Identification of a novel human leucocyte antigen-A*01-restricted cytotoxic T-lymphocyte epitope in the respiratory syncytial virus fusion protein

Virus-specific cytotoxic T lymphocytes (CTL) play a major role in the clearance of respiratory syncytial virus (RSV) infection. To begin monitoring the immunological response to infection, especially in infants, it is important to identify human leucocyte antigen (HLA)-restricted CTL epitopes. Herein, we used a novel, comprehensive peptide panel containing all possible 8-, 9- and 10-mer peptides spanning the RSV fusion protein to screen for novel HLA-restricted T-cell epitopes. These peptide sets were synthesized as 10-mer peptides overlapping by nine amino acids and contained corresponding 8- and 9-mer peptides generated by C-terminal truncation. Unselected and uncultured peripheral blood mononuclear cells from healthy adult subjects were screened by interferon-gamma (IFN-gamma) Elispot assays against the peptide panel. Seven of 19 subjects displayed positive responses against 10 of the 565 peptides analysed. An HLA-A*01-restricted CTL epitope detected in three healthy adult subjects is characterized. This is the first RSV-specific memory CTL response identified in the fusion protein of RSV.