Codelivery of a DNA vaccine and a protein vaccine with aluminum phosphate stimulates a potent and multivalent immune response

The study explores the possibility of efficiently codelivering DNA vaccines and protein-based vaccines by formulation with aluminum phosphate (AlPO4). When mixed with aluminum adjuvants, plasmid DNA bound tightly onto aluminum hydroxide [Al(OH)3] but not to AlPO4. Different doses of DNA vaccines formulated with AlPO4 [but not Al(OH)3] induced enhanced humoral responses and supported priming of MHC class I restricted cellular immunity. Different proteins mixed with the plasmid DNA vaccine in the AlPO4 formulation did not impair its immunogenicity. Coinjection of two different vaccine-relevant antigens in the same AlPO4 formulation, one as a DNA vaccine and the other as a recombinant protein, elicited polyvalent, humoral, and cellular immune responses to all antigens delivered. The isotype profiles of the induced humoral responses and the cytokine profiles of the specifically primed T cell responses indicated that the combined vaccines supported copriming of Th1- and Th2-biased as well as balanced responses. These findings indicate that the AlPO4 adjuvant, a widely accepted adjuvant in human vaccination practice, can be used to combine protein- and DNA-based vaccination to prime an enhanced and balanced specific immunity.