DNA vaccines for viral diseases

DNA vaccines, with which the antigen is synthesized in vivo after direct in troduction of its encoding sequences, offer a unique method of immunization that may overcome many of the deficits of traditional antigen-based vaccin es. By virtue of the sustained in vive antigen synthesis and the comprised stimulatory CpG motifs, plasmid DNA vaccines appear to induce strong and lo nglasting humoral (antibodies) and cell-mediated (T-help, other cytokine fu nctions and cytotoxic T cells) immune responses without the risk of infecti on and without boost. Other advantages over traditional antigen-containing vaccines are their low cost, the relative ease with which they are manufact ured, their heat stability, the possibility of obtaining multivalent vaccin es and the rapid development of new vaccines in response to new strains of pathogens. The antigen-encoding DNA may be in different forms and formulati ons, and may be introduced into cells of the body by numerous methods. To d ate, animal models have shown the possibility of producing effective prophy lactic DNA vaccines against numerous viruses as well as other infectious pa thogens. The strong cellular responses also open up the possibility of effe ctive therapeutic DNA vaccines to treat chronic viral infections. (C) Elsev ier, Paris.