Modulating APOBEC expression enhances DNA vaccine immunogenicity

Immunol Cell Biol. 2015 Nov;93(10):868-76. doi: 10.1038/icb.2015.53. Epub 2015 May 8.

Abstract

DNA vaccines have failed to induce satisfactory immune responses in humans. Several mechanisms of double-stranded DNA (dsDNA) sensing have been described, and modulate DNA vaccine immunogenicity at many levels. We hypothesized that the immunogenicity of DNA vaccines in humans is suppressed by APOBEC (apolipoprotein B (APOB) mRNA-editing, catalytic polypeptide)-mediated plasmid degradation. We showed that plasmid sensing via STING (stimulator of interferon (IFN) genes) and TBK-1 (TANK-binding kinase 1) leads to IFN-β induction, which results in APOBEC3A mRNA upregulation through a mechanism involving protein kinase C signaling. We also showed that murine APOBEC2 expression in HEK293T cells led to a 10-fold reduction in intracellular plasmid levels and plasmid-encoded mRNA, and a 2.6-fold reduction in GFP-expressing cells. A bicistronic DNA vaccine expressing an immunogen and an APOBEC2-specific shRNA efficiently silenced APOBEC2 both in vitro and in vivo, increasing the frequency of induced IFN-γ-secreting T cells. Our study brings new insights into the intracellular machinery involved in dsDNA sensing and how to modulate it to improve DNA vaccine immunogenicity in humans.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • APOBEC Deaminases
  • Animals
  • Antigens, Viral / genetics
  • Apolipoproteins B / genetics
  • Apolipoproteins B / metabolism*
  • Cytidine Deaminase / genetics
  • Cytidine Deaminase / metabolism*
  • HEK293 Cells
  • HIV-1 / physiology*
  • HLA-DR Antigens / genetics
  • Humans
  • Immunomodulation
  • Interferon-beta / metabolism
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Mice, Transgenic
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Peptide Fragments / genetics
  • Protein-Serine-Threonine Kinases / metabolism
  • Proteins / genetics
  • Proteins / metabolism*
  • RNA Editing
  • RNA, Small Interfering / genetics
  • Signal Transduction / genetics
  • T-Lymphocytes / immunology*
  • Transgenes / genetics
  • Vaccines, DNA / genetics
  • Vaccines, DNA / immunology*

Substances

  • Antigens, Viral
  • Apolipoproteins B
  • HLA-DR Antigens
  • Membrane Proteins
  • Muscle Proteins
  • Peptide Fragments
  • Proteins
  • RNA, Small Interfering
  • STING1 protein, human
  • Vaccines, DNA
  • Interferon-beta
  • Protein-Serine-Threonine Kinases
  • TBK1 protein, human
  • APOBEC Deaminases
  • APOBEC3A protein, human
  • Apobec2 protein, mouse
  • Cytidine Deaminase