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  • Health sciences -- Medical conditions -- Infections -- Haemophilus ducreyi
  • Journal of infectious diseases  (16)
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  • Journal of infectious diseases  (16)
  • 1
    Language: English
    In: The Journal of infectious diseases, 15 June 2011, Vol.203(12), pp.1859-65
    Description: Haemophilus ducreyi 35000HP contains a homolog of the CpxRA 2-component signal transduction system, which controls the cell envelope stress response system in other gram-negative bacteria and regulates some important H. ducreyi virulence factors. A H. ducreyi cpxR mutant was compared with its parent for virulence in the human challenge model of experimental chancroid. The pustule formation rate in 5 volunteers was 33% (95% confidence interval [CI], 1.3%-65.3%) at 15 parent sites and 40% (95% CI, 18.1%-61.9%) at 15 mutant sites (P = .35). Thus, the cpxR mutant was not attenuated for virulence. Inactivation of the H. ducreyi cpxR gene did not reduce the ability of this mutant to express certain proven virulence factors, including the DsrA serum resistance protein and the LspA2 protein, which inhibits phagocytosis. These results expand our understanding of the involvement of the CpxRA system in regulating virulence expression in H. ducreyi.
    Keywords: Bacterial Proteins -- Genetics ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Genetics
    ISSN: 00221899
    E-ISSN: 1537-6613
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  • 2
    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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  • 3
    Language: English
    In: The Journal of infectious diseases, 15 June 2010, Vol.201(12), pp.1839-48
    Description: Haemophilus ducreyi causes chancroid, a genital ulcer disease. Among human volunteers, the majority of experimentally infected individuals fail to clear the infection and form pustules. Here, we investigated the role played by CD4(+)FOXP3(+) regulatory T (T(reg)) cells in the formation of pustules. In pustules, there was a significant enrichment of CD4(+)FOXP3(+) T cells, compared with that in peripheral blood. The majority of lesional FOXP3(+) T cells were CD4(+), CD25(+), CD127(lo/-), and CTLA-4(+). FOXP3(+) T cells were found throughout pustules but were most abundant at their base. Significantly fewer lesional CD4(+)FOXP3(+) T cells expressed interferon gamma, compared with lesional CD4(+)FOXP3(-) effector T cells. Depletion of CD4(+)CD25(+) T cells from the peripheral blood of infected and uninfected volunteers significantly enhanced proliferation of H. ducreyi-reactive CD4(+) T cells. Our results indicate that the population of CD4(+)CD25(+)CD127(lo/-)FOXP3(+) T(reg) cells are expanded at H. ducreyi-infected sites and that these cells may play a role in suppressing the host immune response to the bacterium.
    Keywords: Immune Tolerance ; Cd4-Positive T-Lymphocytes -- Immunology ; Forkhead Transcription Factors -- Analysis ; Haemophilus Infections -- Immunology ; Haemophilus Ducreyi -- Immunology ; T-Lymphocytes, Regulatory -- Immunology
    ISSN: 00221899
    E-ISSN: 1537-6613
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  • 4
    Language: English
    In: The Journal of infectious diseases, 01 June 2009, Vol.199(11), pp.1671-9
    Description: Haemophilus ducreyi causes chancroid, which facilitates transmission of human immunodeficiency virus type 1. To better understand the biology of H. ducreyi, we developed a human inoculation model. In the present article, we describe clinical outcomes for 267 volunteers who were infected with H. ducreyi. There was a relationship between papule formation and estimated delivered dose. The outcome (either pustule formation or resolution) of infected sites for a given subject was not independent; the most important determinants of pustule formation were sex and host effects. When 41 subjects were infected a second time, their outcomes segregated toward their initial outcome, confirming the host effect. Subjects with pustules developed local symptoms that required withdrawal from the study after a mean of 8.6 days. There were 191 volunteers who had tissue biopsy performed, 173 of whom were available for follow-up analysis; 28 (16.2%) of these developed hypertrophic scars, but the model was otherwise safe. Mutant-parent trials confirmed key features in H. ducreyi pathogenesis, and the model has provided an opportunity to study differential human susceptibility to a bacterial infection.
    Keywords: Chancroid -- Microbiology ; Haemophilus Ducreyi -- Pathogenicity
    ISSN: 0022-1899
    E-ISSN: 15376613
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  • 5
    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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  • 6
    Language: English
    In: The Journal of infectious diseases, 01 August 2009, Vol.200(3), pp.409-16
    Description: Haemophilus ducreyi 35000HP contains a homologue of the luxS gene, which encodes an enzyme that synthesizes autoinducer 2 (AI-2) in other gram-negative bacteria. H. ducreyi 35000HP produced AI-2 that functioned in a Vibrio harveyi-based reporter system. A H. ducreyi luxS mutant was constructed by insertional inactivation of the luxS gene and lost the ability to produce AI-2. Provision of the H. ducreyi luxS gene in trans partially restored AI-2 production by the mutant. The luxS mutant was compared with its parent for virulence in the human challenge model of experimental chancroid. The pustule-formation rate in 5 volunteers was 93.3% (95% confidence interval, 81.7%-99.9%) at 15 parent sites and 60.0% (95% confidence interval, 48.3%-71.7%) at 15 mutant sites (1-tailed P 〈 .001). Thus, the luxS mutant was partially attenuated for virulence. This is the first report of AI-2 production contributing to the pathogenesis of a genital ulcer disease.
    Keywords: Bacterial Proteins -- Metabolism ; Carbon-Sulfur Lyases -- Metabolism ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Genetics
    ISSN: 0022-1899
    E-ISSN: 15376613
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  • 7
    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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  • 8
    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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  • 9
    Language: English
    In: The Journal of Infectious Diseases, 1 June 1997, Vol.175(6), pp.1390-1395
    Description: The performance of two EIAs (adsorption EIA and lipooligosaccharide [LOS] EIA) that detect antibodies to Haemophilus ducreyi was evaluated with serum specimens obtained from 163 patients (96 with genital ulcer disease [GUD]). Paired serum specimens (initial and follow-up) were obtained from 52 of the GUD patients. By use of initial serum specimens from 82 GUD patients whose etiologic agents for their ulcers had been identified, the adsorption EIA had a sensitivity and specificity for chancroid of 53% and 71%, while the LOS EIA had a sensitivity and specificity of 48% and 89%, respectively. Sensitivity and specificity of the adsorption EIA increased to 78% and 84%, respectively, when the results of follow-up serum specimens were used to calculate optimal performance. The proportion of patients testing positive for H. ducreyi who had anti-H. ducreyi IgG antibodies, as determined by adsorption EIA, increased with the duration of infection, thus limiting the role of EIAs in the diagnosis of chancroid.
    Keywords: Health sciences -- Medical conditions -- Physical trauma -- Haemophilus ducreyi ; Health sciences -- Medical conditions -- Infections -- Haemophilus ducreyi ; Physical sciences -- Chemistry -- Chemical reactions -- Haemophilus ducreyi ; Health sciences -- Medical sciences -- Immunology -- Haemophilus ducreyi ; Biological sciences -- Biology -- Microbiology -- Haemophilus ducreyi ; Health sciences -- Medical conditions -- Diseases -- Haemophilus ducreyi ; Biological sciences -- Biology -- Anatomy -- Haemophilus ducreyi ; Health sciences -- Medical conditions -- Infections -- Haemophilus ducreyi ; Health sciences -- Medical sciences -- Immunology -- Haemophilus ducreyi ; Physical sciences -- Earth sciences -- Geology -- Haemophilus ducreyi
    ISSN: 00221899
    E-ISSN: 15376613
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  • 10
    Language: English
    In: The Journal of infectious diseases, 15 May 2007, Vol.195(10), pp.1443-51
    Description: We infected 11 HIV-seropositive volunteers whose CD4(+) cell counts were 〉350 cells/ microL (7 of whom were receiving antiretrovirals) with Haemophilus ducreyi. The papule and pustule formation rates were similar to those observed in HIV-seronegative historical control subjects. No subject experienced a sustained change in CD4(+) cell count or HIV RNA level. The cellular infiltrate in biopsy samples obtained from the HIV-seropositive and HIV-seronegative subjects did not differ with respect to the percentage of leukocytes, neutrophils, macrophages, or T cells. The CD4(+):CD8(+) cell ratio in biopsy samples from the HIV-seropositive subjects was 1:3, the inverse of the ratio seen in the HIV-seronegative subjects (P〈.0001). Although CD4(+) cells proliferated in lesions, in situ hybridization and reverse-transcription polymerase chain reaction for HIV RNA was negative. We conclude that experimental infection in HIV-seropositive persons is clinically similar to infection in HIV-seronegative persons and does not cause local or augment systemic viral replication. Thus, prompt treatment of chancroid may abrogate increases in viral replication associated with natural disease.
    Keywords: Chancroid -- Complications ; HIV Infections -- Complications ; Haemophilus Ducreyi -- Physiology
    ISSN: 0022-1899
    E-ISSN: 15376613
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