ABSTRACT
DNA vaccines have emerged as an attractive approach to induce CTL responses against cancer and infectious agents in recent years. Although CTL induction by DNA vaccination would be a valuable strategy for controlling viral infections, increasing the potency of DNA vaccines is mandatory before DNA vaccines can make it to the clinic. In this study, we developed and characterized a new and safe adjuvanted delivery system for DNA vaccination using cationic influenza virosomes (CIV). CIV were produced by reconstitution of detergent-solubilized influenza virus membranes in the presence of cationic lipids. Plasmid DNA (pDNA) mixed with these virosomes was efficiently transfected into cells of a mouse macrophage cell line (RAW-Blue cells). Moreover, the cells were effectively activated as demonstrated by production of an NFκB/AP-1-inducible reporter enzyme. Following three intradermal immunizations, CIV-delivered epitope-encoding pDNA induced equal numbers of IFNγ- and granzyme B-producing T cells than a 10-fold higher dose of naked pDNA. Virosomes without cationic lipids also improved induction of cellular immunity by pDNA but to a significantly lower extent than CIV. These findings suggest that pDNA-CIV complexes could be an efficacious delivery system suitable for CTL induction by DNA vaccination.
