Mapping of CD8 T cell epitopes in human respiratory syncytial virus L protein.

Objectives: Since it has been reported that in humans there is a relationship between human respiratory syncytial virus (hRSV)-specific cytotoxic T lymphocytes and symptom reduction, and that the polymerase (structural L protein) is highly conserved among different strains, this work aimed to identify the CD8 T cell epitopes H-2(d) restricted within the L sequence for immunization purposes.

Methods: We screened the hRSV strain A2 L protein sequence using two independent algorithms, SYFPEITHI and PRED/(BALB/c), to predict CD8 T cell epitopes. The selected peptides were synthesized and used to immunize BALB/c mice for the evaluation of T cell response. The production of IFN-γ from splenocytes of hRSV-infected animals stimulated by these peptides was assayed by ELISPOT.

Results: Nine peptides showing the best binding scores to the BALB/c MHC-I molecules (H-2K(d), L(d) and D(d)) were selected. Sequence homology analysis showed that these sequences are conserved among different hRSV strains. Two of these peptides induced significant IFN-γ production by ex vivo-stimulated T cells.

Conclusions: Our results indicate that the hRSV L protein contains H-2(d)-restricted epitopes.