Frequency of CD8+ T lymphocytes specific for lytic and latent antigens of Epstein-Barr virus in healthy virus carriers

Abstract

We investigated CD8+ T cell frequencies of five different Epstein-Barr virus-specific cytotoxic T lymphocyte epitopes located within proteins of the replicative cycle and the latent state in healthy long-term virus carriers with IFN-γ enzyme-linked immunospot assay. Frequencies of the HLA-A3- restricted epitope RVRAYTYSK (RVR) whose minimal length was mapped in this study to amino acid position 148-156 of the immediate-early protein BRLF1 were compared with those of a further known HLA-A3-restricted epitope within EBNA3A, RLRAEAQVK (RLR). Determination of frequencies of CD8+ T lymphocytes directed against lytic antigen epitope RVR revealed that only one of eight donors recognized this epitope. Frequency was calculated to be 65 RVR- specific CD8+ T lymphocytes per 106 PBMC. None of the HLA-A3-positive donors exhibited IFN-γ release after antigenic stimulation with the EBNA3A- specific peptide epitope RLR. Furthermore, we chose three known HLA-B8- restricted epitopes, RAKFKQLL (RAK), FLRGRAYGL (FLR), and QAKWRLQTL (QAK), of the lytic protein BZLF1 and the latent protein EBNA3A. Examination of eight HLA-B8-positive virus carriers revealed that the BZLF1-specific epitope RAK was recognized by all donors with a median frequency of 233 RAK-specific CD8+ T lymphocytes per 106 PBMC. Only 50% of these donors reacted against EBNA3A-specific epitope FLR and a minority (25%) reacted against EBNA3A- specific epitope QAK.