The present invention pertains to the field of vaccination, and moreparticularly to the fields of antitumor and antiviral vaccination. Theinvention relates to the use of a native peptide in a medicinal composition,for selecting and/or boosting part of a CTL immune response which has beeninitiated by an optimized immunogenic peptide derived from said nativepeptide. The invention also concerns vaccination kits which comprise severaldoses of optimized peptides and of their cognate native peptides.
