154 results found
Ponnusamy R, Khatri R, Correia PB, et al., 2019, Increased association between Epstein-Barr virus EBNA2 from type 2 strains and the transcriptional repressor BS69 restricts EBNA2 activity, PLoS Pathogens, Vol: 15, ISSN: 1553-7366
Natural variation separates Epstein-Barr virus (EBV) into type 1 and type 2 strains. Type 2 EBV is less transforming in vitro due to sequence differences in the EBV transcription factor EBNA2. This correlates with reduced activation of the EBV oncogene LMP1 and some cell genes. Transcriptional activation by type 1 EBNA2 can be suppressed through the binding of two PXLXP motifs in its transactivation domain (TAD) to the dimeric coiled-coil MYND domain (CC-MYND) of the BS69 repressor protein (ZMYND11). We identified a third conserved PXLXP motif in type 2 EBNA2. We found that type 2 EBNA2 peptides containing this motif bound BS69CC-MYND efficiently and that the type 2 EBNA2TAD bound an additional BS69CC-MYND molecule. Full-length type 2 EBNA2 also bound BS69 more efficiently in pull-down assays. Molecular weight analysis and low-resolution structures obtained using small-angle X-ray scattering showed that three BS69CC-MYND dimers bound two molecules of type 2 EBNA2TAD, in line with the dimeric state of full-length EBNA2 in vivo. Importantly, mutation of the third BS69 binding motif in type 2 EBNA2 improved B-cell growth maintenance and the transcriptional activation of the LMP1 and CXCR7 genes. Our data indicate that increased association with BS69 restricts the function of type 2 EBNA2 as a transcriptional activator and driver of B cell growth and may contribute to reduced B-cell transformation by type 2 EBV.
Alizon S, Bravo IG, Farrell PJ, et al., 2019, Towards a multi-level and a multi-disciplinary approach to DNA oncovirus virulence, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 374, ISSN: 0962-8436
Bridges R, Correia S, Wegner F, et al., 2019, Essential role of inverted repeat in Epstein–Barr virus IR-1 in B cell transformation; geographical variation of the viral genome, Philosophical Transactions B: Biological Sciences, Vol: 374, ISSN: 0962-8436
Many regions of the Epstein‐Barr virus (EBV) genome, repeated and unique sequences, contribute to the geographic variation observed between strains. Here we use a large alignment of curated EBV genome sequences to identify major sites of variation in the genome of type 1 EBV strains; the CAO deletion in latent membrane protein 1 (LMP1) is the most frequent major indel present in the unique regions of EBV strains from various parts of the world. Principal component analysis was used to identify patterns of sequence variation and nucleotide positions in the sequences which can distinguish EBV from some different geographic regions. Viral genome sequence variation also affects interpretation of genetic content; known genes, origins of replication and gene expression control regions explain most of the viral genome but there are still a few sections of unknown function. One of these EBV genome regions contains a large inverted repeat sequence (invR) within the IR‐1 major internal repeat array. We deleted this invR sequence and showed that this abolished the ability of the virus to transform human B cells into lymphoblastoid cell lines.
Farrell P, Paschos K, 2019, Requirement for PRC1 subunit BMI1 in host gene activation by Epstein-Barr virus potein EBNA3C, Nucleic Acids Research, Vol: 47, Pages: 2807-2821, ISSN: 0305-1048
Epstein–Barr virus proteins EBNA3A, EBNA3B and EBNA3C control hundreds of host genes after infection. Changes in epigenetic marks around EBNA3-regulated genes suggest that they exert transcriptional control in collaboration with epigenetic factors. The roles of polycomb repressive complex (PRC)2 subunit SUZ12 and of PRC1 subunit BMI1 were assessed for their importance in EBNA3-mediated repression and activation. ChIP-seq experiments for SUZ12 and BMI1 were performed to determine their global localization on chromatin and analysis offered further insight into polycomb protein distribution in differentiated cells. Their localization was compared to that of each EBNA3 to resolve longstanding questions about the EBNA3–polycomb relationship. SUZ12 did not co-localize with any EBNA3, whereas EBNA3C co-localized significantly and co-immunoprecipitated with BMI1. In cells expressing a conditional EBNA3C, BMI1 was sequestered to EBNA3C-binding sites after EBNA3C activation. When SUZ12 or BMI1 was knocked down in the same cells, SUZ12 did not contribute to EBNA3C-mediated regulation. Surprisingly, after BMI1 knockdown, EBNA3C repressed equally efficiently but host gene activation by EBNA3C was impaired. This overturns previous assumptions about BMI1/PRC1 functions during EBNA3C-mediated regulation, for the first time identifies directly a host factor involved in EBNA3-mediated activation and provides a new insight into how PRC1 can be involved in gene activation.
Farrell PJ, Epstein‐Barr virus and cancer, Annual Review of Pathology: Mechanisms of Disease, ISSN: 1553-4014
Epstein‐Barr virus (EBV) contributes to about 1.5% of all cases of human cancer worldwide and viral genes are expressed in the malignant cells. EBV also very efficiently causes proliferation of infected human B lymphocytes. The functions of the viral proteins and small RNAs that may contribute to the EBV associated cancers are becoming increasingly clear and a broader understanding of sequence variation of the virus genome has helped to interpret their roles. The improved understanding of the mechanisms of these cancers means that the EBV associated cancers offer great opportunities for early diagnosis of treatable stages of disease and immunotherapy to target EBV infected cells or overcome immune evasion. There is also scope for prevention of disease by immunisation and for development of therapeutic agents that target EBV gene products expressed in the cancers.
Correia S, Bridges R, Wegner F, et al., 2018, Sequence variation of Epstein-Barr virus: viral types, geography, codon usage and diseases, Journal of Virology, Vol: 92, ISSN: 1098-5514
138 new Epstein-Barr virus (EBV) genome sequences have been determined. 125 of these and 116 from previous reports were combined to produce a multiple sequence alignment of 241 EBV genomes, which we have used to analyze variation within the viral genome. The type 1/type2 classification of EBV remains the major form of variation and is defined mostly by EBNA2 and EBNA3, but the type 2 SNPs at the EBNA3 locus extend into the adjacent gp350 and gp42 genes, whose products mediate infection of B cells by EBV. A small insertion within the BART miRNA region of the genome was present in 21 EBV strains. EBV from saliva of USA patients with chronic active EBV infection aligned with the wild type EBV genome, with no evidence of WZhet rearrangements. The V3 polymorphism in the Zp promoter for BZLF1 was found to be frequent in nasopharyngeal carcinoma cases both from Hong Kong and Indonesia. Codon usage was found to differ between latent and lytic cycle EBV genes and the main forms of variation of the EBNA1 protein have been identified.IMPORTANCE Epstein-Barr virus causes most cases of infectious mononucleosis and post-transplant lymphoproliferative disease. It contributes to several types of cancer including Hodgkin's lymphoma, Burkitt's lymphoma, diffuse large B cell lymphoma, nasopharyngeal carcinoma and gastric carcinoma. EBV genome variation is important because some of the diseases associated with EBV have very different incidences in different populations and geographic regions - differences in the EBV genome might contribute to these diseases. Some specific EBV genome alterations that appear to be significant in EBV associated cancers are already known and current efforts to make an EBV vaccine and antiviral drugs should also take account of sequence differences in the proteins used as targets.
Bristol J, Djavadian R, Albright E, et al., 2018, A cancer-associated Epstein-Barr virus BZLF1 promoter variant enhances lytic infection, PLoS Pathogens, Vol: 14, ISSN: 1553-7366
Latent Epstein-Barr virus (EBV) infection contributes to both B-cell and epithelial-cell malignancies. However, whether lytic EBV infection also contributes to tumors is unclear, although the association between malaria infection and Burkitt lymphomas (BLs) may involve excessive lytic EBV replication. A particular variant of the viral promoter (Zp) that controls lytic EBV reactivation is over-represented, relative to its frequency in non-malignant tissue, in EBV-positive nasopharyngeal carcinomas and AIDS-related lymphomas. To date, no functional differences between the prototype Zp (Zp-P) and the cancer-associated variant (Zp-V3) have been identified. Here we show that a single nucleotide difference between the Zp-V3 and Zp-P promoters creates a binding site for the cellular transcription factor, NFATc1, in the Zp-V3 (but not Zp-P) variant, and greatly enhances Zp activity and lytic viral reactivation in response to NFATc1-inducing stimuli such as B-cell receptor activation and ionomycin. Furthermore, we demonstrate that restoring this NFATc1-motif to the Zp-P variant in the context of the intact EBV B95.8 strain genome greatly enhances lytic viral reactivation in response to the NFATc1-activating agent, ionomycin, and this effect is blocked by the NFAT inhibitory agent, cyclosporine, as well as NFATc1 siRNA. We also show that the Zp-V3 variant is over-represented in EBV-positive BLs and gastric cancers, and in EBV-transformed B-cell lines derived from EBV-infected breast milk of Kenyan mothers that had malaria during pregnancy. These results demonstrate that the Zp-V3 enhances EBV lytic reactivation to physiologically-relevant stimuli, and suggest that increased lytic infection may contribute to the increased prevalence of this variant in EBV-associated malignancies.
Styles CT, Paschos K, White R, et al., 2018, The cooperative functions of the EBNA3 Proteins are central to EBV persistence and latency, Pathogens, Vol: 31, ISSN: 2076-0817
The Epstein–Barr nuclear antigen 3 (EBNA3) family of proteins, comprising EBNA3A, EBNA3B, and EBNA3C, play pivotal roles in the asymptomatic persistence and life-long latency of Epstein–Barr virus (EBV) in the worldwide human population. EBNA3-mediated transcriptional reprogramming of numerous host cell genes promotes in vitro B cell transformation and EBV persistence in vivo. Despite structural and sequence similarities, and evidence of substantial cooperative activity between the EBNA3 proteins, they perform quite different, often opposing functions. Both EBNA3A and EBNA3C are involved in the repression of important tumour suppressive pathways and are considered oncogenic. In contrast, EBNA3B exhibits tumour suppressive functions. This review focuses on how the EBNA3 proteins achieve the delicate balance required to support EBV persistence and latency, with emphasis on the contribution of the Allday laboratory to the field of EBNA3 biology.
Correia S, Palser A, Elgueta Karstegl C, et al., 2017, Natural variation of Epstein-Barr virus genes, proteins and pri-microRNA, Journal of Virology, Vol: 91, ISSN: 1098-5514
Viral gene sequences from an enlarged set of about 200 Epstein-Barr virus (EBV) strains including many primary isolates have been used to investigate variation in key viral genetic regions, particularly LMP1, Zp, gp350, EBNA1 and the BART miRNA cluster 2. Determination of type 1 and type 2 EBV in saliva samples from people from a wide range of geographic and ethnic backgrounds demonstrates a small percentage of healthy white Caucasian British people carrying predominantly type 2 EBV. Linkage of Zp and gp350 variants to type 2 EBV is likely to be due to their genes being adjacent to the EBNA3 locus, which is one of the major determinants of the type 1/type 2 distinction. A novel classification of EBNA1 DNA binding domains named QCIGP results from phylogeny analysis of their protein sequences but is not linked to the type 1/type 2 classification. The BART cluster 2 miRNA region is classified into three major variants through SNPs in the pri-miRNA outside of the mature miRNA sequences. These SNPs can result in altered levels of expression of some miRNAs from the BART variant frequently present in Chinese and Indonesian nasopharyngeal carcinoma (NPC) samples. The EBV genetic variants identified here provide a basis for future more directed analysis of association of specific EBV variation with EBV biology and EBV associated diseases.IMPORTANCE Incidence of diseases associated with EBV varies greatly in different parts of the world. Relationships between EBV genome sequence variation and health, disease, geography and ethnicity of the host may thus be important for understanding the role of EBV in diseases and for development of an effective EBV vaccine. This paper provides the most comprehensive analysis so far of variation in specific EBV genes relevant to these diseases and proposed EBV vaccines. By focussing on variation in LMP1, Zp, gp350, EBNA1 and the BART miRNA cluster 2, new relationships to the known type 1/type 2 strains are demonstrated and novel classificati
Brady G, Haas DA, Farrell PJ, et al., 2017, Molluscum Contagiosum Virus Protein MC005 Inhibits NF-kappa B Activation by Targeting NEMO-Regulated I kappa B Kinase Activation, Journal of Virology, Vol: 91, ISSN: 1098-5514
Molluscum contagiosum virus (MCV), the only known extant human-adapted poxvirus, causes a long-duration infection characterized by skin lesions that typically display an absence of inflammation despite containing high titers of live virus. Despite this curious presentation, MCV is very poorly characterized in terms of host-pathogen interactions. The absence of inflammation around MCV lesions suggests the presence of potent inhibitors of human antiviral immunity and inflammation. However, only a small number of MCV immunomodulatory genes have been characterized in detail. It is likely that many more remain to be discovered, given the density of such sequences in other poxvirus genomes. NF-κB activation occurs in response to both virus-induced pattern recognition receptor (PRR) signaling and cellular activation by virus-induced proinflammatory cytokines like tumor necrosis factor and interleukin-1. Activated NF-κB drives cytokine and interferon gene expression, leading to inflammation and virus clearance. We report that MC005, which has no orthologs in other poxvirus genomes, is a novel inhibitor of PRR- and cytokine-stimulated NF-κB activation. MC005 inhibited NF-κB proximal to the IκB kinase (IKK) complex, and unbiased affinity purification revealed that MC005 interacts with the IKK subunit NEMO (NF-κB essential modulator). MC005 binding to NEMO prevents the conformational priming of the IKK complex that occurs when NEMO binds to ubiquitin chains during pathway activation. These data reveal a novel mechanism of poxvirus inhibition of human innate immunity, validate current dynamic models of NEMO-dependent IKK complex activation, and further clarify how the human-adapted poxvirus MCV can so effectively evade antiviral immunity and suppress inflammation to persist in human skin lesions.
West MJ, Farrell PJ, 2017, Roles of RUNX in B Cell Immortalisation, RUNX Proteins in Development and Cancer, Editors: Groner, Ito, Liu, Neil, Speck, VanWijnen, Publisher: SPRINGER-VERLAG SINGAPORE PTE LTD, Pages: 283-298, ISBN: 978-981-10-3231-8
RUNX1 and RUNX3 are the main RUNX genes expressed in B lymphocytes. Both are expressed throughout B-cell development and play key roles at certain key developmental transitions. The tumour-associated Epstein-Barr virus (EBV) has potent B-cell transforming ability and manipulates RUNX3 and RUNX1 transcription through novel mechanisms to control B cell growth. In contrast to resting mature B cells where RUNX1 expression is high, in EBV-infected cells RUNX1 levels are low and RUNX3 levels are high. Downregulation of RUNX1 in these cells results from cross-regulation by RUNX3 and serves to relieve RUNX1-mediated growth repression. RUNX3 is upregulated by the EBV transcription factor (TF) EBNA2 and represses RUNX1 transcription through RUNX sites in the RUNX1 P1 promoter. Recent analysis revealed that EBNA2 activates RUNX3 transcription through an 18 kb upstream super-enhancer in a manner dependent on the EBNA2 and Notch DNA-binding partner RBP-J. This super-enhancer also directs RUNX3 activation by two further RBP-J-associated EBV TFs, EBNA3B and 3C. Counter-intuitively, EBNA2 also hijacks RBP-J to target a super-enhancer region upstream of RUNX1 to maintain some RUNX1 expression in certain cell backgrounds, although the dual functioning EBNA3B and 3C proteins limit this activation. Interestingly, the B-cell genome binding sites of EBV TFs overlap extensively with RUNX3 binding sites and show enrichment for RUNX motifs. Therefore in addition to B-cell growth manipulation through the long-range control of RUNX transcription, EBV may also use RUNX proteins as co-factors to deregulate the transcription of many B cell genes during immortalisation.
Gunnell A, Webb HM, Wood CD, et al., 2016, RUNX super-enhancer control through the Notch pathway by Epstein-Barr virus transcription factors regulates B cell growth., Nucleic Acids Research, Vol: 44, Pages: 4636-4650, ISSN: 1362-4962
In B cells infected by the cancer-associated Epstein-Barr virus (EBV), RUNX3 and RUNX1 transcription is manipulated to control cell growth. The EBV-encoded EBNA2 transcription factor (TF) activates RUNX3 transcription leading to RUNX3-mediated repression of the RUNX1 promoter and the relief of RUNX1-directed growth repression. We show that EBNA2 activates RUNX3 through a specific element within a -97 kb super-enhancer in a manner dependent on the expression of the Notch DNA-binding partner RBP-J. We also reveal that the EBV TFs EBNA3B and EBNA3C contribute to RUNX3 activation in EBV-infected cells by targeting the same element. Uncovering a counter-regulatory feed-forward step, we demonstrate EBNA2 activation of a RUNX1 super-enhancer (-139 to -250 kb) that results in low-level RUNX1 expression in cells refractory to RUNX1-mediated growth inhibition. EBNA2 activation of the RUNX1 super-enhancer is also dependent on RBP-J. Consistent with the context-dependent roles of EBNA3B and EBNA3C as activators or repressors, we find that these proteins negatively regulate the RUNX1 super-enhancer, curbing EBNA2 activation. Taken together our results reveal cell-type-specific exploitation of RUNX gene super-enhancers by multiple EBV TFs via the Notch pathway to fine tune RUNX3 and RUNX1 expression and manipulate B-cell growth.
Gregorovic G, Boulden EA, Bosshard R, et al., 2015, Epstein-Barr viruses deficient in EBER RNAs give higher LMP2 RNA expression in lymphoblastoid cell lines and efficiently establish persistent infection in humanized mice., Journal of Virology, Vol: 89, Pages: 1171-11714, ISSN: 1098-5514
Functions of EBER RNAs were tested in lymphoblastoid cell lines containing EBER mutants of Epstein-Barr Virus (EBV). Binding of EBER1 to RPL22 was confirmed. Deletion of EBER1 or EBER2 correlated with increased cytoplasmic EBV LMP2 RNA and with small effects on specific cellular miRNA levels but protein levels of LMP1 and LMP2A were not affected. Wild type and EBER deletion EBV had approximately equal ability to infect immunodeficient mice reconstituted with a human haematopoietic system.
Brady G, Haas DA, Farrell PJ, et al., 2015, Poxvirus Protein MC132 from Molluscum Contagiosum Virus Inhibits NF-kappa B Activation by Targeting p65 for Degradation, JOURNAL OF VIROLOGY, Vol: 89, Pages: 8406-8415, ISSN: 0022-538X
Palser AL, Grayson NE, White RE, et al., 2015, Genome Diversity of Epstein-Barr Virus from Multiple Tumor Types and Normal Infection, Journal of Virology, Vol: 89, Pages: 5222-5237, ISSN: 1098-5514
Epstein-Barr virus (EBV) infects most of the world’s population and is causally associated with several human cancers, but littleis known about how EBV genetic variation might influence infection or EBV-associated disease. There are currently no publishedwild-type EBV genome sequences from a healthy individual and very few genomes from EBV-associated diseases. We havesequenced 71 geographically distinct EBV strains from cell lines, multiple types of primary tumor, and blood samples and thefirst EBV genome from the saliva of a healthy carrier. We show that the established genome map of EBV accurately represents allstrains sequenced, but novel deletions are present in a few isolates. We have increased the number of type 2 EBV genomes sequencedfrom one to 12 and establish that the type 1/type 2 classification is a major feature of EBV genome variation, definedalmost exclusively by variation of EBNA2 and EBNA3 genes, but geographic variation is also present. Single nucleotide polymorphism(SNP) density varies substantially across all known open reading frames and is highest in latency-associated genes. SomeT-cell epitope sequences in EBNA3 genes show extensive variation across strains, and we identify codons under positive selection,both important considerations for the development of vaccines and T-cell therapy. We also provide new evidence for recombinationbetween strains, which provides a further mechanism for the generation of diversity. Our results provide the firstglobal view of EBV sequence variation and demonstrate an effective method for sequencing large numbers of genomes to furtherunderstand the genetics of EBV infection.
Foerster A, Maertens GN, Farrell PJ, et al., 2015, Dimerization of Matrix Protein Is Required for Budding of Respiratory Syncytial Virus, Journal of Virology, Vol: 89, Pages: 4624-4635, ISSN: 1098-5514
Respiratory syncytial virus (RSV) infects epithelial cells of the respiratory tract and is a major cause of bronchiolitis and pneumonia in children and the elderly. The virus assembles and buds through the plasma membrane, forming elongated membrane filaments, but details of how this happens remain obscure. Oligomerization of the matrix protein (M) is a key step in the process of assembly and infectious virus production. In addition, it was suggested to affect the conformation of the fusion protein, the major current target for RSV antivirals, in the mature virus. The structure and assembly of M are thus key parameters in the RSV antiviral development strategy. The structure of RSV M was previously published as a monomer. Other paramyxovirus M proteins have been shown to dimerize, and biochemical data suggest that RSV M also dimerizes. Here, using size exclusion chromatography-multiangle laser light scattering, we show that the protein is dimeric in solution. We also crystallized M in two crystal forms and show that it assembles into equivalent dimers in both lattices. Dimerization interface mutations destabilize the M dimer in vitro. To assess the biological relevance of dimerization, we used confocal imaging to show that dimerization interface mutants of M fail to assemble into viral filaments on the plasma membrane. Additionally, budding and release of virus-like particles are prevented in M mutants that fail to form filaments. Importantly, we show that M is biologically active as a dimer and that the switch from M dimers to higher-order oligomers triggers viral filament assembly and virus production.
Farrell PJ, 2015, Epstein-Barr Virus Strain Variation, EPSTEIN BARR VIRUS, VOL 1: ONE HERPES VIRUS: MANY DISEASES, Vol: 390, Pages: 45-69, ISSN: 0070-217X
Tzellos S, Correia PB, Karstegl CE, et al., 2014, A Single Amino Acid in EBNA-2 Determines Superior B Lymphoblastoid Cell Line Growth Maintenance by Epstein-Barr Virus Type 1 EBNA-2, JOURNAL OF VIROLOGY, Vol: 88, Pages: 8743-8753, ISSN: 0022-538X
Pereira C, Sousa H, Silva J, et al., 2014, The-1195G Allele Increases the Transcriptional Activity of Cyclooxygenase-2 Gene (COX-2) in Colon Cancer Cell Lines, MOLECULAR CARCINOGENESIS, Vol: 53, Pages: E92-E95, ISSN: 0899-1987
Hill ER, Koganti S, Zhi J, et al., 2013, Signal Transducer and Activator of Transcription 3 Limits Epstein-Barr Virus Lytic Activation in B Lymphocytes, JOURNAL OF VIROLOGY, Vol: 87, Pages: 11438-11446, ISSN: 0022-538X
Brady G, Karstegl CE, Farrell PJ, 2013, Novel function of the unique N-terminal region of RUNX1c in B cell growth regulation, NUCLEIC ACIDS RESEARCH, Vol: 41, Pages: 1555-1568, ISSN: 0305-1048
Tzellos S, Farrell PJ, 2012, Epstein-barr virus sequence variation-biology and disease., Pathogens, Vol: 1, Pages: 156-174, ISSN: 2076-0817
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.
Hatzimichael E, Lo Nigro C, Lattanzio L, et al., 2012, The collagen prolyl hydroxylases are novel transcriptionally silenced genes in lymphoma, British Journal of Cancer, Vol: 107, Pages: 1423-1432, ISSN: 1532-1827
Tzartos J, Khan G, Cruz-Sadaba M, et al., 2012, Association of innate immune activation with latent Epstein - Barr virus infection in active multiple sclerosis lesions, European Congress of Immunology, Publisher: WILEY-BLACKWELL, Pages: 51-51, ISSN: 0019-2805
Kwok H, Tong AHY, Lin CH, et al., 2012, Genomic Sequencing and Comparative Analysis of Epstein-Barr Virus Genome Isolated from Primary Nasopharyngeal Carcinoma Biopsy, PLOS ONE, Vol: 7, ISSN: 1932-6203
Buettner M, Lang A, Tudor CS, et al., 2012, Lytic Epstein-Barr virus infection in epithelial cells but not in B-lymphocytes is dependent on Blimp1, JOURNAL OF GENERAL VIROLOGY, Vol: 93, Pages: 1059-1064, ISSN: 0022-1317
Tzartos JS, Khan G, Vossenkamper A, et al., 2012, Association of innate immune activation with latent Epstein-Barr virus in active MS lesions, NEUROLOGY, Vol: 78, Pages: 15-23, ISSN: 0028-3878
Cancian L, Bosshard R, Lucchesi W, et al., 2011, C-terminal region of EBNA-2 determines the superior transforming ability of type 1 Epstein-Barr virus by enhanced gene regulation of LMP-1 and CXCR7., PLoS Pathog, Vol: 7
Type 1 Epstein-Barr virus (EBV) strains immortalize B lymphocytes in vitro much more efficiently than type 2 EBV, a difference previously mapped to the EBNA-2 locus. Here we demonstrate that the greater transforming activity of type 1 EBV correlates with a stronger and more rapid induction of the viral oncogene LMP-1 and the cell gene CXCR7 (which are both required for proliferation of EBV-LCLs) during infection of primary B cells with recombinant viruses. Surprisingly, although the major sequence differences between type 1 and type 2 EBNA-2 lie in N-terminal parts of the protein, the superior ability of type 1 EBNA-2 to induce proliferation of EBV-infected lymphoblasts is mostly determined by the C-terminus of EBNA-2. Substitution of the C-terminus of type 1 EBNA-2 into the type 2 protein is sufficient to confer a type 1 growth phenotype and type 1 expression levels of LMP-1 and CXCR7 in an EREB2.5 cell growth assay. Within this region, the RG, CR7 and TAD domains are the minimum type 1 sequences required. Sequencing the C-terminus of EBNA-2 from additional EBV isolates showed high sequence identity within type 1 isolates or within type 2 isolates, indicating that the functional differences mapped are typical of EBV type sequences. The results indicate that the C-terminus of EBNA-2 accounts for the greater ability of type 1 EBV to promote B cell proliferation, through mechanisms that include higher induction of genes (LMP-1 and CXCR7) required for proliferation and survival of EBV-LCLs.
Gregorovic G, Bosshard R, Karstegl CE, et al., 2011, Cellular Gene Expression That Correlates with EBER Expression in Epstein-Barr Virus-Infected Lymphoblastoid Cell Lines, JOURNAL OF VIROLOGY, Vol: 85, Pages: 3535-3545, ISSN: 0022-538X
Lai IY-C, Farrell PJ, Kellam P, 2011, X-box binding protein 1 induces the expression of the lytic cycle transactivator of Kaposi's sarcoma-associated herpesvirus but not Epstein Barr virus in co-infected primary effusion lymphoma, Journal of General Virology, Vol: 92, Pages: 421-431, ISSN: 1465-2099
Cells of primary effusion lymphoma (PEL), a B-cell non-Hodgkin's lymphoma, are latently infected by Kaposi's sarcoma-associated herpesvirus (KSHV), with about 80 % of PEL also co-infected with Epstein–Barr virus (EBV). Both viruses can be reactivated into their lytic replication cycle in PEL by chemical inducers. However, simultaneous activation of both lytic cascades leads to mutual lytic cycle co-repression. The plasma cell-differentiation factor X-box binding protein 1 (XBP-1) transactivates the KSHV immediate–early promoter leading to the production of the replication and transcription activator protein (RTA), and reactivation of KSHV from latency. XBP-1 has been reported to act similarly on the EBV immediate–early promoter Zp, leading to the production of the lytic-cycle transactivator protein BZLF1. Here we show that activated B-cell terminal-differentiation transcription factor X-box binding protein 1 (XBP-1s) does not induce EBV BZLF1 and BRLF1 expression in PEL and BL cell lines, despite inducing lytic reactivation of KSHV in PEL. We show that XBP-1s transactivates the KSHV RTA promoter but does not transactivate the EBV BZLF1 promoter in non-B-cells by using a luciferase assay. Co-expression of activated protein kinase D, which can phosphorylate and inactivate class II histone deacetylases (HDACs), does not rescue XBP-1 activity on Zp nor does it induce BZLF1 and BRLF1 expression in PEL. Finally, chemical inducers of KSHV and EBV lytic replication in PEL, including HDAC inhibitors, do not lead to XBP-1 activation. We conclude that XBP-1 specifically reactivates the KSHV lytic cycle in dually infected PELs.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.