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  • Bacterial Outer Membrane Proteins
  • 11
    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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  • 12
    In: Infection and Immunity, 2006, Vol. 74(5), p.2651
    Description: Haemophilus ducreyi, the etiologic agent of the sexually transmitted genital ulcer disease chancroid, has been shown to associate with dermal collagen fibers within infected skin lesions. Here we describe NcaA, a previously uncharacterized outer membrane protein that is important for H. ducreyi collagen binding and host colonization. An H. ducreyi strain lacking the ncaA gene was impaired in adherence to type I collagen but not fibronectin (plasma or cellular form) or heparin. The mutation had no effect on serum resistance or binding to HaCaT keratinocytes or human foreskin fibroblasts in vitro. Escherichia coli expressing H. ducreyi NcaA bound to type I collagen, demonstrating that NcaA is sufficient to confer collagen attachment. The importance of NcaA in H. ducreyi pathogenesis was assessed using both swine and human experimental models of chancroid. In the swine model, 20% of lesions from sites inoculated with the ncaA mutant were culture positive for H. ducreyi 7 days after inoculation, compared to 73% of wild-type-inoculated sites. The average number of CFU recovered from mutant-inoculated lesions was also significantly reduced compared to that recovered from wild-type-inoculated sites at both 2 and 7 days after inoculation. In the human challenge model, 8 of 30 sites inoculated with wild-type H. ducreyi progressed to the pustular stage, compared to 0 of 30 sites inoculated with the ncaA mutant. Together these results demonstrate that the collagen binding protein NcaA is required for H. ducreyi infection.
    Keywords: Fibers ; Outer Membrane Proteins ; Skin Diseases ; Ulcers ; Fibronectin ; Colony-Forming Cells ; Chancroid ; Keratinocytes ; Heparin ; Collagen (Type I) ; Fibroblasts ; Escherichia Coli ; Haemophilus Ducreyi ; Sexually-Transmitted Diseases ; Bacteria ; Ncaa Protein;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 13
    In: Infection and Immunity, 2000, Vol. 68(5), p.2602
    Description: Haemophilus ducreyi expresses 2 OmpA homologs, designated MOMP and OmpA2, whose genes are arranged in tandem on the chromosome. Northern blot analysis indicated that momp and ompA2 are transcribed independently. Sequences of the momp open reading frame (ORF) lacking the transcriptional start site were amplified by PCR, and an Omega-Km2 cassette was ligated into the ORF. A plasmid containing this construction was electroporated into H. ducreyi 35000HP, and an isogenic MOMP-deficient mutant (35000HP-SMS2) was generated by allele exchange. In Southern blotting, 35000HP-SMS2 contained one copy of the Omega-Km2 cassette in momp. 35000HP and 35000HP-SMS2 had similar outer membrane protein (OMP) and lipooligosaccharide profiles and growth rates except for up-regulation of a putative porin protein in the mutant. Five subjects were inoculated with three doses of live 35000HP-SMS2 on one arm and two doses of live 35000HP and one dose of a heat-killed control on the other arm in a double-blind escalating dose-response trial. Pustules developed at 7 of 10 sites inoculated with 35000HP and at 6 of 15 sites inoculated with 35000HP-SMS2 (P = 0.14). 35000HP and 35000HP-SMS2 were recovered at similar rates from daily surface cultures and semiquantitative cultures. The data suggest that expression of MOMP is not required for pustule formation by H. ducreyi in the human model of infection.
    Keywords: Medicine ; Biology;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 14
    Language: English
    In: Microbial Pathogenesis, 1990, Vol.9(6), pp.417-426
    Description: Twelve strains of Haemophilus ducreyi isolated primarily from chancroid outbreaks in North America were examined for the presence of pili by transmission electron microscopy. We identified piliated cells in 10 of the 12 strains. Pilin extracts were prepared from the mechanically sheared cells of the 12 H. ducreyi strains as well as the stably piliated H. influenzae strain R890 and its non-piliated parent R906. Pili were present in 12 out of 12 H. ducreyi extracts and in the R890 extract but not in the R906 preparation. Pili were purified by cycles of differential pH solubilization and crystallization. In SDS-PAGE, the preparation consisted predominantly of a protein whose apparent relative molecular mass was 24,000 (24 k), and an electron micrograph showed that the preparation contained pili. Three H. ducreyi strains were passed 52 times on agar plates, and extracts prepared from these strains contained pili. There was no evidence of binding of erythrocytes obtained from nine mammalian and avian species to colonies of one of the stably piliated H. ducreyi strains. We conclude that H. ducreyi expressed pili, that the relative molecular mass of the pilin monomer was 24 k, that pilus expression was not readily lost in passage and that H. ducreyi pili may not bind to an erythrocyte receptor.
    Keywords: Haemophilus Ducreyi ; Pili ; Fimbriae ; Biology ; Chemistry
    ISSN: 0882-4010
    E-ISSN: 1096-1208
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  • 15
    Language: English
    In: Microbial Pathogenesis, February 1999, Vol.26(2), pp.93-102
    Description: A bactericidal assay was developed in order to test the effect of hyperimmune rabbit sera on the viability of serum-resistant Haemophilus ducreyi 35000HP. Testing of several lots of rabbit complement and time course experiments showed that the serum-sensitive H. ducreyi CIPA77 was killed efficiently by 25% complement at 35°C in 3 h. We hypothesized that incubation of 35000HP under these conditions with the appropriate bactericidal antibody would kill this strain. A panel of high titre rabbit antisera was developed and tested against 35000HP. The panel included antisera raised to whole cells, total membranes, Sarkosyl-insoluble outer membrane proteins, the H. ducreyi lipoprotein, and the peptidoglycan-associated lipoprotein. None of the antisera convincingly showed bactericidal activity. The bactericidal assay was also used to determine the effect of normal human serum (NHS) on isogenic mutants of 35000HP. 35000HP-RSM2, an kan insertion mutant that expresses a truncated lipooligosaccharide, was as resistant to NHS as its parent. A mutant deficient in expression of the major outer membrane protein (35000.60) was sensitive to NHS. We conclude that 35000HP is relatively resistant to normal and hyperimmune sera, and that the major outer membrane protein contributes to this resistance. Copyright 1999 Academic Press
    Keywords: Haemophilus Ducreyi, Bactericidal Activity, Chancroid ; Biology ; Chemistry
    ISSN: 0882-4010
    E-ISSN: 1096-1208
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