Project description:The aim of the study was to carry out a CGH study utilizing a set of 39 diverse Bacillus isolates. Thirty four B. cereus and five B. anthracis strains and isolates were chosen so as to represent different lineages based on previous characterizations, including MLEE and MLST (Helgason, Okstad et al. 2000; Helgason, Tourasse et al. 2004). They represent the spectrum of B. cereus phenotypic diversity by including soil, dairy and periodontal isolates in addition to virulent B. anthracis strains.
Project description:The spore forming pathogen Bacillus anthracis is the etiologic agent of anthrax in humans and animals. It cycles through infected hosts as vegetative cells and is eventually introduced into the environment where it generates an endospore resistant to many harsh conditions. The endospores are subsequently ingested by the next host to begin the next cycle. Outbreaks of anthrax occur regularly worldwide in wildlife and livestock, and the potential for human infection exists whenever humans encounter infected animals. It is also possible to encounter intentional releases of anthrax spores, as was the case in October 2001. Consequently, it is important to be able to rapidly establish the provenance of infectious strains of B. anthracis. Here, we compare protein expression in seven low-passage wild isolates and four laboratory strains of B. anthracis grown under identical conditions using LC-MS/MS proteomic analysis. Of the 1,023 total identified proteins, 96 had significant abundance differences between wild and laboratory strains. Of those, 28 proteins directly related to sporulation were upregulated in wild isolates, with expression driven by Spo0A, CodY, and AbrB/ScoC. In addition, we observed evidence of changes in cell division and fatty acid biosynthesis between the two classes of strains, despite being grown under identical experimental conditions. These results suggest wild B. anthracis cells are more highly tuned to sporulate than their laboratory cousins, and this difference should be exploited as a method to differentiate between laboratory adapted cultures and low passage wild strains isolated during an anthrax outbreak. This knowledge should distinguish between intentional releases and exposure to strains in nature providing a basis for the type of response by public health officials and investigators.
Project description:AtxA, the master virulence regulator of Bacillus anthracis, regulates the expression of three toxins that are required for the pathogenicity of Bacillus anthracis. Recent transcriptome analyses also showed that AtxA affects a large number of genes on both chromosome and plasmid, suggesting its role as a global regulator. Its mechanism of gene regulation nor binding target in vivo was, however, not well understood. In this work, we conducted ChIP-seq for cataloging binding sites of AtxA in vivo and Cappable-seq for catalogging the transcription start sites on the B. anthracis genome. For detected regulons, single knockout strains were constructed and RNA-seq was conducted for each strain.
Project description:Investigation of whole genome expression level changes in Bacillus anthracis Sterne deltaClpX mutant compared to the wild-type strain after growth in nutrient rich media. The deltaClpX mutant used in this study is described in McGillivray et al. 2009. ClpX Protease Contributes to Antimicrobial Peptide Resistance and Virulence Phenotypes of Bacillus anthracis. Journal of Innate Immunity 1(5): 494-506.
Project description:Bacillus anthracis causes anthrax infections in mammals. Large-scale mortality resulting from the intentional release of B. anthracis spores represents a potential bioterrorism threat. Inhalational anthrax almost invariably proceeds to fatal systemic infection, characterized by massive bacteremia. A better understanding of host-pathogen interactions is urgently needed for effective treatment of this lethal disease. However, virulence mechanisms used by B. anthracis to survive and multiply in human blood are not completely understood. Identification of genes that are differentially expressed during the growth of B. anthracis in human serum can elucidate how this pathogen successfully colonizes the bloodstream. We compared the transcriptional profile of B. anthracis growing in heat-inactivated human serum to that in LB medium. Genes involved in the biosynthesis of purines, certain amino acids and riboflavin and lipid metabolism, genes encoding ABC transporters, respiratory enzymes and several genes with hypothetical function were identified as being upregulated during growth in serum.