title: AnIn VitroCo-culture Mouse Model Demonstrates Efficient Vaccine-Mediated Control ofFrancisella tularensisSCHU S4 and Identifies Nitric Oxide as a Predictor of Efficacy.
abstract: Francisella tularensisis a highly virulent intracellular bacterium and cell-mediated immunity is critical for protection, but mechanisms of protection against highly virulent variants, such as the prototypic strainF. tularensisstrain SCHU S4, are poorly understood. To this end, we established a co-culture system, based on splenocytes from naïve, or immunized mice andin vitroinfected bone marrow-derived macrophages that allowed assessment of mechanisms controlling infection withF. tularensis. We utilized the system to understand why theclpBgene deletion mutant, ΔclpB, of SCHU S4 shows superior efficacy as a vaccine in the mouse model as compared to the existing human vaccine, the live vaccine strain (LVS). Compared to naïve splenocytes, ΔclpB-, or LVS-immune splenocytes conferred very significant control of a SCHU S4 infection and the ΔclpB-immune splenocytes were superior to the LVS-immune splenocytes. Cultures with the ΔclpB-immune splenocytes also contained higher levels of IFN-γ, IL-17, and GM-CSF and nitric oxide, and T cells expressing combinations of IFN-γ, TNF-α, and IL-17, than did cultures with LVS-immune splenocytes. There was strong inverse correlation between bacterial replication and levels of nitrite, an end product of nitric oxide, and essentially no control was observed when BMDM from iNOS-/-mice were infected. Collectively, the co-culture model identified a critical role of nitric oxide for protection against a highly virulent strain ofF. tularensis.
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden.
authors.forename: Igor
authors.initials: I
authors.lastname: Golovliov
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Lindgren
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden.
authors.forename: Kjell
authors.initials: K
authors.lastname: Eneslätt
authors.affiliation: National Research Council Canada, Institute for Biological Sciences Ottawa, ON, Canada.
authors.forename: Wayne
authors.initials: W
authors.lastname: Conlan
authors.affiliation: Centre International de Recherche en Infectiologie, Institut national de la santé et de la recherche médicale, U1111 Lyon, France.
authors.forename: Amandine
authors.initials: A
authors.lastname: Mosnier
authors.affiliation: Centre International de Recherche en Infectiologie, Institut national de la santé et de la recherche médicale, U1111 Lyon, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Henry
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Clinical Bacteriology, and Umeå University Umeå, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Sjöstedt
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001428:Bacterial Vaccines / Q000235:genetics / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes; D018414:CD8-Positive T-Lymphocytes; D018920:Coculture Techniques / Q000379:methods*; D016207:Cytokines / Q000378:metabolism; D004269:DNA, Bacterial; D004274:DNA, Recombinant; D004195:Disease Models, Animal; D049071:Endopeptidase Clp; D005604:Francisella tularensis / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D006360:Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology; D007371:Interferon-gamma / Q000378:metabolism; D020381:Interleukin-17 / Q000378:metabolism; D008264:Macrophages; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000032:analysis*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000032:analysis; D012141:Respiratory Tract Infections / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D017384:Sequence Deletion; D013601:T-Lymphocytes / Q000276:immunology; D014406:Tularemia / Q000276:immunology / Q000517:prevention & control*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014611:Vaccination; D014612:Vaccines / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000276:immunology
chemical_list: D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D016207:Cytokines; D004269:DNA, Bacterial; D004274:DNA, Recombinant; D006360:Heat-Shock Proteins; D020381:Interleukin-17; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha; D014612:Vaccines; D014613:Vaccines, Attenuated; D009569:Nitric Oxide; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D049071:Endopeptidase Clp; C424712:ClpB protein, Brucella suis
keywords: F. tularensis SCHU S4; correlates of protection; in vitro co-culture model; mouse immune response