title: Plasmid DNA vaccine encoding prostatic acid phosphatase is effective in eliciting autologous antigen-specific CD8+ T cells.
abstract: Prostatic acid phosphatase (PAP) is a prostate cancer tumor antigen and a prostate-specific protein shared by rats and humans. Previous studies indicated that Copenhagen rats immunized with a recombinant vaccinia virus expressing human PAP (hPAP) developed PAP-specific cytotoxic T cells (CTL) with cross reactivity to rat PAP (rPAP) and evidence of prostate inflammation. Viral delivery of vaccine antigens is an active area of clinical investigation. However, a potential difficulty with viral-based immunizations is that immune responses elicited to the viral vector might limit the possibility of multiple immunizations. In this paper, we investigate the ability of another genetic immunization method, a DNA vaccine encoding PAP, to elicit antigen-specific CD8+ T cell immune responses. Specifically, Lewis rats were immunized with either a plasmid DNA-based (pTVG-HP) or vaccinia-based (VV-HP) vaccine each encoding hPAP. We determined that rats immunized with a DNA vaccine encoding hPAP developed a Th1-biased immune response as indicated by proliferating PAP-specific CD4+ and CD8+ cells and IFNgamma production. Rats immunized with vaccinia virus encoding PAP did not develop a PAP-specific response unless boosted with a heterologous vaccination scheme. Most importantly, multiple immunizations with a DNA vaccine encoding the rat PAP homologue (pTVG-RP) could overcome peripheral self-tolerance against rPAP and generate a Th1-biased antigen-specific CD4+ and CD8+ T cell response. Overall, DNA vaccines provide a safe and effective method of generating prostate antigen-specific T cell responses. These findings support the investigation of PAP-specific DNA vaccines in human clinical trials.
authors.affiliation: Department of Medicine, University of Wisconsin, Madison, WI 53792, USA.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Johnson
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Frye
authors.forename: Nachimuthu
authors.initials: N
authors.lastname: Chinnasamy
authors.forename: Dhanalakshmi
authors.initials: D
authors.lastname: Chinnasamy
authors.forename: Douglas G
authors.initials: DG
authors.lastname: McNeel
mesh_terms: D000135:Acid Phosphatase; D000818:Animals; D001324:Autoantigens / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D019496:Cancer Vaccines / Q000008:administration & dosage / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005822:Genetic Vectors / Q000276:immunology; D006801:Humans; D008297:Male; D010957:Plasmids; D011471:Prostatic Neoplasms / Q000276:immunology / Q000628:therapy*; D017027:Protein Tyrosine Phosphatases / Q000276:immunology*; D051381:Rats; D011917:Rats, Inbred Lew; D014161:Transduction, Genetic; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology*; D014616:Vaccinia virus / Q000235:genetics
chemical_list: D001324:Autoantigens; D019496:Cancer Vaccines; D019444:Vaccines, DNA; D000135:Acid Phosphatase; C428439:prostatic acid phosphatase; D017027:Protein Tyrosine Phosphatases