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  • 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: Infection and Immunity, 2010, Vol. 78(11), p.4779
    Description: The Haemophilus ducreyi 35000HP genome encodes a homolog of the CpxRA two-component cell envelope stress response system originally characterized in Escherichia coli. CpxR, the cytoplasmic response regulator, was shown previously to be involved in repression of the expression of the lspB-lspA2 operon (M. Labandeira-Rey, J. R. Mock, and E. J. Hansen, Infect. Immun. 77:3402-3411, 2009). In the present study, the H. ducreyi CpxR and CpxA proteins were shown to closely resemble those of other well-studied bacterial species. A cpxA deletion mutant and a CpxR-overexpressing strain were used to explore the extent of the CpxRA regulon. DNA microarray and real-time reverse transcriptase (RT) PCR analyses indicated several potential regulatory targets for the H. ducreyi CpxRA two-component regulatory system. Electrophoretic mobility shift assays (EMSAs) were used to prove that H. ducreyi CpxR interacted with the promoter regions of genes encoding both known and putative virulence factors of H. ducreyi, including the lspB-lspA2 operon, the flp operon, and dsrA. Interestingly, the use of EMSAs also indicated that H. ducreyi CpxR did not bind to the promoter regions of several genes predicted to encode factors involved in the cell envelope stress response. Taken together, these data suggest that the CpxRA system in H. ducreyi, in contrast to that in E. coli, may be involved primarily in controlling expression of genes not involved in the cell envelope stress response.
    Keywords: Gene Expression Regulation, Bacterial ; Signal Transduction ; Bacterial Proteins -- Metabolism ; Haemophilus Ducreyi -- Metabolism ; Protein Kinases -- Metabolism;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 3
    Language: English
    In: Infection and immunity, January 2015, Vol.83(1), pp.146-60
    Description: There are a paucity of data concerning gene products that could contribute to the ability of Moraxella catarrhalis to colonize the human nasopharynx. Inactivation of a gene (mesR) encoding a predicted response regulator of a two-component signal transduction system in M. catarrhalis yielded a mutant unable to grow in liquid media. This mesR mutant also exhibited increased sensitivity to certain stressors, including polymyxin B, SDS, and hydrogen peroxide. Inactivation of the gene (mesS) encoding the predicted cognate sensor (histidine) kinase yielded a mutant with the same inability to grow in liquid media as the mesR mutant. DNA microarray and real-time reverse transcriptase PCR analyses indicated that several genes previously shown to be involved in the ability of M. catarrhalis to persist in the chinchilla nasopharynx were upregulated in the mesR mutant. Two other open reading frames upregulated in the mesR mutant were shown to encode small proteins (LipA and LipB) that had amino acid sequence homology to bacterial adhesins and structural homology to bacterial lysozyme inhibitors. Inactivation of both lipA and lipB did not affect the ability of M. catarrhalis O35E to attach to a human bronchial epithelial cell line in vitro. Purified recombinant LipA and LipB fusion proteins were each shown to inhibit human lysozyme activity in vitro and in saliva. A lipA lipB deletion mutant was more sensitive than the wild-type parent strain to killing by human lysozyme in the presence of human apolactoferrin. This is the first report of the production of lysozyme inhibitors by M. catarrhalis.
    Keywords: Signal Transduction ; Moraxella (Branhamella) Catarrhalis -- Growth & Development ; Muramidase -- Antagonists & Inhibitors ; Protein Kinases -- Metabolism ; Transcription Factors -- Metabolism
    ISSN: 00199567
    E-ISSN: 1098-5522
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  • 4
    Language: English
    In: Infection and immunity, November 2013, Vol.81(11), pp.4160-70
    Description: Expression of the lspB-lspA2 operon encoding a virulence-related two-partner secretion system in Haemophilus ducreyi 35000HP is directly regulated by the CpxRA regulatory system (M. Labandeira-Rey, J. R. Mock, and E. J. Hansen, Infect. Immun. 77:3402-3411, 2009). In the present study, we show that this secretion system is also regulated by the small nucleoid-associated protein Fis. Inactivation of the H. ducreyi fis gene resulted in a reduction in expression of both the H. ducreyi LspB and LspA2 proteins. DNA microarray experiments showed that a H. ducreyi fis deletion mutant exhibited altered expression levels of genes encoding other important H. ducreyi virulence factors, including DsrA and Flp1, suggesting a possible global role for Fis in the control of virulence in this obligate human pathogen. While the H. ducreyi Fis protein has a high degree of sequence and structural similarity to the Fis proteins of other bacteria, its temporal pattern of expression was very different from that of enterobacterial Fis proteins. The use of a lacZ-based transcriptional reporter provided evidence which indicated that the H. ducreyi Fis homolog is a positive regulator of gyrB, a gene that is negatively regulated by Fis in enteric bacteria. Taken together, the Fis protein expression data and the observed regulatory effects of Fis in H. ducreyi suggest that this small DNA binding protein has a regulatory role in H. ducreyi which may differ in substantial ways from that of other Fis proteins.
    Keywords: Gene Expression Regulation, Bacterial ; Operon ; Bacterial Outer Membrane Proteins -- Biosynthesis ; Bacterial Proteins -- Biosynthesis ; Factor For Inversion Stimulation Protein -- Metabolism ; Haemophilus Ducreyi -- Genetics
    ISSN: 00199567
    E-ISSN: 1098-5522
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  • 5
    Language: English
    In: Science (New York, N.Y.), 23 February 2007, Vol.315(5815), pp.1130-3
    Description: The Staphylococcus aureus Panton-Valentine leukocidin (PVL) is a pore-forming toxin secreted by strains epidemiologically associated with the current outbreak of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and with the often-lethal necrotizing pneumonia. To investigate the role of PVL in pulmonary disease, we tested the pathogenicity of clinical isolates, isogenic PVL-negative and PVL-positive S. aureus strains, as well as purified PVL, in a mouse acute pneumonia model. Here we show that PVL is sufficient to cause pneumonia and that the expression of this leukotoxin induces global changes in transcriptional levels of genes encoding secreted and cell wall-anchored staphylococcal proteins, including the lung inflammatory factor staphylococcal protein A (Spa).
    Keywords: Exotoxins -- Physiology ; Leukocidins -- Physiology ; Lung -- Pathology ; Pneumonia, Staphylococcal -- Microbiology ; Staphylococcal Protein A -- Metabolism ; Staphylococcus Aureus -- Pathogenicity ; Virulence Factors -- Physiology
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 6
    Language: English
    In: Infection and Immunity, 2012, Vol. 80(3), p.982
    Description: Young adult chinchillas were atraumatically inoculated with Moraxella catarrhalis via the nasal route. Detailed histopathologic examination of nasopharyngeal tissues isolated from these M. catarrhalis-infected animals revealed the presence of significant inflammation within the epithelium. Absence of similar histopathologic findings in sham-inoculated animals confirmed that M. catarrhalis was exposed to significant host-derived factors in this environment. Twenty-four hours after inoculation, viable M. catarrhalis organisms were recovered from the nasal cavity and nasopharynx of the animals in numbers sufficient for DNA microarray analysis. More than 100 M. catarrhalis genes were upregulated in vivo, including open reading frames (ORFs) encoding proteins that are involved in a truncated denitrification pathway or in the oxidative stress response, as well as several putative transcriptional regulators. Additionally, 200 M. catarrhalis genes were found to be downregulated when this bacterium was introduced into the nasopharynx. These downregulated genes included ORFs encoding several well-characterized M. catarrhalis surface proteins including Hag, McaP, and MchA1. Real-time reverse transcriptase PCR (RT-PCR) was utilized as a stringent control to validate the results of in vivo gene expression patterns as measured by DNA microarray analysis. Inactivation of one of the genes (MC ORF 1550) that was upregulated in vivo resulted in a decrease in the ability of M. catarrhalis to survive in the chinchilla nasopharynx over a 3-day period. This is the first evaluation of global transcriptome expression by M. catarrhalis cells in vivo.
    Keywords: Gene Expression Regulation, Bacterial ; Host-Pathogen Interactions ; Moraxella (Branhamella) Catarrhalis -- Pathogenicity ; Moraxellaceae Infections -- Microbiology ; Nasopharynx -- Microbiology;
    ISSN: 1098-5522
    ISSN: 10985522
    ISSN: 00199567
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  • 7
    In: Infection and Immunity, 2001, Vol. 69(1), p.446
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
    Source: American Society of Microbiology
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  • 8
    Language: English
    In: Antimicrobial agents and chemotherapy, April 2017, Vol.61(4)
    Description: is a highly virulent, multidrug-resistant pathogen that causes significant morbidity and mortality in hospitalized patients and is particularly devastating in patients with cystic fibrosis. Increasing antibiotic resistance coupled with decreasing numbers of antibiotics in the developmental pipeline demands novel antibacterial approaches. Here, we tested peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs), which inhibit translation of complementary mRNA from specific, essential genes in PPMOs targeted to , , and , inhibited growth in many clinical strains and activity of PPMOs could be enhanced 2- to 8-fold by the addition of polymyxin B nonapeptide at subinhibitory concentrations. The PPMO targeting was also effective at preventing PAO1 biofilm formation and at reducing existing biofilms. Importantly, treatment with various combinations of a PPMO and a traditional antibiotic demonstrated synergistic growth inhibition, the most effective of which was the PPMO targeting with tobramycin. Furthermore, treatment of PA103-infected mice with PPMOs targeting , , or significantly reduced the bacterial burden in the lungs at 24 h by almost 3 logs. Altogether, this study demonstrates that PPMOs targeting the essential genes , , or in are highly effective at inhibiting growth and These data suggest that PPMOs alone or in combination with antibiotics represent a novel approach to addressing the problems associated with rapidly increasing antibiotic resistance in .
    Keywords: Ppmo ; Pseudomonas Aeruginosa ; Antibiotic Resistance ; Antimicrobial Agents ; Antisense ; Experimental Therapeutics ; Phosphorodiamidate Morpholino Oligomer ; Gene Expression Regulation, Bacterial ; Anti-Bacterial Agents -- Pharmacology ; Morpholinos -- Pharmacology ; Oligonucleotides, Antisense -- Pharmacology ; Peptides -- Pharmacology ; Pseudomonas Infections -- Drug Therapy ; Pseudomonas Aeruginosa -- Drug Effects
    ISSN: 00664804
    E-ISSN: 1098-6596
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  • 9
    In: Infection and Immunity, 2009, Vol. 77(8), p.3402
    Description: The LspA1, LspA2, and LspB proteins of Haemophilus ducreyi comprise a two-partner secretion system that has been shown to be necessary for H. ducreyi to inhibit phagocytosis by immune cells in vitro. Inactivation of lspA1 resulted in increased levels of LspA2, suggesting that these two proteins are differentially controlled (C. J. Ward et al., Infect. Immun. 71:2478-2486, 2003). Expression of LspA2 but not LspA1 was shown to be both growth phase dependent and affected by the presence of fetal calf serum (FCS) in the growth medium. In addition, neither LspA1 nor LspA2 could be detected in culture supernatant fluid in the absence of FCS. DNA microarray analysis revealed that 324 H. ducreyi genes were differentially regulated after growth in the presence of FCS. Among these, the CpxRA two-component sensory transduction system was downregulated by the presence of FCS. Inactivation of cpxR resulted in increased expression of both LspB and LspA2. Electrophoretic mobility shift assays showed that a recombinant H. ducreyi CpxR protein bound the promoter region of the lspB-lspA2 operon. The cpxR and cpxA genes were shown to be part of an operon containing two additional genes in H. ducreyi 35000HP. This is the first description of a two-component sensory transduction system regulating a proven virulence factor of H. ducreyi.
    Keywords: Medicine ; Biology;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 10
    In: Infection and Immunity, 2001, Vol. 69(3), p.1409
    Description: We have previously described the expression cloning of nine Borrelia burgdorferi antigens, using rabbit serum enriched for antibodies specific for infection-associated antigens, and determined that seven of these antigens were associated with infectious B. burgdorferi strain B31. One of these infection-associated antigens encoded a 451-amino-acid putative lipoprotein containing 21 consecutive and invariant 9-amino-acid repeat sequences near the amino terminus that we have designated VraA for virulent strain-associated repetitive antigen A. The vraA locus (designated BBI16 by The Institute for Genomic Research) maps to one of the 28-kb linear plasmids (designated lp28-4) that is not present in noninfectious strain B31 isolates. Subsequent PCR analysis of clonal isolates of B. burgdorferi B31 from infected mouse skin revealed a clone that lacked only lp28-4. Southern blot and Western blot analyses indicated that the lp28-4 and VraA proteins, respectively, were missing from this clone. We have also determined that VraA is a surface-exposed protein based on protease accessibility assays of intact whole cells. Furthermore, vraA expression is modestly derepressed when cells are grown at 37 degree C relative to cells grown at 32 degree C, suggesting that VraA is, in part, a temperature-inducible antigen. Homologues cross-reactive to B. burgdorferi B31 VraA, most with different molecular masses, were identified in several B. burgdorferi sensu lato isolates, including B. andersonii, suggesting that the immunogenic epitope(s) present in strain B31 VraA is conserved between Borrelia spp. In protection studies, only 8.3% of mice (1 of 12) immunized with full-length recombinant VraA fused to glutathione S-transferase (GST) were susceptible to infectious challenge with 10 super(2) B. burgdorferi strain B31, whereas naive mice or mice immunized with GST alone were infected 40% or 63 to 67% (depending on tissues assayed) of the time, respectively. As such, the partial protection elicited by VraA immunization provides an additional testable vaccine candidate to help protect against Lyme borreliosis.
    Keywords: Borrelia Burgdorferi ; Borreliosis ; Lyme Disease ; Antibody Response ; Vaccines ; Lipoproteins ; Gene Mapping ; Gene Expression ; Cell Surface ; Epitopes ; Immunization ; Disease Resistance ; Borrelia Burgdorferi ; Bbi16 Protein ; Vraa Protein ; Vraa Antigen ; Antigenic Properties and Virulence ; Bacteria ; Mice ; Bbi16 Protein ; Borrelia Burgdorferi ; Vraa Antigen ; Vraa Protein ; Mice;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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