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Nanbo A. Current Insights into the Maturation of Epstein-Barr Virus Particles. Microorganisms 2024; 12:806. [PMID: 38674750 PMCID: PMC11051851 DOI: 10.3390/microorganisms12040806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/12/2024] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
The three subfamilies of herpesviruses (alphaherpesviruses, betaherpesviruses, and gammaherpesviruses) appear to share a unique mechanism for the maturation and egress of virions, mediated by several budding and fusion processes of various organelle membranes during replication, which prevents cellular membrane disruption. Newly synthesized viral DNA is packaged into capsids within the nucleus, which are subsequently released into the cytoplasm via sequential fusion (primary envelopment) and budding through the inner and outer nuclear membranes. Maturation concludes with tegumentation and the secondary envelopment of nucleocapsids, which are mediated by budding into various cell organelles. Intracellular compartments containing mature virions are transported to the plasma membrane via host vesicular trafficking machinery, where they fuse with the plasma membrane to extracellularly release mature virions. The entire process of viral maturation is orchestrated by sequential interactions between viral proteins and intracellular membranes. Compared with other herpesvirus subfamilies, the mechanisms of gammaherpesvirus maturation and egress remain poorly understood. This review summarizes the major findings, including recently updated information of the molecular mechanism underlying the maturation and egress process of the Epstein-Barr virus, a ubiquitous human gammaherpesvirus subfamily member that infects most of the population worldwide and is associated with a number of human malignancies.
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Affiliation(s)
- Asuka Nanbo
- National Research Center for the Control and Prevention of Infectious Diseases, Nagasaki University, Nagasaki 852-8523, Japan
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Epstein-Barr Virus Exploits the Secretory Pathway to Release Virions. Microorganisms 2020; 8:microorganisms8050729. [PMID: 32414202 PMCID: PMC7285239 DOI: 10.3390/microorganisms8050729] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 01/06/2023] Open
Abstract
Herpesvirus egress mechanisms are strongly associated with intracellular compartment remodeling processes. Previously, we and other groups have described that intracellular compartments derived from the Golgi apparatus are the maturation sites of Epstein-Barr virus (EBV) virions. However, the mechanism by which these virions are released from the host cell to the extracellular milieu is poorly understood. Here, I adapted two independent induction systems of the EBV lytic cycle in vitro, in the context of Rab GTPase silencing, to characterize the EBV release pathway. Immunofluorescence staining revealed that p350/220, the major EBV glycoprotein, partially co-localized with three Rab GTPases: Rab8a, Rab10, and Rab11a. Furthermore, the knockdown of these Rab GTPases promoted the intracellular accumulation of viral structural proteins by inhibiting its distribution to the plasma membrane. Finally, the knockdown of the Rab8a, Rab10, and Rab11a proteins suppressed the release of EBV infectious virions. Taken together, these findings support the hypothesis that mature EBV virions are released from infected cells to the extracellular milieu via the secretory pathway, as well as providing new insights into the EBV life cycle.
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Nanbo A, Noda T, Ohba Y. Epstein-Barr Virus Acquires Its Final Envelope on Intracellular Compartments With Golgi Markers. Front Microbiol 2018; 9:454. [PMID: 29615992 PMCID: PMC5864893 DOI: 10.3389/fmicb.2018.00454] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/27/2018] [Indexed: 01/18/2023] Open
Abstract
Herpesvirus subfamilies typically acquire their final envelope in various cytoplasmic compartments such as the trans-Golgi network (TGN), and endosomes prior to their secretion into the extracellular space. However, the sites for the final envelopment of Epstein–Barr virus (EBV), a ubiquitous human gamma herpesvirus, are poorly understood. Here, we characterized the sites for the final envelopment of EBV in Burkitt’s lymphoma cell lines induced into the lytic cycle by crosslinking cell surface IgG. Electron microscopy revealed the various stages of maturation and egress of progeny virions including mature EBV in irregular cytoplasmic vesicles. Immunofluorescence staining showed that gp350/220, the major EBV glycoprotein, and the viral capsid antigen, p18, efficiently colocalized with a cis-Golgi marker, GM130. gp350/220 partly colocalized with the TGN, which was distributed in a fragmented and dispersed pattern in the cells induced into the lytic cycle. In contrast, limited colocalization was observed between gp350/220 and endosomal markers, such as a multi-vesicular bodies marker, CD63, a recycling endosome marker, Rab11, and a regulatory secretion vesicles marker, Rab27a. Finally, we observed that treatment of cells with brefeldin A, an inhibitor of vesicle trafficking between the endoplasmic reticulum and Golgi apparatus, resulted in the perinuclear accumulation of gp350/220 and inhibition of its distribution to the plasma membrane. Brefeldin A also inhibited the release of infectious EBV. Taken together, our findings support a model in which EBV acquires its final envelope in intracellular compartments containing markers of Golgi apparatus, providing new insights into how EBV matures.
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Affiliation(s)
- Asuka Nanbo
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Takeshi Noda
- Laboratory of Ultrastructural Virology, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Yusuke Ohba
- Department of Cell Physiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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Peng L, Ryazantsev S, Sun R, Zhou ZH. Three-dimensional visualization of gammaherpesvirus life cycle in host cells by electron tomography. Structure 2010; 18:47-58. [PMID: 20152152 DOI: 10.1016/j.str.2009.10.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2009] [Revised: 09/03/2009] [Accepted: 10/30/2009] [Indexed: 12/27/2022]
Abstract
Gammaherpesviruses are etiologically associated with human tumors. A three-dimensional (3D) examination of their life cycle in the host is lacking, significantly limiting our understanding of the structural and molecular basis of virus-host interactions. Here, we report the first 3D visualization of key stages of the murine gammaherpesvirus 68 life cycle in NIH 3T3 cells, including viral attachment, entry, assembly, and egress, by dual-axis electron tomography. In particular, we revealed the transient processes of incoming capsids injecting viral DNA through nuclear pore complexes and nascent DNA being packaged into progeny capsids in vivo as a spool coaxial with the putative portal vertex. We discovered that intranuclear invagination of both nuclear membranes is involved in nuclear egress of herpesvirus capsids. Taken together, our results provide the structural basis for a detailed mechanistic description of gammaherpesvirus life cycle and also demonstrate the advantage of electron tomography in dissecting complex cellular processes of viral infection.
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Affiliation(s)
- Li Peng
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
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Haga T, Uchide N, Tugizov S, Palefsky JM. Role of E-cadherin in the induction of apoptosis of HPV16-positive CaSki cervical cancer cells during multicellular tumor spheroid formation. Apoptosis 2007; 13:97-108. [PMID: 17906929 DOI: 10.1007/s10495-007-0132-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Multicellular tumor spheroids (MCTS) are three dimensional cell culture systems induced by suspension culture. MCTS are widely used in cancer research because of their similarity to solid tumors. CaSki cells are derived from a metastatic cervical cancer containing human papillomavirus 16 (HPV16). Cell death of CaSki cells in MCTS has been previously reported, and our model is used to better characterize the mechanisms of cell death of HPV16-positive keratinocytes. In this study, we found that apoptosis of CaSki cells was induced by suspension culture along with the formation of MCTS after 24 h of incubation. In suspended CaSki cells, monoclonal antibodies blocking E-cadherin function inhibited MCTS formation and suppressed suspension-induced apoptosis in a dose-dependent manner. Western blot for E-cadherin detected upregulation of the authentic 120 kDa band from MCTS of CaSki cells as well as a shorter 100 kDa band. Addition of EGF, whose receptor is known to form a complex with E-cadherin, abrogated apoptosis of suspended CaSki cells in a dose-dependent manner. These findings suggest that E-cadherin-dependent cell-cell contact, directly or indirectly, mediates the signal to undergo apoptosis of CaSki cells during MCTS formation, and thus provides new information on the role of E-cadherin in cervical cancer cell apoptosis.
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Affiliation(s)
- Takeshi Haga
- Department of Veterinary Microbiology, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki, Japan.
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Alemañ N, Quiroga MI, López-Peña M, Vázquez S, Guerrero FH, Nieto JM. L-particle production during primary replication of pseudorabies virus in the nasal mucosa of swine. J Virol 2003; 77:5657-67. [PMID: 12719558 PMCID: PMC154012 DOI: 10.1128/jvi.77.10.5657-5667.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2002] [Accepted: 02/19/2003] [Indexed: 01/14/2023] Open
Abstract
Different tissue culture cell lines infected with a number of alphaherpesviruses produce, in addition to virions, light particles (L particles). L particles are composed of the envelope and tegument components of the virion but totally lack the proteins of the capsid and the virus genome; therefore, they are noninfectious. In this electron microscopy report, we show that L particles are produced during primary replication of the alphaherpesvirus pseudorabies virus (PRV) in the nasal mucosa of experimentally infected swine, its natural host. Although PRV infected different types of cells of the respiratory and olfactory mucosae, PRV L particles were found to be produced exclusively by epithelial cells and fibroblasts. We observed that formation of noninfectious particles occurred by budding of condensed tegument at the inner nuclear membrane and at membranes of cytoplasmic vesicles, resulting in intracisternal and intravesicular L particles, respectively. Both forms of capsidless particles were clearly distinguishable by the presence of prominent surface projections on the envelope and the higher electron density of the tegument, morphological features which were only observed in intravesicular L particles. Moreover, intravesicular but not intracisternal L particles were found to be released by exocytosis and were also identified extracellularly. Comparative analysis between PRV virion and L-particle morphogenesis indicates that both types of virus particles share a common intracellular pathway of assembly and egress but that they show different production patterns during the replication cycle of PRV.
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Affiliation(s)
- Nuria Alemañ
- Departamento de Anatomía y Producción Animal, Facultad de Veterinaria, Universidad de Santiago de Compostela, E-27002 Lugo, Spain.
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Mizuki H. In situ staining with DNA-binding fluorescent dye, Hoechst 33258, to detect microorganisms in the epithelial cells of oral leukoplakia. Oral Oncol 2001; 37:521-6. [PMID: 11435179 DOI: 10.1016/s1368-8375(01)00016-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study was performed to investigate the presence of microorganisms in the epithelial cells of leukoplakia. Frozen sections of 20 specimens of leukoplakia were stained with DNA-binding bisbenzimide Hoechst 33258. As a control, 20 specimens of normal oral mucosa and five specimens of normal skin were used. In all preparations of leukoplakia, small granular fluorescing structures were observed within the cytoplasm of the epithelial cells, predominantly within the cytoplasm of prickle cells, although the amount of the granular structures varied between specimens, layers of the epithelium and even areas of the epithelium within a single section. Less granular structures were observed, or none at all, in the cytoplasm of the epithelial cells of normal mucosa. No structures were observed in the cytoplasm of the epithelium of skin. The results in this study strongly suggest that microorganisms are present in the epithelial cells of oral mucosa, and that they are closely associated with the development of oral leukoplakia. It is postulated that the microorganisms in the epithelial cells could be bacteria, particularly mycoplasmas.
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Affiliation(s)
- H Mizuki
- Department of Oral and Maxillo-Facial Surgery, Oita Medical University, Hasama-machi, 879-5593, Oita, Japan.
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Guccion JG, Redman RS. Oral hairy leukoplakia: an ultrastructural study and review of the literature. Ultrastruct Pathol 1999; 23:181-7. [PMID: 10445285 DOI: 10.1080/019131299281680] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
A 39-year-old, homosexual, Caucasian man with a 9-month history of acquired immunodeficiency syndrome by reduced CD4 lymphocyte count alone was found to have extensive, asymptomatic, nonremovable, corrugated, white patches on the lateral borders and ventral aspects of the tongue typical of oral hairy leukoplakia (OHL). Histologically, irregular hyperparakeratosis, acanthosis, and clusters of ballooned keratinocytes in the stratum spinosum were present in the biopsied lateral tongue. Some of the superficial ballooned keratinocytes had peripherally beaded nuclei, whereas others had ground glass intranuclear inclusions. Ultrastructurally, the ballooned keratinocytes had three important findings of diagnostic significance. First, frequent herpesvirus nucleocapsids were largely confined to superficial ballooned keratinocytes having marginated and condensed chromatin. In searching for herpesvirus nucleocapsids, the marginated and condensed chromatin was an invaluable marker for cells harboring the virions. Second, the marginated and condensed chromatin frequently had a distinctive punched-out or cribriform appearance. Third, the ground glass intranuclear inclusion bodies consisted of central, medium electron-dense, finely granular material containing frequent herpesvirus nucleocapsids and partially surrounded or capped by prominent, clumped chromatin. The patient died with progressive multifocal leukoencephalopathy 24 months after OHL was diagnosed.
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Affiliation(s)
- J G Guccion
- Department of Veterans Affairs Medical Center, Washington, DC, USA
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Greenspan JS, De Souza YG, Regezi JA, Daniels TE, Greenspan D, MacPhail LA, Hilton JF. Comparison of cytopathic changes in oral hairy leukoplakia with in situ hybridization for EBV DNA. Oral Dis 1998; 4:95-9. [PMID: 9680897 DOI: 10.1111/j.1601-0825.1998.tb00264.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE It has been observed that the cytopathic changes in hairy leukoplakia (HL) correlate with ultrastructural evidence of intra-keratinocyte herpes-type viral particles. In situ hybridization is considered to be the definitive confirmation of Epstein-Barr virus (EBV)-induced HL. This study evaluated the consistency of histopathological findings, which many believe to be diagnostic, with in situ hybridization for EBV-DNA in 60 patients with lesions clinically suggestive of HL. MATERIALS AND METHODS Hematoxylin and eosin (H&E)-stained sections were reviewed independently by three oral pathologists who did not know the hybridization results. The presence in keratinocytes of nuclear inclusions and/or homogenization, believed to be specific for EBV in these lesions, was used as an indicator for infection. Cytoplasmic changes were evaluated separately. RESULTS With in situ hybridization, 48 cases were positive and 12 were negative. When the two methods were compared, pathologist concurrence ranged from 83% to 92%. False negatives ranged from 6% to 19%, and false positives ranged from 8% to 25%. Cytoplasmic ballooning, homogenization, and perinuclear clearing were evident in all cases of hybridization-confirmed HL; however, these changes were also noted in 75% (9/12) of the cases with negative hybridization results. Most confirmed HL cases exhibited both nuclear homogenization and inclusions, although the former was more consistently seen. CONCLUSION Cytoplasmic changes did not agree well with EBV-DNA hybridization results, whereas nuclear changes demonstrated good, but not complete, agreement. In appropriate clinical settings, the finding of nuclear inclusions and/or homogenization may be of diagnostic value. However, because the potential for false positives and negatives is high, H&E cytopathology should not be used as a substitute for in situ hybridization in the definitive diagnosis of oral hairy leukoplakia.
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Affiliation(s)
- J S Greenspan
- Department of Stomatology and Oral AIDS Center, University of California San Francisco, USA. stom%
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Boulter A, Johnson NW, Birnbaum W, Teo CG. Epstein-Barr virus (EBV) associated lesions of the head and neck. Oral Dis 1996; 2:117-24. [PMID: 8957923 DOI: 10.1111/j.1601-0825.1996.tb00211.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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11
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Reichart PA. Oral pathology of acquired immunodeficiency syndrome and oro-facial Kaposi's sarcoma. CURRENT TOPICS IN PATHOLOGY. ERGEBNISSE DER PATHOLOGIE 1996; 90:97-123. [PMID: 8791749 DOI: 10.1007/978-3-642-80169-3_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- P A Reichart
- Abteilung für Oralchirurgie und Zahnärztliche Röntgenologie, Universitatsklinikum Charité Medizinische Fakultät der Humboldt-Universitat zu Berlin, Germany
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12
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Affiliation(s)
- P H Itin
- Department of Dermatology, University Hospital, Basel, Switzerland
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13
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Greenspan D, Greenspan JS. Significance of oral hairy leukoplakia. ORAL SURGERY, ORAL MEDICINE, AND ORAL PATHOLOGY 1992; 73:151-4. [PMID: 1312689 DOI: 10.1016/0030-4220(92)90187-u] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Since the original description of oral hairy leukoplakia among homosexual men in San Francisco in 1984, this white lesion of the tongue has been seen in the mouths of persons infected with the human immunodeficiency virus (HIV) worldwide. Its presence in HIV-positive persons usually but not always indicates fairly rapid progression to acquired immunodeficiency syndrome in the absence of antiretroviral therapy. Although the lesion appears to be common in HIV-positive persons, it is also, albeit rarely, seen in other conditions associated with immunosuppression. Epstein-Barr virus is associated with and presumably causes hairy leukoplakia, and the lesion offers insights into the biology of this ubiquitous DNA-oncogenic virus.
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Affiliation(s)
- D Greenspan
- Department of Stomatology, University of California, San Francisco
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Scully C, Laskaris G, Pindborg J, Porter SR, Reichart P. Oral manifestations of HIV infection and their management. I. More common lesions. ORAL SURGERY, ORAL MEDICINE, AND ORAL PATHOLOGY 1991; 71:158-66. [PMID: 2003011 DOI: 10.1016/0030-4220(91)90459-p] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Oral lesions are common at all stages of HIV infection. This first of two articles reviews the clinical features and pathogenesis of common oral manifestations of HIV disease (candidiasis, hairy leukoplakia, Kaposi's sarcoma, and HIV-related periodontal disease) and considers current treatment measures.
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Affiliation(s)
- C Scully
- Department of Oral Medicine, Surgery and Pathology, Bristol Dental Hospital and School, U.K
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