Novel approach to the formulation of an Epstein-Barr virus antigen-based nasopharyngeal carcinoma vaccine.

Epstein-Barr virus (EBV) is associated with several malignant diseases including nasopharyngeal carcinoma (NPC), a common neoplasm throughout southeast Asia. Radiotherapy and chemotherapy can achieve remission, but a reemergence of disease is not uncommon. Therefore, there is a need for specific therapies that target the tumor through the recognition of EBV antigens. In NPC, latent membrane protein 1 (LMP1) and LMP2 offer the best opportunity for specific targeting since they are typically expressed and T-cell determinants in each of these proteins have been defined. We have attempted to maximize the opportunity of incorporating every possible CD4 and CD8 determinant in a single formulation. We have achieved this by generating a scrambled protein incorporating random overlapping peptide sets from EBNA1, LMP1, and LMP2, which was then inserted into a replication-deficient strain of adenovirus (adenovirus scrambled antigen vaccine [Ad-SAVINE]). This report describes the construction of this Ad-SAVINE construct, its utility in generating LMP1 and LMP2 responses in healthy individuals as well as NPC patients, and its capacity to define new epitopes. This formulation could have a role in NPC immunotherapy for all ethnic groups since it has the potential to activate all possible CD4 and CD8 responses within EBNA1 and LMPs.

Reconstitution of the latent T-lymphocyte response to Epstein-Barr virus is coincident with long-term recovery from posttransplant lymphoma after adoptive immunotherapy.

BACKGROUND: Adoptive transfer of Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTLs) has been used to treat EBV-induced posttransplant lymphoproliferative disease (PTLD) in solid-organ recipients. This study defines, in detail, the temporal relationship between adoptive transfer and the clinical response, EBV DNA load, and CTL response to EBV latent and lytic antigens in a patient with a subcutaneous PTLD presentation treated with adoptive transfer of autologous CTL. METHODS: A heart transplant patient developed multiple subcutaneous PTLD deposits and was treated with a total of six doses (20 x 106 CTL per dose) of cultured autologous polyclonal EBV-specific CTL by adoptive transfer. RESULTS: Complete regression occurred after the sixth CTL dose, and the patient has remained disease-free from 47 weeks to the present (136 weeks). Real-time polymerase chain reaction analysis showed a reduction in viral load after therapy. Enzyme-linked immunospot analysis using defined EBV CTL epitopes showed that the CTL precursor frequency (pCTL) toward a lytic antigen epitope was elevated early in the course of disease but tended to decrease to lower levels after long-term regression of PTLD. The most dramatic result was seen in relation to three latent CTL epitopes studied. Long-term regression of PTLD was characterized by high pCTL toward the latent antigens. CONCLUSIONS: Increased pCTL reactivity to latent EBV CTL epitopes is coincident with recovery from disease after adoptive transfer of autologous CTL. Furthermore, the results are compatible with the belief that activation of a sustained CTL response to EBV latent epitopes is protective and may be a characteristic of patients in long-term remission from PTLD.

Use of CD107-based cell sorting ex vivo to enrich subdominant CD8+ T cells in culture.

CD8+ T lymphocytes are key effectors in the control of viral diseases and some tumours. In general, the majority of CD8+ T cells recognize a few immunodominant epitopes, but in some circumstances, subdominant specificities may be more relevant as targets for vaccines or immunotherapy. Epstein-Barr virus (EBV)-associated cancers are an example where knowledge of subdominant-specific CD8+ T cells is important because the immunodominant EBV proteins are not expressed in these cancers. We have developed a live-cell sorting method based on CD107 detection to remove CD8+ T cells recognising dominant EBV epitopes and show that this allows enrichment of subdominant-specific CD8+ T cells in subsequent cultures. This work shows that immunodomination in vitro suppresses the outgrowth of subdominant-specific CD8+ T cells in culture. The method may have broad applications for finding subdominant targets for immunotherapy and vaccines, and the principle suggests a means of improving subdominant CD8+ T-cell cultures grown for immunotherapy.

Determining virological, serological and immunological parameters of EBV infection in the development of PTLD.

Post-transplant lymphoproliferative disease (PTLD) in Epstein-Barr virus (EBV) seronegative solid organ transplant recipients remains a significant problem, particularly in the first year post-transplant. Immune monitoring of a cohort of high-risk patients indicated that four EBV seronegative transplant recipients developed early-onset PTLD prior to evidence of an EBV humoral response. EBV status has been classically defined serologically, however these patients demonstrated multiple parameters of EBV infection, including the generation of EBV-specific CTL, outgrowth of spontaneous lymphoblastoid cell lines, and elevated EBV DNA levels, despite the absence of a classic EBV antibody response. As EBV serology is influenced by both immunosuppression and cytomegalovirus immunoglobulin treatment, both the EBV-specific CTL response and elevated EBV levels are more reliable indicators of EBV infection post-transplant.