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Distinct memory CD4+ T-cell subsets mediate immune recognition of Epstein Barr virus nuclear antigen 1 in healthy virus carriers.

ABSTRACT: CD4+ T cells, specific for transforming latent infection with the Epstein Barr virus (EBV), consistently recognize the nuclear antigen 1 of EBV (EBNA1). EBNA1-specific effector CD4+ T cells are primarily T-helper 1 (TH1) polarized. Here we show that most healthy EBV carriers have such IFN-secreting EBNA1-specific CD4+ T cells at a frequency of 0.03% of circulating CD4+ T cells. In addition, healthy carriers have a large pool of CD4+ T cells that proliferated in response to EBNA1 and consisted of distinct memory-cell subsets. Despite continuous antigen presence due to persistent EBV infection, half of the proliferating EBNA1-specific CD4+ T cells belonged to the central-memory compartment (TCM). The remaining EBNA1-specific CD4+ T cells displayed an effector-memory phenotype (TEM), of which a minority rapidly secreted IFN upon stimulation with EBNA1. Based on chemokine receptor analysis, all EBNA1-specific TCM CD4+ T cells were TH1 committed. Our results suggest that protective immune control of chronic infections, like EBV, includes a substantial reservoir of TCM CD4+ TH1 precursors, which continuously fuels TH1-polarized effector cells.

SUBMITTER: Heller KN

PROVIDER: S-EPMC1785143 | biostudies-literature | 2007 Feb

REPOSITORIES: biostudies-literature

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Distinct memory CD4+ T-cell subsets mediate immune recognition of Epstein Barr virus nuclear antigen 1 in healthy virus carriers.

Heller Kevin N KN Upshaw Jenica J Seyoum Beza B Zebroski Henry H Münz Christian C

Blood 20060919 3

CD4+ T cells, specific for transforming latent infection with the Epstein Barr virus (EBV), consistently recognize the nuclear antigen 1 of EBV (EBNA1). EBNA1-specific effector CD4+ T cells are primarily T-helper 1 (TH1) polarized. Here we show that most healthy EBV carriers have such IFN-secreting EBNA1-specific CD4+ T cells at a frequency of 0.03% of circulating CD4+ T cells. In addition, healthy carriers have a large pool of CD4+ T cells that proliferated in response to EBNA1 and consisted of ...[more]

PMID: 16985171

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Project description:Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is the only viral protein consistently expressed in all EBV-associated malignancies, and play a critical role in the onset, progression, and/or maintenance of these tumors. Based on the signature changes at amino acid residue 487, EBNA1 is classified into five distinct subtypes: P-ala, P-thr, V-leu, V-val and V-pro. In the present study, the sequence variations of EBNA1 in EBV-associated gastric carcinoma (EBVaGC) and throat washing (TW) samples of healthy EBV carriers in Guangzhou, southern China, where nasopharyngeal carcinoma (NPC) is endemic, were analyzed by PCR and DNA sequencing. V-val subtype was the most predominant (53.6%, 15/28) in EBVaGC, followed by P-ala (42.9%, 12/28) and V-leu (32.1%, 9/28) subtypes. In TWs of healthy EBV carriers, V-val subtype was also predominant (85.7%, 18/21). The sequence variations of EBNA1 in EBVaGC were similar to those in TW of healthy EBV carriers (p>0.05), suggesting that the EBV strains in EBVaGC might originate from the viral strains prevalent within the background population. The predominance of V-val subtype in EBVaGC in Guangzhou was similar to that in EBVaGC in northern China and Japan, but was different from that in EBVaGC in America, suggesting that the variations of EBNA1 in EBVaGC represent geographic-associated polymorphisms rather than tumor-specific mutations. In addition, the EBNA1 variations in EBVaGC in gastric remnant carcinoma were also determined. V-leu subtype was detected in all 4 (100%) cases, although 2 cases occurred as mixed infection with P-ala subtype. This is different from the predominant V-val subtype in EBVaGC in conventional gastric carcinoma, suggesting that V-leu might be a subtype that adapts particularly well to the microenvironment within the gastric stump and enters the remnant gastric mucosa epithelia easily. This, to our best knowledge, is the first investigation of EBNA1 polymorphisms in EBVaGC from endemic area of NPC.

Project description:Epstein-Barr virus nuclear antigen (EBNA) leader protein (EBNALP) is one of the first viral genes expressed upon B-cell infection. EBNALP is essential for EBV-mediated B-cell immortalization. EBNALP is thought to function primarily by coactivating EBNA2-mediated transcription. Chromatin immune precipitation followed by deep sequencing (ChIP-seq) studies highlight that EBNALP frequently cooccupies DNA sites with host cell transcription factors (TFs), in particular, EP300, implicating a broader role in transcription regulation. In this study, we investigated the mechanisms of EBNALP transcription coactivation through EP300. EBNALP greatly enhanced EP300 transcription activation when EP300 was tethered to a promoter. EBNALP coimmunoprecipitated endogenous EP300 from lymphoblastoid cell lines (LCLs). EBNALP W repeat serine residues 34, 36, and 63 were required for EP300 association and coactivation. Deletion of the EP300 histone acetyltransferase (HAT) domain greatly reduced EBNALP coactivation and abolished the EBNALP association. An EP300 bromodomain inhibitor also abolished EBNALP coactivation and blocked the EP300 association with EBNALP. EBNALP sites cooccupied by EP300 had significantly higher ChIP-seq signals for sequence-specific TFs, including SPI1, RelA, EBF1, IRF4, BATF, and PAX5. EBNALP- and EP300-cooccurring sites also had much higher H3K4me1 and H3K27ac signals, indicative of activated enhancers. EBNALP-only sites had much higher signals for DNA looping factors, including CTCF and RAD21. EBNALP coactivated reporters under the control of NF-κB or SPI1. EP300 inhibition abolished EBNALP coactivation of these reporters. Clustered regularly interspaced short palindromic repeat interference targeting of EBNALP enhancer sites significantly reduced target gene expression, including that of EP300 itself. These data suggest a previously unrecognized mechanism by which EBNALP coactivates transcription through subverting of EP300 and thus affects the expression of LCL genes regulated by a broad range of host TFs.IMPORTANCE Epstein-Barr virus was the first human DNA tumor virus discovered over 50 years ago. EBV is causally linked to ∼200,000 human malignancies annually. These cancers include endemic Burkitt lymphoma, Hodgkin lymphoma, lymphoma/lymphoproliferative disease in transplant recipients or HIV-infected people, nasopharyngeal carcinoma, and ∼10% of gastric carcinoma cases. EBV-immortalized human B cells faithfully model key aspects of EBV lymphoproliferative diseases and are useful models of EBV oncogenesis. EBNALP is essential for EBV to transform B cells and transcriptionally coactivates EBNA2 by removing repressors from EBNA2-bound DNA sites. Here, we found that EBNALP can also modulate the activity of the key transcription activator EP300, an acetyltransferase that activates a broad range of transcription factors. Our data suggest that EBNALP regulates a much broader range of host genes than was previously appreciated. A small-molecule inhibitor of EP300 abolished EBNALP coactivation of multiple target genes. These findings suggest novel therapeutic approaches to control EBV-associated lymphoproliferative diseases.

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Distinct memory CD4+ T-cell subsets mediate immune recognition of Epstein Barr virus nuclear antigen 1 in healthy virus carriers.

Publications

Distinct memory CD4+ T-cell subsets mediate immune recognition of Epstein Barr virus nuclear antigen 1 in healthy virus carriers.

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