Nucleic acid vaccines represent a promising alternative to killed bacterial antigen, recombinant protein or peptide vaccines for infectious diseases and cancer immunotherapy. Although significant advances are made with DNA vaccines in animal studies, there are severe limitations to deliver these vaccines effectively and considerable reservations exist about current methods used. In this study, a liposome-based vaccine platform, VacciMax (VM), and its modified water-free version, DepoVax (DPX), were tested for their ability to improve in vivo delivery of plasmid DNA (pDNA), mRNA and siRNA. Subcutaneously injected pDNA for IL12 and pDNA as well as mRNA for green fluorescent protein (GFP) in VM/DPX significantly enhanced their in vivo expression. Enhanced IL12 secretion and GFP expression was restricted to CD11b(+) and CD11c(+) antigen-presenting cells, but not B cells. Further, significant inhibition of plasmid/antigen-induced IL12 secretion was seen after injection of IL12-siRNA in VM. These findings suggest VM and DPX to be promising means of delivering nucleic acid vaccines in vivo, and warrant further studies on their role in inducing effective immune responses.
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