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Agwati EO, Oduor CI, Ayieko C, Ong’echa JM, Moormann AM, Bailey JA. Profiling genome-wide recombination in Epstein Barr virus reveals type-specific patterns and associations with endemic-Burkitt lymphoma. Virol J 2022; 19:208. [PMID: 36482473 PMCID: PMC9733152 DOI: 10.1186/s12985-022-01942-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Accepted: 11/30/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Endemic Burkitt lymphoma (eBL) is potentiated through the interplay of Epstein Barr virus (EBV) and holoendemic Plasmodium falciparum malaria. To better understand EBV's biology and role in eBL, we characterized genome-wide recombination sites and patterns as a source of genetic diversity in EBV genomes in our well-defined population of eBL cases and controls from Western Kenya. METHODS EBV genomes representing 54 eBL cases and 32 healthy children from the same geographic region in Western Kenya that we previously sequenced were analyzed. Whole-genome multiple sequence alignment, recombination analyses, and phylogenetic inference were made using multiple alignment with fast Fourier transform, recombination detection program 4, and molecular evolutionary genetics analysis. RESULTS We identified 28 different recombination events and 71 (82.6%) of the 86 EBV genomes analyzed contained evidence of one or more recombinant segments. Associated recombination breakpoints were found to occur in a total of 42 different genes, with only 7 (16.67%) being latent genes. Recombination events were major drivers of clustering within genome-wide phylogenetic trees. The occurrence of recombination segments was comparable between genomes from male and female participants and across age groups. More recombinant segments were found in EBV type 1 genomes (p = 6.4e - 06) and the genomes from the eBLs (p = 0.037). Two recombination events were enriched in the eBLs; event 47 (OR = 4.07, p = 0.038) and event 50 (OR = 14.24, p = 0.012). CONCLUSIONS EBV genomes have extensive evidence of recombination likely acquired progressively and cumulatively over time. Recombination patterns display a heterogeneous occurrence rate across the genome with enrichment in lytic genes. Overall, recombination appears to be a major evolutionary force impacting EBV diversity and genome structure with evidence of the association of specific recombinants with eBL.
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Affiliation(s)
- Eddy O. Agwati
- grid.442486.80000 0001 0744 8172Department of Zoology, Maseno University, Maseno, Kenya ,grid.33058.3d0000 0001 0155 5938Center for Global Health Research (CGHR), Kenya Medical Research Institute, Kisumu, Kenya
| | - Cliff I. Oduor
- grid.40263.330000 0004 1936 9094Department of Pathology and Laboratory Medicine, Warren Alpert Medical School, Brown University, Providence, RI 02903 USA
| | - Cyrus Ayieko
- grid.442486.80000 0001 0744 8172Department of Zoology, Maseno University, Maseno, Kenya
| | - John Michael Ong’echa
- grid.33058.3d0000 0001 0155 5938Center for Global Health Research (CGHR), Kenya Medical Research Institute, Kisumu, Kenya
| | - Ann M. Moormann
- grid.168645.80000 0001 0742 0364Program in Molecular Medicine and the Diabetes Center of Excellence, University of Massachusetts Chan Medical School, Worcester, MA 01605 USA
| | - Jeffrey A. Bailey
- grid.40263.330000 0004 1936 9094Department of Pathology and Laboratory Medicine, Warren Alpert Medical School, Brown University, Providence, RI 02903 USA
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Bauer M, Jasinski-Bergner S, Mandelboim O, Wickenhauser C, Seliger B. Epstein-Barr Virus-Associated Malignancies and Immune Escape: The Role of the Tumor Microenvironment and Tumor Cell Evasion Strategies. Cancers (Basel) 2021; 13:cancers13205189. [PMID: 34680337 PMCID: PMC8533749 DOI: 10.3390/cancers13205189] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/06/2021] [Accepted: 10/11/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary The Epstein–Barr virus, also termed human herpes virus 4, is a human pathogenic double-stranded DNA virus. It is highly prevalent and has been linked to the development of 1–2% of cancers worldwide. EBV-associated malignancies encompass various structural and epigenetic alterations. In addition, EBV-encoded gene products and microRNAs interfere with innate and adaptive immunity and modulate the tumor microenvironment. This review provides an overview of the characteristic features of EBV with a focus on the intrinsic and extrinsic immune evasion strategies, which contribute to EBV-associated malignancies. Abstract The detailed mechanisms of Epstein–Barr virus (EBV) infection in the initiation and progression of EBV-associated malignancies are not yet completely understood. During the last years, new insights into the mechanisms of malignant transformation of EBV-infected cells including somatic mutations and epigenetic modifications, their impact on the microenvironment and resulting unique immune signatures related to immune system functional status and immune escape strategies have been reported. In this context, there exists increasing evidence that EBV-infected tumor cells can influence the tumor microenvironment to their own benefit by establishing an immune-suppressive surrounding. The identified mechanisms include EBV gene integration and latent expression of EBV-infection-triggered cytokines by tumor and/or bystander cells, e.g., cancer-associated fibroblasts with effects on the composition and spatial distribution of the immune cell subpopulations next to the infected cells, stroma constituents and extracellular vesicles. This review summarizes (i) the typical stages of the viral life cycle and EBV-associated transformation, (ii) strategies to detect EBV genome and activity and to differentiate various latency types, (iii) the role of the tumor microenvironment in EBV-associated malignancies, (iv) the different immune escape mechanisms and (v) their clinical relevance. This gained information will enhance the development of therapies against EBV-mediated diseases to improve patient outcome.
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Affiliation(s)
- Marcus Bauer
- Department of Pathology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 14, 06112 Halle (Saale), Germany; (M.B.); (C.W.)
| | - Simon Jasinski-Bergner
- Department of Medical Immunology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 2, 06112 Halle (Saale), Germany;
| | - Ofer Mandelboim
- Department of Immunology, Faculty of Medicine, The Hebrew University of Jerusalem, En Kerem, P.O. Box 12271, Jerusalem 91120, Israel;
| | - Claudia Wickenhauser
- Department of Pathology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 14, 06112 Halle (Saale), Germany; (M.B.); (C.W.)
| | - Barbara Seliger
- Department of Medical Immunology, Martin Luther University Halle-Wittenberg, Magdeburger Str. 2, 06112 Halle (Saale), Germany;
- Fraunhofer Institute for Cell Therapy and Immunology, Perlickstr. 1, 04103 Leipzig, Germany
- Correspondence: ; Tel.: +49-(345)-557-1357
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Rüeger S, Hammer C, Loetscher A, McLaren PJ, Lawless D, Naret O, Khanna N, Bernasconi E, Cavassini M, Günthard HF, Kahlert CR, Rauch A, Depledge DP, Morfopoulou S, Breuer J, Zdobnov E, Fellay J. The influence of human genetic variation on Epstein-Barr virus sequence diversity. Sci Rep 2021; 11:4586. [PMID: 33633271 PMCID: PMC7907281 DOI: 10.1038/s41598-021-84070-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 02/11/2021] [Indexed: 02/07/2023] Open
Abstract
Epstein-Barr virus (EBV) is one of the most common viruses latently infecting humans. Little is known about the impact of human genetic variation on the large inter-individual differences observed in response to EBV infection. To search for a potential imprint of host genomic variation on the EBV sequence, we jointly analyzed paired viral and human genomic data from 268 HIV-coinfected individuals with CD4 + T cell count < 200/mm3 and elevated EBV viremia. We hypothesized that the reactivated virus circulating in these patients could carry sequence variants acquired during primary EBV infection, thereby providing a snapshot of early adaptation to the pressure exerted on EBV by the individual immune response. We searched for associations between host and pathogen genetic variants, taking into account human and EBV population structure. Our analyses revealed significant associations between human and EBV sequence variation. Three polymorphic regions in the human genome were found to be associated with EBV variation: one at the amino acid level (BRLF1:p.Lys316Glu); and two at the gene level (burden testing of rare variants in BALF5 and BBRF1). Our findings confirm that jointly analyzing host and pathogen genomes can identify sites of genomic interactions, which could help dissect pathogenic mechanisms and suggest new therapeutic avenues.
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Affiliation(s)
- Sina Rüeger
- School of Life Sciences, EPFL, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | | | - Alexis Loetscher
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Paul J McLaren
- JC Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, Winnipeg, MB, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada
| | - Dylan Lawless
- School of Life Sciences, EPFL, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Olivier Naret
- School of Life Sciences, EPFL, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Nina Khanna
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Enos Bernasconi
- Division of Infectious Diseases, Regional Hospital Lugano, Lugano, Switzerland
| | - Matthias Cavassini
- Division of Infectious Diseases, University Hospital Lausanne, University of Lausanne, Lausanne, Switzerland
| | - Huldrych F Günthard
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Christian R Kahlert
- Division of Infectious Diseases and Hospital Epidemiology, Cantonal Hospital St.Gallen, St.Gallen, Switzerland
- Childrens Hospital of Eastern Switzerland, St. Gallen, Switzerland
| | - Andri Rauch
- Department of Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Daniel P Depledge
- Division of Infection and Immunity, University College London, London, UK
| | - Sofia Morfopoulou
- Division of Infection and Immunity, University College London, London, UK
| | - Judith Breuer
- Division of Infection and Immunity, University College London, London, UK
| | - Evgeny Zdobnov
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Jacques Fellay
- School of Life Sciences, EPFL, Lausanne, Switzerland.
- Swiss Institute of Bioinformatics, Lausanne, Switzerland.
- Precision Medicine Unit, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
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Epstein–Barr Virus Infection Related to Low White Blood Cell Count in Cancer Patients Receiving Chemotherapy in Al-Najaf Governorate/Iraq. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2020. [DOI: 10.22207/jpam.14.2.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Roy Chattopadhyay N, Das P, Chatterjee K, Choudhuri T. Higher incidence of nasopharyngeal carcinoma in some regions in the world confers for interplay between genetic factors and external stimuli. Drug Discov Ther 2019; 11:170-180. [PMID: 28867748 DOI: 10.5582/ddt.2017.01030] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Nasopharyngeal carcinoma (NPC) is a rare variety of head and neck cancers. The risk factors include three major causes: genetic factors, viral infection, and environmental and dietary factors. The types of NPC show strong ethnic and geographic variations. The keratinizing and non-keratinizing types are prevalent in the lower incidence regions like North America and Europe; whereas the undifferentiated type is mostly found in the regions with higher incidences like China, North Africa, Arctic, and Nagaland of North-East India. These suggest a possible major role of the internal genetic factors for generation and promotion of this disease. Viral infections might accelerate the process of carcinogenesis by helping in cellular proliferation and loss of apoptosis. Diet and other environmental factors promote these neoplastic processes and further progression of the disease occurs.
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Affiliation(s)
| | - Piyanki Das
- Department of Biotechnology, Visva-Bharati, Siksha Bhavana
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Natural Variations in BRLF1 Promoter Contribute to the Elevated Reactivation Level of Epstein-Barr Virus in Endemic Areas of Nasopharyngeal Carcinoma. EBioMedicine 2018; 37:101-109. [PMID: 30420297 PMCID: PMC6286269 DOI: 10.1016/j.ebiom.2018.10.065] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/25/2018] [Accepted: 10/26/2018] [Indexed: 12/12/2022] Open
Abstract
Background Epstein-Barr virus (EBV) infection is a crucial risk factor for nasopharyngeal carcinoma (NPC), but the mechanism for its elevated activation level in NPC endemic areas remains unclear. This study aims to identify the EBV natural variations contributed to the different reactivation potential between NPC endemic and non-endemic areas. Methods 1030 subjects were recruited in China, including 303 healthy individuals from two NPC non-endemic areas, 483 healthy people from three endemic areas and 244 NPC patients. Among which, saliva DNA samples from 244 participants were sequenced for the EBV immediate early (IE) genes of BRLF1 and BZLF1, their promoters were included; the rest 786 subjects were used for the validation of significant variations among three different populations. Haplotype and population structure analysis were conducted. Dual-luciferase assay was used to detect the promoter activity. Results A total of 246 distinct variations were detected, 29 showed significant difference in the frequencies between healthy people from NPC endemic area and non-endemic area. Population structure analysis clustered EBV strains into 9 subgroups mostly in accordance with the geographical origin of samples. Interestingly, two EBV genotypes, Rp-V1 and Rp-V2, were identified according to the linkage relationship of the variations in BRLF1 promoter (Rp). Rp-V1 has higher frequency in NPC endemic areas than in non-endemic areas (52.38% vs 18.15%, P = 2.07 × 10−14), and was associated with higher oral EBV DNA levels (adjusted OR = 1.64, 95% CI = 1.21–2.24, P = .002), suggesting a more powerful activation ability of Rp-V1 than that of the prototype Rp-of the EBV strain; On the contrary, Rp-V2 has higher frequency in NPC non-endemic areas than in endemic areas (18.48% vs 0.38%, P = 1.17 × 10−7), might represent a reduced activation potential of EBV. Further dual-luciferase assay showed Rp-V1 has higher promoter activity while compared with Rp-V2 (P < .0001). Notably, Rp-V1 impaired the transcription repression effect of YY1 while Rp-V2 strengthened the transcription repression effect of EBF1 on Rp. In addition, significant differences of Rta 393–407 CTL epitope which may influence the recognition of Rta by CD8+ T cells were detected between healthy people from NPC endemic area and non-endemic area. Conclusions This study identified natural variations in cis-acting elements (YY1 and EBF1) of EBV Rp altering Rp transcription activities, which may contribute to the elevated EBV activation level in NPC endemic areas than non-endemic areas.
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Abstract
What is wild-type Epstein-Barr virus and are there genetic differences in EBV strains that contribute to some of the EBV-associated diseases? Recent progress in DNA sequencing has resulted in many new Epstein-Barr virus (EBV) genome sequences becoming available. EBV isolates worldwide can be grouped into type 1 and type 2, a classification based on the EBNA2 gene sequence. Type 1 transforms human B cells into lymphoblastoid cell lines much more efficiently than type 2 EBV and molecular mechanisms that may account for this difference in cell transformation are now becoming understood. Study of geographic variation of EBV strains independent of the type 1/type 2 classification and systematic investigation of the relationship between viral strains, infection and disease are now becoming possible. So we should consider more directly whether viral sequence variation might play a role in the incidence of some EBV-associated diseases.
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Affiliation(s)
- Paul J Farrell
- Section of Virology, Department of Medicine, Imperial College, St Mary's Campus, Norfolk Place, London, W2 1PG, UK.
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Yang Y, Jia Y, Wang Y, Wang X, Sun Z, Luo B. Sequence analysis of EBV immediate-early gene BZLF1 and BRLF1 in lymphomas. J Med Virol 2014; 86:1788-95. [PMID: 24615673 DOI: 10.1002/jmv.23911] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2014] [Indexed: 12/20/2022]
Abstract
The immediate-early (IE) genes, BZLF1 and BRLF1, play an important role in switching Epstein-Barr virus from the latent to the lytic state. The functions of the two IE genes and their respective proteins: ZEBRA and Rta have been well studied, but little is known about their DNA coding sequence variations and disease association. In order to investigate the sequence variation patterns and elucidate their association with lymphomas, BZLF1 and BRLF1 were analyzed in 26 and 33 lymphomas using PCR-direct sequencing method respectively. Three sequence variation types of BZLF1 gene were identified. The type BZLF1-A and BZLF1-B was detected in 34.6% (9/26) and 57.7% (15/26) of the tumor specimens, respectively. Among the three functional domains of ZEBRA, the transactivation domain had the most mutations. Three variation types were also identified in BRLF1 gene where type BR1-A and BR1-C were detected in 27.3% (9/33) and 69.7% (23/33) of specimens, respectively. Among the three functional domains of Rta, the dimerization domain was well conserved while multiple mutations were detected in both the DNA binding domain and the transactivation domain. The variation types BZLF1-B and BR1-C were more frequent in the lymphomas, compared with the throat washing samples from the healthy donors. These results suggest that the type BZLF1-B and BR1-C may be associated with the tumorigenesis of lymphoma.
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Affiliation(s)
- Ying Yang
- Department of Medical Microbiology, Qingdao University Medical College, Qingdao, 266021, China
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Atypical Epstein-Barr viral genomic structure in lymphoma tissue and lymphoid cell lines. ACTA ACUST UNITED AC 2014; 22:91-101. [PMID: 23628820 DOI: 10.1097/pdm.0b013e318273fb43] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Epstein-Barr virus (EBV) DNA is found within the malignant cells of some subtypes of lymphoma, and viral presence is being exploited for improved diagnosis, monitoring, and management of affected patients. Recent work suggests that viral genomic polymorphism, such as partial deletion of the viral genome, could interfere with virus detection in tumor tissues. To test for atypical forms of the EBV genome, 98 lymphomas and 6 infected cell lines were studied using a battery of 6 quantitative polymerase chain reaction assays targeting disparate sections of EBV DNA. Fifty of the lymphomas (51%) had no amplifiable EBV DNA, and 38 lymphomas (39%) had low-level EBV infection that was deemed incidental based on EBV-encoded RNA (EBER) in situ hybridization results. The remaining 10 lymphomas (10%) had high EBV loads and EBER localization to malignant cells by EBER in situ hybridization. All 10 represented lymphoma subtypes were previously associated with EBV (Burkitt, diffuse large B-cell, or T-cell type), whereas no remnants of EBV were detected in other lymphoma subtypes (follicular, small lymphocytic, mantle cell, or marginal zone type). Interestingly, 4 of the 10 infected lymphomas had evidence of atypical viral genomes, including 3 of 4 infected T-cell lymphomas with aberrant loss of LMP2 amplicons, and a single diffuse large B-cell lymphoma lacking the central part of the viral genome spanning BamH1W, BZLF1, and EBNA1 gene segments. A reasonable screening strategy for infected malignancy involves applying EBER1 and LMP1 quantitative polymerase chain reaction assays and confirming that values exceeding 2000 copies of EBV per 100,000 cells have EBER localization to malignant cells.
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Gourzones C, Busson P, Raab-Traub N. Epstein-Barr Virus and the Pathogenesis of Nasopharyngeal Carcinomas. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013. [DOI: 10.1007/978-1-4614-5947-7_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Epstein-barr virus sequence variation-biology and disease. Pathogens 2012; 1:156-74. [PMID: 25436768 PMCID: PMC4235690 DOI: 10.3390/pathogens1020156] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 10/16/2012] [Accepted: 10/30/2012] [Indexed: 12/12/2022] Open
Abstract
Some key questions in Epstein-Barr virus (EBV) biology center on whether naturally occurring sequence differences in the virus affect infection or EBV associated diseases. Understanding the pattern of EBV sequence variation is also important for possible development of EBV vaccines. At present EBV isolates worldwide can be grouped into Type 1 and Type 2, a classification based on the EBNA2 gene sequence. Type 1 EBV is the most prevalent worldwide but Type 2 is common in parts of Africa. Type 1 transforms human B cells into lymphoblastoid cell lines much more efficiently than Type 2 EBV. Molecular mechanisms that may account for this difference in cell transformation are now becoming clearer. Advances in sequencing technology will greatly increase the amount of whole EBV genome data for EBV isolated from different parts of the world. Study of regional variation of EBV strains independent of the Type 1/Type 2 classification and systematic investigation of the relationship between viral strains, infection and disease will become possible. The recent discovery that specific mutation of the EBV EBNA3B gene may be linked to development of diffuse large B cell lymphoma illustrates the importance that mutations in the virus genome may have in infection and human disease.
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Wang X, Wang Y, Wu G, Chao Y, Sun Z, Luo B. Sequence analysis of Epstein-Barr virus EBNA-2 gene coding amino acid 148-487 in nasopharyngeal and gastric carcinomas. Virol J 2012; 9:49. [PMID: 22348267 PMCID: PMC3312847 DOI: 10.1186/1743-422x-9-49] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 02/21/2012] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA-2) plays a key role in the B-cell growth transformation by initiating and maintaining the proliferation of infected B-cell upon EBV infection in vitro. Most studies about EBNA-2 have focused on its functions yet little is known for its intertypic polymorphisms. RESULTS Coding region for amino acid (aa) 148-487 of the EBNA-2 gene was sequenced in 25 EBV-associated gastric carcinomas (EBVaGCs), 56 nasopharyngeal carcinomas (NPCs) and 32 throat washings (TWs) from healthy donors in Northern China. Three variations (g48991t, c48998a, t49613a) were detected in all of the samples (113/113, 100%). EBNA-2 could be classified into four distinct subtypes: E2-A, E2-B, E2-C and E2-D based on the deletion status of three aa (294Q, 357K and 358G). Subtypes E2-A and E2-C were detected in 56/113 (49.6%), 38/113 (33.6%) samples, respectively. E2-A was observed more in EBVaGCs samples and subtype E2-D was only detected in the NPC samples. Variation analysis in EBNA-2 functional domains: the TAD residue (I438L) and the NLS residues (E476G, P484H and I486T) were only detected in NPC samples which located in the carboxyl terminus of EBNA-2 gene. CONCLUSIONS The subtypes E2-A and E2-C were the dominant genotypes of the EBNA-2 gene in Northern China. The subtype E2-D may be associated with the tumorigenesis of NPC. The NPC isolates were prone harbor to more mutations than the other two groups in the functional domains.
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Affiliation(s)
- Xinying Wang
- Department of Medical Microbiology, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, China
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