This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Pidwill, Grace Title: Investigating the molecular mechanisms of pathogenic Group B Streptococcus interactions with fungus Candida albicans General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. 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This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Pidwill, Grace Title: Investigating the molecular mechanisms of pathogenic Group B Streptococcus interactions with fungus Candida albicans General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. However, if you have discovered material within the thesis that you consider to be unlawful e.g. breaches of copyright (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please contact [email protected] and include the following information in your message: • Your contact details • Bibliographic details for the item, including a URL • An outline nature of the complaint Your claim will be investigated and, where appropriate, the item in question will be removed from public view as soon as possible. Investigating the molecular mechanisms of pathogenic Group B Streptococcus interactions with fungus Candida albicans Grace Pidwill A dissertation submitted to the University of Bristol in accordance with the requirements for award of the degree of Doctor of Philosophy in the Faculty of Health Sciences Bristol Dental School December 2018 Word count: 52,394 ii Abstract Group B Streptococcus (GBS) is the leading cause of neonatal sepsis and meningitis in developed countries. In the majority of cases, GBS is vertically transmitted from the mother during or preceding birth. Candida albicans is an opportunistic fungal pathogen of the female GU tract, causing vaginal thrush, for which pregnancy is a risk factor. As C. albicans is known to synergistically interact with Streptococcus bacteria within the oral cavity, it was hypothesised that C. albicans and GBS may interact within the vaginal tract. Using a vaginal epithelial cell association assay, it was shown that C. albicans significantly promoted GBS association with vaginal epithelial cells (VECs) and, likewise, GBS significantly promoted C. albicans. The AgI/II family surface-expressed adhesins of GBS, designated Bsp proteins, were found to contribute to GBS interactions with VECs and with C. albicans, while the C. albicans cell surface protein Als3 was pivotal for the coassociation between these species. Investigations into the VEC response to GBS and C. albicans implied that coassociation may reduce neutrophil chemotaxis, despite enhanced transcription of proinflammatory cytokine genes. Proteomics studies revealed that extracellular matrix (ECM) components, or proteins that modulate ECM components, were significantly elevated in dual-species-infected VECs, while apoptosis- related proteins and proteins involved in MAPK signalling were largely downregulated. Taken together, these data suggest that GBS and C. albicans synergistically interact in a manner that could promote GU tract colonisation and persistence, and that this coassociation is dependent on C. albicans Als3 and partially dependent on GBS Bsp proteins. iii iv Dedication I dedicate this thesis to my family, and to Chris. To my family, thank you for your unwavering support and advice. To mum and dad, thank you for believing in me and motivating me. To Amy, thank you for your excellent advice and encouragement. Last, but by no means least, thank you to Chris for keeping me going in what has been a very difficult year. v vi Acknowledgements I want to express my immense gratitude to my supervisors, Dr Angela Nobbs and Prof Howard Jenkinson, who have helped me grow so much over the course of my PhD. I could not have achieved this work without your direction, inspiration and support. Thank you to Dr Lindsay Dutton and Dr Jane Brittan for taking the time to teach me so much, and for their crucial assistance whenever I needed it. Thank you to Dr Mark Jepson for his insight and helpful suggestions. Thank you also to Dr Rebecca Hall for inviting me to visit her at the University of Birmingham and training me to work with neutrophils. Thank you to her postdoc, Dr Joao Correia, for his patience and instruction in the workings of FIJI. Thank you to Dr Paul Race for allowing me to purify proteins in his lab, and to Dr Catherine Back, for training me in this as well as providing support and vital assistance throughout my PhD. To Sara, thank you for providing the groundwork for such an interesting project. Your work and advice were invaluable. To Catherine, Debbie, Emily and everyone else in Oral Micro, thank you for sharing this journey with me. Together, you made my PhD years absolutely fantastic. To Catherine Klein, thank you for your friendship. I am so grateful that you were there when I needed it the most. vii viii Author’s declaration I declare that the work in this dissertation was carried out in accordance with the requirements of the University's Regulations and Code of Practice for Research Degree Programmes and that it has not been submitted for any other academic award. Except where indicated by specific reference in the text, the work is the candidate's own work. Work done in collaboration with, or with the assistance of, others, is indicated as such. Any views expressed in the dissertation are those of the author. SIGNED: DATE: ix x Table of contents Abstract .................................................................................................................... iii Dedication ................................................................................................................. v Acknowledgements .................................................................................................. vii Author’s declaration.................................................................................................. ix Table of contents ...................................................................................................... xi List of figures ......................................................................................................... xvii List of tables............................................................................................................. xx Abbreviations ......................................................................................................... xxi Chapter 1 Introduction ......................................................................................... 1 1.1 Vaginal epithelium overview ....................................................................... 1 1.2 Genitourinary tract in health and pregnancy ................................................ 3 1.2.1 Cervico-vaginal fluid ................................................................................... 3 1.2.2 Resident microbiota ................................................................................... 3 1.2.3 Effects of pregnancy on the GU tract ......................................................... 4 1.3 Group B Streptococcus ................................................................................. 6 1.3.1 Genus Streptococcus .................................................................................. 6 1.3.2 GBS overview.............................................................................................. 8 1.3.3 GBS carriage and disease rate .................................................................... 9 1.3.4 Risk factors for GBS disease and colonisation .......................................... 10 1.3.5 GBS disease in neonates ........................................................................... 11