Project description:Our understanding of the synergism between S. pneumoniae and influenza virus remains incomplete. The classic dogma has been that influenza attenuates the host innate immunity and increase the susceptibility to subsequent bacterial infection. Therefore, the majority of current studies have been focusing on the interaction of S. pneumoniae and influenza in the context of host cells. By contrast, in this study, we set out to investigate the response of pneumococcus alone to virus infection. Our hypothesis was that prior to causing any damages to host cells, influenza may have induced (lethal) changes to pneumococcus cell itself. Indeed, a very recent evidence has shown that direct viral treatment to pneumococcus will increase its adhesion to macrophage cells. Here, using quantitative phosphoproteomic approach, we attempt to investigate the global alterations of S. pneumoniae phosphorylation by influenza virus challenge, and provide a landscape of synergism between the IAV and pneumococcus.
Project description:Our understanding of the synergism between S. pneumoniae and influenza virus remains incomplete. The classic dogma has been that influenza attenuates the host innate immunity and increase the susceptibility to subsequent bacterial infection. Therefore, the majority of current studies have been focusing on the interaction of S. pneumoniae and influenza in the context of host cells. By contrast, in this study, we set out to investigate the response of pneumococcus alone to virus infection. Our hypothesis was that prior to causing any damages to host cells, influenza may have induced (lethal) changes to pneumococcus cell itself. Indeed, a very recent evidence has shown that direct viral treatment to pneumococcus will increase its adhesion to macrophage cells. Here, using quantitative shotgun approach, we attempt to investigate the proteomic alterations of S. pneumoniae by influenza virus challenge, and provide a landscape of interactions between the IAV and pneumococcus.
Project description:<p><em>Streptococcus pneumoniae</em> is a leading cause of community-acquired pneumonia and bacteraemia and is capable of remarkable phenotypic plasticity, responding rapidly to environmental change. Pneumococcus is a nasopharyngeal commensal, but is responsible for severe, acute infections following dissemination within-host. Pneumococcus is adept at utilising host resources, but the airways are compartmentalised and those resources are not evenly distributed. Challenges and opportunities in metabolite acquisition within different airway niches may contribute to the commensal-pathogen switch when pneumococcus moves from nasopharynx into lungs. We used NMR to characterise the metabolic landscape of the mouse airways, in health and during infection. Using paired nasopharynx and lung samples from naïve animals, we identified fundamental differences in metabolite bioavailability between airway niches. Pneumococcal pneumonia was associated with rapid and dramatic shifts in the lung metabolic environment, whilst nasopharyngeal carriage led to only modest change in upper airway metabolite profiles. NMR spectra derived from the nasopharynx of mice infected with closely-related pneumococcal strains that differ in their colonisation potential could be distinguished from one another using multivariate dimensionality reduction methods. The resulting models highlighted that increased branched-chain amino acid (BCAA) bioavailability in nasopharynx is a feature of infection with the high colonisation potential strain. Subsequent analysis revealed increased expression of BCAA transport genes and increased intracellular concentrations of BCAA in that same strain. Movement from upper to lower airway environments is associated with shifting challenges in metabolic resource allocation for pneumococci. Efficient biosynthesis, liberation or acquisition of BCAA is a feature of adaptation to nasopharyngeal colonisation.</p>
Project description:we characterized the zebrafish innate immune response to pneumococcus through a whole-genome level transcriptome analysis. The analysis revealed the induction of genes coding for pro-inflammatory cytokines, chemokines, acute phase proteins, and antimicrobial peptides, indicating a well-conserved innate immune response to the human pathogen pneumococcus in zebrafish embryos. To gain understanding of the genetic factors associated with the increased risk for severe pneumococcal infection in humans, we carried out a medium-scale forward genetic screen in zebrafish. We identified a mutant fish line, which showed compromised defense against pneumococcus in septic larval infection model. Poor survival upon infection was associated with increased bacterial counts indicating defect in resistance. The transcriptome analysis of the mutant zebrafish embryos revealed otherwise normal innate immune response to pneumococcal infection but a deficient expression of a gene homologous for human C-reactive protein (CRP).
Project description:This study reports the impact of cadmium toxicity on the transcriptome of S. pneumoniae. The most transcriptionally-responsive pathways were found to be carbon source metabolism, fatty acid biosynthesis, cellular metal homeostasis and competence. This data provides a global overview of how the pneumococcus responds to metal ion intoxication, and subsequently, how it maintains viability during this stress.
Project description:PFGRC has developed a cost effective alternative to complete genome sequencing in order to study the genetic differences between closely related species and/or strains. The comparative genomics approach combines Gene Discovery (GD) and Comparative Genomic Hybridization (CGH) techniques, resulting in the design and production of species microarrays that represent the diversity of a species beyond just the sequenced reference strain(s) used in the initial microarray design. These species arrays may then be used to interrogate hundreds of closely related strains in order to further unravel their evolutionary relationships. The Pneumococcus are among most deadly pathogens world-wide. The infections and outbreaks caused by this pathogens is quite frequent despite existing diagnostic network and therapeutic means. Therefore, developing reliable diagnostic tools and efficient (broad-spectrum) therapeutics for Streptococcus pneumoniae remain a public health priority for every country in world today. The comparative genomics study will provide the largest hitherto genomic data sets regarding this pathogen.These large data sets will enable us as well as other members of scientific community to conduct comprehensive data mining in the form of gene association studies with statistical power and significance.
Project description:Control of Streptococcus pneumoniae colonisation at human mucosal surfaces is critical to reducing the burden of pneumonia and invasive disease, interrupting onward transmission, and in achieving herd protection. We hypothesised that the pattern of pneumococcal-epithelial engagement dictates the inflammatory response to colonisation, and that this epithelial sensing is linked to bacterial clearance. Here we have used nasal curette biopsies from a serotype 6B Experimental Human Pneumococcal Carriage Model (EHPC) to visualize S. pneumoniae colonisation and relate these interactions to epithelial surface marker expression and transcriptomic profile upregulation. We have used a Detroit 562 cell co-culture model to further understand these processes and develop an integrated epithelial transcriptomic module to interrogate gene expression in the EHPC model. We have shown for the first time that pneumococcal colonisation in humans is characterised by microcolony formation at the epithelial surface, microinvasion, cell junction protein association, epithelial sensing, and both epithelial endocytosis and paracellular transmigration. Comparisons with other clinical strains in vitro has revealed that the degree of pneumococcal epithelial surface adherence and microinvasion determines the host cell surface marker expression (ICAM-1 and CD107), cytokine production (IL-6, IL-8 and ICAM-1) and the transcriptomic response. In the context of retained barrier function, epithelial microinvasion is associated with the upregulation of a wide range of epithelial innate signalling and regulatory pathways, inflammatory mediators, adhesion molecules, cellular metabolism and stress response genes. The prominence of epithelial TLR4R signalling pathways implicates pneumolysin, a key virulence factor, but although pneumolysin gene deletion partially ameliorates the inflammatory transcriptional response in vitro, critical inflammatory pathways persist in association with enhanced epithelial adhesion and microinvasion. Importantly, the pattern of the host-bacterial interaction seen with the 6B strain in vitro is also reflected in the EHPC model, with evidence of microinvasion and a relatively silent epithelial transcriptomic profile that becomes most prominent around the time of bacterial clearance. Together these data suggest that epithelial sensing of the pneumococcus during colonisation in humans is enhanced by microinvasion, resulting in innate epithelial responses that are associated with bacterial clearance.