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 goal of this study is the discovery of (a) meaningful phylogenomic relationships among members of this B. cereus/B. anthracis group, and (b) reliable gene-phenotype associations, e.g. recognition of links between genomic traits and the ability of certain strains to cause various forms of disease. We also tried to elucidate genome evolution aspects that may lead to the emergence of variants that are capable (or have the potential) of causing anthrax-like disease. This large-scale comparative genomics approach is unprecedented for this taxonomic group. Dr. A. Hoffmaster (CDC) provided the PFGRC with 73 B. cereus and B. anthracis isolates from the CDC culture collection. Of these, 27 were isolated from patients with severe or systemic disease; ten isolates of this group were obtained from patients (welding factory workers) with anthrax-like disease or from the environment near their workplace. Another set of 26 represented isolates from food-born illnesses. Of the 26 gastrointestinal disease isolates (GIDI), 10 were obtained from patients with diarrhea, whereas another set of 10 had been shown to harbor the emetic (vomit) toxin gene by PCR. The rest of the group consisted of 20 isolates with various phenotypes. All strains were screened for their genomic content using the B. cereus/B. anthracis species microarray.
Project description:One of the cornerstones of an effective biodefense strategy is the ability to detect infectious agents with a high degree of sensitivity and specificity in the context of a complex sample background. The nature of the B. anthracis genome, however, renders specific detection difficult, due to close homology with B. cereus and B. thuringiensis. We therefore elected to determine the efficacy of next-generation sequencing analysis and microarrays for detection of B. anthracis in an environmental background. We applied next-generation sequencing to titrated genome copy numbers of B. anthracis in the presence of background nucleic acid extracted from aerosol and soil samples. We found next-generation sequencing to be capable of detecting as few as 10 genomic equivalents of B. anthracis DNA per nanogram of background nucleic acid. Detection was accomplished by mapping reads to either a defined subset of reference genomes or to the full GenBank database. Moreover, sequence data obtained from B. anthracis could be reliably distinguished from sequence data mapping to either B. cereus or B. thuringiensis. We also demonstrated the efficacy of a microbial census microarray in detecting B. anthracis in the same samples, representing a cost-effective and high-throughput approach, complementary to next-generation sequencing.
Project description:Raw reads of 170 isolates of Bacillus cereus biovar anthracis (Bcbva) from Tai National Park, Côte d'Ivoire and eight Bcbva isolates from neighboring Grebo, Liberia
Project description:BACKGROUND:Bacillus cereus biovar anthracis (Bcbva) is an emergent bacterium closely related to Bacillus anthracis, the etiological agent of anthrax. The latter has a worldwide distribution and usually causes infectious disease in mammals associated with savanna ecosystems. Bcbva was identified in humid tropical forests of Côte d'Ivoire in 2001. Here, we characterize the potential geographic distributions of Bcbva in West Africa and B. anthracis in sub-Saharan Africa using an ecological niche modeling approach. METHODOLOGY/PRINCIPAL FINDINGS:Georeferenced occurrence data for B. anthracis and Bcbva were obtained from public data repositories and the scientific literature. Combinations of temperature, humidity, vegetation greenness, and soils values served as environmental variables in model calibrations. To predict the potential distribution of suitable environments for each pathogen across the study region, parameter values derived from the median of 10 replicates of the best-performing model for each pathogen were used. We found suitable environments predicted for B. anthracis across areas of confirmed and suspected anthrax activity in sub-Saharan Africa, including an east-west corridor from Ethiopia to Sierra Leone in the Sahel region and multiple areas in eastern, central, and southern Africa. The study area for Bcbva was restricted to West and Central Africa to reflect areas that have likely been accessible to Bcbva by dispersal. Model predicted values indicated potential suitable environments within humid forested environments. Background similarity tests in geographic space indicated statistical support to reject the null hypothesis of similarity when comparing environments associated with B. anthracis to those of Bcbva and when comparing humidity values and soils values individually. We failed to reject the null hypothesis of similarity when comparing environments associated with Bcbva to those of B. anthracis, suggesting that additional investigation is needed to provide a more robust characterization of the Bcbva niche. CONCLUSIONS/SIGNIFICANCE:This study represents the first time that the environmental and geographic distribution of Bcbva has been mapped. We document likely differences in ecological niche-and consequently in geographic distribution-between Bcbva and typical B. anthracis, and areas of possible co-occurrence between the two. We provide information crucial to guiding and improving monitoring efforts focused on these pathogens.
Project description:One of the cornerstones of an effective biodefense strategy is the ability to detect infectious agents with a high degree of sensitivity and specificity in the context of a complex sample background. The nature of the B. anthracis genome, however, renders specific detection difficult, due to close homology with B. cereus and B. thuringiensis. We therefore elected to determine the efficacy of next-generation sequencing analysis and microarrays for detection of B. anthracis in an environmental background. We applied next-generation sequencing to titrated genome copy numbers of B. anthracis in the presence of background nucleic acid extracted from aerosol and soil samples. We found next-generation sequencing to be capable of detecting as few as 10 genomic equivalents of B. anthracis DNA per nanogram of background nucleic acid. Detection was accomplished by mapping reads to either a defined subset of reference genomes or to the full GenBank database. Moreover, sequence data obtained from B. anthracis could be reliably distinguished from sequence data mapping to either B. cereus or B. thuringiensis. We also demonstrated the efficacy of a microbial census microarray in detecting B. anthracis in the same samples, representing a cost-effective and high-throughput approach, complementary to next-generation sequencing. This Series contains the NimbleGen array data only (no next-generation sequencing data). B. anthracis DNA was spiked at 6 different concentrations (1, 10, 100, 1000, 10000 and 100000 genome copies) into 1 ng of background nucleic acids extracted either from a soil sample or from an aerosol (air filter) sample. Two replicates of each combination of B. anthracis copy number and background sample were analyzed.
Project description:RNA-seq experiment comparing the transcriptomes of Bacillus cereus G9241 WT to B. cereus G9241 ∆pBCXO1 when cultured both 37 and 25 degree celsius. B. cereus G9241 is a B. cereus sensu stricto strain that was isolated from a welder with and anthrax-like illness. B. cereus G9241 carries the plasmids pBCXO1 and pBC210. pBCX01 has 99.6% sequence identity to pXO1 carried by Bacillus anthracis and encodes the tripartite anthrax toxin genes and atxA, a mammalian virulence transcriptional regulator. B. cereus G9241 WT and B. cereus G9241 ∆pBCXO1 were cultured to exponential phase at either 37 or 25 degree celsius before samples were taken for RNA extraction, library prep and sequencing.