Volume 8, Issue 6, Pages 992-998 (December 2003) Needle-free topical electroporation improves gene expression from plasmids administered in porcine skin  Shawn Babiuk, Maria E Baca-Estrada, Marianna Foldvari, Lawrence Baizer, Richard Stout, Michael Storms, Dietmar Rabussay, Georg Widera, Lorne Babiuk  Molecular Therapy  Volume 8, Issue 6, Pages 992-998 (December 2003) DOI: 10.1016/j.ymthe.2003.09.008 Copyright © 2003 The American Society of Gene Therapy Terms and Conditions

FIG. 1 Electroporation improves gene expression levels, and intradermal jet injection is more effective than intradermal needle injection. Luciferase-encoding plasmid DNA was administered to abdominal porcine skin, and enzymatic activity was measured 48 h following administration. Gene expression levels are shown for intradermal BioJect (b.j.) and needle (i.d.n.) injections, without or with electroporation at the voltages indicated. Error bars represent SEM. Statistical differences were i.d.n. vs b.j. (*P < 0.05) and i.d.n. vs i.d.n. plus electroporation (*P < 0.05) by one-way ANOVA followed by Tukey's multiple comparison test. Molecular Therapy 2003 8, 992-998DOI: (10.1016/j.ymthe.2003.09.008) Copyright © 2003 The American Society of Gene Therapy Terms and Conditions

FIG. 2 Effect of electroporation on tissue damage and cellular infiltration. Skin tissues were collected 48 h following electroporation at 60 (A), 70 (B), and 80 V (C) and stained with H&E. Cellular infiltration of macrophages and neutrophils in the stratum corneum was found in (A). Moderate cellular infiltration of macrophages and neutrophils in the epidermis was found in (B). Severe cellular infiltration in the epidermis as well as the dermis was observed in (C). Bar represents 100 μm. Molecular Therapy 2003 8, 992-998DOI: (10.1016/j.ymthe.2003.09.008) Copyright © 2003 The American Society of Gene Therapy Terms and Conditions

FIG. 3 Immune responses to hepatitis B after the different DNA-prime/protein-boost immunizations. HBsAg antibody titers at 10 weeks (2 weeks after the protein boost) were determined using the AUSAB EIA and are the geometric means of five animals for all the groups except for the i.m.n. subunit group, which had four animals. Error bars are SEM. Statistical differences were determined using a one-way ANOVA followed by Tukey's multiple comparison test; **P < 0.01, ***P < 0.001 vs prebleed. Molecular Therapy 2003 8, 992-998DOI: (10.1016/j.ymthe.2003.09.008) Copyright © 2003 The American Society of Gene Therapy Terms and Conditions

FIG. 4 Antibody isotype responses elicited by hepatitis B immunizations. Hepatitis B-specific IgG1 (A, D) and IgG2 (B, E) titers at 8 (A, B) and 10 (D, E) weeks and IgG1/IgG2 ratios from responding animals (C, F) are shown; data represent individual animals at 8 and 10 weeks and the bars are the geometric means. Group 1 is BioJect DNA, Group 2 BioJect DNA + EP, Group 3 intradermal injection DNA, Group 4 intradermal injection DNA + EP, Group 5 BioJect administration of the subunit vaccine, and Group 6 intramuscular injection of the subunit vaccine. At week 8, prior to boosting with protein, the level of antibody (IgG1) in the BioJect DNA plus electroporation group vs i.d.n. DNA plus electroporation (P < 0.001) was statistically different by one-way ANOVA followed by Tukey's multiple comparison test. There was no statistical difference between the levels of antibody (IgG1) in the BioJect DNA + electroporation and the Engerix-B groups at 8 weeks by one-way ANOVA followed by Tukey's multiple comparison test. Molecular Therapy 2003 8, 992-998DOI: (10.1016/j.ymthe.2003.09.008) Copyright © 2003 The American Society of Gene Therapy Terms and Conditions