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Berlin Brandenburg

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  • 1
    Language: English
    In: The Journal of infectious diseases, November 2012, Vol.206(9), pp.1407-14
    Description: Haemophilus ducreyi encounters several classes of antimicrobial peptides (APs) in vivo and utilizes the sensitive-to-antimicrobial-peptides (Sap) transporter as one mechanism of AP resistance. A mutant lacking the periplasmic solute-binding component, SapA, was somewhat more sensitive to the cathelicidin LL-37 than the parent strain and was partially attenuated for virulence. The partial attenuation led us to question whether the transporter is fully abrogated in the sapA mutant. We generated a nonpolar sapBC mutant, which lacks both inner membrane permeases of the Sap transporter, and tested the mutant for virulence in human volunteers. In vitro, we compared LL-37 resistance phenotypes of the sapBC and sapA mutants. Unlike the sapA mutant, the sapBC mutant was fully attenuated for virulence in human volunteers. In vitro, the sapBC mutant exhibited significantly greater sensitivity than the sapA mutant to killing by LL-37. Similar to the sapA mutant, the sapBC mutant did not affect H. ducreyi's resistance to human defensins. Compared with the sapA mutant, the sapBC mutant exhibited greater attenuation in vivo, which directly correlated with increased sensitivity to LL-37 in vitro. These results strongly suggest that the SapBC channel retains activity when SapA is removed.
    Keywords: Drug Resistance, Bacterial ; Antimicrobial Cationic Peptides -- Pharmacology ; Haemophilus Ducreyi -- Enzymology ; Membrane Transport Proteins -- Metabolism ; Virulence Factors -- Metabolism
    ISSN: 00221899
    E-ISSN: 1537-6613
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  • 2
    Language: English
    In: The Journal of infectious diseases, 01 March 2009, Vol.199(5), pp.684-92
    Description: A gene expression study of Haemophilus ducreyi identified the hypothetical lipoprotein HD0192, renamed here "fibrinogen binder A" (FgbA), as being preferentially expressed in vivo. To test the role played by fgbA in virulence, an isogenic fgbA mutant (35000HPfgbA) was constructed using H. ducreyi 35000HP, and 6 volunteers were experimentally infected with 35000HP or 35000HPfgbA. The overall pustule-formation rate was 61.1% at parent sites and 22.2% at mutant sites (P = .019). Papules were significantly smaller at mutant sites than at parent sites (13.3 vs. 37.9 mm(2); P = .002) 24 h after inoculation. Thus, fgbA contributed significantly to the virulence of H. ducreyi in humans. In vitro experiments demonstrated that fgbA encodes a fibrinogen-binding protein; no other fibrinogen-binding proteins were identified in 35000HP. fgbA was conserved among clinical isolates of both class I and II H. ducreyi strains, supporting the finding that fgbA is important for H. ducreyi infection.
    Keywords: Bacterial Proteins -- Metabolism ; Chancroid -- Microbiology ; Fibrinogen -- Metabolism ; Haemophilus Ducreyi -- Genetics ; Lipoproteins -- Metabolism
    ISSN: 0022-1899
    E-ISSN: 15376613
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  • 3
    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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