title: Modulating APOBEC expression enhances DNA vaccine immunogenicity.
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.
authors.affiliation: Department of Medicine, Laboratory of Clinical Immunology and Allergy-LIM60, Division of Clinical Immunology and Allergy, Department of Medicine, University of São Paulo School of Medicine, São Paulo, Brazil.|Institute for Investigation in Immunology-INCT, São Paulo, Brazil.
authors.forename: Rafael Ribeiro
authors.initials: RR
authors.lastname: Almeida
authors.affiliation: Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC, USA.
authors.forename: Rui André Saraiva
authors.initials: RA
authors.lastname: Raposo
authors.affiliation: Department of Medicine, Laboratory of Clinical Immunology and Allergy-LIM60, Division of Clinical Immunology and Allergy, Department of Medicine, University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Fernanda Caroline
authors.initials: FC
authors.lastname: Coirada
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Jamile Ramos
authors.initials: JR
authors.lastname: da Silva
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Luís Carlos
authors.initials: LC
authors.lastname: de Souza Ferreira
authors.affiliation: Department of Medicine, Laboratory of Clinical Immunology and Allergy-LIM60, Division of Clinical Immunology and Allergy, Department of Medicine, University of São Paulo School of Medicine, São Paulo, Brazil.|Institute for Investigation in Immunology-INCT, São Paulo, Brazil.|Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Jorge
authors.initials: J
authors.lastname: Kalil
authors.affiliation: Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC, USA.
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Nixon
authors.affiliation: Department of Medicine, Laboratory of Clinical Immunology and Allergy-LIM60, Division of Clinical Immunology and Allergy, Department of Medicine, University of São Paulo School of Medicine, São Paulo, Brazil.|Institute for Investigation in Immunology-INCT, São Paulo, Brazil.|Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo, Brazil.
authors.forename: Edecio
authors.initials: E
authors.lastname: Cunha-Neto
mesh_terms: D000071478:APOBEC Deaminases; D000818:Animals; D000956:Antigens, Viral / Q000235:genetics; D001055:Apolipoproteins B / Q000235:genetics / Q000378:metabolism*; D003564:Cytidine Deaminase / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D015497:HIV-1 / Q000502:physiology*; D006684:HLA-DR Antigens / Q000235:genetics; D006801:Humans; D056747:Immunomodulation; D016899:Interferon-beta / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D017393:RNA Editing; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology*; D019076:Transgenes / Q000235:genetics; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*; D000099197:STING Protein
chemical_list: D000071478:APOBEC Deaminases; D000956:Antigens, Viral; D001055:Apolipoproteins B; D003564:Cytidine Deaminase; D006684:HLA-DR Antigens; D016899:Interferon-beta; D008565:Membrane Proteins; D009124:Muscle Proteins; D010446:Peptide Fragments; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D034741:RNA, Small Interfering; D019444:Vaccines, DNA; C532857:STING1 protein, human; D000099197:STING Protein; C403191:TBK1 protein, human; C121399:APOBEC3A protein, human; C485629:Apobec2 protein, mouse