Identification of tandem genes involved in lipooligosaccharide expression by Haemophilus ducreyi

Marla K. Stevens, Julia Klesney-Tait, Sheryl Lumbley, K. A. Walters, A. Mark Joffe, Justin D. Radolf, Eric J. Hansen

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


A transposon insertion mutant of Haemophilus ducreyi 35000 possessing a truncated lipooligosaccharide (LOS) failed to hind the LOS-specific monoclonal antibody 3E6 (M. K. Stevens, L. D. Cope, J. D. Radolf and E. J. Hansen, Infect. Immun. 63:2976-2982, 1995). This transposon was found to have inserted into the first of two tandem genes and also caused a deletion of chromosomal DNA upstream of this gene. These two genes, designated lbgA and lbgB, encoded predicted proteins with molecular masses of 25,788 and 40,236 Da which showed homology with proteins which function in lipopolysaccharide biosynthetic in other gram-negative bacteria. The tandem arrangement of the lbgA and lbgB genes was found to be conserved among H. ducreyi strains. Isogenic LOS mutants, constructed by the insertion of a cat cartridge into either the lbgA or the lbgB gene, expressed an LOS phenotype indistinguishable from that of the original transposon-derived LOS mutant. The wild-type LOS phenotype could be restored by complementation with the appropriate wild-type allele. These two LOS mutants proved to be as virulent as the wild-type parent strain in an animal model. A double mutant with a deletion of the lbgA and lbgB genes yielded equivocal results when its virulence was tested in an animal model.

Original languageEnglish (US)
Pages (from-to)651-660
Number of pages10
JournalInfection and immunity
Issue number2
StatePublished - Feb 1997

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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