Dual stimulation of Epstein-Barr Virus (EBV)-specific CD4+- and CD8+-T-cell responses by a chimeric antigen construct: potential therapeutic vaccine for EBV-positive nasopharyngeal carcinoma.
Virus-associated malignancies are potential targets for immunotherapeutic vaccines aiming to stimulate T-cell responses against viral antigens expressed in tumor cells. Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma, a high-incidence tumor in southern China, expresses a limited set of EBV proteins, including the nuclear antigen EBNA1, an abundant source of HLA class II-restricted CD4(+) T-cell epitopes, and the latent membrane protein LMP2, a source of subdominant CD8(+) T-cell epitopes presented by HLA class I alleles common in the Chinese population. We used appropriately modified gene sequences from a Chinese EBV strain to generate a modified vaccinia virus Ankara recombinant, MVA-EL, expressing the CD4 epitope-rich C-terminal domain of EBNA1 fused to full-length LMP2. The endogenously expressed fusion protein EL is efficiently processed via the HLA class I pathway, and MVA-EL-infected dendritic cells selectively reactivate LMP2-specific CD8(+) memory T-cell responses from immune donors in vitro. Surprisingly, endogenously expressed EL also directly accesses the HLA class II presentation pathway and, unlike endogenously expressed EBNA1 itself, efficiently reactivates CD4(+) memory T-cell responses in vitro. This unscheduled access to the HLA class II pathway is coincident with EL-mediated redirection of the EBNA1 domain from its native nuclear location to dense cytoplasmic patches. Given its immunogenicity to both CD4(+) and CD8(+) T cells, MVA-EL has potential as a therapeutic vaccine in the context of nasopharyngeal carcinoma.
Taylor
G S
GS
CRUK Institute for Cancer Studies and MRC Centre for Immune Regulation, University of Birmingham, Birmingham B15 2TT, United Kingdom.
Haigh
T A
TA
Gudgeon
N H
NH
Phelps
R J
RJ
Lee
S P
SP
Steven
N M
NM
Rickinson
A B
AB
D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002277:Carcinoma / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D002460:Cell Line; D020031:Epstein-Barr Virus Infections / Q000276:immunology / Q000517:prevention & control; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005822:Genetic Vectors; D006367:HeLa Cells; D004854:Herpesvirus 4, Human / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D009303:Nasopharyngeal Neoplasms / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D014616:Vaccinia virus / Q000235:genetics; D014763:Viral Matrix Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology*
C037662:EBV-associated membrane antigen, Epstein-Barr virus; D019309:Epstein-Barr Virus Nuclear Antigens; D011993:Recombinant Fusion Proteins; D014763:Viral Matrix Proteins; D014765:Viral Vaccines; C417029:EBV-encoded nuclear antigen 1