Targeting anti-tumor DNA vaccines to dendritic cells via a short CD11c promoter sequence

We describe for the first time a short sequence of the CD11c promoter (700 bp, named as CD11cS) which induces selective antigen expression in dendritic cells (DCs). It showed a stronger promoter activity than the hitherto used long CD11c promoter (5.5 kb, named as CD11cL), which had been reported inefficient to induce immune responses. After application to the ear pinna and electroporation (EP), CD11cS based DNA vaccines induced specific B- and T-cell responses, including IFN-γ secretion. Such vaccines achieved induction of anti-tumor immunity comparable in strength to vaccines having the strong tissue non-specific CMV promoter, in both prophylactic and therapeutic settings of mouse tumor models. This short CD11c promoter appears to be a safe and a practical tool for DC-specific gene targeting and for vaccination.