title: Enhancement of DNA vaccine potency by linkage of antigen gene to a gene encoding the extracellular domain of Fms-like tyrosine kinase 3-ligand.
abstract: Recently, Flt3 (Fms-like tyrosine kinase 3)-ligand has been identified as an important cytokine for the generation of professional antigen-presenting cells (APCs), particularly dendritic cells (DCs). A recombinant chimera of the extracellular domain of Flt3-ligand (FL) linked to a model antigen may potentially target the antigen to DCs and their precursor cells. Using human papillomavirus-16 E7 as a model antigen, we evaluated the effect of linkage to FL on the potency of antigen-specific immunity generated by naked DNA vaccines administered intradermally via gene gun. We found that vaccines containing chimeric FL-E7 fusion genes significantly increased the frequency of E7-specific CD8+ T cells relative to vaccines containing the wild-type E7 gene. In vitro studies indicated that cells transfected with FL-E7 DNA presented E7 antigen through the MHC class I pathway more efficiently than wild-type E7 DNA. Furthermore, bone marrow-derived DCs pulsed with cell lysates containing FL-E7 fusion protein presented E7 antigen through the MHC class I pathway more efficiently than DCs pulsed with cell lysates containing wild-type E7 protein. More importantly, this fusion converted a less effective vaccine into one with significant potency against established E7-expressing metastatic tumors. The FL-E7 fusion vaccine mainly targeted CD8+ T cells, and antitumor effects were completely CD4 independent. These results indicate that fusion of a gene encoding the extracellular domain of FL to an antigen gene may greatly enhance the potency of DNA vaccines via CD8-dependent pathways.
authors.affiliation: Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
authors.forename: C F
authors.initials: CF
authors.lastname: Hung
authors.forename: K F
authors.initials: KF
authors.lastname: Hsu
authors.forename: W F
authors.initials: WF
authors.lastname: Cheng
authors.forename: C Y
authors.initials: CY
authors.lastname: Chai
authors.forename: L
authors.initials: L
authors.lastname: He
authors.forename: M
authors.initials: M
authors.lastname: Ling
authors.forename: T C
authors.initials: TC
authors.lastname: Wu
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019496:Cancer Vaccines / Q000235:genetics / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D008040:Genetic Linkage; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D016233:Immunotherapy, Active; D008175:Lung Neoplasms / Q000628:therapy; D008285:Major Histocompatibility Complex / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000276:immunology*; D050725:Papillomavirus E7 Proteins; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology*; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*
chemical_list: D000956:Antigens, Viral; D019496:Cancer Vaccines; D018984:Epitopes, T-Lymphocyte; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; C084881:flt3 ligand protein; C059731:oncogene protein E7, Human papillomavirus type 16