Immunostimulatory effects of plasmid DNA and synthetic oligodeoxynucleotides.
Nucleic acid immunization is a new vaccination technology. DNA vaccines do not only carry the genetic information for the antigen of interest but also deliver an adjuvant effect due to the presence of immunostimulatory sequences within the plasmid backbone. It is generally assumed that the adjuvant properties of plasmid DNA are equal to those described for oligodeoxynucleotides (ODN) containing immunostimulatory CpG motifs. To challenge this hypothesis we have carried out a series of experiments comparing the ability of single- and double-stranded ODN containing CpG motifs to induce the activation of mouse spleen cells. Moreover, we compared the immunostimulatory properties of plasmids that were modified by the addition of two to four CpG motifs. Our results establish that plasmid DNA express their adjuvanticity as either double or single strands, and no differences were observed between modified and unmodified plasmids. On the other hand, the strongest stimulatory ODN sequences lost their adjuvant properties when administered as double-strand DNA. Furthermore, the profile of cytokines induced on spleen cells by plasmid DNA and ODN is different. Strikingly, plasmid DNA induces a moderate synthesis of IL-6 and a strong synthesis of IFN-gamma, whereas stimulation with ODN showed an inverse profile with a higher increase in the synthesis of IL-6 but a moderate increase in IFN-gamma. Finally, in vivo studies were consistent with the results obtained in vitro. Mice immunized with modified or unmodified plasmids encoding the glycoprotein D of HSV showed similar levels of cellular and humoral immune responses.
Laboratorio de Inmunoquímica, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Santiago
S
Zelenay
Fernanda
F
Elías
Juan
J
Fló
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D019013:CD40 Antigens / Q000096:biosynthesis; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D010957:Plasmids / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology; D019444:Vaccines, DNA / Q000276:immunology; D014759:Viral Envelope Proteins / Q000276:immunology
D000276:Adjuvants, Immunologic; D019013:CD40 Antigens; C408982:CPG-oligonucleotide; D016207:Cytokines; D009838:Oligodeoxyribonucleotides; D013873:Thionucleotides; D019444:Vaccines, DNA; D014759:Viral Envelope Proteins; C040570:glycoprotein D-herpes simplex virus type 2; D007371:Interferon-gamma