Cutaneous transfection and immune responses to intradermal nucleic acid vaccination are significantly enhanced by in vivo electropermeabilization

Naked DNA injection with electropermeabilization (EP) is a promising method for nucleic acid vaccination (NAV) and in vivo gene therapy. Skin is an id eal target for NAV due to ease of administration and the accessibility of l arge numbers of antigen-presenting cells within the tissue. This study demo nstrates that in vivo skin EP may be used to increase transgene expression up to an average of 83-fold relative to naked DNA injection (50 mug DNA per dose, P < 0.005). Transfected cells were principally located in dermis and included adipocytes, fibroblasts, endothelial cells, and numerous mononucl ear cells with dendritic processes in a porcine model. Transfected cells we re also observed in lymph nodes draining electropermeabilized sites. A HBV sAg-coding plasmid was used to test skin EP-mediated NAV in a murine model. Analysis of humoral immune responses including immunoglobulin subclass pro files revealed strong enhancement of EP-mediated NAV relative to naked DNA injection, with a Th1-dominant, mixed-response pattern compared to immuniza tion with HBV sAg protein that was exclusively Th2 (P = 0.02). Applications for these findings include NAV-based modulation of immune responses to pat hogens, allergens, and tumor-associated antigens and the modification of to lerance.