Efficiency of peptides and lipopeptides for in vivo priming of virus-specific cytotoxic T cells.

Synthetic peptides and a novel type of lipopeptide vaccine, both containing T cell epitopes recognized by Kd-restricted, influenza virus-specific cytotoxic T cells (CTL) were compared in their efficiency to induce virus-specific CTL in vivo. All attempts to induce virus-specific CTL with synthetic peptide (in the absence of adjuvants) failed. However, a latent immunization was observed, resulting in an increased response to the injected peptide seen only after boosting the recipients with immunogenic virus. In contrast, priming with synthetic lipopeptide vaccine (tripalmitoyl-S-glycerylcysteinyl-seryl-serine [P3CSS] coupled to peptide) was successful under most conditions, and matched the priming efficiency seen with infectious virus. The requirements for in vivo priming of virus-specific CTL using lipopeptide suggest that attachment of the lipopeptide to a hydrophobic entity, such as the cell membrane, is responsible for its efficiency.