title: Legionella dumoffii Tex-KL Mutated in an Operon Homologous to traC-traD is Defective in Epithelial Cell Invasion.
abstract: OBJECTIVE
  To understand the mechanism of invasion by Legionella dumoffii.
  
  
  METHODS
  The L. dumoffii strain Tex-KL was mutated using the Tn903 derivative, Tn903dIIlacZ. After screening 799 transposon insertion mutants, we isolated one defective mutant. We then constructed the gene-disrupted mutant, KL16, and studied its invasion of and intracellular growth in HeLa and A549 cells, and in A/J mice survival experiments. The structure of traC-traD operon was analyzed by RT-PCR.
  
  
  RESULTS
  The transposon insertion was in a gene homologous to Salmonella typhi traC, which is required for the assembly of F pilin into the mature F pilus structure and for conjugal DNA transmission. Results from RT-PCR suggested that the traC-traD region formed an operon. We found that when the traC gene was disrupted, invasion and intracellular growth of L. dumoffii Tex-KL were impaired in human epithelial cells. When mice were infected by intranasal inoculation with a traC deficient mutant, their survival significantly increased when compared to mice infected with the wild-type strain..
  
  
  CONCLUSIONS
  Our results indicated that the traC-traD operon is required for the invasion and intracellular growth abilities of L. dumoffii Tex-KL in epithelial cells.
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, Zhejiang, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Qin
authors.affiliation: Departments of Bacteriology, Faculty of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Iida
authors.initials: I
authors.lastname: Ken-Ichiro
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, Zhejiang, China.
authors.forename: Hong Yu
authors.initials: HY
authors.lastname: Ren
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, Zhejiang, China.
authors.forename: Hai Jian
authors.initials: HJ
authors.lastname: Zhou
authors.affiliation: Departments of Bacteriology, Faculty of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Yoshida
mesh_terms: D000072283:A549 Cells; D000818:Animals; D005798:Genes, Bacterial; D006367:HeLa Cells; D006801:Humans; D007875:Legionella / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D009154:Mutation; D009876:Operon
keywords: Epithelial cells; Invasion ability; L. dumoffii Tex-KL; traC-traD operon