title: [Construction of the XZ113 delta eaeA, XZ113 delta stx2 and XZ113 delta ehxA mutants of STEC O18 XZ113 and their pathogenicity in mice].
abstract: OBJECTIVE
  To study the contribution of virulence genes of STEC O18 XZ113 isolate to the pathogenicity in mice.
  
  
  METHODS
  The eaeA, stx2 and ehxA knock-out mutants of STEC strain XZ113 were generated using lambda-Red recombination system.
  
  
  RESULTS
  Bacterial adherence test showed that the eaeA mutant adhered to HEp-2 cells in a diffuse manner with no microcolony formation. Vero cells assay showed that the stx mutant had no cytotoxicity to Vero cells. Enterohemolytic activity test showed that the ehxA mutant lost the ability to express the enterohemolytic activity. Competition assay between the wild-type strain XZ113 and its mutants in vivo and in vitro showed that all mutants were mildly attenuated in vitro, but in vivo, XZ113 delta eaeA was moderate attenuated, XZ113 delta stx2 and XZ113 delta ehxA were all highly attenuated.
  
  
  CONCLUSIONS
  These results indicate that the virulence factors encoded by the stx2 and ehxA genes were important for the pathogenesis of STEC O18 in mice.
authors.affiliation: Key Laboratory of Animal Infectious Diseases of Agriculture Ministry, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China. netbf1982@sina.com
authors.forename: Tao
authors.initials: T
authors.lastname: Xue
authors.forename: Xianliang
authors.initials: X
authors.lastname: Chen
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.forename: Xiufan
authors.initials: X
authors.lastname: Liu
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D022641:Shiga Toxin 2 / Q000235:genetics / Q000378:metabolism*; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity* / Q000502:physiology
chemical_list: D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D022641:Shiga Toxin 2; C073819:eaeA protein, E coli