Needle-free, non-adjuvanted skin immunization by electroporation-enhanced transdermal delivery of diphtheria toxoid and a candidate peptide vaccine against hepatitis B virus

To explore the feasibility of non-adjuvanted, needle-free skin immunization , we examined the immune responses of mice immunized by three routes with t wo antigens (Ag) differing in molecular size and lipophilicity. Diphtheria toroid (DT) or a myristylated peptide (MYR) administered either by transder mal electroporation (EP) or intradermally (i.d.) with a needle elicited mar kedly different responses. The EP route elicited higher responses to MYR th an i.d. immunization, but lower responses to DT. Intraperitoneal (i.p.) imm unization evoked responses against MYR that were higher than those evoked b y EP. It was inferred that EP is a promising technique for non-adjuvanted s kin immunization, specially with low molecular weight, weakly immunogenic A g. (C) 1999 Elsevier Science Ltd. All rights reserved.