DNA vaccines: a role for liposomes.

Vaccination with attenuated or killed microbes, purified or recombinant subunit proteins and synthetic peptides is often hampered by toxicity, the presence of infectious agents, weak immune responses and prohibiting costs, especially in the developing world. Such problems may be circumvented by genetic immunization, which, by the use of plasmid DNA encoding antigens from bacteria, viruses, protozoa and cancers leads to protective humoral and cell-mediated immunity. This review deals with the background and progress made so far with DNA vaccines and evaluates the role of liposomes in their optimization.