Project description:Pseudomonas aeruginosa is an opportunistic human pathogen, infecting immuno-compromised patients and causing persistent respiratory infections in people affected from cystic fibrosis. Pseudomonas strain Pseudomonas aeruginosa PA14 shows higher virulence than Pseudomonas aeruginosa PAO1 in a wide range of hosts including insects, nematodes and plants but the precise cause of this difference is not fully understood. Little is known about the host response upon infection with Pseudomonas and whether or not transcription is being affected as a host defense mechanism or altered in the benefit of the pathogen. In this context the social amoeba Dictyostelium discoideum has been described as a suitable host to study virulence of Pseudomonas and other opportunistic pathogens.
Project description:The opportunistic bacterium Pseudomonas aeruginosa is a major nosocomial pathogen causing both devastating acute and chronic persistent infections. During the course of an infection, P. aeruginosa rapidly adapts to the specific conditions within the host. In the present study, we aimed at the identification of genes that are highly expressed during biofilm infections such as in chronically infected lungs of patients with cystic fibrosis (CF), burn wounds and subcutaneous mouse tumours. We found a common subset of differentially regulated genes in all three in vivo habitats and evaluated whether their inactivation impacts on the bacterial capability to form biofilms in vitro and to establish biofilm-associated infections in a murine model. Additive effects on biofilm formation and host colonization were discovered by the combined inactivation of several highly expressed genes. However, even combined inactivation was not sufficient to abolish the establishment of an infection completely. These findings can be interpreted as evidence that either redundant traits encode functions that are essential for in vivo survival and chronic biofilm infections and/or bacterial adaptation is considerably achieved independently of transcription levels. Supplemental screens, will have to be applied in order to identify the minimal set of key genes essential for the establishment of chronic infectious diseases. Ex-vivo samples were collected from burn wound, cystic fibrosis patients mucous and mice tumor and stabilized for the RNA extraction. Recovered clinical strains were cultivated in rich medium control conditions untill the early stationary phase and RNA was extracted. The murine tumors were infected with burn wound isolated strains
Project description:Aspergillus fumigatus is a ubiquitous mould but also an opportunistic human pathogen causing life-threatening infections in immunocompromised patients. Survival of the fungus in different habitats depends on effective mechanisms of signal perception and transduction such as the cAMP dependent protein kinase A (PKA) pathway, which is involved in virulence of A. fumigatus. Here, by transcriptome analysis putative targets of this important signaling cascade were identified, revealing 632 differently regulated genes including 23 putative transcriptional regulators. The highest up-regulated transcription factor gene was located in the until now unknown fmp secondary metabolite gene cluster encoding an incomplete non-ribosomal peptide synthetase as core enzyme. Overexpression of the fmp cluster resulted in formation of fumipyrrole, which was not described as natural product yet. Although genes of the fmp cluster are transcribed in infected mouse lungs, deletion of its regulatory gene fmpR resulted in wild-type virulence in a murine infection model.
Project description:An opportunistic intracellular pathogen Mycobacterium avium subsp. hominissuis, a member of the nontuberculous mycobacteria (NTM) cluster, causes respiratory disease in immunosuppressed hosts. In particular, infected companion dogs are a potential role to transmit the agent to children or immunosuppressed people. The purpose of this study is to investigate a host-M. avium hominissuis interactome in canine PBMCs during the infection.
Project description:Pseudomonas aeruginosa, a human opportunistic pathogen, is a common cause of nosocomial infections. Its ability to survive under different conditions relies on a complex regulatory network engaging transcriptional regulators controlling metabolic pathways and capabilities to efficiently use the available resources. P. aeruginosa PA3973 encodes a putative TetR family transcriptional regulator, with a helix-turn-helix motif involved in DNA binding. We applied transcriptome profiling (RNA-seq), and genome-wide identification of binding sites using ChIP-seq to unravel the biological role of PA3973.
Project description:Acinetobacter baumannii is an opportunistic nosocomial pathogen that is the causative agent of several serious infections in humans. Here, we investigate the response of A. baumannii toward sodium sulfide (Na2S), known to be associated with some biofilms at oxic/anoxic interfaces, as a model for how this major human pathogen manages sulfide homeostasis. These results reveal that A. baumannii encodes two persulfide‑sensing transcriptional regulators, a primary sigma54‑dependent transcriptional activator (FisR), and a secondary system controlled by the persulfide‑sensing repressor biofilm growth‑associated repressor (BigR) both of which regulate operons encoding for sulfide detoxification or transportation. In addition, sulfide induces an alternative cytochrome bd oxidase which is refractory to inhibition by H2S and represses importers of alternate sulfur sources. Lastly, our results suggest additional genes regulated by BigR beyond sulfide detoxification including genes associated with assembly of type 1 chaperone-usher pilus.
Project description:The opportunistic bacterium Pseudomonas aeruginosa is a major nosocomial pathogen causing both devastating acute and chronic persistent infections. During the course of an infection, P. aeruginosa rapidly adapts to the specific conditions within the host. In the present study, we aimed at the identification of genes that are highly expressed during biofilm infections such as in chronically infected lungs of patients with cystic fibrosis (CF), burn wounds and subcutaneous mouse tumours. We found a common subset of differentially regulated genes in all three in vivo habitats and evaluated whether their inactivation impacts on the bacterial capability to form biofilms in vitro and to establish biofilm-associated infections in a murine model. Additive effects on biofilm formation and host colonization were discovered by the combined inactivation of several highly expressed genes. However, even combined inactivation was not sufficient to abolish the establishment of an infection completely. These findings can be interpreted as evidence that either redundant traits encode functions that are essential for in vivo survival and chronic biofilm infections and/or bacterial adaptation is considerably achieved independently of transcription levels. Supplemental screens, will have to be applied in order to identify the minimal set of key genes essential for the establishment of chronic infectious diseases.
Project description:An opportunistic intracellular pathogen Mycobacterium intracellulare, a member of the nontuberculous mycobacteria (NTM) cluster, causes respiratory disease in immunosuppressed hosts, including companion dogs. The purpose of this study is to investigate a host-M.intracellulare interactome in canine monocyte-derived macrophages during the infection.
Project description:Escherichia coli is the most widely studied strains, which has irreplaceable position in medicine and biology research. Pseudomonas aeruginosa, an opportunistic human pathogen, tends to cause potentially lethal acute or chronic infections in patients with cystic fibrosis (CF), immunocompromised individuals and burn victims. However, it is little know about the effect of the special secondary structure rG4 (G-quadruplex) in the mRNA on virulence regulation. Here, we aim to reveal the new and important post-transcriptional regulatory roles of rG4 in bacterial pathogenicity and metabolic pathways.