JNK activation, which is blocked by dominant-negative TRAF2 but not TRAF5. However, TRAF1 is absent in many established epithelial cell lines and primary nasopharyngeal carcinoma (NPC) biopsy specimens. In these cells, JNK activation by the TRAF-binding domain of LMP1 depends on the reconstitution of TRAF1 expression. The critical role of TRAF1 in the regulation of TRAF2-dependent JNK signaling is particular to the TRAF-binding domain of LMP1, since a homologous region in the cytoplasmic tail of CD40 or the TRADD-interacting domain of LMP1 signal on the JNK axis independently of TRAF1 status. These data further dissect the signaling components used by LMP1 and identify a novel role for TRAF1 as a modulator of oncogenic signals.

scholarly journals Chromosomal rearrangements after ex vivo Epstein–Barr virus (EBV) infection of human B cells

Oncogene ◽  
2009 ◽  
Vol 29 (4) ◽  
pp. 503-515 ◽  
Author(s):  
S Lacoste ◽  
E Wiechec ◽  
A G dos Santos Silva ◽  
A Guffei ◽  
G Williams ◽  
...  
Keyword(s):  
B Cells ◽  
Epstein Barr Virus ◽  
Ex Vivo ◽  
Chromosomal Rearrangements ◽  
Barr Virus ◽  
Ebv Infection ◽  
Human B Cells ◽  
Epstein Barr

HAUSP/USP7 as an Epstein–Barr virus target

2004 ◽  
Vol 32 (5) ◽  
pp. 731-732 ◽  
Author(s):  
M.N. Holowaty ◽  
L. Frappier
Keyword(s):  
Epstein Barr Virus ◽  
Latent Infection ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
High Affinity ◽  
Cellular Immortalization ◽  
Epstein Barr ◽  
Epstein Barr Nuclear Antigen

USP7 (also called HAUSP) is a de-ubiquitinating enzyme recently identified as a key regulator of the p53–mdm2 pathway, which stabilizes both p53 and mdm2. We have discovered that the Epstein–Barr nuclear antigen 1 protein of Epstein–Barr virus binds with high affinity to USP7 and disrupts the USP7–p53 interaction. The results have important implications for the role of Epstein–Barr nuclear antigen 1 in the cellular immortalization that is typical of an Epstein–Barr virus latent infection.

scholarly journals Epstein-Barr Virus Facilitates Expression of KLF14 by Regulating the Cooperative Binding of the E2F-Rb-HDAC Complex in Latent Infection

2020 ◽  
Vol 94 (22) ◽  
Author(s):  
Yonggang Pei ◽  
Josiah Hiu-yuen Wong ◽  
Hem Chandra Jha ◽  
Tian Tian ◽  
Zhi Wei ◽  
...  
Keyword(s):  
Gene Expression ◽  
Human Population ◽  
Regulatory Networks ◽  
Epstein Barr Virus ◽  
Latent Infection ◽  
Human Tumor ◽  
Barr Virus ◽  
Repressor Complex ◽  
Tumor Virus ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) was discovered as the first human tumor virus more than 50 years ago. EBV infects more than 90% of the human population worldwide and is associated with numerous hematologic malignancies and epithelial malignancies. EBV establishes latent infection in B cells, which is the typical program seen in lymphomagenesis. Understanding EBV-mediated transcription regulatory networks is one of the current challenges that will uncover new insights into the mechanism of viral-mediated lymphomagenesis. Here, we describe the regulatory profiles of several cellular factors (E2F6, E2F1, Rb, HDAC1, and HDAC2) together with EBV latent nuclear antigens using next-generation sequencing (NGS) analysis. Our results show that the E2F-Rb-HDAC complex exhibits similar distributions in genomic regions of EBV-positive cells and is associated with oncogenic super-enhancers involving long-range regulatory regions. Furthermore, EBV latent antigens cooperatively hijack this complex to bind at KLFs gene loci and facilitate KLF14 gene expression in lymphoblastoid cell lines (LCLs). These results demonstrate that EBV latent antigens can function as master regulators of this multisubunit repressor complex (E2F-Rb-HDAC) to reverse its suppressive activities and facilitate downstream gene expression that can contribute to viral-induced lymphomagenesis. These results provide novel insights into targets for the development of new therapeutic interventions for treating EBV-associated lymphomas. IMPORTANCE Epstein-Barr virus (EBV), as the first human tumor virus, infects more than 90% of the human population worldwide and is associated with numerous human cancers. Exploring EBV-mediated transcription regulatory networks is critical to understand viral-associated lymphomagenesis. However, the detailed mechanism is not fully explored. Now we describe the regulatory profiles of the E2F-Rb-HDAC complex together with EBV latent antigens, and we found that EBV latent antigens cooperatively facilitate KLF14 expression by antagonizing this multisubunit repressor complex in EBV-positive cells. This provides potential therapeutic targets for the treatment of EBV-associated cancers.

scholarly journals Epstein-Barr Virus Nuclear Antigen 1 Does Not Cause Lymphoma in C57BL/6J Mice

2008 ◽  
Vol 82 (8) ◽  
pp. 4180-4183 ◽  
Author(s):  
Myung-Soo Kang ◽  
Vishal Soni ◽  
Roderick Bronson ◽  
Elliott Kieff
Keyword(s):  
Transgenic Mice ◽  
Epstein Barr Virus ◽  
Latent Infection ◽  
Nuclear Antigen ◽  
Barr Virus ◽  
Epstein Barr ◽  
Negative Controls ◽  
Mouse Lymphocytes

ABSTRACT To test whether transgenic Epstein-Barr virus nuclear antigen 1 (EBNA1) expression in C57BL/6 mouse lymphocytes causes lymphoma, EBNA1 expressed in three FVB lineages at two or three times the level of latent infection was crossed up to six successive times into C57BL/6J mice. After five or six crosses, 14/36, (38%) EBNA1 transgenic mice, 11/31 (36%) littermate EBNA1-negative controls, and 9/25 (36%) inbred C57BL/6J mice housed in the same facility had lymphoma. These data indicate that EBNA1 does not significantly increase lymphoma prevalence in C57BL/6J mice.

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