DNA vaccines for viral diseases

DNA plasmids encoding foreign proteins may be used as immunogens by direct intramuscular injection alone, or with various adjuvants and excipients, or by delivery of DNA-coated gold particles to the epidermis through biolisti c immunization. Antibody, helper T lymphocyte, and cytotoxic T lymphocyte ( CTL) responses have been induced in laboratory and domesticated animals by these methods. Ln a number of animal models, immune responses induced by DN A vaccination have been shown to be protective against challenge with vario us infectious agents. Immunization by injection of plasmids encoding foreig n proteins has been used successfully as a research tool. This review summa rizes the types of DNA vaccine vectors in common use, the immune responses and protective responses that have been obtained in animal models, the safe ty considerations pertinent to the evaluation of DNA vaccines in humans and the very limited information that is available from early clinical studies .