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  • 1
    Online Resource
    Online Resource
    Competing Isogenic Campylobacter Strains Exhibit Variable Population Structures In Vivo
    American Society for Microbiology ; 2008
    In:  Applied and Environmental Microbiology Vol. 74, No. 12 ( 2008-06-15), p. 3857-3867
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 74, No. 12 ( 2008-06-15), p. 3857-3867
    Abstract: Consumption of poultry contaminated with Campylobacter jejuni is a risk factor for human gastrointestinal disease. The rational development of control strategies for Campylobacter within chickens requires an understanding of the colonization process at the molecular and population levels, both within and between hosts. Experiments employing competing strains of Campylobacter have been used to investigate colonization. Implicit in these studies is the assumption that the behavior of competing strains is reproducible between experiments. Variability in the recovery of mutants from the chicken gastrointestinal tract during signature-tagged mutagenesis studies demonstrated that this is not always the case. To further investigate this phenomenon in the absence of confounding factors due to phenotypic differences between mutants, we constructed individually identifiable w ild-type i sogenic t agged s trains (WITS) that have indistinguishable phenotypes in pure culture. By using mixtures of WITS, it is possible to monitor the relative amounts of subpopulations of essentially wild-type bacteria. Using a 2-week-old chicken model of colonization, we observed unpredictable variations in population structure both within and between experiments, even in the simplest case of two competing strains. This variation occurred both when birds were simultaneously infected with two WITS and when birds inoculated with different WITS were cohoused. We present evidence for founder effects during initial colonization with subsequent bird-to-bird transmission. We suggest that these and phenotypic variation contribute to the observed variability. These factors render simple models of colonization which do not take them into account inappropriate for Campylobacter and impact the planning and interpretation of competition experiments using this organism.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02835-07
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2008
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Signature-Tagged Transposon Mutagenesis Studies Demonstrate the Dynamic Nature of Cecal Colonization of 2-Week-Old Chickens by Campylobacter jejuni
    American Society for Microbiology ; 2005
    In:  Applied and Environmental Microbiology Vol. 71, No. 12 ( 2005-12), p. 8031-8041
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 71, No. 12 ( 2005-12), p. 8031-8041
    Abstract: We have constructed plasmids to be used for in vitro signature-tagged mutagenesis (STM) of Campylobacter jejuni and used these to generate STM libraries in three different strains. Statistical analysis of the transposon insertion sites in the C. jejuni NCTC 11168 chromosome and the plasmids of strain 81-176 indicated that their distribution was not uniform. Visual inspection of the distribution suggested that deviation from uniformity was not due to preferential integration of the transposon into a limited number of hot spots but rather that there was a bias towards insertions around the origin. We screened pools of mutants from the STM libraries for their ability to colonize the ceca of 2-week-old chickens harboring a standardized gut flora. We observed high-frequency random loss of colonization proficient mutants. When cohoused birds were individually inoculated with different tagged mutants, random loss of colonization-proficient mutants was similarly observed, as was extensive bird-to-bird transmission of mutants. This indicates that the nature of campylobacter colonization in chickens is complex and dynamic, and we hypothesize that bottlenecks in the colonization process and between-bird transmission account for these observations.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.71.12.8031-8041.2005
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2005
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    CD4-T-Lymphocyte Interactions with Pneumolysin and Pneumococci Suggest a Crucial Protective Role in the Host Response to Pneumococcal Infection
    American Society for Microbiology ; 2004
    In:  Infection and Immunity Vol. 72, No. 5 ( 2004-05), p. 2689-2697
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 72, No. 5 ( 2004-05), p. 2689-2697
    Abstract: Previously, we had shown that T cells accumulated in peribronchiolar and perivascular areas of lungs soon after intranasal infection with Streptococcus pneumoniae . We have now presented new evidence, using major histocompatibility class II-deficient mice, that CD4 cells are important for early protective immunity. In addition, we have also shown that a population of human CD4 cells migrates towards pneumococci and that in vivo-passaged pneumococci are substantially more potent at inducing migration than in vitro-grown bacteria. This migratory process is unique to a specific population of CD4 cells, is highly reproducible, and is independent of prior CD4 cell activation, and yet the migratory process results in a significant proportion of CD4 cells becoming activated. The production of pneumolysin is a key facet in the induction of migration of CD4 cells by in vivo bacteria, as pneumolysin-deficient bacteria do not induce migration, but the data also show that pneumolysin alone is not sufficient to explain the enhanced migration. Increased CD25 expression occurs during migration, and a higher percentage of cells in the migrated population express gamma interferon or interleukin 4 (IL-4) than in the population that did not migrate. There is evidence that the activation of IL-4 expression occurs during migration.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.72.5.2689-2697.2004
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2004
    detail.hit.zdb_id: 1483247-1
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  • 4
    Online Resource
    Online Resource
    Identification of Cj1051c as a Major Determinant for the Restriction Barrier of Campylobacter jejuni Strain NCTC11168
    American Society for Microbiology ; 2012
    In:  Applied and Environmental Microbiology Vol. 78, No. 22 ( 2012-11-15), p. 7841-7848
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 78, No. 22 ( 2012-11-15), p. 7841-7848
    Abstract: Campylobacter jejuni is a leading cause of human diarrheal illness in the world, and research on it has benefitted greatly by the completion of several genome sequences and the development of molecular biology tools. However, many hurdles remain for a full understanding of this unique bacterial pathogen. One of the most commonly used strains for genetic work with C. jejuni is NCTC11168. While this strain is readily transformable with DNA for genomic recombination, transformation with plasmids is problematic. In this study, we have identified a determinant of this to be cj1051c , predicted to encode a restriction-modification type IIG enzyme. Knockout mutagenesis of this gene resulted in a strain with a 1,000-fold-enhanced transformation efficiency with a plasmid purified from a C. jejuni host. Additionally, this mutation conferred the ability to be transformed by plasmids isolated from an Escherichia coli host. Sequence analysis suggested a high level of variability of the specificity domain between strains and that this gene may be subject to phase variation. We provide evidence that cj1051c is active in NCTC11168 and behaves as expected for a type IIG enzyme. The identification of this determinant provides a greater understanding of the molecular biology of C. jejuni as well as a tool for plasmid work with strain NCTC11168.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01799-12
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2012
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    Vaccines That Reduce Viral Shedding Do Not Prevent Transmission of H1N1 Pandemic 2009 Swine Influenza A Virus Infection to Unvaccinated Pigs
    American Society for Microbiology ; 2021
    In:  Journal of Virology Vol. 95, No. 4 ( 2021-01-28)
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 95, No. 4 ( 2021-01-28)
    Abstract: Swine influenza A virus (swIAV) infection causes substantial economic loss and disease burden in humans and animals. The 2009 pandemic H1N1 (pH1N1) influenza A virus is now endemic in both populations. In this study, we evaluated the efficacy of different vaccines in reducing nasal shedding in pigs following pH1N1 virus challenge. We also assessed transmission from immunized and challenged pigs to naive, directly in-contact pigs. Pigs were immunized with either adjuvanted, whole inactivated virus (WIV) vaccines or virus-vectored (ChAdOx1 and MVA) vaccines expressing either the homologous or heterologous influenza A virus hemagglutinin (HA) glycoprotein, as well as an influenza virus pseudotype (S-FLU) vaccine expressing heterologous HA. Only two vaccines containing homologous HA, which also induced high hemagglutination inhibitory antibody titers, significantly reduced virus shedding in challenged animals. Nevertheless, virus transmission from challenged to naive, in-contact animals occurred in all groups, although it was delayed in groups of vaccinated animals with reduced virus shedding. IMPORTANCE This study was designed to determine whether vaccination of pigs with conventional WIV or virus-vectored vaccines reduces pH1N1 swine influenza A virus shedding following challenge and can prevent transmission to naive in-contact animals. Even when viral shedding was significantly reduced following challenge, infection was transmissible to susceptible cohoused recipients. This knowledge is important to inform disease surveillance and control strategies and to determine the vaccine coverage required in a population, thereby defining disease moderation or herd protection. WIV or virus-vectored vaccines homologous to the challenge strain significantly reduced virus shedding from directly infected pigs, but vaccination did not completely prevent transmission to cohoused naive pigs.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.01787-20
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 1495529-5
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  • 6
    Online Resource
    Online Resource
    Phase-Variable Surface Structures Are Required for Infection of Campylobacter jejuni by Bacteriophages
    American Society for Microbiology ; 2006
    In:  Applied and Environmental Microbiology Vol. 72, No. 7 ( 2006-07), p. 4638-4647
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 72, No. 7 ( 2006-07), p. 4638-4647
    Abstract: This study characterizes the interaction between Campylobacter jejuni and the 16 phages used in the United Kingdom typing scheme by screening spontaneous mutants of the phage-type strains and transposon mutants of the sequenced strain NCTC 11168. We show that the 16 typing phages fall into four groups based on their patterns of activity against spontaneous mutants. Screens of transposon and defined mutants indicate that the phage-bacterium interaction for one of these groups appears to involve the capsular polysaccharide (CPS), while two of the other three groups consist of flagellatropic phages. The expression of CPS and flagella is potentially phase variable in C. jejuni , and the implications of these findings for typing and intervention strategies are discussed.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00184-06
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2006
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
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