The Co-Transcriptional Response of Intracellular Group B Streptococcus (GBS) and Monocytes
Author(s)
Primary Supervisor
Ulett, Glen
Other Supervisors
Sullivan, Matthew
Year published
2019-10-31
Metadata
Show full item recordAbstract
Group B Streptococcus (GBS) is a species of gram positive bacteria representing a significant human pathogen; namely, as the most prolific cause of neonatal disease and mortality globally, but also increasingly reported in adult disease (especially among the elderly and those with compromised immune systems). The first chapter of this thesis reviews the extensive literature covering GBS; with a focus on classification and disease. Selected virulence factors are also discussed. In chapter 2, eight strains of GBS were selected for whole genome sequencing by Third Generation, Pacific Biosystems (PacBio) sequencing technology. ...
View more >Group B Streptococcus (GBS) is a species of gram positive bacteria representing a significant human pathogen; namely, as the most prolific cause of neonatal disease and mortality globally, but also increasingly reported in adult disease (especially among the elderly and those with compromised immune systems). The first chapter of this thesis reviews the extensive literature covering GBS; with a focus on classification and disease. Selected virulence factors are also discussed. In chapter 2, eight strains of GBS were selected for whole genome sequencing by Third Generation, Pacific Biosystems (PacBio) sequencing technology. A protocol was optimised to provide sufficient, high quality genomic preparations from multiple strains of GBS - suitable for the PacBio technology. Using a sequenced strain of GBS from chapter 2, an infection model was optimised in chapter 3 for the purpose of providing quality RNA for co-transcript analysis. U937 human monocytes were infected with GBS (strain 874391) and the host/pathogen RNA prepared from the same reaction (monocytes with internalised GBS) - with an emphasis on yielding sufficient pathogen RNA; which can sometime be an impediment for co-transcript studies. Pathogen RNA derived from the optimised infection protocol was demonstrated to amplify with RT-qPCR for 12 tested GBS genes (cylE, 1010, rib, czcD, pil2B, cpsE, scpB, htp, cfb, copA, hvgA and maeA). In chapter 4, RT-qPCR was used to analyse differential gene expression from the mixed, host/pathogen RNA. Twelve human genes and 12 GBS genes were assessed for differential gene expression. Seven of the tested human genes (IL8, IL1A, IL1B, IL10, TNF, LMO2 and MCP-1) and 6 of the tested GBS genes (scpB, 1010, rib, czcD, htp, hvgA) were significantly upregulated in RNA derived from the infection samples. Of the GBS genes tested, htp was the most upregulated. An htp knockout mutant of GBS strain 874391 (Δhtp) was constructed for chapter 5 of this thesis to assess the impact of htp transcription on GBS survival in an infection context. The infection assays optimised in chapter 3 were performed with the Δhtp GBS construct. Contrary to expectation, the Δhtp GBS construct survived the internalised environment of the monocytes in significantly higher numbers than the wild-type over 48 hours of infection.
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View more >Group B Streptococcus (GBS) is a species of gram positive bacteria representing a significant human pathogen; namely, as the most prolific cause of neonatal disease and mortality globally, but also increasingly reported in adult disease (especially among the elderly and those with compromised immune systems). The first chapter of this thesis reviews the extensive literature covering GBS; with a focus on classification and disease. Selected virulence factors are also discussed. In chapter 2, eight strains of GBS were selected for whole genome sequencing by Third Generation, Pacific Biosystems (PacBio) sequencing technology. A protocol was optimised to provide sufficient, high quality genomic preparations from multiple strains of GBS - suitable for the PacBio technology. Using a sequenced strain of GBS from chapter 2, an infection model was optimised in chapter 3 for the purpose of providing quality RNA for co-transcript analysis. U937 human monocytes were infected with GBS (strain 874391) and the host/pathogen RNA prepared from the same reaction (monocytes with internalised GBS) - with an emphasis on yielding sufficient pathogen RNA; which can sometime be an impediment for co-transcript studies. Pathogen RNA derived from the optimised infection protocol was demonstrated to amplify with RT-qPCR for 12 tested GBS genes (cylE, 1010, rib, czcD, pil2B, cpsE, scpB, htp, cfb, copA, hvgA and maeA). In chapter 4, RT-qPCR was used to analyse differential gene expression from the mixed, host/pathogen RNA. Twelve human genes and 12 GBS genes were assessed for differential gene expression. Seven of the tested human genes (IL8, IL1A, IL1B, IL10, TNF, LMO2 and MCP-1) and 6 of the tested GBS genes (scpB, 1010, rib, czcD, htp, hvgA) were significantly upregulated in RNA derived from the infection samples. Of the GBS genes tested, htp was the most upregulated. An htp knockout mutant of GBS strain 874391 (Δhtp) was constructed for chapter 5 of this thesis to assess the impact of htp transcription on GBS survival in an infection context. The infection assays optimised in chapter 3 were performed with the Δhtp GBS construct. Contrary to expectation, the Δhtp GBS construct survived the internalised environment of the monocytes in significantly higher numbers than the wild-type over 48 hours of infection.
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Thesis Type
Thesis (PhD Doctorate)
Degree Program
Doctor of Philosophy (PhD)
School
School of Medical Science
Copyright Statement
The author owns the copyright in this thesis, unless stated otherwise.
Subject
Group B Streptococcus (GBS)
Disease
Monocytes
Infection