Characterisation of putative virulence factors in adherent-invasive Escherichia coli
Crohn’s disease (CD) is a chronic inflammatory bowel disease. CD is driven by a synergy of predisposing genetic variants, diet, gut colonisation with a perturbed pro-inflammatory microbiome, and infection with CD-associated pathobionts, including Adherent-Invasive Escherichia coli (AIEC). AIEC is a...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
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2020
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| Online Access: | https://eprints.nottingham.ac.uk/59803/ |
| _version_ | 1848799679029968896 |
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| author | Cogger-Ward, Robert |
| author_facet | Cogger-Ward, Robert |
| author_sort | Cogger-Ward, Robert |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Crohn’s disease (CD) is a chronic inflammatory bowel disease. CD is driven by a synergy of predisposing genetic variants, diet, gut colonisation with a perturbed pro-inflammatory microbiome, and infection with CD-associated pathobionts, including Adherent-Invasive Escherichia coli (AIEC). AIEC is a non-diarrhoeagenic intestinal E. coli pathotype, the virulence of which is characterised by adhesion to and invasion of intestinal epithelial cells (IECs); intracellular replication within IECs and macrophages; flagella-mediated motility; and biofilm formation.
Preliminary evidence suggests the prototypical AIEC strain, LF82, mediates pathogenesis in some part via two uncharacterised Type VI Secretion Systems (T6SS). The T6SS may secrete anti-eukaryotic and anti-bacterial effectors and is implicated in host cytomodulation and niche establishment via inter-bacterial antagonism in several proteobacterial pathogens. This study therefore used phenotypic screening approaches to define the roles of the T6SS in host-AIEC interactions, and anti-bacterial competition. A high-throughput screen was also employed to identify putative anti-eukaryotic T6SS effectors. No evidence of a role for the T6SS in IEC invasion, intramacrophage replication, or anti-bacterial competition was found in this study. Intra-IEC replication could not be reliably assayed. However, a high-throughput screen identified four putative anti-eukaryotic T6SS effectors, which might conceivably modulate intra-IEC survival and intracellular replication in AIEC.
Prior work in the Huett lab identified a conserved hypothetical protein – LF82_314 – which promoted AIEC invasion of IECs. This study sought to validate this finding, and to characterise the role of LF82_314 in biofilm formation, motility, and host colonisation, using a Caenorhabditis elegans infection model. Bioinformatic, genetic, and proteomic characterisations of LF82_314 were also conducted. This study found LF82_314 mediates biofilm formation and C. elegans gut colonisation via flagella-mediated motility. Genetic and biochemical characterisations suggest LF82_314 may modulate motility by regulating anaerobiosis. LF82_314 is widespread in γ-proteobacterial pathogens. This study therefore found LF82_314 is a significant novel virulence factor, with consequence in both CD and other enteric infections. |
| first_indexed | 2025-11-14T20:39:30Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-59803 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T20:39:30Z |
| publishDate | 2020 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-598032025-02-28T14:46:26Z https://eprints.nottingham.ac.uk/59803/ Characterisation of putative virulence factors in adherent-invasive Escherichia coli Cogger-Ward, Robert Crohn’s disease (CD) is a chronic inflammatory bowel disease. CD is driven by a synergy of predisposing genetic variants, diet, gut colonisation with a perturbed pro-inflammatory microbiome, and infection with CD-associated pathobionts, including Adherent-Invasive Escherichia coli (AIEC). AIEC is a non-diarrhoeagenic intestinal E. coli pathotype, the virulence of which is characterised by adhesion to and invasion of intestinal epithelial cells (IECs); intracellular replication within IECs and macrophages; flagella-mediated motility; and biofilm formation. Preliminary evidence suggests the prototypical AIEC strain, LF82, mediates pathogenesis in some part via two uncharacterised Type VI Secretion Systems (T6SS). The T6SS may secrete anti-eukaryotic and anti-bacterial effectors and is implicated in host cytomodulation and niche establishment via inter-bacterial antagonism in several proteobacterial pathogens. This study therefore used phenotypic screening approaches to define the roles of the T6SS in host-AIEC interactions, and anti-bacterial competition. A high-throughput screen was also employed to identify putative anti-eukaryotic T6SS effectors. No evidence of a role for the T6SS in IEC invasion, intramacrophage replication, or anti-bacterial competition was found in this study. Intra-IEC replication could not be reliably assayed. However, a high-throughput screen identified four putative anti-eukaryotic T6SS effectors, which might conceivably modulate intra-IEC survival and intracellular replication in AIEC. Prior work in the Huett lab identified a conserved hypothetical protein – LF82_314 – which promoted AIEC invasion of IECs. This study sought to validate this finding, and to characterise the role of LF82_314 in biofilm formation, motility, and host colonisation, using a Caenorhabditis elegans infection model. Bioinformatic, genetic, and proteomic characterisations of LF82_314 were also conducted. This study found LF82_314 mediates biofilm formation and C. elegans gut colonisation via flagella-mediated motility. Genetic and biochemical characterisations suggest LF82_314 may modulate motility by regulating anaerobiosis. LF82_314 is widespread in γ-proteobacterial pathogens. This study therefore found LF82_314 is a significant novel virulence factor, with consequence in both CD and other enteric infections. 2020-07-17 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en arr https://eprints.nottingham.ac.uk/59803/1/Robert%20Cogger-Ward%20Thesis.pdf Cogger-Ward, Robert (2020) Characterisation of putative virulence factors in adherent-invasive Escherichia coli. PhD thesis, University of Nottingham. Adherent invasive Escherichia coli; AIEC; Biofilm; Motility; Crohn's disease; bcmA; LF82_314 |
| spellingShingle | Adherent invasive Escherichia coli; AIEC; Biofilm; Motility; Crohn's disease; bcmA; LF82_314 Cogger-Ward, Robert Characterisation of putative virulence factors in adherent-invasive Escherichia coli |
| title | Characterisation of putative virulence factors in adherent-invasive Escherichia coli |
| title_full | Characterisation of putative virulence factors in adherent-invasive Escherichia coli |
| title_fullStr | Characterisation of putative virulence factors in adherent-invasive Escherichia coli |
| title_full_unstemmed | Characterisation of putative virulence factors in adherent-invasive Escherichia coli |
| title_short | Characterisation of putative virulence factors in adherent-invasive Escherichia coli |
| title_sort | characterisation of putative virulence factors in adherent-invasive escherichia coli |
| topic | Adherent invasive Escherichia coli; AIEC; Biofilm; Motility; Crohn's disease; bcmA; LF82_314 |
| url | https://eprints.nottingham.ac.uk/59803/ |