Efficacy of novel plasmid DNA encoding vaccinia antigens in improving current smallpox vaccination strategy.

We tested a DNA vaccine strategy in order to improve the efficacy and safety of the current live smallpox vaccine involving priming with DNA vaccines and boosting with live vaccinia virus (VacV). We generated DNA plasmids encoding the A4L, A27L and H5R VacV genes. A considerable increase in antigen-specific IFN-gamma responses, high proliferative and humoral antigen-specific responses were detected in experimental primed Balb/C mice compared to controls after VacV boost. The VacV-DNA plasmids elicited IFN-gamma production in HLA-A2.1 transgenic mice in response to predicted HLA-A2.1 restricted peptide epitopes, providing valuable data for further vaccine development.