101
|
Rovedo M, Longnecker R. Epstein-barr virus latent membrane protein 2B (LMP2B) modulates LMP2A activity. J Virol 2007; 81:84-94. [PMID: 17035319 PMCID: PMC1797235 DOI: 10.1128/jvi.01302-06] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Accepted: 09/28/2006] [Indexed: 12/14/2022] Open
Abstract
Latent membrane protein 2A (LMP2A) and LMP2B are viral proteins expressed during Epstein-Barr virus (EBV) latency in EBV-infected B cells both in cell culture and in vivo. LMP2A has important roles in modulating B-cell receptor (BCR) signal transduction by associating with the cellular tyrosine kinases Lyn and Syk via specific phosphotyrosine motifs found within the LMP2A N-terminal tail domain. LMP2A has been shown to alter normal BCR signal transduction in B cells by reducing levels of Lyn and by blocking tyrosine phosphorylation and calcium mobilization following BCR cross-linking. Although little is currently known about the function of LMP2B in B cells, the similarity in structure between LMP2A and LMP2B suggests that they may localize to the same cellular compartments. To investigate the function of LMP2B, B-cell lines expressing LMP2A, LMP2B, LMP2A/LMP2B, and the relevant vector controls were analyzed. As was previously shown, cells expressing LMP2A had a dramatic block in normal BCR signal transduction as measured by calcium mobilization and tyrosine phosphorylation. There was no effect on BCR signal transduction in cells expressing LMP2B. Interestingly, when LMP2B was expressed in conjunction with LMP2A, there was a restoration of normal BCR signal transduction upon BCR cross-linking. The expression of LMP2B did not alter the cellular localization of LMP2A but did bind to and prevent the phosphorylation of LMP2A. A restoration of Lyn levels, but not a change in LMP2A levels, was also observed in cells coexpressing LMP2B with LMP2A. From these results, we conclude that LMP2B modulates LMP2A activity.
Collapse
Affiliation(s)
- Mark Rovedo
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Ward 6-231, 303 E. Chicago Avenue, Chicago, IL 60611, USA
| | | |
Collapse
|
102
|
Pappworth IY, Wang EC, Rowe M. The switch from latent to productive infection in epstein-barr virus-infected B cells is associated with sensitization to NK cell killing. J Virol 2007; 81:474-82. [PMID: 17079298 PMCID: PMC1797427 DOI: 10.1128/jvi.01777-06] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 10/25/2006] [Indexed: 01/14/2023] Open
Abstract
Following activation of Epstein-Barr virus (EBV)-infected B cells from latent to productive (lytic) infection, there is a concomitant reduction in the level of cell surface major histocompatibility complex (MHC) class I molecules and an impaired antigen-presenting function that may facilitate evasion from EBV-specific CD8+ cytotoxic T cells. In some other herpesviruses studied, most notably human cytomegalovirus (HCMV), evasion of virus-specific CD8+ effector responses via downregulation of surface MHC class I molecules is supplemented with specific mechanisms for evading NK cells. We now report that EBV differs from HCMV in this respect. While latently infected EBV-positive B cells were resistant to lysis by two NK lines and by primary polyclonal NK cells from peripheral blood, these effectors efficiently killed cells activated into the lytic cycle. Susceptibility to NK lysis coincided not only with downregulation of HLA-A, -B, and -C molecules that bind to the KIR family of inhibitory receptors on NK cells but also with downregulation of HLA-E molecules binding the CD94/NKG2A inhibitory receptors. Conversely, ULBP-1 and CD112, ligands for the NK cell-activating receptors NKG2D and DNAM-1, respectively, were elevated. Susceptibility of the virus-producing target cells to NK cell lysis was partially reversed by blocking ULBP-1 or CD112 with specific antibodies. These results highlight a fundamental difference between EBV and HCMV with regards to evasion of innate immunity.
Collapse
Affiliation(s)
- Isabel Y Pappworth
- Department of Medical Biochemistry and Immunology, Wales College of Medicine, Cardiff University, Heath Park CF14 4XX, United Kingdom
| | | | | |
Collapse
|
103
|
Kimura H. Pathogenesis of chronic active Epstein-Barr virus infection: is this an infectious disease, lymphoproliferative disorder, or immunodeficiency? Rev Med Virol 2006; 16:251-61. [PMID: 16791843 DOI: 10.1002/rmv.505] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Chronic active Epstein-Barr virus infection (CAEBV) is characterised by chronic or recurrent infectious mononucleosis-like symptoms, such as fever, hepatosplenomegaly, persistent hepatitis and extensive lymphadenopathy. Patients with CAEBV have high viral loads in their peripheral blood and/or an unusual pattern of EBV-related antibodies. This disease is rare but severe with high morbidity and mortality. Nearly three decades have passed since this disease was first identified, and recent advances in technology have increased our understanding of CAEBV pathophysiology. There is accumulating evidence that the clonal expansion of EBV-infected T or natural killer (NK) cells plays a central role in the pathogenesis of CAEBV. However, it remains unclear whether CAEBV is truly a monoclonal lymphoproliferative disorder. EBV-infected T or NK cells are able to evade the host cellular immune system due to the limited expression of viral proteins of reduced antigenicity. Recent studies suggest that infection of T or NK cells is a common event during primary EBV infection. A defect or single nucleotide polymorphism in host immune-modulating genes may allow for the expansion of virus infected cells giving rise to CAEBV. In this review, I summarise our current understanding of the pathogenesis of CAEBV and propose a model of CAEBV pathogenicity.
Collapse
Affiliation(s)
- Hiroshi Kimura
- Department of Virology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Japan.
| |
Collapse
|
104
|
Souza TA, Stollar BD, Sullivan JL, Luzuriaga K, Thorley-Lawson DA. Peripheral B cells latently infected with Epstein-Barr virus display molecular hallmarks of classical antigen-selected memory B cells. Proc Natl Acad Sci U S A 2005; 102:18093-8. [PMID: 16330748 PMCID: PMC1306799 DOI: 10.1073/pnas.0509311102] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Indexed: 11/18/2022] Open
Abstract
Epstein-Barr virus (EBV) establishes a lifelong persistent infection within peripheral blood B cells with the surface phenotype of memory cells. To date there is no proof that these cells have the genotype of true germinal-center-derived memory B cells. It is critical to understand the relative contribution of viral mimicry versus antigen signaling to the production of these cells because EBV encodes proteins that can affect the surface phenotype of infected cells and provide both T cell help and B cell receptor signals in the absence of cognate antigen. To address these questions we have developed a technique to identify single EBV-infected cells in the peripheral blood and examine their expressed Ig genes. The genes were all isotype-switched and somatically mutated. Furthermore, the mutations do not cause stop codons and display the pattern expected for antigen-selected memory cells based on their frequency, type, and location within the Ig gene. We conclude that latently infected peripheral blood B cells display the molecular hallmarks of classical antigen-selected memory B cells. Therefore, EBV does not disrupt the normal processing of latently infected cells into memory, and deviations from normal B cell biology are not tolerated in the infected cells. This article provides definitive evidence that EBV in the peripheral blood persists in true memory B cells.
Collapse
Affiliation(s)
- Tatyana A Souza
- Department of Pathology, Tufts University School of Medicine, Boston, MA 02111, USA
| | | | | | | | | |
Collapse
|
105
|
Pegtel DM, Subramanian A, Sheen TS, Tsai CH, Golub TR, Thorley-Lawson DA. Epstein-Barr-virus-encoded LMP2A induces primary epithelial cell migration and invasion: possible role in nasopharyngeal carcinoma metastasis. J Virol 2005; 79:15430-42. [PMID: 16306614 PMCID: PMC1316046 DOI: 10.1128/jvi.79.24.15430-15442.2005] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 09/28/2005] [Indexed: 01/20/2023] Open
Abstract
Nonkeratinizing nasopharyngeal carcinomas (NPC) are >95% associated with the expression of the Epstein-Barr virus (EBV) LMP2A latent protein. However, the role of EBV, in particular, LMP2A, in tumor progression is not well understood. Using Affymetrix chips and a pattern-matching computational technique (neighborhood analysis), we show that the level of LMP2A expression in NPC biopsy samples correlates with that of a cellular protein, integrin-alpha-6 (ITGalpha6), that is associated with cellular migration in vitro and metastasis in vivo. We have recently developed a primary epithelial model from tonsil tissue to study EBV infection in epithelial cells. Here we report that LMP2A expression in primary tonsil epithelial cells causes them to become migratory and invasive, that ITGalpha6 RNA levels are up-regulated in epithelial cells expressing LMP2, and that ITGalpha6 protein levels are increased in the migrating cells. Blocking antibodies against ITGalpha6 abrogated LMP2-induced invasion through Matrigel by primary epithelial cells. Our results provide a link between LMP2A expression, ITGalpha6 expression, epithelial cell migration, and NPC metastasis and suggest that EBV infection may contribute to the high incidence of metastasis in NPC progression.
Collapse
Affiliation(s)
- Dirk M Pegtel
- Department of Pathology, Tufts University School of Medicine, Jaharis Building, 150 Harrison Ave., Boston, MA 02111, USA
| | | | | | | | | | | |
Collapse
|
106
|
Abstract
Epstein-Barr virus (EBV) is a tumorigenic herpes virus that infects and persists in B lymphocytes in the majority of humans, generally without causing disease. However, in a few individuals the virus is associated with significant pathology, particularly benign and malignant lymphoproliferations. Recently acquired knowledge on the mechanisms of EBV persistence, immune control of primary and persistent infection, and disease pathogenesis is now being translated into the clinic with novel methods of diagnosis, prevention and treatment contributing to improved patient care. This review concentrates on these recent advances in the field of hematology/oncology.
Collapse
Affiliation(s)
- Hilary Williams
- Basic and Clinical Virology Laboratory, Centre for Infectious Diseases, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, United Kingdom
| | | |
Collapse
|
107
|
Hislop AD, Kuo M, Drake-Lee AB, Akbar AN, Bergler W, Hammerschmitt N, Khan N, Palendira U, Leese AM, Timms JM, Bell AI, Buckley CD, Rickinson AB. Tonsillar homing of Epstein-Barr virus-specific CD8+ T cells and the virus-host balance. J Clin Invest 2005; 115:2546-55. [PMID: 16110323 PMCID: PMC1187932 DOI: 10.1172/jci24810] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Accepted: 06/07/2005] [Indexed: 11/17/2022] Open
Abstract
Patients with infectious mononucleosis (IM) undergoing primary EBV infection show large expansions of EBV-specific CD8+ T cells in the blood. While latent infection of the B cell pool is quickly controlled, virus shedding from lytically infected cells in the oropharynx remains high for several months. We therefore studied how responses localize to the tonsil, a major target site for EBV, during primary infection and persistence. In acute IM, EBV-specific effectors were poorly represented among CD8+ T cells in tonsil compared with blood, coincident with absence of the CCR7 lymphoid homing marker on these highly activated cells. In patients who had recently recovered from IM, latent epitope reactivities were quicker than lytic reactivities both to acquire CCR7 and to accumulate in the tonsil, with some of these cells now expressing the CD103 integrin, which mediates retention at mucosal sites. By contrast, in long-term virus carriers in whom both lytic and latent infections had been controlled, there was 2- to 5-fold enrichment of lytic epitope reactivities and 10- to 20-fold enrichment of latent epitope reactivities in tonsil compared with blood; up to 20% of tonsillar CD8+ T cells were EBV specific, and many now expressed CD103. We suggest that efficient control of EBV infection requires appropriate CD8+ T cell homing to oropharyngeal sites.
Collapse
Affiliation(s)
- Andrew D Hislop
- Institute for Cancer Studies and Medical Research Council Centre for Immune Regulation, University of Birmingham, Birmingham, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
108
|
Gross AJ, Hochberg D, Rand WM, Thorley-Lawson DA. EBV and systemic lupus erythematosus: a new perspective. THE JOURNAL OF IMMUNOLOGY 2005; 174:6599-607. [PMID: 15905498 DOI: 10.4049/jimmunol.174.11.6599] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have proposed that EBV uses mature B cell biology to access memory B cells as a site of persistent infection. A central feature of this model is that EBV adapts its gene expression profile to the state of the B cell it resides in and that the level of infection is stable over time. This led us to question whether changes in the behavior or regulation of mature B cells would alter the state of EBV persistence. To investigate this, we studied the impact of systemic lupus erythematosus (SLE), a disease characterized by immune dysfunction, on EBV infection. We show that patients with SLE have abnormally high frequencies of EBV-infected cells in their blood, and this is associated with the occurrence of SLE disease flares. Although patients with SLE have frequencies of infected cells comparable to those seen in immunosuppressed patients, in SLE the effect was independent of immunosuppressive therapy. Aberrant expression of viral lytic (BZLF1) and latency (latency membrane proteins 1 and 2a) genes was also detected in the blood of SLE patients. We conclude that the abnormal regulation of EBV infection in SLE patients reflects the sensitivity of the virus to perturbation of the immune system.
Collapse
Affiliation(s)
- Andrew J Gross
- Division of Rheumatology, Tufts-New England Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA
| | | | | | | |
Collapse
|
109
|
Abstract
The general problem in cancer treatment centres on finding agents that specifically affect cancer cells without damaging normal cells. The differences between cancer cells and normal cells are usually very subtle but about 15% of all human cancers involve a virus infection, for example the Epstein-Barr virus associated cancers. In these cancers, every tumour cell carries the virus in a latent infection but the number of normal cells infected is very low. So a treatment that could somehow cause the elimination of EBV infected cells would be very specific for the cancer in such cases. One potential approach could involve finding ways to reactivate the latent virus in cancer cells into the early part of the lytic cycle, impeding cell proliferation, targeting chemotherapeutic agents to the cancer and causing the cancer cells to become targets for immune surveillance. This review considers the mechanisms by which EBV reactivation is controlled and discusses possible therapeutic approaches.
Collapse
Affiliation(s)
- Wolfgang Amon
- Ludwig Institute for Cancer Research and Department of Virology, Imperial College Faculty of Medicine, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | | |
Collapse
|
110
|
Khan G, Lake A, Shield L, Freeland J, Andrew L, Alexander FE, Jackson R, Taylor PRA, McCruden EAB, Jarrett RF. Phenotype and frequency of Epstein-Barr virus-infected cells in pretreatment blood samples from patients with Hodgkin lymphoma. Br J Haematol 2005; 129:511-9. [PMID: 15877733 DOI: 10.1111/j.1365-2141.2005.05483.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An accumulating body of data suggests that the Epstein-Barr virus (EBV), a lymphotropic herpesvirus, is involved in the pathogenesis of a proportion of cases of Hodgkin lymphoma (HL). In this study, we showed that the frequency of circulating EBV-infected cells was significantly higher (P < 0.001) in pretreatment blood samples from EBV-associated cases when compared with non-EBV-associated cases. We further showed that in patients with EBV-associated disease, the virus persisted in the peripheral blood in memory B cells. This phenotype is consistent with that seen in healthy seropositive controls, post-transplant patients and patients with acute infectious mononucleosis. The data suggest that an increased frequency of EBV carrying B cells in peripheral blood is associated with EBV-associated HL.
Collapse
Affiliation(s)
- Gulfaraz Khan
- Leukaemia Research Fund Virus Centre, Institute of Comparative Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, Scotland, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
111
|
Willer DO, Speck SH. Establishment and maintenance of long-term murine gammaherpesvirus 68 latency in B cells in the absence of CD40. J Virol 2005; 79:2891-9. [PMID: 15709008 PMCID: PMC548450 DOI: 10.1128/jvi.79.5.2891-2899.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Murine gammaherpesvirus 68 (gammaHV68), like Epstein-Barr virus (EBV), establishes a chronic infection in its host by gaining access to the memory B-cell reservoir, where it persists undetected by the host's immune system. EBV encodes a membrane protein, LMP1, that appears to function as a constitutively active CD40 receptor, and is hypothesized to play a central role in EBV-driven differentiation of infected naive B cells to a memory B-cell phenotype. However, it has recently been shown that there is a critical role for CD40-CD40L interaction in B-cell immortalization by EBV (K.-I. Imadome, M. Shirakata, N. Shimizu, S. Nonoyama, and Y. Yamanashi, Proc. Natl. Acad. Sci. USA 100:7836-7840, 2003), indicating that LMP1 does not adequately recapitulate all of the necessary functions of CD40. The role of CD40 receptor expression on B cells for the establishment and maintenance of gammaHV68 latency is unclear. Data previously obtained with a competition model, demonstrated that in the face of CD40-sufficient B cells, gammaHV68 latency in CD40-deficient B cells waned over time in chimeric mice (I.-J. Kim, E. Flano, D. L. Woodland, F. E. Lund, T. D. Randall, and M. A. Blackman, J. Immunol. 171:886-892, 2003). To further investigate the role of CD40 in gammaHV68 latency in vivo, we have characterized the infection of CD40 knockout (CD40(-/-)) mice. Here we report that, consistent with previous observations, gammaHV68 efficiently established a latent infection in B cells of CD40(-/-) mice. Notably, unlike the infection of normal C57BL/6 mice, significant ex vivo reactivation from splenocytes harvested from infected CD40(-/-) mice 42 days postinfection was observed. In addition, in contrast to gammaHV68 infection of C57BL/6 mice, the frequency of infected naive B cells remained fairly stable over a 3-month period postinfection. Furthermore, a slightly higher frequency of gammaHV68 infection was observed in immunoglobulin D (IgD)-negative B cells, which was stably maintained over a period of 3 months postinfection. The presence of virus in IgD-negative B cells indicates that gammaHV68 may either directly infect memory B cells present in CD40(-/-) mice or be capable of driving differentiation of naive CD40(-/-) B cells. A possible explanation for the apparent discrepancy between the failure of gammaHV68 latency to be maintained in CD40-deficient B cells in the presence of CD40-sufficient B cells and the stable maintenance of gammaHV68 B-cell latency in CD40(-/-) mice came from examining virus replication in the lungs of infected CD40(-/-) mice, where we observed significantly higher levels of virus replication at late times postinfection compared to those in infected C57BL/6 mice. Taken together, these findings are consistent with a model in which chronic virus infection of CD40(-/-) mice is maintained through virus reactivation in the lungs and reseeding of latency reservoirs.
Collapse
Affiliation(s)
- David O Willer
- Center for Emerging Infectious Diseases, Yerkes National Primate Research Center, 954 Gatewood Rd. N.E., Atlanta, GA 30329, USA
| | | |
Collapse
|
112
|
Schaadt E, Baier B, Mautner J, Bornkamm GW, Adler B. Epstein-Barr virus latent membrane protein 2A mimics B-cell receptor-dependent virus reactivation. J Gen Virol 2005; 86:551-559. [PMID: 15722514 DOI: 10.1099/vir.0.80440-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Latent membrane protein 2A (LMP2A) of Epstein-Barr virus (EBV) shares protein motifs with the B-cell receptor that play a role in B-cell receptor signalling and has been shown to mimic an activated B-cell receptor by providing a survival signal for mature B cells in transgenic mice. Conversely, LMP2A has been reported not to support but to inhibit B-cell receptor signalling with respect to virus reactivation and to block lytic virus induction after anti-Ig treatment of EBV-infected B cells. To solve this apparent paradox, the role of LMP2A in lytic-cycle induction was re-examined in B cells conditionally immortalized by EBV. It was shown that, in the absence of other stimuli, LMP2A expression alone could lead to induction of the virus lytic cycle. Similarly to B-cell receptor stimulation by anti-Ig treatment, this LMP2A-mediated reactivation was dependent on the mitogen-activated protein kinase pathway and could be inhibited by the viral LMP1. Our data reinforce the notion that LMP2A is a functional homologue of the B-cell receptor, not only with respect to B-cell survival but also with respect to regulation of the lytic cycle.
Collapse
Affiliation(s)
- Eveline Schaadt
- GSF-Research Center for Environment and Health, Institute for Clinical Molecular Biology and Tumor Genetics, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Barbara Baier
- GSF-Research Center for Environment and Health, Institute for Clinical Molecular Biology and Tumor Genetics, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Josef Mautner
- GSF-Research Center for Environment and Health, Institute for Clinical Molecular Biology and Tumor Genetics, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Georg W Bornkamm
- GSF-Research Center for Environment and Health, Institute for Clinical Molecular Biology and Tumor Genetics, Marchioninistrasse 25, D-81377 Munich, Germany
| | - Barbara Adler
- GSF-Research Center for Environment and Health, Institute for Clinical Molecular Biology and Tumor Genetics, Marchioninistrasse 25, D-81377 Munich, Germany
| |
Collapse
|
113
|
Pegtel DM, Middeldorp J, Thorley-Lawson DA. Epstein-Barr virus infection in ex vivo tonsil epithelial cell cultures of asymptomatic carriers. J Virol 2004; 78:12613-24. [PMID: 15507648 PMCID: PMC525079 DOI: 10.1128/jvi.78.22.12613-12624.2004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) is found frequently in certain epithelial pathologies, such as nasopharyngeal carcinoma and oral hairy leukoplakia, indicating that the virus can infect epithelial cells in vivo. Recent studies of cell lines imply that epithelial cells may also play a role in persistent EBV infection in vivo. In this report, we show the establishment and characterization of an ex vivo culture model of tonsil epithelial cells, a likely site for EBV infection in vivo. Primary epithelial-cell cultures, generated from tonsil explants, contained a heterogeneous mixture of cells with an ongoing process of differentiation. Keratin expression profiles were consistent with the presence of cells from both surface and crypt epithelia. A small subset of cells could be latently infected by coculture with EBV-releasing cell lines, but not with cell-free virus. We also detected viral-DNA, -mRNA, and -protein expression in cultures from EBV-positive tonsil donors prior to in vitro infection. We conclude that these cells were either already infected at the time of explantation or soon after through cell-to-cell contact with B cells replicating EBV in the explant. Taken together, these findings suggest that the tonsil epithelium of asymptomatic virus carriers is able to sustain EBV infection in vivo. This provides an explanation for the presence of EBV in naso- and oropharyngeal pathologies and is consistent with epithelial cells playing a role in the egress of EBV during persistent infection.
Collapse
Affiliation(s)
- Dirk M Pegtel
- Department of Pathology, Tufts University School of Medicine, Jaharis Bldg., 150 Harrison Avenue, Boston, MA 02111, USA
| | | | | |
Collapse
|
114
|
Abstract
Epstein-Barr virus (EBV) was discovered 40 years ago from examining electron micrographs of cells cultured from Burkitt's lymphoma, a childhood tumour that is common in sub-Saharan Africa, where its unusual geographical distribution - which matches that of holoendemic malaria -indicated a viral aetiology. However, far from showing a restricted distribution, EBV - a gamma-herpesvirus - was found to be widespread in all human populations and to persist in the vast majority of individuals as a lifelong, asymptomatic infection of the B-lymphocyte pool. Despite such ubiquity, the link between EBV and 'endemic' Burkitt's lymphoma proved consistent and became the first of an unexpectedly wide range of associations discovered between this virus and tumours.
Collapse
MESH Headings
- Antigens, Viral/genetics
- Antigens, Viral/physiology
- B-Lymphocytes/pathology
- B-Lymphocytes/virology
- Burkitt Lymphoma/epidemiology
- Burkitt Lymphoma/virology
- Carcinoma/therapy
- Carcinoma/virology
- Cell Transformation, Neoplastic
- Cell Transformation, Viral
- Epstein-Barr Virus Infections/pathology
- Epstein-Barr Virus Infections/virology
- Herpesvirus 4, Human/genetics
- Herpesvirus 4, Human/pathogenicity
- Herpesvirus 4, Human/physiology
- Humans
- Immunocompromised Host
- Killer Cells, Natural/pathology
- Lymphoma/therapy
- Lymphoma/virology
- Lymphoma, B-Cell/immunology
- Lymphoma, B-Cell/virology
- Lymphoma, T-Cell/virology
- Nasopharyngeal Neoplasms/epidemiology
- Nasopharyngeal Neoplasms/virology
- Stomach Neoplasms/virology
- Viral Proteins/genetics
- Viral Proteins/physiology
- Virus Latency
Collapse
Affiliation(s)
- Lawrence S Young
- Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham, B15 2TT, UK.
| | | |
Collapse
|