title: Immune response profile elicited by the model antigen ovalbumin expressed in fusion with the bacterial OprI lipoprotein.
abstract: The use of immunogenic formulations targeting pattern recognition receptors towards modulation of immune responses is a promising strategy to develop better vaccines against infectious and malignant diseases. Molecules targeting TLR2 offer interesting properties that are relevant for vaccine development, including the possibility to covalently attach the lipidic ligands to the antigens. However, the type of immune response elicited by these formulations is still controversial. In this work, we used the model antigen ovalbumin (OVA) expressed in fusion with the bacterial lipoprotein OprI in order to characterize the immunomodulatory properties of this TLR ligand. Murine bone marrow-derived dendritic cells stimulated with OprI-OVA fusion lipoprotein produced high levels of the pro-inflammatory cytokines TNF-α and IL-6 and also IL-10, IL-12(p70) and IL-27, while TGF-β and IL-23 were not detected. Using OT-II and OT-I mice, an enhancement of MHC class II and class I antigen presentation was observed for the OVA antigen in fusion with OprI. Mice immunized by intraperitoneal route with this fusion lipoprotein in prime-boost protocols developed strong specific antibody responses including IgG1, IgG2c, IgG2b, IgG3 and IgE. These results, together with data obtained by restimulation of splenocytes from the immunized mice, point to an immune response profile that does not correspond to a strict Th1 or Th2 polarization. Finally, in a challenge experiment using a melanoma syngeneic mouse model (B16-OVA), prophylactic inoculation with OprI fused with the unrelated antigen eGFP increased the tumor growth, while the fusion with the tumor-associated antigen OVA delayed the tumor growth and increased mice survival.
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, ULisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal. Electronic address: abasto@fmv.ulisboa.pt.
authors.forename: Afonso P
authors.initials: AP
authors.lastname: Basto
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, ULisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal; Instituto Gulbenkian de Ciência, 2781-901 Oeiras, Portugal.
authors.forename: Marina
authors.initials: M
authors.lastname: Badenes
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal.
authors.forename: Sílvia C P
authors.initials: SC
authors.lastname: Almeida
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, ULisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Martins
authors.affiliation: CIISA, Faculdade de Medicina Veterinária, ULisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal; Instituto Gulbenkian de Ciência, 2781-901 Oeiras, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Duarte
authors.affiliation: Instituto de Investigação Científica Tropical, CVZ, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal; CIISA, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal.
authors.forename: Dulce M
authors.initials: DM
authors.lastname: Santos
authors.affiliation: Instituto de Investigação Científica Tropical, CVZ, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal; CIISA, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal. Electronic address: alexandre@fmv.ulisboa.pt.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Leitão
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D017951:Antigen Presentation / Q000276:immunology; D000941:Antigens / Q000276:immunology*; D001426:Bacterial Proteins / Q000276:immunology*; D001854:Bone Marrow Cells / Q000166:cytology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology; D007109:Immunity; D007114:Immunization; D008074:Lipoproteins / Q000276:immunology*; D008297:Male; D008546:Melanoma, Experimental / Q000276:immunology / Q000473:pathology; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology
chemical_list: D000906:Antibodies; D000941:Antigens; D001426:Bacterial Proteins; D016207:Cytokines; D008074:Lipoproteins; D011993:Recombinant Fusion Proteins; C060507:outer membrane lipoprotein I, Bacteria; D010047:Ovalbumin
keywords: Adjuvant; Immunomodulation; Melanoma mouse model; Outer membrane lipoprotein I; TLR2; Vaccine