51
|
Abstract
Human periodontitis is associated with a wide range of bacteria and viruses and with complex innate and adaptive immune responses. Porphyromonas gingivalis, Tannerella forsythia, Aggregatibacter actinomycetemcomitans, Treponema denticola, cytomegalovirus and other herpesviruses are major suspected pathogens of periodontitis, and a combined herpesvirus–bacterial periodontal infection can potentially explain major clinical features of the disease. Cytomegalovirus infects periodontal macrophages and T‐cells and elicits a release of interleukin‐1β and tumor necrosis factor‐α. These proinflammatory cytokines play an important role in the host defense against the virus, but they also have the potential to induce alveolar bone resorption and loss of periodontal ligament. Gingival fibroblasts infected with cytomegalovirus also exhibit diminished collagen production and release of an increased level of matrix metalloproteinases. This article reviews innate and adaptive immunity to cytomegalovirus and suggests that immune responses towards cytomegalovirus can play roles in controlling, as well as in exacerbating, destructive periodontal disease.
Collapse
|
52
|
DEVELOPMENT OF EPSTEIN-BARR VIRUS UVEITIS AFTER REMISSION OF PRIMARY VITREORETINAL LYMPHOMA. Retin Cases Brief Rep 2015; 10:131-3. [PMID: 26267526 DOI: 10.1097/icb.0000000000000188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To describe a case of Epstein-Barr virus (EBV) uveitis that occurred after the treatment and remission of primary vitreoretinal lymphoma (PVRL). METHODS Descriptive case report. Complete ophthalmologic evaluation, cytology, polymerase chain reaction, cytokine analysis of aqueous humor, and diagnostic vitrectomy were performed. RESULTS A 66-year-old Caucasian woman developed uveitis in the same eye 20 months after remission of PVRL. Empiric chemotherapy failed to treat the suspected PVRL recurrence, and aqueous humor cytology showed an absence of malignant cells. Qualitative polymerase chain reaction of aqueous humor confirmed the presence of EBV. Treatment for EBV resulted in remission of the uveitis. CONCLUSION The authors describe a rare case of EBV uveitis that was preceded by PVRL. It is important to consider EBV in cases where suspected recurrence of PVRL does not respond to appropriate treatment.
Collapse
|
53
|
Hui KF, Cheung AKL, Choi CK, Yeung PL, Middeldorp JM, Lung ML, Tsao SW, Chiang AKS. Inhibition of class I histone deacetylases by romidepsin potently induces Epstein-Barr virus lytic cycle and mediates enhanced cell death with ganciclovir. Int J Cancer 2015. [PMID: 26205347 DOI: 10.1002/ijc.29698] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Pan-histone deacetylase (HDAC) inhibitors, which inhibit 11 HDAC isoforms, are widely used to induce Epstein-Barr virus (EBV) lytic cycle in EBV-associated cancers in vitro and in clinical trials. Here, we hypothesized that inhibition of one or several specific HDAC isoforms by selective HDAC inhibitors could potently induce EBV lytic cycle in EBV-associated malignancies such as nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC). We found that inhibition of class I HDACs, particularly HDAC-1, -2 and -3, was sufficient to induce EBV lytic cycle in NPC and GC cells in vitro and in vivo. Among a panel of selective HDAC inhibitors, the FDA-approved HDAC inhibitor romidepsin was found to be the most potent lytic inducer, which could activate EBV lytic cycle at ∼0.5 to 5 nM (versus ∼800 nM achievable concentration in patients' plasma) in more than 75% of cells. Upregulation of p21(WAF1) , which is negatively regulated by class I HDACs, was observed before the induction of EBV lytic cycle. The upregulation of p21(WAF1) and induction of lytic cycle were abrogated by a specific inhibitor of PKC-δ but not the inhibitors of PI3K, MEK, p38 MAPK, JNK or ATM pathways. Interestingly, inhibition of HDAC-1, -2 and -3 by romidepsin or shRNA knockdown could confer susceptibility of EBV-positive epithelial cells to the treatment with ganciclovir (GCV). In conclusion, we demonstrated that inhibition of class I HDACs by romidepsin could potently induce EBV lytic cycle and mediate enhanced cell death with GCV, suggesting potential application of romidepsin for the treatment of EBV-associated cancers.
Collapse
Affiliation(s)
- Kwai Fung Hui
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China
| | - Arthur Kwok Leung Cheung
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China
| | - Chung King Choi
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China
| | - Po Ling Yeung
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China
| | - Jaap M Middeldorp
- Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Maria Li Lung
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.,Center for Nasopharyngeal Carcinoma Research, The University of Hong Kong, Hong Kong SAR, China
| | - Sai Wah Tsao
- Center for Nasopharyngeal Carcinoma Research, The University of Hong Kong, Hong Kong SAR, China.,Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Alan Kwok Shing Chiang
- Department of Paediatrics and Adolescent Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China.,Center for Nasopharyngeal Carcinoma Research, The University of Hong Kong, Hong Kong SAR, China
| |
Collapse
|
54
|
Watanabe T, Tsuruoka M, Narita Y, Katsuya R, Goshima F, Kimura H, Murata T. The Epstein-Barr virus BRRF2 gene product is involved in viral progeny production. Virology 2015; 484:33-40. [PMID: 26057150 DOI: 10.1016/j.virol.2015.05.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 05/06/2015] [Accepted: 05/11/2015] [Indexed: 12/12/2022]
Abstract
The Epstein-Barr virus (EBV) predominantly establishes a latent infection in B lymphocytes, and occasionally switches from the latent state to the lytic cycle. In this report, we identified and examined the role of a lytic gene, BRRF2. We first prepared an antibody against BRRF2 and identified the gene product as a viral lytic protein expressed in B95-8 cells with late kinetics. Immunofluorescence revealed that BRRF2 localized in the cytoplasm of cells during the lytic phase. We also found that BRRF2 protein was phosphorylated in lytic cells, but the only viral protein kinase, BGLF4, was not involved in the phosphorylation. Knockout EBV and a repaired strain were then prepared, and we found that BRRF2 disruption did not affect viral gene expression and DNA replication, but decreased virus production. These results demonstrated that BRRF2 is involved in production of infectious progeny, although it is not essential for lytic replication.
Collapse
Affiliation(s)
- Takahiro Watanabe
- Department of Virology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550, Japan
| | - Miyuki Tsuruoka
- Department of Virology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550, Japan
| | - Yohei Narita
- Department of Virology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550, Japan
| | - Ryotaro Katsuya
- Department of Virology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550, Japan
| | - Fumi Goshima
- Department of Virology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550, Japan
| | - Hiroshi Kimura
- Department of Virology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550, Japan
| | - Takayuki Murata
- Department of Virology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550, Japan.
| |
Collapse
|
55
|
Interference with the Autophagic Process as a Viral Strategy to Escape from the Immune Control: Lesson from Gamma Herpesviruses. J Immunol Res 2015; 2015:546063. [PMID: 26090494 PMCID: PMC4451563 DOI: 10.1155/2015/546063] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 04/13/2015] [Accepted: 04/28/2015] [Indexed: 12/14/2022] Open
Abstract
We summarized the most recent findings on the role of autophagy in antiviral immune response. We described how viruses have developed strategies to subvert the autophagic process. A particular attention has been given to Epstein-Barr and Kaposi's sarcoma associated Herpesvirus, viruses studied for many years in our laboratory. These two viruses belong to γ-Herpesvirus subfamily and are associated with several human cancers. Besides the effects on the immune response, we have described how autophagy subversion by viruses may also concur to the enhancement of their replication and to viral tumorigenesis.
Collapse
|
56
|
Watanabe T, Fuse K, Takano T, Narita Y, Goshima F, Kimura H, Murata T. Roles of Epstein-Barr virus BGLF3.5 gene and two upstream open reading frames in lytic viral replication in HEK293 cells. Virology 2015; 483:44-53. [PMID: 25965794 DOI: 10.1016/j.virol.2015.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 03/23/2015] [Accepted: 04/07/2015] [Indexed: 12/12/2022]
Abstract
The Epstein-Barr virus (EBV) predominantly establishes a latent infection in B lymphocytes, but a small percentage of infected cells switch from the latent state to the lytic cycle, leading to potent viral DNA replication and progeny viruses production. We here focused on a lytic gene BGLF3.5, and first established BGLF3.5 mutants by marker cassette insertion. Unexpectedly, this insertion mutant failed to produce BGLF4 protein and thus progeny production was severely inhibited. Then we carefully made two point mutant viruses (stop codon insertion or frame-shift mutation) and found that BGLF3.5 is not essential for EBV lytic replication processes, such as viral gene expression, DNA replication, or progeny production in the HEK293 cells although its homolog in murine gammaherpesvirus 68 (MHV-68) was reported to be essential. In addition, we examined the roles of two short, upstream open reading frames within the 5'UTR of BGLF3.5 gene in translation of BGLF4.
Collapse
Affiliation(s)
- Takahiro Watanabe
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Kenshiro Fuse
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Takahiro Takano
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Yohei Narita
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Fumi Goshima
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiroshi Kimura
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Takayuki Murata
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
| |
Collapse
|
57
|
Isotypes of Epstein-Barr virus antibodies in rheumatoid arthritis: association with rheumatoid factors and citrulline-dependent antibodies. BIOMED RESEARCH INTERNATIONAL 2015; 2015:472174. [PMID: 26000294 PMCID: PMC4426970 DOI: 10.1155/2015/472174] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 01/28/2015] [Accepted: 02/23/2015] [Indexed: 12/14/2022]
Abstract
In order to study the humoral immune response against Epstein-Barr virus (EBV) in patients with rheumatoid arthritis (RA) and to compare it with the two major autoantibody types in RA, plasma samples from 77 RA patients, 28 patients with systemic lupus erythematosus (SLE), and 28 healthy controls (HCs) were investigated by enzyme-linked immunosorbent assays (ELISA). Increased percentages of positives and concentrations of IgG/IgA/IgM antibodies against the latent EBV nuclear antigen-1 (EBNA-1) were observed in RA patients compared to SLE patients and HCs. Increased concentrations and percentages of positives of IgG/IgA/IgM against the early lytic EBV antigen diffuse (EAD) were also found in RA patients compared to HCs but were highest in SLE patients. Furthermore, associations between the elevated EBNA-1 IgA and EBNA-1 IgM levels and the presence of IgM and IgA rheumatoid factors (RFs) and anti-citrullinated protein antibodies (ACPAs, IgG) and between elevated IgA concentrations against EAD and the presence of RFs and ACPAs in RA patients were found. Thus, RA patients had elevated antibodies of all isotypes characteristic of latent EBV infection (whereas SLE patients had elevated antibodies characteristic of lytic EBV infection). Notably, for IgM and IgA (but not IgG), these were associated with the presence of characteristic RA autoantibodies.
Collapse
|
58
|
Murata T. Regulation of Epstein-Barr virus reactivation from latency. Microbiol Immunol 2015; 58:307-17. [PMID: 24786491 DOI: 10.1111/1348-0421.12155] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 04/03/2014] [Accepted: 04/26/2014] [Indexed: 12/13/2022]
Abstract
The Epstein-Barr virus (EBV) is a human gamma-herpesvirus that is implicated in various types of proliferative diseases. Upon infection, it predominantly establishes latency in B cells and cannot ever be eradicated; it persists for the host's lifetime. Reactivation of the virus from latency depends on expression of the viral immediate-early gene, BamHI Z fragment leftward open reading frame 1 (BZLF1). The BZLF1 promoter normally exhibits only low basal activity but is activated in response to chemical or biological inducers, such as 12-O-tetradecanoylphorbol-13-acetate, calcium ionophore, histone deacetylase inhibitor, or anti-Ig. Transcription from the BZLF1 promoter is activated by myocyte enhancer factor 2, specificity protein 1, b-Zip type transcription factors and mediating epigenetic modifications of the promoter, such as histone acetylation and H3K4me3. In contrast, repression of the promoter is mediated by transcriptional suppressors, such as ZEB, ZIIR-BP, and jun dimerization protein 2, causing suppressive histone modifications like histone H3K27me3, H3K9me2/3 and H4K20me3. Interestingly, there is little CpG DNA methylation of the promoter, indicating that DNA methylation is not crucial for suppression of BZLF1. This review will focus on the molecular mechanisms by which the EBV lytic switch is controlled and discuss the physiological significance of this switching for its survival and oncogenesis.
Collapse
Affiliation(s)
- Takayuki Murata
- Department of Virology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan; Division of Virology, Aichi Cancer Center Research Institute, 1-Kanokoden, Chikusa-ku, Nagoya, 464-8681, Japan
| |
Collapse
|
59
|
Abstract
EBV latent infection is characterized by a highly restricted pattern of viral gene expression. EBV can establish latent infections in multiple different tissue types with remarkable variation and plasticity in viral transcription and replication. During latency, the viral genome persists as a multi-copy episome, a non-integrated-closed circular DNA with nucleosome structure similar to cellular chromosomes. Chromatin assembly and histone modifications contribute to the regulation of viral gene expression, DNA replication, and episome persistence during latency. This review focuses on how EBV latency is regulated by chromatin and its associated processes.
Collapse
|
60
|
Chang KC, Chang Y, Wang LHC, Tsai HW, Huang W, Su IJ. Pathogenesis of virus-associated human cancers: Epstein–Barr virus and hepatitis B virus as two examples. J Formos Med Assoc 2014; 113:581-90. [DOI: 10.1016/j.jfma.2013.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 08/02/2013] [Accepted: 09/02/2013] [Indexed: 12/12/2022] Open
|
61
|
Bernig T, Richter N, Volkmer I, Staege MS. Functional analysis and molecular characterization of spontaneously outgrown human lymphoblastoid cell lines. Mol Biol Rep 2014; 41:6995-7007. [PMID: 25037273 DOI: 10.1007/s11033-014-3587-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 07/05/2014] [Indexed: 01/14/2023]
Abstract
In vitro, the infection of human B-cells with the lymphotropic gammaherpesvirus Epstein-Barr virus (EBV) induces formation of permanently growing lymphoblastoid cell lines (LCL). In a spontaneously outgrown LCL (cell line CSIII), we detected nucleotide sequence variations of the EBV nuclear antigen 1 (EBNA1) RNA that was different from the reference sequence of EBNA1 in the prototypic EBV strain B95-8. In the present study, we molecularly and functionally characterized this virus isolate in comparison to LCL with the prototypic nucleotide sequence. Although we detected high functional similarity between CSIII and the other LCL, our data suggest that the lytic cycle might be ineffective in the CSIII LCL. DNA microarray analysis indicated that RNA binding motif, single stranded interacting protein 1 (RBMS1), which is typically expressed in latency III of EBV to prevent the lytic cycle, was the most overexpressed gene in CSIII LCL.
Collapse
Affiliation(s)
- Toralf Bernig
- Department of Pediatrics, Children's Cancer Research Centre, Martin Luther University Halle-Wittenberg, Ernst-Grube Str. 40, D-06097, Halle, Germany
| | | | | | | |
Collapse
|
62
|
Maloney SR, Almarines D, Goolkasian P. Vitamin D levels and monospot tests in military personnel with acute pharyngitis: a retrospective chart review. PLoS One 2014; 9:e101180. [PMID: 25009977 PMCID: PMC4091874 DOI: 10.1371/journal.pone.0101180] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/02/2014] [Indexed: 12/15/2022] Open
Abstract
Some recent studies have proposed an important role for vitamin D in reducing the risk of infection by assisting in the suppression of viruses and by controlling the inflammatory response. A low vitamin D state may have a detrimental effect on the immune system's ability to produce activated CD8+ T cells, and it may increase the inflammatory reaction to Epstein Barr virus. The aim of this chart review was to see if serum 25 OH vitamin D3 levels in service members with acute pharyngitis were lower in those who had positive rather than negative monospot tests. A retrospective chart review was conducted on the medical records of service members who presented to sick call at Camp Lejeune, NC with acute pharyngitis from October 8, 2010 until June 30, 2011. Serum 25 OH vitamin D3 levels were compared between those with positive and negative monospot test results. Of the 25 records that were reviewed, there were 9 (36%) service members with positive results, and they were found to have lower vitamin D levels (Median = 20.80 ng/ml, Interquartile range = 10.15) than those with negative test results (Median = 30.35 ng/ml, Interquartile range = 17.05), Mann-Whitney U = 41, p = .039. Only 1 of the 9 with positive test results had a normal serum 25 OH vitamin D3 level (30 ng/ml or greater) compared with 9 of the 16 with negative test results. Optimal vitamin D stores may play a significant role in reducing the risk of developing acute mononucleosis but larger, prospective studies will be needed to verify these findings.
Collapse
Affiliation(s)
- Sean R. Maloney
- Navy Mobilization Processing Site, Deployment Processing Command-East, Camp Lejeune, North Carolina, United States of America
- W.G. (Bill) Hefner VA Medical Center, Salisbury, North Carolina, United States of America
| | - David Almarines
- Navy Mobilization Processing Site, Deployment Processing Command-East, Camp Lejeune, North Carolina, United States of America
| | - Paula Goolkasian
- Department of Psychology, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
63
|
Kenney SC, Mertz JE. Regulation of the latent-lytic switch in Epstein-Barr virus. Semin Cancer Biol 2014; 26:60-8. [PMID: 24457012 PMCID: PMC4048781 DOI: 10.1016/j.semcancer.2014.01.002] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 12/17/2013] [Accepted: 01/09/2014] [Indexed: 12/12/2022]
Abstract
Epstein-Barr virus (EBV) infection contributes to the development of several different types of human malignancy, including Burkitt lymphoma, Hodgkin lymphoma, and nasopharyngeal carcinoma. As a herpesvirus, EBV can establish latent or lytic infection in cells. EBV-positive tumors are composed almost exclusively of cells with latent EBV infection. Strategies for inducing the lytic form of EBV infection in tumor cells are being investigated as a potential therapy for EBV-positive tumors. In this article, we review how cellular and viral proteins regulate the latent-lytic EBV switch in infected B cells and epithelial cells, and discuss how harnessing lytic viral reactivation might be used therapeutically.
Collapse
Affiliation(s)
- Shannon C Kenney
- McArdle Laboratory for Cancer Research, 1400 University Avenue, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706-1599, USA; Department of Oncology, 1400 University Avenue, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706-1599, USA; Department of Medicine, 1400 University Avenue, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706-1599, USA.
| | - Janet E Mertz
- McArdle Laboratory for Cancer Research, 1400 University Avenue, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706-1599, USA; Department of Oncology, 1400 University Avenue, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706-1599, USA
| |
Collapse
|
64
|
Activation and repression of Epstein-Barr Virus and Kaposi's sarcoma-associated herpesvirus lytic cycles by short- and medium-chain fatty acids. J Virol 2014; 88:8028-44. [PMID: 24807711 DOI: 10.1128/jvi.00722-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The lytic cycles of Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are induced in cell culture by sodium butyrate (NaB), a short-chain fatty acid (SCFA) histone deacetylase (HDAC) inhibitor. Valproic acid (VPA), another SCFA and an HDAC inhibitor, induces the lytic cycle of KSHV but blocks EBV lytic reactivation. To explore the hypothesis that structural differences between NaB and VPA account for their functional effects on the two related viruses, we investigated the capacity of 16 structurally related short- and medium-chain fatty acids to promote or prevent lytic cycle reactivation. SCFAs differentially affected EBV and KSHV reactivation. KSHV was reactivated by all SCFAs that are HDAC inhibitors, including phenylbutyrate. However, several fatty acid HDAC inhibitors, such as isobutyrate and phenylbutyrate, did not reactivate EBV. Reactivation of KSHV lytic transcripts could not be blocked completely by any fatty acid tested. In contrast, several medium-chain fatty acids inhibited lytic activation of EBV. Fatty acids that blocked EBV reactivation were more lipophilic than those that activated EBV. VPA blocked activation of the BZLF1 promoter by NaB but did not block the transcriptional function of ZEBRA. VPA also blocked activation of the DNA damage response that accompanies EBV lytic cycle activation. Properties of SCFAs in addition to their effects on chromatin are likely to explain activation or repression of EBV. We concluded that fatty acids stimulate the two related human gammaherpesviruses to enter the lytic cycle through different pathways. Importance: Lytic reactivation of EBV and KSHV is needed for persistence of these viruses and plays a role in carcinogenesis. Our direct comparison highlights the mechanistic differences in lytic reactivation between related human oncogenic gammaherpesviruses. Our findings have therapeutic implications, as fatty acids are found in the diet and produced by the human microbiota. Small-molecule inducers of the lytic cycle are desired for oncolytic therapy. Inhibition of viral reactivation, alternatively, may prove useful in cancer treatment. Overall, our findings contribute to the understanding of pathways that control the latent-to-lytic switch and identify naturally occurring molecules that may regulate this process.
Collapse
|
65
|
Tikhmyanova N, Schultz DC, Lee T, Salvino JM, Lieberman PM. Identification of a new class of small molecules that efficiently reactivate latent Epstein-Barr Virus. ACS Chem Biol 2014; 9:785-95. [PMID: 24028149 DOI: 10.1021/cb4006326] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Epstein-Barr Virus (EBV) persists as a latent infection in many lymphoid and epithelial malignancies, including Burkitt's lymphomas, nasopharyngeal carcinomas, and gastric carcinomas. Current chemotherapeutic treatments of EBV-positive cancers include broad-spectrum cytotoxic drugs that ignore the EBV-positive status of tumors. An alternative strategy, referred to as oncolytic therapy, utilizes drugs that stimulate reactivation of latent EBV to enhance the selective killing of EBV-positive tumors, especially in combination with existing inhibitors of herpesvirus lytic replication, like Ganciclovir (GCV). At present, no small molecule, including histone deacetylase (HDAC) inhibitors, have proven safe or effective in clinical trials for treatment of EBV-positive cancers. Aiming to identify new chemical entities that induce EBV lytic cycle, we have developed a robust high-throughput cell-based assay to screen 66,840 small molecule compounds. Five structurally related tetrahydrocarboline derivatives were identified, two of which had EC50 measurements in the range of 150-170 nM. We show that these compounds reactivate EBV lytic markers ZTA and EA-D in all EBV-positive cell lines we have tested independent of the type of latency. The compounds reactivate a higher percentage of latently infected cells than HDAC inhibitors or phorbol esters in many cell types. The most active compounds showed low toxicity to EBV-negative cells but were highly effective at selective cell killing of EBV-positive cells when combined with GCV. We conclude that we have identified a class of small molecule compounds that are highly effective at reactivating latent EBV infection in a variety of cell types and show promise for lytic therapy in combination with GCV.
Collapse
Affiliation(s)
| | - David C. Schultz
- The Wistar Institute, Philadelphia, Pennsylvania 19104, United States
| | - Theresa Lee
- The Wistar Institute, Philadelphia, Pennsylvania 19104, United States
| | - Joseph M. Salvino
- Department
of Pharmacology, School of Medicine, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Paul M. Lieberman
- The Wistar Institute, Philadelphia, Pennsylvania 19104, United States
| |
Collapse
|
66
|
Aligo J, Walker M, Bugelski P, Weinstock D. Is murine gammaherpesvirus-68 (MHV-68) a suitable immunotoxicological model for examining immunomodulatory drug-associated viral recrudescence? J Immunotoxicol 2014; 12:1-15. [PMID: 24512328 DOI: 10.3109/1547691x.2014.882996] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Immunosuppressive agents are used for treatment of a variety of autoimmune diseases including rheumatoid arthritis (RA), systemic lupus erythematosis (SLE), and psoriasis, as well as for prevention of tissue rejection after organ transplantation. Recrudescence of herpesvirus infections, and increased risk of carcinogenesis from herpesvirus-associated tumors are related with immunosuppressive therapy in humans. Post-transplant lymphoproliferative disorder (PTLD), a condition characterized by development of Epstein Barr Virus (EBV)-associated B-lymphocyte lymphoma, and Kaposi's Sarcoma (KS), a dermal tumor associated with Kaposi Sarcoma-associated virus (KSHV), may develop in solid organ transplant patients. KS also occurs in immunosuppressed Acquired Immunodeficiency (AIDS) patients. Kaposi Sarcoma-associated virus (KSHV) is a herpes virus genetically related to EBV. Murine gammaherpes-virus-68 (MHV-68) is proposed as a mouse model of gammaherpesvirus infection and recrudescence and may potentially have relevance for herpesvirus-associated neoplasia. The pathogenesis of MHV-68 infection in mice mimics EBV/KSHV infection in humans with acute lytic viral replication followed by dissemination and establishment of persistent latency. MHV-68-infected mice may develop lymphoproliferative disease that is accelerated by disruption of the immune system. This manuscript first presents an overview of gammaherpesvirus pathogenesis and immunology as well as factors involved in viral recrudescence. A description of different types of immunodeficiency then follows, with particular focus on viral association with lymphomagenesis after immunosuppression. Finally, this review discusses different gammaherpesvirus animal models and describes a proposed MHV-68 model to further examine the interplay of immunomodulatory agents and gammaherpesvirus-associated neoplasia.
Collapse
Affiliation(s)
- Jason Aligo
- Biologics Toxicology, Janssen Research and Development, LLC , Spring House, PA , USA
| | | | | | | |
Collapse
|
67
|
Primary EBV infection induces an expression profile distinct from other viruses but similar to hemophagocytic syndromes. PLoS One 2014; 9:e85422. [PMID: 24465555 PMCID: PMC3894977 DOI: 10.1371/journal.pone.0085422] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 11/26/2013] [Indexed: 12/15/2022] Open
Abstract
Epstein-Barr Virus (EBV) causes infectious mononucleosis and establishes lifelong infection associated with cancer and autoimmune disease. To better understand immunity to EBV, we performed a prospective study of natural infection in healthy humans. Transcriptome analysis defined a striking and reproducible expression profile during acute infection but no lasting gene changes were apparent during latent infection. Comparing the EBV response profile to multiple other acute viral infections, including influenza A (influenza), respiratory syncytial virus (RSV), human rhinovirus (HRV), attenuated yellow fever virus (YFV), and Dengue fever virus (DENV), revealed similarity only to DENV. The signature shared by EBV and DENV was also present in patients with hemophagocytic syndromes, suggesting these two viruses cause uncontrolled inflammatory responses. Interestingly, while EBV induced a strong type I interferon response, a subset of interferon induced genes, including MX1, HERC5, and OAS1, were not upregulated, suggesting a mechanism by which viral antagonism of immunity results in a profound inflammatory response. These data provide an important first description of the response to a natural herpesvirus infection in humans.
Collapse
|
68
|
Abstract
Epstein-Barr virus (EBV) latent antigen EBNA3C is implicated in B-cell immortalization and linked to several B-cell malignancies. Deregulation of H2AX can induce genomic instability with increased chromosomal aberrations, which ultimately leads to tumorigenesis. Here we demonstrated that EBNA3C can attenuate H2AX expression at the transcript and protein levels. A reduction of total H2AX levels was clearly observed upon infection of primary B cells with wild-type EBV but not with EBNA3C knockout recombinant EBV. H2AX also interacted with EBNA3C through its N-terminal domain (residues 1 to 100). Furthermore, H2AX mutated at Ser139 failed to interact with EBNA3C. Luciferase-based reporter assays also revealed that the binding domain of EBNA3C is sufficient for transcriptional inhibition of the H2AX promoter. EBNA3C also facilitated H2AX degradation through recruitment of components of the ubiquitin proteasome pathway. We further demonstrated that knockdown of H2AX in lymphoblastoid cell lines (LCLs) led to the upregulation of the Bub1 oncoprotein and downregulated expression of p53. Overall, our study provides additional insights into EBV-associated B-cell lymphomas, which are linked to the regulation of the DNA damage response system in infected cells. The importance of these insights are as follows: (i) EBNA3C downregulates H2AX expression at the protein and transcript levels in epithelial cells, B cells, and EBV-transformed LCLs, (ii) EBNA3C binds with wild-type H2AX but not with the Ser139 mutant of H2AX, (iii) the N terminus (residues 1 to 100) of EBNA3C is critical for binding to H2AX, (iv) localization of H2AX is predominantly nuclear in the presence of EBNA3C, and (v) H2AX knocked down in LCLs led to enhanced expression of Bub1 and downregulation of the tumor suppressor p53, which are both important for driving the oncogenic process.
Collapse
|
69
|
Jakovljevic A, Andric M. Human Cytomegalovirus and Epstein-Barr Virus in Etiopathogenesis of Apical Periodontitis: A Systematic Review. J Endod 2014; 40:6-15. [DOI: 10.1016/j.joen.2013.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 09/29/2013] [Accepted: 10/01/2013] [Indexed: 02/06/2023]
|
70
|
Murata T, Tsurumi T. Switching of EBV cycles between latent and lytic states. Rev Med Virol 2013; 24:142-53. [DOI: 10.1002/rmv.1780] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 11/19/2013] [Accepted: 11/20/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Takayuki Murata
- Division of Virology; Aichi Cancer Center Research Institute; Nagoya Japan
- Department of Virology; Nagoya University School of Medicine; Nagoya Japan
| | - Tatsuya Tsurumi
- Division of Virology; Aichi Cancer Center Research Institute; Nagoya Japan
| |
Collapse
|
71
|
Liu X, Tang J, Wang M, Ma Q, Wang Y. Visual detection and evaluation of latent and lytic gene expression during Epstein-Barr virus infection using one-step reverse transcription loop-mediated isothermal amplification. Int J Mol Sci 2013; 14:23922-40. [PMID: 24351866 PMCID: PMC3876086 DOI: 10.3390/ijms141223922] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 12/01/2013] [Accepted: 12/02/2013] [Indexed: 12/31/2022] Open
Abstract
Epstein-Barr virus (EBV)-associated disease exhibits distinct gene expression patterns characterized by the transcription of EBV nuclear antigen (EBNA) 1, EBNA2, latent membrane protein (LMP) 1, LMP2A, and BZLF1 (Zebra). A series of visual reverse transcript loop-mediated isothermal amplification (RT-LAMP) assays were performed to examine the expression of EBNA1, EBNA2, LMP1, LMP2A and BZLF1. The sensitivity of RT-LAMP for these transcripts was approximately equivalent to real-time RT-PCR (RT-qPCR), which was developed to quantify relative levels of EBV transcripts, and 10 to 100-fold more sensitive than conventional RT-PCR. Cross-reactions to other viruses were not observed upon examination of cell lines infected with herpes simplex viruses-1 and -2 (HSV-1 and -2), varicella zoster virus (VZV), human cytomegalovirus (HCMV) or Kaposi's sarcoma-associated herpesvirus. When applied to 146 specimens, RT-LAMP exhibited high clinical sensitivity and specificity, with an excellent agreement (κ > 0.92) compared to RT-qPCR. These assays are convenient for rapid early diagnosis and for surveillance of EBV-infected individuals by evaluating the EBV transcriptional profile, because the results can be visualized with the naked eye. These assays may be employed in further investigations because they can aid the design of improved therapeutic regimens and can be used specifically in resource-poor settings.
Collapse
Affiliation(s)
- Xiaoying Liu
- The State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China; E-Mails: (X.L.); (J.T.); (M.W.)
| | - Jingfeng Tang
- The State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China; E-Mails: (X.L.); (J.T.); (M.W.)
| | - Man Wang
- The State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China; E-Mails: (X.L.); (J.T.); (M.W.)
| | - Qiang Ma
- The State Key Laboratory of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, Guangdong, China; E-Mail:
| | - Yefu Wang
- The State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, Hubei, China; E-Mails: (X.L.); (J.T.); (M.W.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +86-27-6875-4627; Fax: +86-27-6875-4592
| |
Collapse
|
72
|
Abstract
The human gammaherpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) establish long-term latent infections associated with diverse human cancers. Viral oncogenesis depends on the ability of the latent viral genome to persist in host nuclei as episomes that express a restricted yet dynamic pattern of viral genes. Multiple epigenetic events control viral episome generation and maintenance. This Review highlights some of the recent findings on the role of chromatin assembly, histone and DNA modifications, and higher-order chromosome structures that enable gammaherpesviruses to establish stable latent infections that mediate viral pathogenesis.
Collapse
|
73
|
Grinde B. Herpesviruses: latency and reactivation - viral strategies and host response. J Oral Microbiol 2013; 5:22766. [PMID: 24167660 PMCID: PMC3809354 DOI: 10.3402/jom.v5i0.22766] [Citation(s) in RCA: 250] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/03/2013] [Accepted: 10/08/2013] [Indexed: 12/12/2022] Open
Abstract
Eight members of the Herpesviridae family commonly infect humans, and close to 100% of the adult population is infected with at least one of these. The five that cause the most health concerns are: herpes simplex virus (HSV) type 1 and 2, Epstein-Barr virus (EBV), cytomegalovirus (CMV), and varicella zoster virus (VZV). In addition, there are human herpes virus (HHV) types 6-8. The review starts by introducing possible viral strategies in general. The particular biology and host relationship of the various human herpesviruses, including their pathology, are examined subsequently. Factors that contribute to the maintenance of latency and reactivation of viral replication are discussed. There will be special reference to how these viruses exploit and contribute to pathology in the oral cavity. Reactivation does not necessarily imply clinical symptoms, as reflected in the asymptomatic shedding of EBV and CMV from oral mucosa. The immune response and the level of viral output are both important to the consequences experienced.
Collapse
Affiliation(s)
- Bjørn Grinde
- Department of Mental Health, Norwegian Institute of Public Health, Oslo, Norway
| |
Collapse
|
74
|
Posttransplant lymphoproliferative disease after pediatric solid organ transplantation. Clin Dev Immunol 2013; 2013:814973. [PMID: 24174972 PMCID: PMC3794558 DOI: 10.1155/2013/814973] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 08/08/2013] [Accepted: 08/09/2013] [Indexed: 02/06/2023]
Abstract
Patients after solid organ transplantation (SOT) carry a substantially increased risk to develop malignant lymphomas. This is in part due to the immunosuppression required to maintain the function of the organ graft. Depending on the transplanted organ, up to 15% of pediatric transplant recipients acquire posttransplant lymphoproliferative disease (PTLD), and eventually 20% of those succumb to the disease. Early diagnosis of PTLD is often hampered by the unspecific symptoms and the difficult differential diagnosis, which includes atypical infections as well as graft rejection. Treatment of PTLD is limited by the high vulnerability towards antineoplastic chemotherapy in transplanted children. However, new treatment strategies and especially the introduction of the monoclonal anti-CD20 antibody rituximab have dramatically improved outcomes of PTLD. This review discusses risk factors for the development of PTLD in children, summarizes current approaches to therapy, and gives an outlook on developing new treatment modalities like targeted therapy with virus-specific T cells. Finally, monitoring strategies are evaluated.
Collapse
|
75
|
Abstract
A central feature of herpesvirus biology is the ability of herpesviruses to remain latent within host cells. Classically, exposure to inducing agents, like activating cytokines or phorbol esters that stimulate host cell signal transduction events, and epigenetic agents (e.g., butyrate) was thought to end latency. We recently showed that Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus-8 [HHV-8]) has another, alternative emergency escape replication pathway that is triggered when KSHV's host cell undergoes apoptosis, characterized by the lack of a requirement for the replication and transcription activator (RTA) protein, accelerated late gene kinetics, and production of virus with decreased infectivity. Caspase-3 is necessary and sufficient to initiate the alternative replication program. HSV-1 was also recently shown to initiate replication in response to host cell apoptosis. These observations suggested that an alternative apoptosis-triggered replication program might be a general feature of herpesvirus biology and that apoptosis-initiated herpesvirus replication may have clinical implications, particularly for herpesviruses that almost universally infect humans. To explore whether an alternative apoptosis-initiated replication program is a common feature of herpesvirus biology, we studied cell lines latently infected with Epstein-Barr virus/HHV-4, HHV-6A, HHV-6B, HHV-7, and KSHV. We found that apoptosis triggers replication for each HHV studied, with caspase-3 being necessary and sufficient for HHV replication. An alternative apoptosis-initiated replication program appears to be a common feature of HHV biology. We also found that commonly used cytotoxic chemotherapeutic agents activate HHV replication, which suggests that treatments that promote apoptosis may lead to activation of latent herpesviruses, with potential clinical significance.
Collapse
|
76
|
Contribution of myocyte enhancer factor 2 family transcription factors to BZLF1 expression in Epstein-Barr virus reactivation from latency. J Virol 2013; 87:10148-62. [PMID: 23843637 DOI: 10.1128/jvi.01002-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Reactivation of Epstein-Barr virus (EBV) from latency is dependent on expression of the viral transactivator BZLF1 protein, whose promoter (Zp) normally exhibits only low basal activity but is activated in response to chemical or biological inducers. Using a reporter assay system, we screened for factors that can activate Zp and isolated genes, including those encoding MEF2B, KLF4, and some cellular b-Zip family transcription factors. After confirming their importance and functional binding sites in reporter assays, we prepared recombinant EBV-BAC, in which the binding sites were mutated. Interestingly, the MEF2 mutant virus produced very low levels of BRLF1, another transactivator of EBV, in addition to BZLF1 in HEK293 cells. The virus failed to induce a subset of early genes, such as that encoding BALF5, upon lytic induction, and accordingly, could not replicate to produce progeny viruses in HEK293 cells, but this restriction could be completely lifted by exogenous supply of BRLF1, together with BZLF1. In B cells, induction of BZLF1 by chemical inducers was inhibited by point mutations in the ZII or the three SP1/KLF binding sites of EBV-BAC Zp, while leaky BZLF1 expression was less affected. Mutation of MEF2 sites severely impaired both spontaneous and induced expression of not only BZLF1, but also BRLF1 in comparison to wild-type or revertant virus cases. We also observed that MEF2 mutant EBV featured relatively high repressive histone methylation, such as H3K27me3, but CpG DNA methylation levels were comparable around Zp and the BRLF1 promoter (Rp). These findings shed light on BZLF1 expression and EBV reactivation from latency.
Collapse
|
77
|
Anagnostopoulos I, Jöhrens K. Frequent expression of the Epstein-Barr virus encoded BZLF1 protein in angioimmunoblastic T-cell lymphoma. Leuk Lymphoma 2013; 55:677-9. [PMID: 23713455 DOI: 10.3109/10428194.2013.809075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
78
|
Constitutive interferon-inducible protein 16-inflammasome activation during Epstein-Barr virus latency I, II, and III in B and epithelial cells. J Virol 2013; 87:8606-23. [PMID: 23720728 DOI: 10.1128/jvi.00805-13] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Epstein-Barr virus (EBV), etiologically linked with human B-cell malignancies and nasopharyngeal carcinoma (NPC), establishes three types of latency that facilitate its episomal genome persistence and evasion of host immune responses. The innate inflammasome responses recognize the pathogen-associated molecular patterns which lead into the association of a cytoplasmic sensor such as NLRP3 and AIM2 proteins or nuclear interferon-inducible protein 16 (IFI16) with adaptor ASC protein (apoptosis-associated speck-like protein with a caspase recruitment domain) and effector procaspase-1, resulting in active caspase-1 formation which cleaves the proforms of inflammatory interleukin-1β (IL-1β), IL-18, and IL-33 cytokines. Whether inflammasome responses recognize and respond to EBV genome in the nuclei was not known. We observed evidence of inflammasome activation, such as the activation of caspase-1 and cleavage of pro-IL-1β, -IL-18, and -IL-33, in EBV latency I Raji cells, latency II NPC C666-1 cells, and latency III lymphoblastoid cell lines (LCL). Interaction between ASC with IFI16 but not with AIM2 or NLRP3 was detected in all three latencies and during EBV infection of primary human B cells. IFI16 and cleaved caspase-1, IL-1β, IL-18, and IL-33 were detected in the exosomes from Raji cells and LCL. Though EBV nuclear antigen 1 (EBNA1) and EBV-encoded small RNAs (EBERs) are common to all forms of EBV latency, caspase-1 cleavage was not detected in cells expressing EBNA1 alone, and blocking EBER transcription did not inhibit caspase-1 cleavage. In fluorescence in situ hybridization (FISH) analysis, IFI16 colocalized with the EBV genome in LCL and Raji cell nuclei. These studies demonstrated that constant sensing of latent EBV genome by IFI16 in all types of latency results in the constitutive induction of the inflammasome and IL-1β, IL-18, and IL-33 maturation.
Collapse
|
79
|
Mansouri S, Wang S, Frappier L. A role for the nucleosome assembly proteins TAF-Iβ and NAP1 in the activation of BZLF1 expression and Epstein-Barr virus reactivation. PLoS One 2013; 8:e63802. [PMID: 23691099 PMCID: PMC3653829 DOI: 10.1371/journal.pone.0063802] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/06/2013] [Indexed: 12/15/2022] Open
Abstract
The reactivation of Epstein-Barr virus (EBV) from latent to lytic infection begins with the expression of the viral BZLF1 gene, leading to a subsequent cascade of viral gene expression and amplification of the EBV genome. Using RNA interference, we show that nucleosome assembly proteins NAP1 and TAF-I positively contribute to EBV reactivation in epithelial cells through the induction of BZLF1 expression. In addition, overexpression of NAP1 or the β isoform of TAF-I (TAF-Iβ) in AGS cells latently infected with EBV was sufficient to induce BZLF1 expression. Chromatin immunoprecipitation experiments performed in AGS-EBV cells showed that TAF-I associated with the BZLF1 promoter upon lytic induction and affected local histone modifications by increasing H3K4 dimethylation and H4K8 acetylation. MLL1, the host protein known to dimethylate H3K4, was found to associate with the BZLF1 promoter upon lytic induction in a TAF-I-dependent manner, and MLL1 depletion decreased BZLF1 expression, confirming its contribution to lytic reactivation. The results indicate that TAF-Iβ promotes BZLF1 expression and subsequent lytic infection by affecting chromatin at the BZLF1 promoter.
Collapse
Affiliation(s)
- Sheila Mansouri
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Shan Wang
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Lori Frappier
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
| |
Collapse
|
80
|
Banerjee S, Lu J, Cai Q, Saha A, Jha HC, Dzeng RK, Robertson ES. The EBV Latent Antigen 3C Inhibits Apoptosis through Targeted Regulation of Interferon Regulatory Factors 4 and 8. PLoS Pathog 2013; 9:e1003314. [PMID: 23658517 PMCID: PMC3642079 DOI: 10.1371/journal.ppat.1003314] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 03/04/2013] [Indexed: 12/15/2022] Open
Abstract
Epstein-Barr virus (EBV) is linked to a broad spectrum of B-cell malignancies. EBV nuclear antigen 3C (EBNA3C) is an encoded latent antigen required for growth transformation of primary human B-lymphocytes. Interferon regulatory factor 4 (IRF4) and 8 (IRF8) are transcription factors of the IRF family that regulate diverse functions in B cell development. IRF4 is an oncoprotein with anti-apoptotic properties and IRF8 functions as a regulator of apoptosis and tumor suppressor in many hematopoietic malignancies. We now demonstrate that EBNA3C can contribute to B-cell transformation by modulating the molecular interplay between cellular IRF4 and IRF8. We show that EBNA3C physically interacts with IRF4 and IRF8 with its N-terminal domain in vitro and forms a molecular complex in cells. We identified the Spi-1/B motif of IRF4 as critical for EBNA3C interaction. We also demonstrated that EBNA3C can stabilize IRF4, which leads to downregulation of IRF8 by enhancing its proteasome-mediated degradation. Further, si-RNA mediated knock-down of endogenous IRF4 results in a substantial reduction in proliferation of EBV-transformed lymphoblastoid cell lines (LCLs), as well as augmentation of DNA damage-induced apoptosis. IRF4 knockdown also showed reduced expression of its targeted downstream signalling proteins which include CDK6, Cyclin B1 and c-Myc all critical for cell proliferation. These studies provide novel insights into the contribution of EBNA3C to EBV-mediated B-cell transformation through regulation of IRF4 and IRF8 and add another molecular link to the mechanisms by which EBV dysregulates cellular activities, increasing the potential for therapeutic intervention against EBV-associated cancers. Interferon regulatory factor (IRF) family members have different roles in context of pathogen response, signal transduction, cell proliferation and hematopoietic development. IRF4 and IRF8 are members of the IRF family and are critical mediators of B-cell development. Enhanced expression of IRF4 is often associated with multiple myeloma and adult T-cell lymphomas. Furthermore, IRF8 can function as a tumor suppressor in myeloid cancers. Epstein-Barr virus (EBV), one of the first characterized human tumor viruses is associated with several lymphoid malignancies. One of the essential antigens, EBV encoded nuclear antigen 3C (EBNA3C), plays a critical role in EBV-induced B-cell transformation. In our study, we now demonstrate that EBNA3C forms a molecular complex with IRF4 and IRF8 specifically through its N-terminal domain. We show that IRF4 is stabilized by EBNA3C, which resulted in downregulation of IRF8 through proteasome-mediated degradation and subsequent inhibition of its tumor suppressive activity. Moreover, si-RNA-mediated inhibition of IRF4 showed a substantial reduction in EBV transformed B-cell proliferation, and also enhanced their sensitivity to DNA-damage induced apoptosis. Therefore, our findings demonstrated that targeted disruption of EBNA3C-mediated differential regulation of IRF4 and IRF8 may have potential therapeutic value for treating EBV induced B-cell malignancies.
Collapse
Affiliation(s)
- Shuvomoy Banerjee
- Department of Microbiology and the Tumor Virology Program, Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jie Lu
- Department of Microbiology and the Tumor Virology Program, Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Qiliang Cai
- Department of Microbiology and the Tumor Virology Program, Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Abhik Saha
- Department of Microbiology and the Tumor Virology Program, Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hem Chandra Jha
- Department of Microbiology and the Tumor Virology Program, Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Richard Kuo Dzeng
- Department of Microbiology and the Tumor Virology Program, Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Erle S. Robertson
- Department of Microbiology and the Tumor Virology Program, Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| |
Collapse
|
81
|
Morscio J, Dierickx D, Tousseyn T. Molecular pathogenesis of B-cell posttransplant lymphoproliferative disorder: what do we know so far? Clin Dev Immunol 2013; 2013:150835. [PMID: 23690819 PMCID: PMC3649442 DOI: 10.1155/2013/150835] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 03/10/2013] [Accepted: 03/11/2013] [Indexed: 12/14/2022]
Abstract
Posttransplant lymphoproliferative disorder (PTLD) is a potentially fatal disease that arises in 2%-10% of solid organ and hematopoietic stem cell transplants and is most frequently of B-cell origin. This very heterogeneous disorder ranges from benign lymphoproliferations to malignant lymphomas, and despite the clear association with Epstein-Barr Virus (EBV) infection, its etiology is still obscure. Although a number of risk factors have been identified (EBV serostatus, graft type, and immunosuppressive regimen), it is currently not possible to predict which transplant patient will eventually develop PTLD. Genetic studies have linked translocations (involving C-MYC, IGH, BCL-2), various copy number variations, DNA mutations (PIM1, PAX5, C-MYC, RhoH/TTF), and polymorphisms in both the host (IFN-gamma, IL-10, TGF-beta, HLA) and the EBV genome to B-cell PTLD development. Furthermore, the tumor microenvironment seems to play an important role in the course of disease representing a local niche that can allow antitumor immune responses even in an immunocompromised host. Taken together, B-cell PTLD pathogenesis is very complex due to the interplay of many different (patient-dependent) factors and requires thorough molecular analysis for the development of novel tailored therapies. This review aims at giving a global overview of the currently known parameters that contribute to the development of B-cell PTLD.
Collapse
Affiliation(s)
- J. Morscio
- KU Leuven, Translational Cell and Tissue Research, Leuven, Belgium
| | - D. Dierickx
- UZ Leuven, Department of Hematology, University Hospitals KU Leuven, Leuven, Belgium
| | - T. Tousseyn
- KU Leuven, Translational Cell and Tissue Research, Leuven, Belgium
- UZ Leuven, Department of Pathology, University Hospitals KU Leuven, Leuven, Belgium
| |
Collapse
|
82
|
Murata T, Tsurumi T. Epigenetic modification of the Epstein-Barr virus BZLF1 promoter regulates viral reactivation from latency. Front Genet 2013; 4:53. [PMID: 23577022 PMCID: PMC3620531 DOI: 10.3389/fgene.2013.00053] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/25/2013] [Indexed: 01/08/2023] Open
Abstract
The Epstein-Barr virus (EBV) is an oncogenic human gamma-herpesvirus that predominantly establishes latent infection in B lymphocytes. Viral genomes exist as extrachromosomal episomes with a nucleosomal structure. Maintenance of virus latency or execution of reactivation is controlled by the expression of BZLF1, a viral immediate-early gene product, tightly controlled at the transcriptional level. In this article, we review how BZLF1 transcription is controlled, in other words how virus reactivation is regulated, especially in terms of epigenetics. We recently found that histone H3 lysine 27 trimethylation (H3K27me3) and H4K20me3 markers are crucial for suppression of BZLF1 in latent Raji cells. In addition, H3K9me2/3, heterochromatin protein 1, and H2A ubiquitination are associated with latency, whereas positive markers, such as higher histone acetylation and H3K4me3, are concomitant with reactivation. Since lytic replication eventually causes cell cycle arrest and cell death, development of oncolytic therapy for EBV-positive cancers is conceivable using epigenetic disruptors. In addition, we note the difficulties in analyzing roles of epigenetics in EBV, including issues like cell type dependence and virus copy numbers.
Collapse
Affiliation(s)
- Takayuki Murata
- Division of Virology, Aichi Cancer Center Research Institute Nagoya, Japan
| | | |
Collapse
|
83
|
Different distributions of Epstein-Barr virus early and late gene transcripts within viral replication compartments. J Virol 2013; 87:6693-9. [PMID: 23552415 DOI: 10.1128/jvi.00219-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Productive replication of the Epstein-Barr virus (EBV) occurs in discrete sites in nuclei, called replication compartments, where viral genome DNA synthesis and transcription take place. The replication compartments include subnuclear domains, designated BMRF1 cores, which are highly enriched in the BMRF1 protein. During viral lytic replication, newly synthesized viral DNA genomes are organized around and then stored inside BMRF1 cores. Here, we examined spatial distribution of viral early and late gene mRNAs within replication compartments using confocal laser scanning microscopy and three-dimensional surface reconstruction imaging. EBV early mRNAs were mainly located outside the BMRF1 cores, while viral late mRNAs were identified inside, corresponding well with the fact that late gene transcription is dependent on viral DNA replication. From these results, we speculate that sites for viral early and late gene transcription are separated with reference to BMRF1 cores.
Collapse
|
84
|
Arvey A, Tempera I, Lieberman PM. Interpreting the Epstein-Barr Virus (EBV) epigenome using high-throughput data. Viruses 2013; 5:1042-54. [PMID: 23549386 PMCID: PMC3705264 DOI: 10.3390/v5041042] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/11/2013] [Accepted: 03/18/2013] [Indexed: 12/24/2022] Open
Abstract
The Epstein-Barr virus (EBV) double-stranded DNA genome is subject to extensive epigenetic regulation. Large consortiums and individual labs have generated a vast number of genome-wide data sets on human lymphoblastoid and other cell lines latently infected with EBV. Analysis of these data sets reveals important new information on the properties of the host and viral chromosome structure organization and epigenetic modifications. We discuss the mapping of these data sets and the subsequent insights into the chromatin structure and transcription factor binding patterns on latent EBV genomes. Colocalization of multiple histone modifications and transcription factors at regulatory loci are considered in the context of the biology and regulation of EBV.
Collapse
Affiliation(s)
- Aaron Arvey
- Memorial Sloan Kettering Cancer Center, NY, NY and Howard Hughes Medical Institute: E-Mail:
| | - Italo Tempera
- The Fels Cancer Institute and Department of Microbiology Temple University School of Medicine, Philadelphia, PA; E-Mail:
| | - Paul M. Lieberman
- The Wistar Institute Philadelphia, PA 19104; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: (F.L.); Tel.: +1-215-898-9491; Fax: +1-215-898-0663
| |
Collapse
|
85
|
Maglennon GA, Doorbar J. The biology of papillomavirus latency. Open Virol J 2012; 6:190-7. [PMID: 23341854 PMCID: PMC3547330 DOI: 10.2174/1874357901206010190] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 09/21/2012] [Accepted: 09/24/2012] [Indexed: 12/12/2022] Open
Abstract
The presence of viral DNA in the absence of disease has suggested that papillomaviruses, like many other viruses, can exist as latent infections in the skin or other epithelial sites. In animal models, where detailed investigation has been carried out, papillomavirus DNA can be found at sites of previous infection following immune regression, with the site of latent infection being the epithelial basal layer. Such studies suggest that immune surveillance can restrict viral gene expression in the basal and parabasal layers without efficiently suppressing viral genome replication, most probably through the action of memory T-cells in the skin or dermis. Although gradual papillomavirus genome loss appears to occur over time at latent sites, immunosuppression can arrest this, and can lead to an elevation in viral genome copy number in experimental systems. In addition to immune-mediated latency, it appears that a similar situation can be achieved following infection at low virus titres and/or infection at epithelial sites where the virus life cycle is not properly supported. Such silent of asymptomatic infections do not necessarily involve the host immune system and may be controlled by different mechanisms. It appears that virus reactivation can be triggered by mechanical irritation, wounding or by UV irradiation which changes the local environment. Although the duration of papillomavirus latency in humans is not yet known, it is likely that some of the basic principles will resemble those elucidated in these model systems, and that persistence in the absence of disease may be the default outcome for at least some period of time following regression.
Collapse
Affiliation(s)
- Gareth Adam Maglennon
- Pathology & Infectious Diseases, The Royal Veterinary College, North Mymms, AL9 7TA, UK
| | - John Doorbar
- Division of Virology, National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK
| |
Collapse
|
86
|
Resveratrol inhibits Epstein Barr Virus lytic cycle in Burkitt's lymphoma cells by affecting multiple molecular targets. Antiviral Res 2012; 96:196-202. [PMID: 22985630 DOI: 10.1016/j.antiviral.2012.09.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/04/2012] [Accepted: 09/05/2012] [Indexed: 12/12/2022]
Abstract
Resveratrol (RV), a polyphenolic natural product present in many plants and fruits, exhibits anti-inflammatory, cardio-protective and anti-proliferative properties. Moreover, RV affects a wide variety of viruses including members of the Herpesviridae family, retroviruses, influenza A virus and polyomavirus by altering cellular pathways that affect viral replication itself. Epstein Barr Virus (EBV), the causative agent of infectious mononucleosis, is associated with different proliferative diseases in which it establishes a latent and/or a lytic infection. In this study, we examined the antiviral activity of RV against the EBV replicative cycle and investigated the molecular targets possibly involved. In a cellular context that allows in vitro EBV activation and lytic cycle progression through mechanisms closely resembling those that in vivo initiate and enable productive infection, we found that RV inhibited EBV lytic genes expression and the production of viral particles in a dose-dependent manner. We demonstrated that RV inhibited protein synthesis, decreased reactive oxygen species (ROS) levels, and suppressed the EBV-induced activation of the redox-sensitive transcription factors NF-kB and AP-1. Further insights into the signaling pathways and molecular targets modulated by RV may provide the basis for exploiting the antiviral activity of this natural product on EBV replication.
Collapse
|
87
|
Characterization and intracellular trafficking of Epstein-Barr virus BBLF1, a protein involved in virion maturation. J Virol 2012; 86:9647-55. [PMID: 22740416 DOI: 10.1128/jvi.01126-12] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epstein-Barr virus (EBV) BBLF1 shares 13 to 15% amino acid sequence identities with the herpes simplex virus 1 UL11 and cytomegalovirus UL99 tegument proteins, which are involved in the final envelopment during viral maturation. This study demonstrates that BBLF1 is a myristoylated and palmitoylated protein, as are UL11 and UL99. Myristoylation of BBLF1 both facilitates its membrane anchoring and stabilizes it. BBLF1 is shown to localize to the trans-Golgi network (TGN) along with gp350/220, a site where final envelopment of EBV particles takes place. The localization of BBLF1 at the TGN requires myristoylation and two acidic clusters, which interact with PACS-1, a cytosolic protein, to mediate retrograde transport from the endosomes to the TGN. Knockdown of the expression of BBLF1 during EBV lytic replication reduces the production of virus particles, demonstrating the requirement of BBLF1 to achieve optimal production of virus particles. BBLF1 is hypothesized to facilitate the budding of tegumented capsid into glycoprotein-embedded membrane during viral maturation.
Collapse
|
88
|
Li L, Su X, Choi GCG, Cao Y, Ambinder RF, Tao Q. Methylation profiling of Epstein-Barr virus immediate-early gene promoters, BZLF1 and BRLF1 in tumors of epithelial, NK- and B-cell origins. BMC Cancer 2012; 12:125. [PMID: 22458933 PMCID: PMC3362778 DOI: 10.1186/1471-2407-12-125] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 03/29/2012] [Indexed: 12/15/2022] Open
Abstract
Background Epstein-Barr virus (EBV) establishes its latency in EBV-associated malignancies, accompanied by occasionally reactivated lytic cycle. Promoter CpG methylation of EBV genome plays an essential role in maintaining viral latency. Two immediate-early (IE) genes, BZLF1 and BRLF1, induce the switch from latent to lytic infection. Studies of methylation-dependent binding of BZLF1 and BRLF1 to EBV promoters have been well reported, but little is known about the methylation status of BZLF1 and BRLF1 promoters (Zp and Rp) in tumor samples. Methods We evaluated the methylation profiles of Zp and Rp by methylation-specific PCR (MSP) and bisulfite genomic sequencing (BGS), as well as BZLF1 and BRLF1 expression by semiquantitative reverse transcription (RT)-PCR in tumors of epithelial, NK- and B-cell origins. Results We found that both Zp and Rp were hypermethylated in all studied EBV-positive cell lines and tumors of lymphoid (B- or NK cell) or epithelial origin, while unmethylated Zp and Rp alleles were detected in cell lines expressing BZLF1 and BRLF1. Following azacytidine treatment or combined with trichostatin A (TSA), the expression of BZLF1 and BRLF1 was restored along with concomitant promoter demethylation, which subsequently induced the reactivation of early lytic gene BHRF1 and late lytic gene BLLF1. Conclusions Hypermethylation of Zp and Rp mediates the frequent silencing of BZLF1 and BRLF1 in EBV-associated tumors, which could be reactivated by demethylation agent and ultimately initiated the EBV lytic cascade.
Collapse
Affiliation(s)
- Lili Li
- Cancer Epigenetics Laboratory, Department of Clinical Oncology, Sir YK Pao Center for Cancer, Hong Kong, China
| | | | | | | | | | | |
Collapse
|
89
|
Hui KF, Ho DN, Tsang CM, Middeldorp JM, Tsao GSW, Chiang AKS. Activation of lytic cycle of Epstein-Barr virus by suberoylanilide hydroxamic acid leads to apoptosis and tumor growth suppression of nasopharyngeal carcinoma. Int J Cancer 2012; 131:1930-40. [PMID: 22261816 DOI: 10.1002/ijc.27439] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 01/03/2012] [Indexed: 11/09/2022]
Abstract
Nasopharyngeal carcinoma (NPC) is strongly associated with Epstein-Barr virus (EBV). We reported that suberoylanilide hydroxamic acid (SAHA) induced EBV lytic cycle in EBV-positive gastric carcinoma cells and mediated enhanced cell death. However, expression of EBV lytic proteins was thought to exert antiapoptotic effect in EBV-infected cells. Here, we examined the in vitro and in vivo effects of SAHA on EBV lytic cycle induction in NPC cells and investigated the cellular consequences. Micromolar concentrations of SAHA significantly induced EBV lytic cycle in EBV-positive NPC cells. Increased apoptosis and proteolytic cleavage of poly(ADP-ribose) polymerase and caspase-3, -7 and -9 in EBV-positive versus EBV-negative NPC cells were observed. More than 85% of NPC cells expressing immediate-early (Zta), early (BMRF1) or late (gp350/220) lytic proteins coexpressed cleaved caspase-3. Tracking of expression of EBV lytic proteins and cleaved caspase-3 over time demonstrated that NPC cells proceeded to apoptosis following EBV lytic cycle induction. Inhibition of EBV DNA replication and late lytic protein expression by phosphonoformic acid did not impact on SAHA's induced cell death in NPC, indicating that early rather than late phase of EBV lytic cycle contributed to the apoptotic effect. In vivo effects of SAHA on EBV lytic cycle induction and tumor growth suppression were also observed in NPC xenografts in nude mice. Taken together, our data indicated that activation of lytic cycle from latent cycle of EBV by SAHA leads to apoptosis and tumor growth suppression of NPC thereby providing experimental evidence for virus-targeted therapy against EBV-positive cancer.
Collapse
Affiliation(s)
- K F Hui
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong, China
| | | | | | | | | | | |
Collapse
|
90
|
Vogl BA, Fagin U, Nerbas L, Schlenke P, Lamprecht P, Jabs WJ. Longitudinal analysis of frequency and reactivity of Epstein-Barr virus-specific T lymphocytes and their association with intermittent viral reactivation. J Med Virol 2012; 84:119-31. [PMID: 22095540 DOI: 10.1002/jmv.22258] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Persistent Epstein-Barr virus (EBV) infection is controlled tightly by virus-specific T cells. EBV infection is reactivated intermittently over time, even in apparently healthy carriers. Changes in frequency and reactivity of memory T cells, particularly of CD8(+) origin, have not been assessed in this context. It is hypothesized that viral reactivation is facilitated by diminished EBV-specific T-cell immunity. To this end, blood samples from 14 healthy donors were collected at irregular time intervals for a period of about 1 year. Samples were screened for both EBV plasma viremia and increases in viral load in PBMCs as parameters of EBV reactivation. PBMCs were subject to IFN-γ ELISPOT analysis using the autologous EBV-transformed lymphoblastoid cell line (EBV-LCL) or appropriate HLA class I-restricted EBV peptides as stimulators. Frequencies of epitope-specific CD8(+) T cells were monitored further using HLA tetramers and flow cytometry. Twelve of 14 donors exhibited signs of asymptomatic EBV reactivation. Viral reactivation was accompanied by either substantially decreased IFN-γ responses against autologous EBV-LCL (eight of 12 study participants) and/or increased responses against particular EBV peptides (six of 12 donors). In seven persons with HLA-A2 and/or -B8 alleles numbers of HLA tetramer-positive CD8(+) T cells also varied over time, but showed no correlation to episodes of detectable viral activity. In summary, IFN-γ reactivity of EBV-specific T cells is not constant. Viral reactivation is detected preferably at times of diminished EBV-LCL-specific cellular immunity. However, increased reactivity of single immunodominant CD8(+) EBV-specific T-cell clones may occur in response to virus replication.
Collapse
Affiliation(s)
- Bastian A Vogl
- Department of Medicine I, University of Luebeck School of Medicine, Luebeck, Germany
| | | | | | | | | | | |
Collapse
|
91
|
Epigenetic histone modification of Epstein-Barr virus BZLF1 promoter during latency and reactivation in Raji cells. J Virol 2012; 86:4752-61. [PMID: 22357272 DOI: 10.1128/jvi.06768-11] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Epstein-Barr virus (EBV) predominantly establishes latent infection in B cells, and the reactivation of the virus from latency is dependent on the expression of the viral BZLF1 protein. The BZLF1 promoter (Zp) normally exhibits only low basal activity but is activated in response to chemical or biological inducers, such as 12-O-tetradecanoylphorbol-13-acetate (TPA), calcium ionophores, or histone deacetylase (HDAC) inhibitors. In some cell lines latently infected with EBV, an HDAC inhibitor alone can induce BZLF1 transcription, while the treatment does not enhance expression in other cell lines, such as B95-8 or Raji cells, suggesting unknown suppressive mechanisms besides histone deacetylation in those cells. Here, we found the epigenetic modification of the BZLF1 promoter in latent Raji cells by histone H3 lysine 27 trimethylation (H3K27me3), H3K9me2/me3, and H4K20me3. Levels of active markers such as histone acetylation and H3K4me3 were low in latent cells but increased upon reactivation. Treatment with 3-deazaneplanocin A (DZNep), an inhibitor of H3K27me3 and H4K20me3, significantly enhanced the BZLF1 transcription in Raji cells when in combination with an HDAC inhibitor, trichostatin A (TSA). The knockdown of Ezh2 or Suv420h1, histone methyltransferases for H3K27me3 or H4K20me3, respectively, further proved the suppression of Zp by the methylations. Taken together, the results indicate that H3K27 methylation and H4K20 methylation are involved, at least partly, in the maintenance of latency, and histone acetylation and H3K4 methylation correlate with the reactivation of the virus in Raji cells.
Collapse
|
92
|
Wollen Steen K, Doseth B, P. Westbye M, Akbari M, Kang D, Falkenberg M, Slupphaug G. mtSSB may sequester UNG1 at mitochondrial ssDNA and delay uracil processing until the dsDNA conformation is restored. DNA Repair (Amst) 2012; 11:82-91. [DOI: 10.1016/j.dnarep.2011.10.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 10/02/2011] [Accepted: 10/27/2011] [Indexed: 12/11/2022]
|
93
|
Frappier L. Promyelocytic leukemia nuclear body disruption as a treatment for EBV-associated nasopharyngeal carcinoma? Future Virol 2012. [DOI: 10.2217/fvl.11.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Lori Frappier
- Department of Molecular Genetics, University of Toronto, 1 Kings College Circle, Toronto M3A 2M1, Canada
| |
Collapse
|
94
|
Li R, Hayward SD. The Ying-Yang of the virus-host interaction: control of the DNA damage response. Future Microbiol 2011; 6:379-83. [PMID: 21526939 DOI: 10.2217/fmb.11.16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Evaluation of: Nikitin PA, Yan CM, Forte E et al.: An ATM/Chk2-mediated DNA damage-responsive signaling pathway suppresses Epstein-Barr virus transformation of primary human B cells. Cell. Host Microbe 8(6), 510-522 (2010). Viruses have evolved elegant strategies to manipulate the host while the host counters with defense systems including the interferon response, apoptosis and the DNA damage response (DDR). Viruses have multiple strategies for manipulating the DDR and the same virus can even activate or inhibit the DDR at different stages of infection. Epstein-Barr virus (EBV) is implicated in several human cancers, including Burkitt's lymphoma, nasopharyngeal carcinoma, post-transplant lymphoproliferative disease and HIV-associated lymphomas. Although multiple viral proteins have been implicated in EBV-associated malignancies, the cellular pathways that control EBV-induced transformation and tumorigenesis remain incompletely understood. In this study, Nikitin et al. demonstrate that early EBV infection induces a cellular DDR that restricts virus-mediated transformation. The EBV-encoded EBNA3C protein subsequently attenuates this response to favor transformation and immortalization of host cells.
Collapse
Affiliation(s)
- Renfeng Li
- Viral Oncology Program, Department of Oncology, Johns Hopkins School of Medicine & Kimmel Cancer Center, Baltimore, MD 21231, USA
| | | |
Collapse
|
95
|
Replication and transcription activator (RTA) of murine gammaherpesvirus 68 binds to an RTA-responsive element and activates the expression of ORF18. J Virol 2011; 85:11338-50. [PMID: 21849436 DOI: 10.1128/jvi.00561-11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The replication and transcription activator (RTA), mainly encoded by open reading frame 50, is an immediate-early gene product that is conserved among all characterized gammaherpesviruses. Previous studies have demonstrated that RTA proteins of Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) can activate the promoter of many viral early lytic genes through direct or indirect mechanisms. Murine gammaherpesvirus 68 (MHV-68) is genetically related to KSHV and EBV, and the RTA homologue from MHV-68 also initiates the lytic cycle of gene expression. Although two RTA-dependent promoters had been identified in MHV-68, the mechanism of the interaction between RTA and the promoters was not characterized. In this study, we first identified an RTA-responsive promoter in the left origin of lytic replication region of MHV-68 through a reporter assay and mapped a 27-bp RTA-responsive element (RRE) through systematic deletions. Interestingly, sequence analysis identified a second RRE in this region. An electrophoretic mobility shift assay (EMSA) and a chromatin immunoprecipitation (ChIP) assay showed that RTA can bind directly to these two RREs in vitro or in vivo. Mutagenesis studies have further characterized the nucleotides important for mediating RTA binding by an EMSA. Moreover, we engineered RRE-deleted viruses and demonstrated in the context of the viral genome that one of the RREs mediates the RTA-dependent activation of an essential lytic gene, ORF18, during de novo infection. To our knowledge, this is the first time that RTA binding sites in MHV-68 have been identified. Since ORF18 regulates viral late gene expression, our study has also contributed to the delineation of the expression cascade of gammaherpesvirus lytic genes.
Collapse
|
96
|
Luo B, Tang X, Jia Y, Wang Y, Chao Y, Zhao C. Sequence variation of Epstein-Barr virus (EBV) BZLF1 gene in EBV-associated gastric carcinomas and nasopharyngeal carcinomas in Northern China. Microbes Infect 2011; 13:776-82. [DOI: 10.1016/j.micinf.2011.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 03/19/2011] [Accepted: 04/06/2011] [Indexed: 12/23/2022]
|
97
|
Lima RT, Seca H, Brás S, Nascimento MSJ, Vasconcelos MH. Treatment of Akata EBV-positive cells with doxorubicin causes more EBV reactivation than treatment with etoposide. Chemotherapy 2011; 57:195-203. [PMID: 21540588 DOI: 10.1159/000323627] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 11/09/2010] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS EBV has been associated with Burkitt lymphoma (BL). It establishes a latent infection but its reactivation has been observed in patients receiving long-term chemotherapy. The effect of doxorubicin on virus reactivation has been described previously, but the effect of etoposide or cytarabine on EBV reactivation has not been reported in the literature. The aim of this work was to carry out such a study. METHODS Akata EBV-positive cell lines were treated with etoposide, doxorubicin or cytarabine. Viable cells were analyzed by trypan blue, programmed cell death by TUNEL assay, mRNA levels by RT-PCR and cellular or viral proteins by Western blot. Viruses were visualized by electron microscopy. RESULTS All of the studied drugs caused cell death by apoptosis. Comparing the effect of etoposide and doxorubicin (at their IC(50)) in the EBV-positive cells, etoposide caused less EBV reactivation than doxorubicin. Cytarabine apparently did not reactivate EBV. CONCLUSION When treating Akata EBV-positive cells with the respective IC(50) of the following drugs, etoposide induced less EBV reactivation than doxorubicin, and cytarabine apparently did not induce EBV reactivation.
Collapse
Affiliation(s)
- Raquel T Lima
- Institute of Molecular Pathology and Immunology, University of Porto, Portugal
| | | | | | | | | |
Collapse
|
98
|
Murata T, Noda C, Saito S, Kawashima D, Sugimoto A, Isomura H, Kanda T, Yokoyama KK, Tsurumi T. Involvement of Jun dimerization protein 2 (JDP2) in the maintenance of Epstein-Barr virus latency. J Biol Chem 2011; 286:22007-16. [PMID: 21525011 DOI: 10.1074/jbc.m110.199836] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Reactivation of the Epstein-Barr virus from latency is dependent on expression of the BZLF1 viral immediate-early protein. The BZLF1 promoter (Zp) normally exhibits only low basal activity but is activated in response to chemical inducers such as 12-O-tetradecanoylphorbol-13-acetate and calcium ionophore. We found that Jun dimerization protein 2 (JDP2) plays a significant role in suppressing Zp activity. Reporter, EMSA, and ChIP assays of a Zp mutant virus revealed JDP2 association with Zp at the ZII cis-element, a binding site for CREB/ATF/AP-1. Suppression of Zp activity by JDP2 correlated with HDAC3 association and reduced levels of histone acetylation. Although introduction of point mutations into the ZII element of the viral genome did not increase the level of BZLF1 production, silencing of endogenous JDP2 gene expression by RNA interference increased the levels of viral early gene products and viral DNA replication. These results indicate that JDP2 plays a role as a repressor of Zp and that its replacement by CREB/ATF/AP-1 at ZII is crucial to triggering reactivation from latency to lytic replication.
Collapse
Affiliation(s)
- Takayuki Murata
- Division of Virology, Aichi Cancer Center Research Institute, 1-1, Kanokoden, Chikusa-ku, Nagoya 464-8681, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
99
|
Progress and problems in understanding and managing primary Epstein-Barr virus infections. Clin Microbiol Rev 2011; 24:193-209. [PMID: 21233512 DOI: 10.1128/cmr.00044-10] [Citation(s) in RCA: 237] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epstein-Barr virus (EBV) is a gammaherpesvirus that infects a large fraction of the human population. Primary infection is often asymptomatic but results in lifelong infection, which is kept in check by the host immune system. In some cases, primary infection can result in infectious mononucleosis. Furthermore, when host-virus balance is not achieved, the virus can drive potentially lethal lymphoproliferation and lymphomagenesis. In this review, we describe the biology of EBV and the host immune response. We review the diagnosis of EBV infection and discuss the characteristics and pathogenesis of infectious mononucleosis. These topics are approached in the context of developing therapeutic and preventative strategies.
Collapse
|
100
|
Traylen CM, Patel HR, Fondaw W, Mahatme S, Williams JF, Walker LR, Dyson OF, Arce S, Akula SM. Virus reactivation: a panoramic view in human infections. Future Virol 2011; 6:451-463. [PMID: 21799704 DOI: 10.2217/fvl.11.21] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Viruses are obligate intracellular parasites, relying to a major extent on the host cell for replication. An active replication of the viral genome results in a lytic infection characterized by the release of new progeny virus particles, often upon the lysis of the host cell. Another mode of virus infection is the latent phase, where the virus is 'quiescent' (a state in which the virus is not replicating). A combination of these stages, where virus replication involves stages of both silent and productive infection without rapidly killing or even producing excessive damage to the host cells, falls under the umbrella of a persistent infection. Reactivation is the process by which a latent virus switches to a lytic phase of replication. Reactivation may be provoked by a combination of external and/or internal cellular stimuli. Understanding this mechanism is essential in developing future therapeutic agents against viral infection and subsequent disease. This article examines the published literature and current knowledge regarding the viral and cellular proteins that may play a role in viral reactivation. The focus of the article is on those viruses known to cause latent infections, which include herpes simplex virus, varicella zoster virus, Epstein-Barr virus, human cytomegalovirus, human herpesvirus 6, human herpesvirus 7, Kaposi's sarcoma-associated herpesvirus, JC virus, BK virus, parvovirus and adenovirus.
Collapse
Affiliation(s)
- Christopher M Traylen
- Department of Microbiology & Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
| | | | | | | | | | | | | | | | | |
Collapse
|