Potential for plasmid DNAs as vaccines for the new millennium

The advent of new technology and the unmet needs of old and new epidemics o f infectious diseases have stimulated a new era of vaccinology. One of the most novel approaches employs plasmid DNA engineered to express one or more genes of the pathogen in mammalian cells. Plasmids may also express cytoki ne or costimulatory molecules to 'direct' the immune response and/or expres s altered forms of the antigen to direct it to a specific intracellular com partment or a specific extracellular receptor. The quality of immune respon ses generated by DNA vaccines in animals has previously only been equaled b y live attenuated viral vaccines. The immune stimulating activity of DNA va ccines, combined with their versatility, suggests vast potential for these vaccines.