Antimicrobial Susceptibility of
            <i>Haemophilus ducreyi</i>

Hammond, Gregory; Lian, Chang; Wilt, J. C.; Ronald, Allan R.

doi:10.1128/aac.13.4.608

Cited by 121 publications

(76 citation statements)

References 13 publications

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“…H. ducreyi strain 35000 (27) and its human-passaged variant 35000HP (7) have been previously described. The relevant mutants constructed in the present study and in previous studies are listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Inhibition of Phagocytosis byHaemophilus ducreyiRequires Expression of the LspA1 and LspA2 Proteins

2003

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Haemophilus ducreyi previously has been shown to inhibit the phagocytosis of both secondary targets and itself by certain cells in vitro. Wild-type H. ducreyi strain 35000HP contains two genes, lspA1 and lspA2, whose encoded protein products are predicted to be 456 and 543 kDa, respectively. An isogenic mutant of H. ducreyi 35000HP with inactivated lspA1 and lspA2 genes has been shown to exhibit substantially decreased virulence in the temperature-dependent rabbit model for chancroid. This lspA1 lspA2 mutant was tested for its ability to inhibit phagocytosis of immunoglobulin G-opsonized particles by differentiated HL-60 and U-937 cells and by J774A.1 cells. The wild-type strain H. ducreyi 35000HP readily inhibited phagocytosis, whereas the lspA1 lspA2 mutant was unable to inhibit phagocytosis. Similarly, the wild-type strain was resistant to phagocytosis, whereas the lspA1 lspA2 mutant was readily engulfed by phagocytes. This inhibitory effect of wild-type H. ducreyi on phagocytic activity was primarily associated with live bacterial cells but could also be found, under certain conditions, in concentrated H. ducreyi culture supernatant fluids that lacked detectable outer membrane fragments. Both the wild-type strain and the lspA1 lspA2 mutant attached to phagocytes at similar levels. These results indicate that the LspA1 and LspA2 proteins of H. ducreyi are involved, directly or indirectly, in the antiphagocytic activity of this pathogen, and they provide a possible explanation for the greatly reduced virulence of the lspA1 lspA2 mutant.

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Section: Methodsmentioning

confidence: 99%

Inhibition of Phagocytosis byHaemophilus ducreyiRequires Expression of the LspA1 and LspA2 Proteins

2003

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“…H. ducreyi strains 35000 (23) and 35000HP (6) have been described. The mutants constructed in this study are listed in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Haemophilus ducreyi Requires the flp Gene Cluster for Microcolony Formation In Vitro

et al. 2002

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Haemophilus ducreyi, the etiologic agent of chancroid, has been shown to form microcolonies when cultured in the presence of human foreskin fibroblasts. We identified a 15-gene cluster in H. ducreyi that encoded predicted protein products with significant homology to those encoded by the tad (for tight adhesion) locus in Actinobacillus actinomycetemcomitans that is involved in the production of fimbriae by this periodontal pathogen. The first three open reading frames in this H. ducreyi gene cluster encoded predicted proteins with a high degree of identity to the Flp (fimbria-like protein) encoded by the first open reading frame of the tad locus; this 15-gene cluster in H. ducreyi was designated flp. RT-PCR analysis indicated that the H. ducreyi flp gene cluster was likely to be a polycistronic operon. Mutations within the flp gene cluster resulted in an inability to form microcolonies in the presence of human foreskin fibroblasts. In addition, the same mutants were defective in the ability to attach to both plastic and human foreskin fibroblasts in vitro. An H. ducreyi mutant with an inactivated tadA gene exhibited a small decrease in virulence in the temperature-dependent rabbit model for experimental chancroid, whereas another H. ducreyi mutant with inactivated flp-1 and flp-2 genes was as virulent as the wild-type parent strain. These results indicate that the flp gene cluster is essential for microcolony formation by H. ducreyi, whereas this phenotypic trait is not linked to the virulence potential of the pathogen, at least in this animal model of infection.

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“…The 11 H. ducreyi strains used in this study are described in Table 1. H. ducreyi 35000 has been extensively characterized (19)(20)(21). H. ducreyi strains were cultivated at 33ЊC in an atmosphere of 95% air and 5% CO 2 on chocolate agar supplemented with Isovitalex (CA) (BBL Microbiology Systems, Becton Dickinson, Cockeysville, Md.)…”

Section: Methodsmentioning

confidence: 99%

The major outer membrane protein of Haemophilus ducreyi consists of two OmpA homologs

et al. 1997

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The major outer membrane protein (MOMP) of Haemophilus ducreyi is an OmpA homolog that migrates on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels as three species with apparent molecular weights ranging from 37,000 to 43,000. Monoclonal antibodies directed against this macromolecule were used to identify recombinant clones containing fragments of the gene encoding this protein. Nucleotide sequence analysis of these fragments confirmed that the MOMP encoded by the intact gene (momp) was a member of the OmpA family of outer membrane proteins. Construction of an isogenic H. ducreyi mutant unable to express the MOMP led to the discovery of a second outer membrane protein which migrated at the same rate on SDS-PAGE gels as the MOMP. N-terminal amino acid sequence analysis of this second protein revealed that its N terminus was nearly identical to that of the MOMP and also had homology with members of the OmpA family. Nucleotide sequence analysis of the region downstream from the momp gene revealed the presence of a partial open reading frame encoding a predicted OmpA-like protein. A modification of anchored PCR technology was used to obtain the nucleotide sequence of this downstream gene which was shown to encode a second OmpA homolog (OmpA2). The N-terminal amino acid sequence of OmpA2 was identical to that of the OmpA-like protein detected in the momp mutant. The H. ducreyi MOMP and OmpA2 proteins, which comigrated on SDS-PAGE gels and which were encoded by the tandem arranged momp and ompA2 genes, were 72% identical.

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Antimicrobial Susceptibility of Haemophilus ducreyi

Abstract: The susceptibility of 19

Cited by 121 publications

References 13 publications

Inhibition of Phagocytosis byHaemophilus ducreyiRequires Expression of the LspA1 and LspA2 Proteins

Inhibition of Phagocytosis byHaemophilus ducreyiRequires Expression of the LspA1 and LspA2 Proteins

Haemophilus ducreyi Requires the flp Gene Cluster for Microcolony Formation In Vitro

The major outer membrane protein of Haemophilus ducreyi consists of two OmpA homologs

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