Project description:The rise of multi-drug resistance in bacterial pathogens imposes the need to study these organisms from new angles. A little explored outset is to scrutinize bacterial niche adaptations and interactions among pathogenic and commensal bacteria, because they can provide a better understanding of the fitness of pathogens in their human host. We have previously shown that co-culturing of the pathogen Staphylococcus aureus with co-resident Klebsiella oxytoca or Bacillus thuringiensis wound isolates resulted in reduced levels of virulence factor secretion, suggesting that the presence of these co-resident bacteria would modulate S. aureus virulence. In the present study, we performed an in-depth investigation of changes in S. aureus gene expression upon co-cultivation with K. oxytoca and B. thuringiensis under infection-mimicking conditions. To this end, we profiled the cellular proteomes of the co-existing bacteria with special focus on S. aureus. In parallel, we employed RNA sequencing to highlight global changes in staphylococcal behaviour. The results imply that co-colonizing bacteria from chronic wounds can pacify S. aureus, and this conclusion was verified in a Galleria mellonella infection model. Altogether, our findings show that the presence of K. oxytoca and B. thuringiensis leads to massive rearrangements in S. aureus physiology and substantial reduction in virulence.
Project description:In planktonic and biofilm mimicking environments, the staphyloccocal transcriptome in t111+t13595 co-cultures showed significant upregulation of genes related to virulence factors contrary to those co-cultures with B. thuringiesis and K. oxytoca. In the biofilm polymicrobial environment, S. aureus transcriptome shows extensive downregulation of gene expression. The animal model co-infection with S. aureus and K. oxytoca proved to be less virulent than when infected only with S. aureus alone, or K. oxytoca alone where higher infection and mortality rates were observed.
Project description:The zig-zag model of host-pathogen interaction describes the relative strength of defense response across a spectrum of pathogen-induced plant phenotypes. A stronger defense response results in increased resistance. Here, we investigate the strength of pathogen virulence during disease and place these findings in the context of the zig-zag model. Xanthomonas vasicola pv. holcicola (Xvh) causes sorghum bacterial leaf streak. Despite being widespread, this disease has not been described in detail at the molecular level. We divided diverse sorghum genotypes into three groups based on disease symptoms: water-soaked lesions, red lesions, and resistance. Bacterial growth assays confirmed that these three phenotypes represent a range of resistance and susceptibility. To simultaneously reveal defense and virulence responses across the spectrum of disease phenotypes, we performed dual RNA-seq on Xvh-infected sorghum. Consistent with the zig-zag model, the expression of plant defense-related genes was strongest in the resistance interaction. Surprisingly, bacterial virulence genes related to the type III secretion system (T3SS) and type III effectors (T3Es) were also most highly expressed in the resistance interaction. This expression pattern was observed at multiple time points within the sorghum-Xvh pathosystem. Further, a similar expression pattern was observed in Arabidopsis infected with Pseudomonas syringae for effector-triggered immunity via AvrRps4 but not AvrRpt2. Specific metabolites were able to repress the Xvh virulence response in vitro and in planta suggesting a possible signaling mechanism. Taken together, these findings reveal multiple permutations of the continually evolving host-pathogen arms race from the perspective of host defense and pathogen virulence responses.
Project description:Chromatin architecture, a key regulator of gene expression, can be inferred using chromatin contact data from chromosome conformation capture, or Hi-C. However, classical Hi-C does not preserve multi-way contacts. Here we use long sequencing reads to map genome-wide multi-way contacts and investigate higher order chromatin organization in the human genome. We use hypergraph theory for data representation and analysis, and quantify higher order structures in neonatal fibroblasts, biopsied adult fibroblasts, and B lymphocytes. By integrating multi-way contacts with chromatin accessibility, gene expression, and transcription factor binding, we introduce a data-driven method to identify cell type-specific transcription clusters. We provide transcription factor-mediated functional building blocks for cell identity that serve as a global signature for cell types.
Project description:Marek’s disease is a contagious lymphoproliferative disease of chickens and is a unique model of viral oncogenesis. Mapping changes or states over the course of infection for both host and pathogen would have the potential to generate important insights into dynamic host-pathogen interactions. Here we introduced 3’ end enriched RNA-seq as a novel method to study host-pathogen interactions in Marek’s disease virus challenged chicken embryo fibroblasts cells, which allowed accurate profiling of gene expression and alternative polyadenylation sites for host and pathogen simultaneously. We totally identified 476 differentially expressed genes and 437 APA switching genes in host, including switching in tandem 3’ UTRs and switching between coding region and 3’ UTR. Most of these genes were related to innate immunity, apoptosis and metabolism, but two sets of genes overlapped a little suggesting two complementary mechanisms for regulating gene expression during infection. In summary, our results gave a relatively comprehensive insight into dynamic host-pathogen interactions in gene transcription regulation during Marek’s disease virus infection and suggested that 3’ end enriched RNA-seq was a promising method to investigate global host-pathogen interactions.