Epstein-Barr Virus (EBV)-derived BARF1 encodes CD4- and CD8-restricted epitopes as targets for T-cell immunotherapy

Abstract

Background: EBV type II latency tumors such as Hodgkin lymphoma (HL), Non-Hodgkin lymphoma (NHL) and nasopharyngeal carcinoma (NPC) express a limited array of EBV antigens including Epstein-Barr nuclear antigen (EBNA)1, latent membrane protein (LMP)1, LMP2, and BamH1-A right frame 1 (BARF1). Adoptive immunotherapy for these malignancies have focused on EBNA1, LMP1, and LMP2 since little is known about the cellular immune response to BARF1. Methods: To investigate if BARF1 is a potential T-cell immunotherapy target, we determined the frequency of BARF1-specific T-cell responses in the peripheral blood of EBV-seropositive healthy donor and patients with EBV-positive malignancies, mapped epitopes, and evaluated the effector function of ex vivo generated BARF1-specific T-cell lines. Results: BARF1-specific T cells were present in the peripheral blood of 12/16 (75%) EBVpositive healthy donors and 13/20 (65%) patients with EBV-positive malignancies. Ex vivo expanded BARF1-specific T-cell lines contained CD4-and CD8-positive T-cell subpopulations, and we identified 23 BARF1 peptides, which encoded MHC class I-and/or II-restricted epitopes. Epitope mapping identified one HLA-A*02-restricted epitope that was recognized by 50% of HLA-A*02, EBV-seropositive donors, and one HLA-B*15(62)-restricted epitope. Ex vivo

The Therapeutic Potential of Targeting BARF1 in EBV-Associated Malignancies

“…Moreover, autologous monocyte-derived dendritic cells pulsed with BARF1-derived peptides could induce BARF1-specific CTLs and these could recognize and lyse cancer cells endogenously expressing the BARF1 protein [ 55 ]. Similar findings were observed in a recent study in which an unbiased, peptide library approach was used to characterize BARF1-specific T responses in EBV-seropositive healthy donors and patients of NPC and NKTL [ 56 ]. BARF1-specific CD4+ and CD8+ T cells were identified in approximately 70% of healthy donors and cancer patients.…”

“…BARF1-specfic T cells recognized both Major histocompatibility complex (MHC) class I and II epitopes clustered in the N-terminal region of BARF1. Also, T cells specific for BARF1 epitopes could be reactivated and expanded from peripheral blood of EBV-seropositive individuals and could recognize and kill EBV-positive cancer cells [ 56 ]. Findings from these two studies indicate that BARF1 is naturally immunogenic for T cells and that BARF1-expressing cancer cells can process and present BARF1 peptides (located in N-terminal region) as natural epitopes for CTL recognition and killing.…”

Immunology of EBV-Related Lymphoproliferative Disease in HIV-Positive Individuals

“…CD4+ T cells that recognize immediate-early, early and late lytic EBV antigens isolated from PBMCs of healthy donors have been identified (86). CD4+ memory T cells responsive to latent EBV proteins EBNA1, EBNA3C, LMP1, LMP2, and BARF1 have also been identified in the blood of healthy carriers (87,88). EBV-specific CD4+ T cell clones capable of IFNγ production in response to stimulation with peptides derived from lytic and latent EBV proteins have been successfully generated (89,90).…”

Hodgkin lymphoma: a review of pathological features and recent advances in pathogenesis

“…There is compelling evidence that EBVpositive HL is an excellent candidate for targeted cellular immunotherapy. [78][79][80][81][82] Since a substantial proportion of HL is EBV-negative, especially in Western countries, two hypotheses have been proposed to reconcile and explain the role of EBV in the pathogenesis of HL. One is the 'hit-and-run' theory; that is, the inability to detect EBV in the negative cases of HL may be due to integrated viral fragments or a defective viral genome.…”