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  • American Society for Microbiology  (3)
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  • American Society for Microbiology  (3)
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  • 1
    In: Infection and Immunity, American Society for Microbiology, Vol. 72, No. 8 ( 2004-08), p. 4668-4679
    Abstract: The mouse model of Helicobacter pylori -induced disease using Sydney strain 1 (SS1) has been used extensively in Helicobacter research. Herein we describe the isolation and characterization of a new mouse-colonizing strain for use in comparative studies. One strain capable of persistent mouse colonization was isolated from a total of 110 clinical isolates and is named here SS2000 (Sydney strain 2000). Genome typing revealed a number of differences between SS1 and SS2000 as well as between them and the respective original clinical isolates. In particular, SS2000 lacked the entire cag pathogenicity island, while SS1 contained all 27 genes of the island. C57BL/6 and BALB/c mice were infected with SS1 or SS2000 or were treated with broth medium (controls). After 6 months host-specific effects were evident, including lower colonization levels in the BALB/c animals. Few pathological differences were observed between SS1- and SS2000-infected animals. However, by 15 months postinfection, SS1-infected C57BL/6 mice had developed more severe gastritis than the SS2000-infected animals. In contrast SS2000-infected BALB/c mice showed increased accumulation of mucosa-associated lymphoid tissue compared to those infected with SS1. This improved comparative model of H. pylori -induced disease allowed dissection of both host and strain effects and thus will prove useful in further studies.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2004
    detail.hit.zdb_id: 1483247-1
    detail.hit.zdb_id: 218698-6
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    American Society for Microbiology ; 2003
    In:  Infection and Immunity Vol. 71, No. 5 ( 2003-05), p. 2643-2655
    In: Infection and Immunity, American Society for Microbiology, Vol. 71, No. 5 ( 2003-05), p. 2643-2655
    Abstract: The global pattern of growth-phase-dependent gene expression of Helicobacter pylori during in vitro culture was analyzed by using a high-density DNA microarray. To detect consistent coordinated gene expression in this bacterium, temporal changes in transcription were assessed in two independent time courses. Cluster analysis of the expression profiles highlighted a major switch in gene expression during the late log-to-stationary phase transition that we have termed the Log-Stat switch. Statistical analysis of the genes that were significantly induced or repressed during the Log-Stat switch revealed that many of these genes were related to virulence. Among these, expression of the genes for the neutrophil activating protein ( napA ) and the major flagellin subunit ( flaA ) were significantly induced. Additionally, the expression of a number of genes involved in iron homeostasis changed dramatically at this switch; the gene for the iron-storage protein, pfr , was induced, while the genes for two putative iron uptake proteins, fecA and frpB , were significantly repressed. These data suggest that the late log phase may correspond to the most virulent phase of growth in H. pylori and may be intimately related to its pathogenesis. The use of microarrays to analyze the kinetics of the transcriptional response of a bacterial pathogen to a changing environment has enabled the discovery of previously unappreciated relationships between genes by elucidation of coordinated gene expression profiles.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2003
    detail.hit.zdb_id: 1483247-1
    detail.hit.zdb_id: 218698-6
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    American Society for Microbiology ; 2003
    In:  Infection and Immunity Vol. 71, No. 11 ( 2003-11), p. 6510-6525
    In: Infection and Immunity, American Society for Microbiology, Vol. 71, No. 11 ( 2003-11), p. 6510-6525
    Abstract: Iron is an essential nutrient that is often found in extremely limited available quantities within eukaryotic hosts. Because of this, many pathogenic bacteria have developed regulated networks of genes important for iron uptake and storage. In addition, it has been shown that many bacteria use available iron concentrations as a signal to regulate virulence gene expression. We have utilized DNA microarray technology to identify genes of the human pathogen Helicobacter pylori that are differentially regulated on a growth-inhibiting shift to iron starvation conditions. In addition, the growth phase-dependent expression of these genes was investigated by examining both exponential and stationary growth phase cultures. We identified known iron-regulated genes, as well as a number of genes whose regulation by iron concentration was not previously appreciated. Included in the list of regulated factors were the known virulence genes cagA , vacA , and napA . We examined the effect of iron starvation on the motility of H. pylori and found that exponential- and stationary-phase cultures responded differently to the stress. We further found that while growing cells are rapidly killed by iron starvation, stationary-phase cells show a remarkable ability to survive iron depletion. Finally, bioinformatic analysis of the predicted promoter regions of the differentially regulated genes led to identification of several putative Fur boxes, suggesting a direct role for Fur in iron-dependent regulation of these genes.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2003
    detail.hit.zdb_id: 1483247-1
    detail.hit.zdb_id: 218698-6
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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