Linear doggybone DNA vaccine induces similar immunological responses to conventional plasmid DNA independently of immune recognition by TLR9 in a pre-clinical model

• Published in: Cancer Immunology, Immunotherapy Vol. 67; no. 4; pp. 627 - 638
• Main Authors: Allen, Alex, Wang, Chuan, Caproni, Lisa J., Sugiyarto, Gessa, Harden, Elena, Douglas, Leon R., Duriez, Patrick J., Karbowniczek, Kinga, Extance, Jon, Rothwell, Paul J., Orefo, Ifeayinwa, Tite, John P., Stevenson, Freda K., Ottensmeier, Christian H., Savelyeva, Natalia
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2018; Springer Nature B.V
• Subjects: Adaptive immunity; Animals; Antibiotic resistance; Antigens; Cancer; Cancer Research; Cancer vaccines; CD8-Positive T-Lymphocytes - immunology; CpG islands; Dendritic Cells - immunology; Deoxyribonucleic acid; Disease Models, Animal; DNA; DNA vaccines; DNA-directed DNA polymerase; Humoral immunity; Immunity, Cellular - immunology; Immunogenicity; Immunology; Immunostimulation; Immunotherapy; Lung Neoplasms - genetics; Lung Neoplasms - immunology; Lung Neoplasms - therapy; Medicine; Medicine & Public Health; Mice; Mice, Inbred C57BL; Nucleotide sequence; Oncology; Original; Original Article; Plasmids - administration & dosage; Plasmids - genetics; Plasmids - immunology; Protelomerase; TLR9 protein; Toll-Like Receptor 9 - immunology; Toll-like receptors; Tumor Cells, Cultured; Tumors; Vaccination; Vaccines; Vaccines, DNA - administration & dosage; Vaccines, DNA - genetics; Vaccines, DNA - immunology; TLR9; Bacteria free production; STING; Cancer vaccine; Doggybone DNA vaccine; CD8+ T cells
• ISSN: 0340-7004; 1432-0851
• DOI: 10.1007/s00262-017-2111-y

Vaccination with DNA that encodes cancer antigens is a simple and convenient way to raise immunity against cancer and has already shown promise in the clinical setting. Conventional plasmid DNA is commonly used which together with the encoded antigen also includes bacterial immunostimulatory CpG motifs to target the DNA sensor Toll-like receptor 9. Recently DNA vaccines using doggybone DNA (dbDNA™), have been developed without the use of bacteria. The cell-free process relies on the use of Phi29 DNA polymerase to amplify the template followed by protelomerase TelN to complete individual closed linear DNA. The resulting DNA contains the required antigenic sequence, a promoter and a poly A tail but lacks bacterial sequences such as an antibiotic resistance gene, prompting the question of immunogenicity. Here we compared the ability of doggybone DNA vaccine with plasmid DNA vaccine to induce adaptive immunity using clinically relevant oncotargets E6 and E7 from HPV. We demonstrate that despite the inability to trigger TLR9, doggybone DNA was able to induce similar levels of cellular and humoral immunity as plasmid DNA, with suppression of established TC-1 tumours.