Multi-antigenic DNA immunization using herpes simplex virus type 2 genomic fragments.

A novel DNA vaccine was generated using genomic fragments of a pathogen as the source of both the antigen coding and regulatory regions. The constructs, termed subgenomic vaccines (SGVs), incorporated genomic DNA sequences up to 45 kbp that encompass 15-20 different genes. The SGVs were developed to generate vaccines capable of expressing multiple genes from a single construct, which could be of great benefit for commercialization. The unique feature of the SGVs is that genes are expressed from their native promoters rather than heterologous promoters typical of DNA vaccines. SGVs composed of genomic fragments from the DS-DNA virus Herpes Simplex Virus Type 2 (HSV-2) induced HSV-2 specific immune responses following particle-mediated epidermal delivery (PMED) in mice and these responses protected animals from lethal infectious challenge. A second generation SGV (SGV-H2), intended as an HSV-2 therapeutic vaccine, was generated that had five HSV-2 genes and was capable of generating multi-antigenic responses in naïve mice, and enhancing responses in infected animals. When compared with standard single plasmid vaccines, immunization with the SGV-H2 was found to be at least as effective as single plasmids or plasmid mixtures. The activity of the SGV-H2 could be greatly enhanced by co-delivering plasmids expressing E. coli heat labile toxin (LT) or cholera toxin CT as adjuvants as has been found previously for standard single-gene DNA vaccines.