Differential Immunogenicity of Epstein-Barr Virus Latent-Cycle Proteins for Human CD4⁺T-Helper 1 Responses

Abstract

Human CD4 ؉ T-helper 1 cell responses to Epstein-Barr virus (EBV) infection are likely to be important in the maintenance of virus-specific CD8؉ memory and/or as antiviral effectors in their own right. The present work has used overlapping peptides as stimulators of gamma interferon release (i) to identify CD4 ؉ epitopes within four EBV latent-cycle proteins, i.e., the nuclear antigens EBNA1 and EBNA3C and the latent membrane proteins LMP1 and LMP2, and (ii) to determine the frequency and magnitude of memory responses to these proteins in healthy virus carriers. Responses to EBNA1 and EBNA3C epitopes were detected in the majority of donors, and in the case of EBNA1, their antigen specificity was confirmed by in vitro reactivation and cloning of CD4 ؉ T cells using protein-loaded dendritic cell stimulators. By contrast, responses to LMP1 and LMP2 epitopes were seen much less frequently. EBV latent-cycle proteins therefore display a marked hierarchy of immunodominance for CD4 ؉ T-helper 1 cells (EBNA1, EBNA3C Ͼ Ͼ Ͼ Ͼ LMP1, LMP2) which is different from that identified for the same proteins with respect to CD8؉ -T-cell responses (EBNA3C > EBNA1 > LMP2 Ͼ Ͼ Ͼ Ͼ LMP1). Furthermore, the range of CD4؉ memory T-cell frequencies in peripheral blood of healthy virus carriers was noticeably lower and narrower than the corresponding range of latent antigen-specific CD8؉ -Tcell frequencies.

Deiminated Epstein‐Barr virus nuclear antigen 1 is a target of anti–citrullinated protein antibodies in rheumatoid arthritis

“…EBNA-1-specific CD4ϩ T cells (45,46), mainly of the Th1 phenotype (47), have recently been detected in healthy EBV carriers and may provide help for the production of antibodies directed to the different epitopes of this protein. In the presence of a higher EBV load, events such as apoptosis, infection, damage, or any stimulus involving calcium influx may activate PAD, which is highly expressed in RA synovia (48,49), and induce the deimination of different proteins, including viral proteins.…”

Identification and prevalence of CD8+ T‐cell responses directed against Epstein‐Barr virus‐encoded latent membrane protein 1 and latent membrane protein 2

“…23,33,34 Furthermore, our recent studies have shown that LMP1 and LMP2 are also a poor source of epitopes for the CD4 ϩ T cell response. 35 Why these molecules should be relatively poorly immunogenic is not understood. In the case of LMP1, it may be that the protein itself has immunosuppressive properties that favor the induction of T cell anergy.…”

Human peripheral blood and bone marrow Epstein–Barr virus‐specific T‐cell repertoire in latent infection reveals distinct memory T‐cell subsets

“…EBV nuclear antigen 1 (EBNA-1) is a latent antigen that is invariably expressed in all EBV-infected proliferating cells [16] and associated malignancies [17], being crucial for viral persistence by acting as replication and transcription factor [18], without viral particle formation. EBNA-1 is an immunodominant latent target of EBVspecific CD4 1 T cells [19,20]. Although it has been described in the past to escape from recognition by CD8 1 T cells due to Gly/Ala repeated domains preventing proteasome-dependent processing for presentation on MHC class I [21], more recent studies revealed the existence of EBNA-1-specific CD8 1 T cells [15,22,23].…”