ABSTRACT
Gene-based vaccines, with which the antigen is synthesized in vivo after direct introduction of its encoding sequences, offer a unique method of immunization that may overcome many of the deficits of traditional antigen-based vaccines. By virtue of the sustained antigen synthesis, plasmid DNA vaccines appear to induce strong and long-lasting humoral (antibodies) and cell-mediated (T-help and cytotoxic T cells) immune responses. To date, animal models have shown the possibility to produce effective prophylactic DNA vaccines against numerous viruses as well as several bacteria and parasites. The strong cellular responses also open up the possibility of effective DNA therapeutic vaccines to treat chronic viral infections or cancer.
