Determination of a HLA II promiscuous peptide cocktail as potential vaccine against EBV latency II malignancies

The Epstein-Barr virus (EBV) is associated with several malignant diseases, which can be distinguished by their patterns of viral latent gene expression. The latency II program is limited to the expression of the nonimmunodominant antigens EBNA1, LMP1 and LMP2 and is seen in EBV-positive Hodgkin disease, nasopharyngeal carcinomas, and peripheral T/NK-cell lymphomas. CD4 T cells may play a crucial role in controlling these EBV latency II malignancies. In this study, we used the prediction software TEPITOPE to predict promiscuous major histocompatibility complex class II epitopes derived from the latency II antigens EBNA1, LMP1, and LMP2. The predicted peptides were then submitted to peptide-binding assays on HLA II purified molecules, which allowed the selection of 6 peptides (EBNA1: 3; LMP1: 1; and LMP2: 2) with a highly promiscuous capability of binding. This peptide cocktail was immunogenic in a model of HLA-DR1 transgenic mice, leading to a specific cellular and humoral TH1 response. The peptides were also recognized by human CD4 T cells from individuals expressing various HLA II genotypes. This promiscuous peptide cocktail could be immunogenic in the majority of the population and may be used as a peptide-based vaccine in EBV latency II malignancies.