Sequence and Functional Analysis of EBNA-LP and EBNA2 Proteins from Nonhuman Primate Lymphocryptoviruses

ABSTRACT The Epstein-Barr virus (EBV) EBNA-LP and EBNA2 proteins are the first to be synthesized during establishment of latent infection in B lymphocytes. EBNA2 is a key transcriptional regulator of both viral and cellular gene expression and is essential for EBV-induced immortalization of B lymphocytes. EBNA-LP is also important for EBV-induced immortalization of B lymphocytes, but far less is known about the functional domains and cellular cofactors that mediate EBNA-LP function. While recent studies suggest that serine phosphorylation of EBNA-LP and coactivation of EBNA2-mediated transactivation are important, more detailed mutational and genetic studies are complicated by the repeat regions that comprise the majority of the EBNA-LP sequence. Therefore, we have used a comparative approach by studying the EBNA-LP homologues from baboon and rhesus macaque lymphocryptoviruses (LCVs) (baboon LCV and rhesus LCV). The predicted baboon and rhesus LCV EBNA-LP amino acid sequences are 61 and 64% identical to the EBV EBNA-LP W1 and W2 exons and 51% identical to the EBV EBNA-LP Y1 and Y2 exons. Five evolutionarily conserved regions can be defined, and four of eight potential serine residues are conserved among all three EBNA-LPs. The major internal repeat sequence also revealed a highly conserved Wp EBNA promoter with strong conservation of upstream activating sequences important for Wp transcriptional regulation. To test whether transcriptional coactivating properties were common to the rhesus LCV EBNA-LP, a rhesus LCV EBNA2 homologue was cloned and expressed. The rhesus LCV EBNA2 transcriptionally transactivates EBNA2-responsive promoters through a CBF1-dependent mechanism. The rhesus LCV EBNA-LP was able to further enhance rhesus LCV or EBV EBNA2 transactivation 5- to 12-fold. Thus, there is strong structural and functional conservation among the simian EBNA-LP homologues. Identification of evolutionarily conserved serine residues and regions in EBNA-LP homologues provides important clues for identifying the cellular cofactors and molecular mechanisms mediating these conserved viral functions.

Download Full-text

Epstein-Barr Virus-Induced Changes in B-Lymphocyte Gene Expression

Journal of Virology ◽

10.1128/jvi.76.20.10427-10436.2002 ◽

2002 ◽

Vol 76 (20) ◽

pp. 10427-10436 ◽

Cited By ~ 102

Author(s):

Kara L. Carter ◽

Ellen Cahir-McFarland ◽

Elliott Kieff

Keyword(s):

Gene Expression ◽

Real Time ◽

B Lymphocytes ◽

Epstein Barr Virus ◽

Molecular Mechanisms ◽

B Lymphocyte ◽

Protein Biosynthesis ◽

Rt Pcr ◽

Barr Virus ◽

Epstein Barr

ABSTRACT To elucidate the mechanisms by which Epstein-Barr virus (EBV) latency III gene expression transforms primary B lymphocytes to lymphoblastoid cell lines (LCLs), the associated alterations in cell gene expression were assessed by using 4,146 cellular cDNAs arrayed on nitrocellulose filters and real-time reverse transcription-PCR (RT-PCR). A total of 1,405 of the 4,146 cDNAs were detected using cDNA probes from poly(A)+ RNA of IB4 LCLs, a non-EBV-infected Burkitt's lymphoma (BL) cell line, BL41, or EBV latency III-converted BL41 cells (BL41EBV). Thirty-eight RNAs were consistently twofold more abundant in the IB4 LCL and BL41EBV than in BL41 by microarray analysis. Ten of these are known to be EBV induced. A total of 23 of 28 newly identified EBV-induced genes were confirmed by real-time RT-PCR. In addition, nine newly identified genes and CD10 were EBV repressed. These EBV-regulated genes encode proteins involved in signal transduction, transcription, protein biosynthesis and degradation, and cell motility, shape, or adhesion. Seven of seven newly identified EBV-induced RNAs were more abundant in newly established LCLs than in resting B lymphocytes. Surveys of eight promoters of newly identified genes implicate NF-κB or PU.1 as potentially important mediators of EBV-induced effects through LMP1 or EBNA2, respectively. Thus, examination of the transcriptional effects of EBV infection can elucidate the molecular mechanisms by which EBV latency III alters B lymphocytes.

Download Full-text

A heterochromatin inducing protein differentially recognizes self versus foreign genomes

PLoS Pathogens ◽

10.1371/journal.ppat.1009447 ◽

2021 ◽

Vol 17 (3) ◽

pp. e1009447

Author(s):

Eric M. Burton ◽

Ibukun A. Akinyemi ◽

Tiffany R. Frey ◽

Huanzhou Xu ◽

Xiaofan Li ◽

...

Keyword(s):

B Lymphocytes ◽

Binding Sites ◽

Viral Genome ◽

Zinc Finger Protein ◽

Repeat Sequence ◽

Barr Virus ◽

Infected Cells ◽

Epstein Barr ◽

Site Recognition

Krüppel-associated box-domain zinc finger protein (KRAB-ZFP) transcriptional repressors recruit TRIM28/KAP1 to heterochromatinize the mammalian genome while also guarding the host by silencing invading foreign genomes. However, how a KRAB-ZFP recognizes target sequences in the natural context of its own or foreign genomes is unclear. Our studies on B-lymphocytes permanently harboring the cancer-causing Epstein-Barr virus (EBV) have shown that SZF1, a KRAB-ZFP, binds to several lytic/replicative phase genes to silence them, thereby promoting the latent/quiescent phase of the virus. As a result, unless SZF1 and its binding partners are displaced from target regions on the viral genome, EBV remains dormant, i.e. refractory to lytic phase-inducing triggers. As SZF1 also heterochromatinizes the cellular genome, we performed in situ-footprint mapping on both viral and host genomes in physically separated B-lymphocytes bearing latent or replicative/active EBV genomes. By analyzing footprints, we learned that SZF1 recognizes the host genome through a repeat sequence-bearing motif near centromeres. Remarkably, SZF1 does not use this motif to recognize the EBV genome. Instead, it uses distinct binding sites that lack obvious similarities to each other or the above motif, to silence the viral genome. Virus mutagenesis studies show that these distinct binding sites are not only key to maintaining the established latent phase but also silencing the lytic phase in newly-infected cells, thus enabling the virus to establish latency and transform cells. Notably, these binding sites on the viral genome, when also present on the human genome, are not used by SZF1 to silence host genes during latency. This differential approach towards target site recognition may reflect a strategy by which the host silences and regulates genomes of persistent invaders without jeopardizing its own homeostasis.

Download Full-text

Epstein-Barr virus infection induces expression in B lymphocytes of a novel gene encoding an evolutionarily conserved 55-kilodalton actin-bundling protein.

Journal of Virology ◽

10.1128/jvi.68.11.7320-7328.1994 ◽

1994 ◽

Vol 68 (11) ◽

pp. 7320-7328 ◽

Cited By ~ 67

Author(s):

G Mosialos ◽

S Yamashiro ◽

R W Baughman ◽

P Matsudaira ◽

L Vara ◽

...

Keyword(s):

Virus Infection ◽

B Lymphocytes ◽

Epstein Barr Virus ◽

Epstein Barr Virus Infection ◽

Gene Encoding ◽

Barr Virus ◽

Novel Gene ◽

Evolutionarily Conserved ◽

Epstein Barr ◽

Barr Virus Infection

Download Full-text

Radio-Susceptibility of Nasopharyngeal Carcinoma: Focus on Epstein- Barr Virus, MicroRNAs, Long Non-Coding RNAs and Circular RNAs

Current Molecular Pharmacology ◽

10.2174/1874467213666191227104646 ◽

2020 ◽

Vol 13 (3) ◽

pp. 192-205 ◽

Cited By ~ 2

Author(s):

Fanghong Lei ◽

Tongda Lei ◽

Yun Huang ◽

Mingxiu Yang ◽

Mingchu Liao ◽

...

Keyword(s):

Nasopharyngeal Carcinoma ◽

Regulatory Networks ◽

Epstein Barr Virus ◽

Molecular Mechanisms ◽

Acquired Resistance ◽

Treatment Strategies ◽

Circular Rnas ◽

Barr Virus ◽

Non Coding Rnas ◽

Epstein Barr

Nasopharyngeal carcinoma (NPC) is a type of head and neck cancer. As a neoplastic disorder, NPC is a highly malignant squamous cell carcinoma that is derived from the nasopharyngeal epithelium. NPC is radiosensitive; radiotherapy or radiotherapy combining with chemotherapy are the main treatment strategies. However, both modalities are usually accompanied by complications and acquired resistance to radiotherapy is a significant impediment to effective NPC therapy. Therefore, there is an urgent need to discover effective radio-sensitization and radio-resistance biomarkers for NPC. Recent studies have shown that Epstein-Barr virus (EBV)-encoded products, microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), which share several common signaling pathways, can function in radio-related NPC cells or tissues. Understanding these interconnected regulatory networks will reveal the details of NPC radiation sensitivity and resistance. In this review, we discuss and summarize the specific molecular mechanisms of NPC radio-sensitization and radio-resistance, focusing on EBV-encoded products, miRNAs, lncRNAs and circRNAs. This will provide a foundation for the discovery of more accurate, effective and specific markers related to NPC radiotherapy. EBVencoded products, miRNAs, lncRNAs and circRNAs have emerged as crucial molecules mediating the radio-susceptibility of NPC. This understanding will improve the clinical application of markers and inform the development of novel therapeutics for NPC.

Download Full-text

Immunization with Epstein–Barr Virus Core Fusion Machinery Envelope Proteins Elicit High Titers of Neutralizing Activities and Protect Humanized Mice from Lethal Dose EBV Challenge

Vaccines ◽

10.3390/vaccines9030285 ◽

2021 ◽

Vol 9 (3) ◽

pp. 285

Author(s):

Xinle Cui ◽

Zhouhong Cao ◽

Yuriko Ishikawa ◽

Sara Cui ◽

Ken-Ichi Imadome ◽

...

Keyword(s):

Epithelial Cells ◽

B Lymphocytes ◽

Neutralizing Antibodies ◽

Epstein Barr Virus ◽

Lethal Dose ◽

Envelope Proteins ◽

Humanized Mice ◽

Target Cells ◽

Barr Virus ◽

Epstein Barr

Epstein–Barr virus (EBV) is the primary cause of infectious mononucleosis and is strongly implicated in the etiology of multiple lymphoid and epithelial cancers. EBV core fusion machinery envelope proteins gH/gL and gB coordinately mediate EBV fusion and entry into its target cells, B lymphocytes and epithelial cells, suggesting these proteins could induce antibodies that prevent EBV infection. We previously reported that the immunization of rabbits with recombinant EBV gH/gL or trimeric gB each induced markedly higher serum EBV-neutralizing titers for B lymphocytes than that of the leading EBV vaccine candidate gp350. In this study, we demonstrated that immunization of rabbits with EBV core fusion machinery proteins induced high titer EBV neutralizing antibodies for both B lymphocytes and epithelial cells, and EBV gH/gL in combination with EBV trimeric gB elicited strong synergistic EBV neutralizing activities. Furthermore, the immune sera from rabbits immunized with EBV gH/gL or trimeric gB demonstrated strong passive immune protection of humanized mice from lethal dose EBV challenge, partially or completely prevented death respectively, and markedly decreased the EBV load in peripheral blood of humanized mice. These data strongly suggest the combination of EBV core fusion machinery envelope proteins gH/gL and trimeric gB is a promising EBV prophylactic vaccine.

Download Full-text

Activated or dominant inhibitory mutants of Rap1A decrease the oxidative burst of Epstein-Barr virus-transformed human B lymphocytes.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)32230-5 ◽

1994 ◽

Vol 269 (29) ◽

pp. 18743-18746 ◽

Cited By ~ 3

Author(s):

F.E. Maly ◽

L.A. Quilliam ◽

O. Dorseuil ◽

C.J. Der ◽

G.M. Bokoch

Keyword(s):

B Lymphocytes ◽

Oxidative Burst ◽

Epstein Barr Virus ◽

Barr Virus ◽

Epstein Barr

Download Full-text

The interplay between Epstein–Barr virus and B lymphocytes: implications for infection, immunity, and disease

Immunologic Research ◽

10.1007/s12026-014-8496-1 ◽

2014 ◽

Vol 58 (2-3) ◽

pp. 268-276 ◽

Cited By ~ 57

Author(s):

Olivia L. Hatton ◽

Aleishia Harris-Arnold ◽

Steven Schaffert ◽

Sheri M. Krams ◽

Olivia M. Martinez

Keyword(s):

B Lymphocytes ◽

Epstein Barr Virus ◽

Barr Virus ◽

Epstein Barr

Download Full-text

Potential Selection of LMP1 Variants in Nasopharyngeal Carcinoma

Journal of Virology ◽

10.1128/jvi.78.2.868-881.2004 ◽

2004 ◽

Vol 78 (2) ◽

pp. 868-881 ◽

Cited By ~ 73

Author(s):

Rachel H. Edwards ◽

Diane Sitki-Green ◽

Dominic T. Moore ◽

Nancy Raab-Traub

Keyword(s):

Amino Acid ◽

Cytotoxic T Lymphocyte ◽

Amino Acid Sequences ◽

Barr Virus ◽

Distinct Sequence ◽

Epstein Barr ◽

Virus Latent Membrane Protein ◽

Multiple Strains ◽

Carboxy Terminal ◽

Selection Of

ABSTRACT Seven distinct sequence variants of the Epstein-Barr virus latent membrane protein 1 (LMP1) have been identified by distinguishing amino acid changes in the carboxy-terminal domain. In this study the transmembrane domains are shown to segregate identically with the distinct carboxy-terminal amino acid sequences. Since strains of LMP1 have been shown to differ in abundance between blood and throat washes, nasopharyngeal carcinomas (NPCs) from areas of endemicity and nonendemicity with matching blood were analyzed by using a heteroduplex tracking assay to distinguish LMP1 variants. Striking differences were found between the compartments with the Ch1 strain prevalent in the NPCs from areas of endemicity and nonendemicity and the B958 strain prevalent in the blood of the endemic samples, whereas multiple strains of LMP1 were prevalent in the blood of the nonendemic samples. The possible selection against the B958 strain appearing in the tumor was highly significant (P < 0.0001). Sequence analysis of the full-length LMP1 variants revealed changes in many of the known and computer-predicted HLA-restricted epitopes with changes in key positions in multiple, potential epitopes for the specific HLA of the patients. These amino acid substitutions at key positions in the LMP1 epitopes may result in a reduced cytotoxic-T-lymphocyte response. These data indicate that strains with specific variants of LMP1 are more likely to be found in NPC. The predominance of specific LMP1 variants in NPC could reflect differences in the biologic or molecular properties of the distinct forms of LMP1 or possible immune selection.

Download Full-text