Doctoral Thesis
Characterising Host and Pathogen Drivers of Neonatal Staphylococcal Sepsis Using Dual RNA-Sequencing
Doctor of Philosophy (PhD), Murdoch University
2024
Abstract
Infants born before 32 weeks of gestational age (GA) are at high risk of developing late-onset neonatal sepsis, most frequently caused by host-colonising bacteria such as Staphylococcus epidermidis and S. aureus. The bacterial virulence factors used by these species to transition from commensalism to invasive pathogens are poorly understood. Dual RNA-sequencing (RNA-seq) enables the concurrent analysis of both host and pathogen gene expression and holds promise for deciphering bacterial virulence mechanisms and their drivers during systemic infections. However, its use in sepsis research is limited due to low bacterial loads and small blood volumes from preterm infants. We have optimised a dual-species RNA purification protocol for use with small (0.5 ml) blood samples suitable for both gram-positive and gram-negative sepsis pathogens and validated the feasibility of dual RNA-seq in a pilot set of clinical adult sepsis samples. We have also established and employed a laboratory sepsis model using blood samples from three host populations with varying sepsis risks: very preterm infants (30-32 weeks GA), term infants (>37 weeks GA), and young adults (18-25 years) (n=8 per cohort), which were challenged with S. epidermidis and S. aureus for 90 minutes. Using dual RNA-seq, we identified shared and distinct host and bacterial gene expression patterns. Developmental age significantly influenced the response to, and interaction with, bacterial pathogens, with several metabolic and immune pathways differentially induced in preterm infants compared to the two other host cohorts. Our data moreover indicate that bacterial gene co-expression is influenced by the host. These findings underscore the complexity of host-pathogen interactions during sepsis and suggest the possibility of identifying host and pathogen specific sepsis interventional pathways. We anticipate that larger cohorts and longitudinal samples will provide further insights into host and bacterial gene coexpression underlying sepsis progression and outcomes in individual sepsis patients.
Details
- Title
- Characterising Host and Pathogen Drivers of Neonatal Staphylococcal Sepsis Using Dual RNA-Sequencing
- Authors/Creators
- Isabella A Joubert
- Contributors
- Professor Andrew Currie (Supervisor) - Murdoch University, Centre for Molecular Medicine and Innovative TherapeuticsTobias Strunk (Supervisor) - The Kids Research Institute AustraliaPenghao Wang (Supervisor) - Murdoch University, Centre for Crop and Food InnovationSam Abraham (Supervisor) - Murdoch University, Centre for Biosecurity and One Health
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005651566507891
- Murdoch Affiliation
- Centre for Molecular Medicine and Innovative Therapeutics
- Resource Type
- Doctoral Thesis
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