title: Improvement in T helper 1-related immune responses in BALB/c mice immunized with an HIV-1 gag plasmid combined with a chimeric plasmid encoding interleukin-18 and flagellin.
abstract: Both flagellin (fliC) and IL-18 (INF-γ-inducing factor) have been developed as adjuvants for improving immunogenicity in DNA-vaccinated hosts. An HIV-1 gag plasmid encodes a protein harboring broad epitopes for cytotoxic T-lymphocytes. In this study, the immunogenicity of BALB/c mice immunized with an HIV-1 gag plasmid (pVAX/gag) combined with a chimeric plasmid encoding IL-18 fused to flagellin (pcDNA3/IL-18_fliC) or a single plasmid encoding IL-18 (pcDNA3/IL-18) and/or flagellin (pcDNA3/fliC) was assessed. Through in vitro transcription and translation, it was demonstrated that both mRNA and protein were appropriately expressed by each construct. The IL-18 and flagellin fusion protein, which could be detected in supernatants from transfected cells, was effective in inducing IFN-γ by lymphocytes. Following i.m. immunization, expressions of flagellin or IL-18 were detected in muscle cells by immunohistochemistry analysis from 72 hr. At 12 weeks post-immunization, both gag-specific IgG in sera and spleen cell proliferation were high in all murine groups. However, the IgG2a/IgG1 ratio, Th1 cytokine (IL-2 and IFN-γ) production and proportion of gag-specific CD3(+) CD8(+) IFN-γ-secreting cells were significantly higher in the murine group co-immunized with pVAX/gag plasmid and pcDNA3/IL-18_fliC than in the mice immunized with pVAX/gag plasmid combined with either pcDNA3/fliC or pcDNA3/IL-18 plasmid or both. These findings suggest that a chimeric plasmid encoding IL-18 fused to flagellin can be used as an adjuvant-like plasmid to improve the Th1 immune response, particularly for induction of CD3(+) CD8(+) IFN-γ-secreting cells in gag plasmid-vaccinated mice.
authors.affiliation: Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan.
authors.forename: Ya-Lei
authors.initials: YL
authors.lastname: Chen
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, Kaohsiung Veterans General Hospital, Kaohsiung/National Yang-Ming University, Taipei.
authors.forename: Yao-Shen
authors.initials: YS
authors.lastname: Chen
authors.affiliation: Department of Medicine, Section of Infectious Disease, E-Da Hospital/I-Shou University, Kaohsiung.
authors.forename: Yi-Chien
authors.initials: YC
authors.lastname: Hung
authors.affiliation: Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan.
authors.forename: Pei-Ju
authors.initials: PJ
authors.lastname: Liu
authors.affiliation: Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan.
authors.forename: Hsi-Ying
authors.initials: HY
authors.lastname: Tasi
authors.affiliation: Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan.
authors.forename: Wei-Feng
authors.initials: WF
authors.lastname: Ni
authors.affiliation: Department of Biological Science, National Sun Yat-sen University, Kaohsiung, Taiwan.
authors.forename: Pei-Tan
authors.initials: PT
authors.lastname: Hseuh
authors.affiliation: Department of Medicine, Section of Infectious Disease, E-Da Hospital/I-Shou University, Kaohsiung.
authors.forename: Hsi-Hsun
authors.initials: HH
authors.lastname: Lin
mesh_terms: D016915:AIDS Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D000276:Adjuvants, Immunologic / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D049109:Cell Proliferation; D005260:Female; D005408:Flagellin / Q000235:genetics / Q000378:metabolism*; D015483:HIV Antibodies / Q000097:blood; D015497:HIV-1 / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood; D007273:Injections, Intramuscular; D007371:Interferon-gamma / Q000378:metabolism; D020382:Interleukin-18 / Q000235:genetics / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008807:Mice, Inbred BALB C; D010957:Plasmids; D013154:Spleen / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000276:immunology*
chemical_list: D016915:AIDS Vaccines; D000276:Adjuvants, Immunologic; D015483:HIV Antibodies; D007074:Immunoglobulin G; D020382:Interleukin-18; D019444:Vaccines, DNA; D054301:gag Gene Products, Human Immunodeficiency Virus; D005408:Flagellin; D007371:Interferon-gamma
keywords: DNA vaccination; adjuvant; flagellin; interleukin-18