Dual Stimulation of Epstein-Barr Virus (EBV)-Specific CD4+- and CD8+-T-Cell Responses by a Chimeric Antigen Construct: Potential Therapeutic Vaccine for EBV …

GS Taylor, TA Haigh, NH Gudgeon, RJ Phelps… - Journal of …, 2004 - Am Soc Microbiol
GS Taylor, TA Haigh, NH Gudgeon, RJ Phelps, SP Lee, NM Steven, AB Rickinson
Journal of virology, 2004Am Soc Microbiol
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 …
Abstract
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.
American Society for Microbiology