Project description:Peptoclostridium difficile, an anaerobic pathogen, known as causative agent of pseudomembranous colitis and nosocomial diarrhoea. It can also form highly resistant endospores which lay the basic foundations of infection prior germination in the human guts. P. difficile exploits toxins TcdA and TcdB as well as a plethora of other proteins to infect the host. The present study is exclusively focused on the interconnection between vegetative cell and spore proteomes. A novel method developed for 15N metabolic labelling of P. difficile vegetative cells has enabled mass spectrometric quantification of relative protein levels of this pathogen. A total of 1095 proteins has been identified over the combined spores and vegetative cells. From this 796 proteins have been relatively and reproducibly quantified between spores and vegetative cells. Of the quantified proteins 80% are common to both the vegetative cells and spores, indicating that pathogenic P. difficile employs a relatively modest proteomic changeover for survival. Also of the identified proteins are 20%putative membrane proteins which may provide essential targets to combat P. difficile infections. Detailed data analysis has qualified potential biomarkers for diagnostic purposes.
Project description:Clostridium difficile is a gram-positive, spore-forming enteric anaerobe which can infect humans and a wide variety of animal species. Recently, the incidence and severity of human C. difficile infection has markedly increased. In this study, we evaluated the genomic content of 73 C. difficile strains isolated from humans, horses, cattle, and pigs by comparative genomic hybridization with microarrays containing coding sequences from C. difficile strains 630 and QCD-32g58. The sequenced genome of C. difficile strain 630 was used as a reference to define a candidate core genome of C. difficile and to explore correlations between host origins and genetic diversity. Approximately 16% of the genes in strain 630 were highly conserved among all strains, representing the core complement of functional genes defining C. difficile. Absent or divergent genes in the tested strains were distributed across the entire C. difficile 630 genome and across all the predicted functional categories. Interestingly, certain genes were conserved among strains from a specific host species, but divergent in isolates with other host origins. This information provides insight into the genomic changes which might contribute to host adaptation. Due to a high degree of divergence among C. difficile strains, a core gene list from this study offers the first step toward the construction of diagnostic arrays for C. difficile.
Project description:Clostridium difficile is a gram-positive, spore-forming enteric anaerobe which can infect humans and a wide variety of animal species. Recently, the incidence and severity of human C. difficile infection has markedly increased. In this study, we evaluated the genomic content of 73 C. difficile strains isolated from humans, horses, cattle, and pigs by comparative genomic hybridization with microarrays containing coding sequences from C. difficile strains 630 and QCD-32g58. The sequenced genome of C. difficile strain 630 was used as a reference to define a candidate core genome of C. difficile and to explore correlations between host origins and genetic diversity. Approximately 16% of the genes in strain 630 were highly conserved among all strains, representing the core complement of functional genes defining C. difficile. Absent or divergent genes in the tested strains were distributed across the entire C. difficile 630 genome and across all the predicted functional categories. Interestingly, certain genes were conserved among strains from a specific host species, but divergent in isolates with other host origins. This information provides insight into the genomic changes which might contribute to host adaptation. Due to a high degree of divergence among C. difficile strains, a core gene list from this study offers the first step toward the construction of diagnostic arrays for C. difficile.investigated by determining changes in transcript profiles when aerobic steady-state cultures were depleted of air.