The Immune Response to Glycine-Rich Sequences of Epstein-Barr Nuclear Antigen-1 (EBNA-1) in Autoimmunity: B and T Cell Epitopes

Abstract Despite advances in T-cell immunotherapy against Epstein-Barr virus (EBV)-infected lymphomas that express the full EBV latency III program, a critical barrier has been that most EBV+ lymphomas express the latency I program, in which the single Epstein-Barr nuclear antigen (EBNA1) is produced. EBNA1 is poorly immunogenic, enabling tumors to evade immune responses. Using a high-throughput screen, we identified decitabine as a potent inducer of immunogenic EBV antigens, including LMP1, EBNA2, and EBNA3C. Induction occurs at low doses and persists after removal of decitabine. Decitabine treatment of latency I EBV+ Burkitt lymphoma (BL) sensitized cells to lysis by EBV-specific cytotoxic T cells (EBV-CTLs). In latency I BL xenografts, decitabine followed by EBV-CTLs results in T-cell homing to tumors and inhibition of tumor growth. Collectively, these results identify key epigenetic factors required for latency restriction and highlight a novel therapeutic approach to sensitize EBV+ lymphomas to immunotherapy.

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Endogenous Presentation of CD8+ T Cell Epitopes from Epstein-Barr Virus–encoded Nuclear Antigen 1

Journal of Experimental Medicine ◽

10.1084/jem.20040191 ◽

2004 ◽

Vol 199 (10) ◽

pp. 1421-1431 ◽

Cited By ~ 104

Author(s):

Judy Tellam ◽

Geoff Connolly ◽

Katherine J. Green ◽

John J. Miles ◽

Denis J. Moss ◽

...

Keyword(s):

T Cell ◽

B Cells ◽

Antigen Processing ◽

Epstein Barr Virus ◽

Cd8 T Cell ◽

Nuclear Antigen ◽

T Cell Epitopes ◽

Barr Virus ◽

Degradation Rates ◽

Epstein Barr

Epstein-Barr virus (EBV)–encoded nuclear antigen (EBNA)1 is thought to escape cytotoxic T lymphocyte (CTL) recognition through either self-inhibition of synthesis or by blockade of proteasomal degradation by the glycine-alanine repeat (GAr) domain. Here we show that EBNA1 has a remarkably varied cell type–dependent stability. However, these different degradation rates do not correspond to the level of major histocompatibility complex class I–restricted presentation of EBNA1 epitopes. In spite of the highly stable expression of EBNA1 in B cells, CTL epitopes derived from this protein are efficiently processed and presented to CD8+ T cells. Furthermore, we show that EBV-infected B cells can readily activate EBNA1-specific memory T cell responses from healthy virus carriers. Functional assays revealed that processing of these EBNA1 epitopes is proteasome and transporter associated with antigen processing dependent. We also show that the endogenous presentation of these epitopes is dependent on the newly synthesized protein rather than the long-lived stable EBNA1. Based on these observations, we propose that defective ribosomal products, not the full-length antigen, are the primary source of endogenously processed CD8+ T cell epitopes from EBNA1.

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Altered immune response to glycine-rich sequences of epstein-barr nuclear antigen-1 in patients with rheumatoid arthritis and systemic lupus erythematosus

Arthritis & Rheumatism ◽

10.1002/art.1780330711 ◽

1990 ◽

Vol 33 (7) ◽

pp. 993-1000 ◽

Cited By ~ 26

Author(s):

Jorgen Petersen ◽

Gary Rhodes ◽

Jean Roudier ◽

John H. Vaughan

Keyword(s):

Rheumatoid Arthritis ◽

Systemic Lupus Erythematosus ◽

Immune Response ◽

Lupus Erythematosus ◽

Nuclear Antigen ◽

Systemic Lupus ◽

Altered Immune Response ◽

Epstein Barr ◽

Epstein Barr Nuclear Antigen

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Human T cell responses to the Epstein-Barr nuclear antigen-1 (EBNA-1) as evaluated by synthetic peptides

Cellular Immunology ◽

10.1016/0008-8749(89)90293-1 ◽

1989 ◽

Vol 123 (2) ◽

pp. 325-333 ◽

Cited By ~ 6

Author(s):

Jørgen Petersen ◽

Gary Rhodes ◽

Kevin Patrick ◽

Jean Roudier ◽

John H. Vaughan

Keyword(s):

T Cell ◽

Synthetic Peptides ◽

T Cell Responses ◽

Nuclear Antigen ◽

Cell Responses ◽

Human T Cell ◽

Epstein Barr ◽

Epstein Barr Nuclear Antigen

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Nuclear location of an endogenously expressed antigen, EBNA1, restricts access to macroautophagy and the range of CD4 epitope display

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0909448107 ◽

2010 ◽

Vol 107 (5) ◽

pp. 2165-2170 ◽

Cited By ~ 74

Author(s):

Carol S. Leung ◽

Tracey A. Haigh ◽

Laura K. Mackay ◽

Alan B. Rickinson ◽

Graham S. Taylor

Keyword(s):

T Cell ◽

Mhc Class Ii ◽

Nuclear Antigen ◽

Antigen Delivery ◽

T Cell Epitopes ◽

Barr Virus ◽

Cell Clones ◽

Nuclear Location ◽

Epstein Barr ◽

Antigen Presenting

Whereas exogenously acquired proteins are the major source of antigens feeding the MHC class II pathway in antigen-presenting cells, some endogenously expressed antigens also access that pathway but the rules governing such access are poorly understood. Here we address this using Epstein–Barr virus (EBV)-coded nuclear antigen EBNA1, a protein naturally expressed in EBV-infected B lymphoblastoid cell lines (LCLs) and a source of multiple CD4+ T cell epitopes. Using CD4+ T cell clones against three indicator epitopes, we find that two epitopes are weakly displayed on the LCL surface whereas the third is undetectable, a pattern of limited epitope presentation that is maintained even when nuclear expression of EBNA1 is induced to high supraphysiological levels. Inhibitor and siRNA studies show that, of the two epitopes weakly presented under these conditions, one involves macroautophagy, and the second involves antigen delivery to the MHC II pathway by another endogenous route. In contrast, when EBNA1 is expressed as a cytoplasmic protein, all three CD4 epitopes are processed and presented much more efficiently, and all involve macroautophagy. We conclude that EBNA1’s nuclear location limits its accessibility to the macroautophagy pathway and, in consequence, limits the level and range of EBNA1 CD4 epitopes naturally displayed on the infected cell surface.

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T Cell Epitope Clustering in the Highly Immunogenic BZLF1 Antigen of Epstein-Barr Virus

Journal of Virology ◽

10.1128/jvi.02642-14 ◽

2014 ◽

Vol 89 (1) ◽

pp. 703-712 ◽

Cited By ~ 5

Author(s):

Melissa J. Rist ◽

Michelle A. Neller ◽

Jacqueline M. Burrows ◽

Scott R. Burrows

Keyword(s):

Immune Response ◽

T Cells ◽

T Cell ◽

Cell Response ◽

Epstein Barr Virus ◽

T Cell Response ◽

T Cell Epitopes ◽

Barr Virus ◽

Epstein Barr ◽

Hla Molecules

ABSTRACTPolymorphism in the human leukocyte antigen (HLA) loci ensures that the CD8+T cell response to viruses is directed against a diverse range of antigenic epitopes, thereby minimizing the impact of virus escape mutation across the population. The BZLF1 antigen of Epstein-Barr virus is an immunodominant target for CD8+T cells, but the response has been characterized only in the context of a limited number of HLA molecules due to incomplete epitope mapping. We have now greatly expanded the number of defined CD8+T cell epitopes from BZLF1, allowing the response to be evaluated in a much larger proportion of the population. Some regions of the antigen fail to be recognized by CD8+T cells, while others include clusters of overlapping epitopes presented by different HLA molecules. These highly immunogenic regions of BZLF1 include polymorphic sequences, such that up to four overlapping epitopes are impacted by a single amino acid variation common in different regions of the world. This focusing of the immune response to limited regions of the viral protein could be due to sequence similarity to human proteins creating “immune blind spots” through self-tolerance. This study significantly enhances the understanding of the immune response to BZLF1, and the precisely mapped T cell epitopes may be directly exploited in vaccine development and adoptive immunotherapy.IMPORTANCEEpstein-Barr virus (EBV) is an important human pathogen, associated with several malignancies, including nasopharyngeal carcinoma and Hodgkin lymphoma. T lymphocytes are critical for virus control, and clinical trials aimed at manipulating this arm of the immune system have demonstrated efficacy in treating these EBV-associated diseases. These trials have utilized information on the precise location of viral epitopes for T cell recognition, for either measuring or enhancing responses. In this study, we have characterized the T cell response to the highly immunogenic BZLF1 antigen of EBV by greatly expanding the number of defined T cell epitopes. An unusual clustering of epitopes was identified, highlighting a small region of BZLF1 that is targeted by the immune response of a high proportion of the world's population. This focusing of the immune response could be utilized in developing vaccines/therapies with wide coverage, or it could potentially be exploited by the virus to escape the immune response.

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