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Berlin Brandenburg

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  • Katz, B  (9)
  • Virulence
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  • 1
    Language: English
    In: The Journal of infectious diseases, 15 April 2008, Vol.197(8), pp.1103-9
    Description: Haemophilus ducreyi contains 3 TonB-dependent receptors: the hemoglobin receptor HgbA, which is required for virulence in humans; the heme receptor TdhA; and an uncharacterized conserved hypothetical protein TdX (HD0646). A double tdX/tdhA mutant (FX527) was constructed on the background of a human-passaged variant of strain 35000 (35000HP). Six volunteers were infected with 35000HP at 3 sites on one arm and with FX527 at 3 sites on the other. The pustule formation rate was 55.6% (95% confidence interval [CI], 35.7%-75.4%) at 18 parent-strain sites and 44.4% (95% CI, 15.0%-73.9%) at 18 mutant-strain sites (P = .51). Similar amounts of 35000HP and FX527 were recovered from pustules in semiquantitative culture. Thus, TdX and TdhA are not necessary for virulence, whereas HgbA is both necessary and sufficient for virulence in humans. The data suggest that hemoglobin is the sole source of heme/iron used by H. ducreyi in vivo and has implications for the potential of HgbA as a vaccine.
    Keywords: Bacterial Outer Membrane Proteins -- Biosynthesis ; Bacterial Proteins -- Biosynthesis ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Pathogenicity ; Membrane Proteins -- Biosynthesis
    ISSN: 0022-1899
    E-ISSN: 15376613
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  • 2
    Language: English
    In: The Journal of infectious diseases, 01 June 2008, Vol.197(11), pp.1531-6
    Description: Haemophilus ducreyi 35000HP contains a cluster of homologues of genes required for the synthesis of enterobacterial common antigen (ECA), suggesting that H. ducreyi may express a putative ECA-like glycoconjugate. WecA initiates the synthesis of ECA by transferring N-acetylglucosamine to undecaprenyl-P, to form lipid I. A wecA mutant (35000HPwecA) was constructed, and 5 volunteers were inoculated at 3 sites with fixed doses of 35000HP on one arm and at 3 sites with varying doses of 35000HPwecA on the other arm. 35000HPwecA caused pustules to form at 3 sites inoculated with a dose 2.5-fold higher than that of 35000HP. However, at sites inoculated with similar doses of 35000HP and 35000HPwecA, pustules developed at 46.7% (95% confidence interval [CI], 23.3%-70.0%) of 15 parent-strain sites and at 8.3% (95% CI, 0.01%-23.6%) of 12 mutant-strain sites (P = .013). Thus, the expression of wecA contributes to the ability of H. ducreyi to cause pustules in humans.
    Keywords: Multigene Family ; Antigens, Bacterial -- Genetics ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Genetics
    ISSN: 0022-1899
    E-ISSN: 15376613
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  • 3
    In: Infection and Immunity, 2002, Vol. 70(3), p.1367
    Description: Haemophilus ducreyi produces a periplasmic copper-zinc superoxide dismutase (Cu-Zn SOD), which is thought to protect the organism from exogenous reactive oxygen species generated by neutrophils during an inflammatory response. We had previously identified the gene, sodC, responsible for the production and secretion of Cu-Zn SOD and constructed an isogenic H. ducreyi strain with a mutation in the sodC gene (35000HP-sodC-cat). Compared to the parent, the mutant does not survive in the presence of exogenous superoxide (L. R. San Mateo, M. Hobbs, and T. H. Kawula, Mol. Microbiol. 27:391-404, 1998) and is impaired in the swine model of H. ducreyi infection (L. R. San Mateo, K. L. Toffer, P. E. Orndorff, and T. H. Kawula, Infect. Immun. 67:5345-5351, 1999). To test whether Cu-Zn SOD is important for bacterial survival in vivo, six human volunteers were experimentally infected with 35000HP and 35000HP- sodC-cat and observed for papule and pustule formation. Papules developed at similar rates at sites inoculated with the mutant or parent. The pustule formation rates were 75% (95% confidence intervals [CI], 43 to 95%) at 12 parent-inoculated sites and 67% (95% CI, 41 to 88%) at 18 mutant-inoculated sites (P = 0.47). There was no significant difference in levels of H. ducreyi recovery from mutant- and parent-inoculated biopsy sites. These results suggest that expression of Cu-Zn SOD does not play a major role in the survival of this pathogen in the initial stages of experimental infection of humans.
    Keywords: Mutants ; Virulence ; Inflammation ; Leukocytes (Neutrophilic) ; Reactive Oxygen Species ; Superoxide Dismutase ; Mutants ; Virulence ; Inflammation ; Leukocytes (Neutrophilic) ; Reactive Oxygen Species ; Superoxide Dismutase ; Bacterial Genetics ; Human Bacteriology: Others ; Papules ; Pustules ; Man ; Papules ; Pustules ; Man ; Man ; Papules ; Pustules;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 4
    In: Infection and Immunity, 2003, Vol. 71(12), p.7178
    Description: 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.
    Keywords: Medicine ; Biology;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 5
    In: Infection and Immunity, 2000, Vol. 68(11), p.6441
    Description: Haemophilus ducreyi expresses a peptidoglycan-associated lipoprotein (PAL) that exhibits extensive homology to Haemophilus influenzae protein 6. We constructed an isogenic PAL mutant (35000HP-SMS4) by the use of a suicide vector that contains lacZ as a counterselectable marker. H. ducreyi 35000HP-SMS4 and its parent, 35000HP, had similar growth rates in broth and similar lipooligosaccharide profiles. 35000HP-SMS4 formed smaller, more transparent colonies than 35000HP and, unlike its parent, was hypersensitive to antibiotics. Complementation of the mutant in trans restored the parental phenotypes. To test whether expression of PAL is required for virulence, nine human volunteers were experimentally infected. Each subject was inoculated with two doses (41 to 89 CFU) of live 35000HP and one dose of heat-killed bacteria on one arm and with three doses (ranging from 28 to 800 CFU) of live 35000HP-SMS4 on the other arm. Papules developed at similar rates at sites inoculated with the mutant or parent but were significantly smaller at mutant-inoculated sites than at parent-inoculated sites. The pustule formation rate was 72% (95% confidence interval [CI], 46.5 to 90.3%) at 18 parent sites and 11% (95% CI, 2.4 to 29.2%) at 27 mutant sites (P 〈 0.0001). The rates of recovery of H. ducreyi from surface cultures were 8% (n = 130; 95% CI, 4.3 to 14.6%) for parent-inoculated sites and 0% (n = 120; 95% CI, 0.0 to 2.5%) for mutant-inoculated sites (P 〈 0.001). H. ducreyi was recovered from six of seven biopsied parent-inoculated sites and from one of three biopsied mutant-inoculated sites. Confocal microscopy confirmed that the bacteria present in a mutant inoculation site pustule lacked a PAL-specific epitope. Although biosafety regulations precluded our testing the complemented mutant in humans, these results suggest that expression of PAL facilitates the ability of H. ducreyi to progress to the pustular stage of disease.
    Keywords: Bacterial Outer Membrane Proteins ; Proteoglycans ; Haemophilus Infections -- Etiology ; Haemophilus Ducreyi -- Pathogenicity ; Lipoproteins -- Metabolism ; Peptidoglycan -- Metabolism;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 6
    Language: English
    In: The Journal of Infectious Diseases, 1 March 2000, Vol.181(3), pp.1049-1054
    Description: Haemophilus ducreyi expresses a conserved hemoglobin-binding outer-membrane protein (HgbA). To test the role of HgbA in pathogenesis, we infected 9 adults with isolate 35000 and its isogenic hgbA-inactivated mutant (FX504) on their upper arms in a double-blinded, escalating dose-response study. Papules developed at similar rates at sites inoculated with the mutant or parent. The pustule-formation rate was 55% (95% confidence interval [CI], 30.8%-78.5%) at parent sites and 0 (95% CI, 0-10.5%) at mutant sites (P 〈 .0001). The recovery rate of H. ducreyi from surface cultures was 16% (n = 142) from parent sites and 0 (n = 213) from mutant sites (P 〈 .0001). H. ducreyi was recovered at biopsy from 6 of 7 parent sites and from 0 of 3 mutant sites. The results indicate that hemoglobin may be a critical source of heme or iron for the establishment of H. ducreyi infection in humans.
    Keywords: Physical sciences -- Chemistry -- Chemical compounds -- Haemophilus ducreyi ; Biological sciences -- Biology -- Microbiology -- Haemophilus ducreyi ; Biological sciences -- Biology -- Microbiology -- Haemophilus ducreyi ; Health sciences -- Medical conditions -- Infections -- Haemophilus ducreyi ; Physical sciences -- Chemistry -- Chemical compounds -- Haemophilus ducreyi ; Health sciences -- Medical diagnosis -- Diagnostic methods -- Haemophilus ducreyi ; Health sciences -- Medical sciences -- Pharmacology -- Haemophilus ducreyi ; Health sciences -- Medical sciences -- Immunology -- Haemophilus ducreyi ; Health sciences -- Medical conditions -- Physical trauma -- Haemophilus ducreyi ; Health sciences -- Health and wellness -- Public health -- Haemophilus ducreyi
    ISSN: 00221899
    E-ISSN: 15376613
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  • 7
    In: Infection and Immunity, 2001, Vol. 69(6), p.4180
    Description: The lipooligosaccharide (LOS) of Haemophilus ducreyi contains a major glycoform that is immunochemically identical to paragloboside, a glycosphingolipid precursor of major human blood group antigens. We recently identified the gene responsible for the glucosyltransferase activity and constructed an isogenic mutant (35000glu-) deficient in this activity. 35000glu- makes an LOS that consists only of the heptose trisaccharide core and 2-keto-deoxyoctulosonic acid (KDO). For this study, the mutant was reconstructed in the 35000HP (human passaged [HP]) background. Five human subjects were inoculated with 35000HP and 35000HPglu- in a dose-response trial. The pustule formation rates were 40% (95% confidence interval [CI], 13.7 to 72.6%) at 10 sites for 35000HP and 46.7% (95% CI, 24.8 to 69.9%) at 15 sites for 35000HPglu-. The histopathology and recovery rates of H. ducreyi from surface cultures and biopsies obtained from mutant and parent sites were similar. These results indicate that the expression of glycoforms with sugar moieties extending beyond the heptose trisaccharide core is not required for pustule formation by H. ducreyi in humans.
    Keywords: Mutation ; Chancroid -- Physiopathology ; Glucosyltransferases -- Metabolism ; Haemophilus Ducreyi -- Pathogenicity ; Lipopolysaccharides -- Metabolism;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 8
    Language: English
    In: Microbial Pathogenesis, 2006, Vol.40(3), pp.110-115
    Description: express two porin proteins, termed OmpP2A and OmpP2B. To test whether expression of OmpP2A and OmpP2B was necessary for virulence in humans, eight volunteers were experimentally infected with the parent (35000HP) in one arm and a double OmpP2A OmpP2B mutant (35000HP::P2AB) in the other arm. The pustule formation rates were 58.3% (95% CI, 33.2–83.5%) for the parent and 41.7% (95% CI, 19.3–64.0%) for the mutant ( =0.25). Biopsy of 35000HP and 35000HP::P2AB-infected sites yielded similar amounts of bacteria in quantitative culture. These results indicate that expression of OmpP2A and OmpP2B is not necessary to initiate disease or to progress to pustule formation in humans.
    Keywords: Pustule Formation ; Haemophilus Ducreyi ; Porin Proteins ; Uirulence ; Human Challenge Model ; Biology ; Chemistry
    ISSN: 0882-4010
    E-ISSN: 1096-1208
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  • 9
    Language: English
    In: The Journal of Infectious Diseases, 1 March 2000, Vol.181(3), pp.1176-1179
    Description: Haemophilus ducreyi expresses fine tangled pili, which are composed predominantly of a major subunit (FtpA). Confocal microscopy showed that an FtpA-specific monoclonal antibody bound to bacteria in biopsy samples obtained from infected human volunteers. To test the role of pili in pathogenesis, an isogenic mutant (35000HP-SMS1) was constructed by insertionally inactivating ftpA 35000HP-SMS1 did not express FtpA and was nonpiliated but was otherwise identical to its parent, 35000HP. Seven healthy adults were challenged on the upper arm with the isogenic isolates in a double-blinded, escalating dose-response study. Sites inoculated with the mutant produced papules and pustules at rates similar to the rates observed at sites inoculated with the parent. The recovery rate of H. ducreyi from cultures and the histopathology of biopsy samples obtained from pustules inoculated with 35000HP or 35000HP-SMS1 were similar. Although pili are expressed in vivo, FtpA is not required for pustule formation in the human challenge model.
    Keywords: Biological sciences -- Biology -- Microbiology -- Haemophilus ducreyi ; Health sciences -- Medical diagnosis -- Diagnostic methods -- Polyclonal antibodies ; Biological sciences -- Biology -- Microbiology -- Polyclonal antibodies ; Health sciences -- Medical conditions -- Physical trauma -- Polyclonal antibodies ; Health sciences -- Medical conditions -- Infections -- Polyclonal antibodies ; Health sciences -- Medical sciences -- Immunology -- Polyclonal antibodies ; Health sciences -- Medical sciences -- Immunology -- Polyclonal antibodies ; Applied sciences -- Laboratory techniques -- Microscopy -- Polyclonal antibodies ; Health sciences -- Medical sciences -- Immunology -- Polyclonal antibodies ; Physical sciences -- Chemistry -- Chemical compounds -- Polyclonal antibodies
    ISSN: 00221899
    E-ISSN: 15376613
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