title: An IL-15 adjuvant enhances the efficacy of a combined DNA vaccine against Brucella by increasing the CD8+ cytotoxic T cell response.
abstract: We investigated whether a combined DNA vaccine delivered together with the IL-15 gene (DNA-IL-15(+)) enhanced the immune response against Brucella abortus in mice. Mice vaccinated with DNA-IL-15(+) developed a robust humoral response; Brucella-specific antibodies exhibited a dominance of immunoglobulin G2a (IgG2a) over IgG1. Splenocytes from DNA-IL-15(+)-vaccinated mice induced significantly higher levels of IFN-gamma (P<0.01) and CD8(+) T cell response (P<0.01), suggesting induction of a T-helper-1-dominated immune response. In a specific cytotoxic-T-lymphocyte activity assay, DNA-IL-15(+) immunization elicited mainly CD8(+) T cells, which mediate cytotoxicity, but also CD4(+) T cells. In vivo depletion of T cell subsets showed that the DNA-IL-15(+)-induced protection against Brucella infection is mediated predominantly by CD8(+) T cells, although CD4(+) T cells also contribute. These data indicate that plasmid-delivered IL-15 increases the efficacy of the Brucella DNA vaccine.
authors.affiliation: The Institute of Veterinary Medicine, Xinjiang Academy of Animal Science, Urumqi 830000, China.
authors.forename: Xi-Dan
authors.initials: XD
authors.lastname: Hu
authors.forename: Su-Ting
authors.initials: ST
authors.lastname: Chen
authors.forename: Jia-Yun
authors.initials: JY
authors.lastname: Li
authors.forename: Da-Hai
authors.initials: DH
authors.lastname: Yu
authors.lastname: Yi-Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Cai
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D002004:Brucella Vaccine / Q000235:genetics / Q000276:immunology*; D002003:Brucella abortus / Q000235:genetics / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D007074:Immunoglobulin G / Q000097:blood; D007371:Interferon-gamma / Q000378:metabolism; D019409:Interleukin-15 / Q000008:administration & dosage* / Q000235:genetics; D015847:Interleukin-4 / Q000378:metabolism; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000276:immunology / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D019444:Vaccines, DNA / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D002004:Brucella Vaccine; D007074:Immunoglobulin G; D019409:Interleukin-15; D019444:Vaccines, DNA; D015847:Interleukin-4; D007371:Interferon-gamma