Inactivation of the Haemophilus ducreyi luxS gene affects the virulence of this pathogen in human subjects.
Haemophilus ducreyi 35000HP contains a homologue of the luxS gene, which encodes an enzyme that synthesizes autoinducer 2 (AI-2) in other gram-negative bacteria. H. ducreyi 35000HP produced AI-2 that functioned in a Vibrio harveyi-based reporter system. A H. ducreyi luxS mutant was constructed by insertional inactivation of the luxS gene and lost the ability to produce AI-2. Provision of the H. ducreyi luxS gene in trans partially restored AI-2 production by the mutant. The luxS mutant was compared with its parent for virulence in the human challenge model of experimental chancroid. The pustule-formation rate in 5 volunteers was 93.3% (95% confidence interval, 81.7%-99.9%) at 15 parent sites and 60.0% (95% confidence interval, 48.3%-71.7%) at 15 mutant sites (1-tailed P < .001). Thus, the luxS mutant was partially attenuated for virulence. This is the first report of AI-2 production contributing to the pathogenesis of a genital ulcer disease.
Labandeira-Rey
Maria
M
Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, USA.
Janowicz
Diane M
DM
Blick
Robert J
RJ
Fortney
Kate R
KR
Zwickl
Beth
B
Katz
Barry P
BP
Spinola
Stanley M
SM
Hansen
Eric J
EJ
D000328:Adult; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001681:Biological Assay; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism*; D002602:Chancroid / Q000382:microbiology* / Q000473:pathology; D005260:Female; D006191:Haemophilus ducreyi / Q000235:genetics* / Q000472:pathogenicity*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D012867:Skin / Q000382:microbiology / Q000473:pathology; D014774:Virulence
D001426:Bacterial Proteins; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria