Gut Bacteroides viruses and the ME/CFS microbiota

Newberry, Fiona (2021) Gut Bacteroides viruses and the ME/CFS microbiota. Doctoral thesis, University of East Anglia.

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The human intestinal microbiome has long been associated with health and disease. Advances in sequencing and computational approaches have enabled more detailed studies investigating the intestinal microbiome. The intestinal microbiome has been implicated in the development of ME/CFS, a multi-faceted disease mainly characterised by persistent unexplained fatigue. A high percentage of patients exhibit irritable bowel syndrome-like symptoms; this has led researchers to investigate the intestinal microbiome as a contributing factor of disease onset. Chapter 2 details the differences in the microbiota between severe ME/CFS patients versus controls and the heterogenous microbiota composition within the patient group.

Additionally, several intestinal microbiota studies have highlighted the differing abundances of Bacteroides spp. within patients compared to controls. Bacteroides spp. play a pivotal role in the maturation of the infant gut microbiome and are believed to contribute towards a healthy adult microbiome. Several Bacteroides spp. have been shown to mediate immune tolerance and maintain inter-species relationships with other bacteria within the microbiome, contributing towards the overall health of the human host. Prokaryotic viruses (bacteriophage) are thought to indirectly influence human host health via the gut microbiota (taxonomic and functional alterations). However, the bacteriophage of Bacteroides spp. have not been extensively investigated compared to other medically relevant bacteria. Chapter 3 details the isolation and characterisation of a novel Bacteroides fragilis bacteriophage and discovery of a novel B. fragilis bacteriophage family through gene-sharing network analysis.

Several Bacteroides spp. are opportunistic pathogens due to their ability to cause extraintestinal infection. Specific B. fragilis isolates can cause intestinal inflammation via secretion of an enterotoxin. The population structure in relation to different B. fragilis types (i.e. enterotoxigenic, clinical, non-clinical) has not been studied to date. Chapter 4 shows the pangenome of phenotypically diverse B. fragilis isolates and reveals a large accessory genome with no clustering according to isolate type.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Chris White
Date Deposited: 05 Jul 2022 08:52
Last Modified: 05 Jul 2022 08:52

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