Virus-specific CTL responses induced by an H-2Kd-restricted, motif-negative 15-mer peptide from the fusion protein of respiratory syncytial virus
Jiang S., Borthwick NJ., Morrison P., Gao GF., Steward MW.
We describe 15-mer peptide P8:F92-106 from the F protein of respiratory syncytial virus (RSV) that can act as an MHC class I-restricted (H-2Kd) epitope for RSV-specific CD8+ CTL. This peptide is interesting because not only is it the first murine CTL epitope to be identified in the F protein but also because it does not contain a known allele-specific motif, as all 15 amino acids appear to be required for effective presentation to CTL. In in vitro MHC class I refolding experiments, peptide P8: F92-106 induced complex formation with H-2Kd heavy chains and β2-microglobulin. Immunization of BALB/c mice with P8:F92-106 resulted in the induction of peptide and RSV-specific CTL responses as well as peptide-specific proliferative responses. Following intranasal challenge with RSV, P8:F92-106-immunized mice showed a significant reduction in viral load in the lungs compared to that seen in unimmunized mice. Furthermore, passive transfer of purified CD8+ lymphocytes into BALB/c scid mice prior to challenge with RSV also resulted in a reduction in the virus load in lungs of challenged mice. These results indicate the potential of synthetic peptide epitopes for the induction of protective immune responses against RSV infection.