title: Role of pathogenicity determinant protein C (PdpC) in determining the virulence of the Francisella tularensis subspecies tularensis SCHU.
abstract: Francisella tularensis subspecies tularensis, the etiological agent of tularemia, is highly pathogenic to humans and animals. However, the SCHU strain of F. tularensis SCHU P0 maintained by passaging in artificial media has been found to be attenuated. To better understand the molecular mechanisms behind the pathogenicity of F. tularensis SCHU, we attempted to isolate virulent bacteria by serial passages in mice. SCHU P5 obtained after 5th passages in mice remained avirulent, while SCHU P9 obtained after 9th passages was completely virulent in mice. Moreover, SCHU P9 grew more efficiently in J774.1 murine macrophages compared with that in the less pathogenic SCHU P0 and P5. Comparison of the nucleotide sequences of the whole genomes of SCHU P0, P5, and P9 revealed only 1 nucleotide difference among P0, P5 and P9 in 1 of the 2 copies of pathogenicity determinant protein C (pdpC) gene. An adenine residue deletion was observed in the pdpC1 gene of SCHU P0, P5, and P9 and in the pdpC2 gene of SCHU P0, and P5, while P9 was characterized by the wild type pdpC2 gene. Thus, SCHU P0 and P5 expressed only truncated forms of PdpC protein, while SCHU P9 expressed both wild type and truncated versions. To validate the pathogenicity of PdpC, both copies of the pdpC gene in SCHU P9 have been inactivated by Targetron mutagenesis. SCHU P9 mutants with inactivated pdpC gene showed low intracellular growth in J774.1 cells and did not induce severe disease in experimentally infected mice, while virulence of the mutants was restored by complementation with expression of the intact PdpC. These results demonstrate that PdpC is crucial in determining the virulence of F. tularensis SCHU.
authors.affiliation: Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Uda
authors.affiliation: Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sekizuka
authors.affiliation: Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Tanabayashi
authors.affiliation: Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Fujita
authors.affiliation: Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuroda
authors.affiliation: Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Akitoyo
authors.initials: A
authors.lastname: Hotta
authors.affiliation: Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan ; United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Sugiura
authors.affiliation: Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan ; United Graduate School of Veterinary Science, Gifu University, Gifu, Japan.
authors.forename: Neekun
authors.initials: N
authors.lastname: Sharma
authors.affiliation: Department of Veterinary Science, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Morikawa
authors.affiliation: Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Science, The University of Tokyo, Bunkyo, Tokyo, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Yamada
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D005604:Francisella tularensis / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D020868:Gene Silencing; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D012692:Serial Passage; D013045:Species Specificity; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C000592473:PdpC protein, Francisella tularensis; D037521:Virulence Factors