title: Alphavirus-based DNA vaccine breaks immunological tolerance by activating innate antiviral pathways.
abstract: Cancer vaccines targeting 'self' antigens that are expressed at consistently high levels by tumor cells are potentially useful in immunotherapy, but immunological tolerance may block their function. Here, we describe a novel, naked DNA vaccine encoding an alphavirus replicon (self-replicating mRNA) and the self/tumor antigen tyrosinase-related protein-1. Unlike conventional DNA vaccines, this vaccine can break tolerance and provide immunity to melanoma. The vaccine mediates production of double-stranded RNA, as evidenced by the autophosphorylation of dsRNA-dependent protein kinase R (PKR). Double-stranded RNA is critical to vaccine function because both the immunogenicity and the anti-tumor activity of the vaccine are blocked in mice deficient for the RNase L enzyme, a key component of the 2',5'-linked oligoadenylate synthetase antiviral pathway involved in double-stranded RNA recognition. This study shows for the first time that alphaviral replicon-encoding DNA vaccines activate innate immune pathways known to drive antiviral immune responses, and points the way to strategies for improving the efficacy of immunization with naked DNA.
authors.affiliation: National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA. wolfgang_leitner@nih.gov
authors.forename: Wolfgang W
authors.initials: WW
authors.lastname: Leitner
authors.forename: Leroy N
authors.initials: LN
authors.lastname: Hwang
authors.forename: Michael J
authors.initials: MJ
authors.lastname: deVeer
authors.forename: Aimin
authors.initials: A
authors.lastname: Zhou
authors.forename: Robert H
authors.initials: RH
authors.lastname: Silverman
authors.forename: Bryan R G
authors.initials: BR
authors.lastname: Williams
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Dubensky
authors.forename: Han
authors.initials: H
authors.lastname: Ying
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Restifo
mesh_terms: D000524:Alphavirus / Q000235:genetics* / Q000276:immunology*; D000818:Animals; D019496:Cancer Vaccines / Q000235:genetics / Q000276:immunology*; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D006801:Humans; D007108:Immune Tolerance; D007114:Immunization; D007167:Immunotherapy; D008545:Melanoma / Q000276:immunology* / Q000628:therapy; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D010088:Oxidoreductases; D010957:Plasmids / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism; D012093:Replicon / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014407:Tumor Cells, Cultured; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D019496:Cancer Vaccines; D008562:Membrane Glycoproteins; D011506:Proteins; D012330:RNA, Double-Stranded; D019444:Vaccines, DNA; D010088:Oxidoreductases; C489799:TYRP1 protein, human; C079621:Tyrp1 protein, mouse; C064056:tyrosinase-related protein-1; D012324:RNA-Dependent RNA Polymerase