DNA immunization site determines the level of gene expression and the magnitude, but not the type of the induced immune response

PLoS One. 2018 Jun 4;13(6):e0197902. doi: 10.1371/journal.pone.0197902. eCollection 2018.

Abstract

Optimization of DNA vaccine delivery improves the potency of the immune response and is crucial to clinical success. Here, we inquired how such optimization impacts the magnitude of the response, its specificity and type. BALB/c mice were DNA-immunized with two model immunogens, HIV-1 protease and reverse transcriptase by intramuscular or intradermal injections with electroporation. DNA immunogens were co-delivered with DNA encoding luciferase. Delivery and expression were monitored by in vivo bioluminescence imaging (BLI). The endpoint immune responses were assessed by IFN-γ/IL-2 FluoroSpot, multiparametric flow cytometry and antibody ELISA. Expression and immunogenicity were compared in relation to the delivery route. Regardless of the route, protease generated mainly IFN-γ, and reverse transcriptase, IL-2 and antibody response. BLI of mice immunized with protease- or reverse transcriptase/reporter plasmid mixtures, demonstrated significant loss of luminescence over time. The rate of decline of luminescence strongly correlated with the magnitude of immunogen-specific response, and depended on the immunogenicity profile and the immunization route. In vitro and in vivo BLI-based assays demonstrated that intradermal delivery strongly improved the immunogenicity of protease, and to a lesser extent, of reverse transcriptase. Immune response polarization and epitope hierarchy were not affected. Thus, by changing delivery/immunogen expression sites, it is possible to modulate the magnitude, but not the type or fine specificity of the induced immune response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Viral / immunology
  • Cytokines / metabolism
  • Epitopes / immunology
  • Female
  • Gene Expression
  • HIV Protease / metabolism
  • Immunization*
  • Intracellular Space / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Muscles / immunology
  • Skin / immunology
  • Vaccines, DNA / genetics
  • Vaccines, DNA / immunology*

Substances

  • Antibodies, Viral
  • Cytokines
  • Epitopes
  • Vaccines, DNA
  • HIV Protease
  • p16 protease, Human immunodeficiency virus 1

Grants and funding

The study was supported by the Russian Foundation of Basic Research project #15-15-30039 (http://www.rfbr.ru/rffi/ru/). Cross-border partner interactions were supported by the EU Twinning project VACTRAIN (Horizon 2020) #692293 (ec.europa.eu) and PI project of the Swedish Institute #19806_2016 (si.se) (MI). Participation of Petkov S, Chiodi F, and Wahren B was supported by VACTRAIN. Participation of Svirskis S was supported by BALTINFECT (ec.europa.eu). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.