DNA vaccination against virus infection and enhancement of antiviral immunity following consecutive immunization with DNA and viral vectors

Recent demonstrations of the immunogenicity of antigens encoded in DNA plasmids following delivery by various routes have heralded a new era in vaccine development. In this article, we review progress in DNA-based antiviral immunoprophylaxis. Preclinical studies have already established the immunogenicity of DNA plasmids encoding protective antigens from a wide variety of viral pathogens and work published in recent months has raised real prospects of broadly protective DNA vaccination against infections with influenza virus and HIV. We also describe a consecutive immunization protocol consisting of a priming dose of vaccine antigen encoded in DNA plasmids followed by a booster with the same antigen encoded in recombinant fowlpox virus vectors. We have used this strategy to generate protective antiviral cell-mediated immunity and sustained, high-level antibody responses both systemically and at mucosae, and to elucidate immunological mechanisms underlying the development of immunity to antigens delivered in DNA vectors.