title: Haemophilus ducreyi requires an intact flp gene cluster for virulence in humans.
abstract: An intact Haemophilus ducreyi flp operon is essential for microcolony formation in vitro. tadA is the 9th of 15 genes in the operon and has homology to NTPases of type IV secretion systems. Fifteen human volunteers were experimentally infected with both H. ducreyi 35000HP and the tadA mutant, 35000HP.400. Papules developed at similar rates at sites inoculated with the mutant and parent, while pustules formed at 36.4% of parent sites and at 0% of mutant sites (P = 0.001). Compared to 35000HP, 35000HP.400 had only a modest but significant reduction in lesion scores in the temperature-dependent rabbit model of chancroid. These data suggest that proteins secreted by the flp locus are required for full expression of virulence by H. ducreyi in humans but have less of a role in virulence in an animal model of infection.
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA. sspinola@iupui.edu
authors.forename: Stanley M
authors.initials: SM
authors.lastname: Spinola
authors.forename: Kate R
authors.initials: KR
authors.lastname: Fortney
authors.forename: Barry P
authors.initials: BP
authors.lastname: Katz
authors.forename: Jo L
authors.initials: JL
authors.lastname: Latimer
authors.forename: Jason R
authors.initials: JR
authors.lastname: Mock
authors.forename: Merja
authors.initials: M
authors.lastname: Vakevainen
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Hansen
mesh_terms: D000328:Adult; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002602:Chancroid / Q000382:microbiology / Q000503:physiopathology*; D004195:Disease Models, Animal; D005260:Female; D006191:Haemophilus ducreyi / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D008297:Male; D008875:Middle Aged; D005810:Multigene Family; D011817:Rabbits; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C113731:Flp protein, bacteria