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The development of therapeutic vaccines for chronic hepatitis B virus (HBV) infection has been hampered by host immune tolerance and the generally low magnitude and inconsistent immune responses to conventional vaccines and proposed new delivery methods. Electroporation (EP) for plasmid DNA (pDNA) vaccine delivery has demonstrated the enhanced immunogenicity of HBV antigens in various animal models. In the present study, the efficiency of the EP-based delivery of pDNA expressing various reporter genes first was evaluated in normal woodchucks, and then the immunogenicity of an analog woodchuck hepatitis virus (WHV) surface antigen (WHsAg) pDNA vaccine was studied in this model. The expression of reporter genes was greatly increased when the cellular uptake of pDNA was facilitated by EP. The EP of WHsAg-pDNA resulted in enhanced, dose-dependent antibody and T-cell responses to WHsAg compared to those of the conventional hypodermic needle injection of WHsAg-pDNA. Although subunit WHsAg protein vaccine elicited higher antibody titers than the DNA vaccine delivered with EP, T-cell response rates were comparable. However, in WHsAg-stimulated mononuclear cell cultures, the mRNA expression of CD4 and CD8 leukocyte surface markers and Th1 cytokines was more frequent and was skewed following DNA vaccination compared to that of protein immunization. Thus, the EP-based vaccination of normal woodchucks with pDNA-WHsAg induced a skew in the Th1/Th2 balance toward Th1 immune responses, which may be considered more appropriate for approaches involving therapeutic vaccines to treat chronic HBV infection. [ABSTRACT FROM AUTHOR]

The HIV Vaccine Trials Network (HVTN) 087 vaccine trial assessed the effect of increasing doses of pIL-12 (interleukin-12 delivered as plasmid DNA) adjuvant on the immunogenicity of an HIV-1 multiantigen (MAG) DNA vaccine delivered by electroporation and boosted with a vaccine comprising an attenuated vesicular stomatitis virus expressing HIV-1 Gag (VSV-Gag). We randomized 100 healthy adults to receive placebo or 3 mg HIV-MAG DNA vaccine (ProfectusVax HIV-1 gag / pol or ProfectusVax nef / tat / vif , env ) coadministered with pIL-12 at 0, 250, 1,000, or 1,500 μg intramuscularly by electroporation at 0, 1, and 3 months followed by intramuscular inoculation with 3.4 × 10 7 PFU VSV-Gag vaccine at 6 months. Immune responses were assessed after the prime and boost and 6 months after the last vaccination. High-dose pIL-12 increased the magnitude of CD8 + T-cell responses postboost compared to no pIL-12 ( P = 0.02), while CD4 + T-cell responses after the prime were higher in the absence of pIL-12 than with low- and medium-dose pIL-12 ( P ≤ 0.05). The VSV boost increased Gag-specific CD4 + and CD8 + T-cell responses in all groups ( P < 0.001 for CD4 + T cells), inducing a median of four Gag epitopes in responders. Six to 9 months after the boost, responses decreased in magnitude, but CD8 + T-cell response rates were maintained. The addition of a DNA prime dramatically improved responses to the VSV vaccine tested previously in the HVTN 090 trial, leading to broad epitope targeting and maintained CD8 + T-cell response rates at early memory. The addition of high-dose pIL-12 given with a DNA prime by electroporation and boosted with VSV-Gag increased the CD8 + T-cell responses but decreased the CD4 + responses. This approach may be advantageous in reshaping the T-cell responses to a variety of chronic infections or tumors. (This study has been registered at ClinicalTrials.gov under registration no. NCT01578889.)., (Copyright © 2017 American Society for Microbiology.)