Role of lipooligosaccharides in experimental dermal lesions caused by Haemophilus ducreyi

Abstract

The mouse and rabbit intradermal injection models have been used to define factors that may be important in Haemophilus ducreyi pathogenesis. We used H. ducreyi strains with diverse geographic origins and phenotypic characteristics to evaluate the experimental models. Injection of live and heat-killed bacteria caused skin abscesses in both models. Semiquantitative cultures of skin injected with live bacteria showed that H. ducreyi failed to replicate in animal tissue. These data suggested that the experimental lesions were caused by a heat-stable substance such as lipooligosaccharide (LOS). In mice, injection of H. ducreyi and Haemophilus influenzae LOS and Escherichia coli lipopolysaccharide caused mild to moderate inflammation. In rabbits, injection of H. ducreyi LOS caused intradermal abscesses that were histologically similar to those caused by live and heat-killed bacteria. H. ducreyi and Neisseria gonorrhoeae LOS caused significantly larger lesions than equivalent amounts of H. influenzae LOS and E. coli lipopolysaccharide in the rabbit model. We conclude that the intradermal injection models are not valid models to study the growth of H. ducreyi in vivo. However, these data indicate that H. ducreyi LOS may play an important role in the pathogenesis of chancroid and that the rabbit model should be useful in studying H. ducreyi LOS toxicity at the cellular level.

Expression of Peptidoglycan-Associated Lipoprotein Is Required for Virulence in the Human Model of Haemophilus ducreyi Infection

“…Southern blots were probed with either the pal coding sequence or the cat cassette. Lipooligosaccharides (LOS) and outer membranes were prepared from strains 35000HP, 35000HP-SMS4, 35000HP-SMS4(pLSKSpal), and 35000HP-SMS4(pLSKS) and subjected to sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE) analysis as described previously (15,26).…”

Chancroid: contemporary appraisal

“…This has fascinated investigators in to forming a detailed profile, including the characters, of this organism worldwide. 2,5-10, [39][40][41][42][43][44] The potential virulence factors in this organism, namely lipo-oligo-saccharide (LOS), pili, extracellular toxins, and hemolysin, 39,[46][47][48][49] have been identified. Several useful animal models, rabbits, primates, and pigs, as well as human volunteers have been employed for defining the characteristics of this fastidious bacteria.…”

“…53,54 Viable H. ducreyi along with LOS, cytolethal distending toxin, fine tangled pili and cells, and associated hemolysis, have also been identified in the lesions. 39,[46][47][48][49]56 An artificial skin model has been developed using neonatal foreskin fibroblasts and keratinocytes in a coculture system composed of dermal, epidermal and stratum corneum layers anchored to a nylon mesh support, and the affects of virulent H. ducreyi have been thoroughly investigated. 39 As with other organisms, the virulence of H. ducreyi is probably multifactorial and is dependent on the presence, relative expression, and cell range of several different virulence factors.…”

Cloning and characterization of the genes encoding the haemolysin of Haemophilus ducreyi

“…However, a few potential virulence factors have been identified. The lipooligosaccharide of H. ducreyi has been shown to cause ulcer formation in the rabbit and mouse models (Tuffrey et aL, 1990;Campagnari et aL, 1991;Lagergard 1992). In addition, two groups have identified putative cytotoxins.…”