title: Identification, recombinant expression, immunolocalization in macrophages, and T-cell responsiveness of the major extracellular proteins of Francisella tularensis.
abstract: A safer and more effective vaccine than the previously developed live attenuated vaccine is needed for combating Francisella tularensis, a highly infectious bacterial pathogen. To search for potential candidates for inclusion in a new vaccine, we characterized the proteins present in the culture filtrates of a virulent recent clinical isolate and the attenuated live vaccine strain of F. tularensis using a proteomic approach. We identified a total of 12 proteins; among these, catalase-peroxidase was much more abundant in the culture filtrate of the virulent clinical isolate, whereas bacterioferritin was more abundant in the culture filtrate of the live vaccine strain. Streptolysin O treatment of infected human macrophages indicated that catalase-peroxidase and the heat shock protein GroEL are released intracellularly by actively growing F. tularensis. Mice immunized with F. tularensis developed significant cell-mediated immune responses to catalase-peroxidase, the heat shock protein GroEL, and bacterioferritin as measured by splenic lymphocyte proliferation and gamma interferon production. Finally, we expressed the major culture filtrate proteins that are promising vaccine candidates in Escherichia coli at high levels in soluble form to facilitate study of their immunobiology and potential role in vaccines.
authors.affiliation: Division of Infectious Diseases, 37-121 Center for the Health Sciences, University of California, Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095-1688, USA.
authors.forename: Bai-Yu
authors.initials: BY
authors.lastname: Lee
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Horwitz
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Clemens
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000276:immunology; D001428:Bacterial Vaccines / Q000276:immunology; D003470:Culture Media / Q000378:metabolism; D005110:Extracellular Space / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D005260:Female; D005604:Francisella tularensis / Q000235:genetics* / Q000254:growth & development / Q000276:immunology; D007111:Immunity, Cellular / Q000235:genetics; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000382:microbiology*; D014406:Tularemia / Q000276:immunology
chemical_list: D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D003470:Culture Media; D011994:Recombinant Proteins