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:Anthrax lethal toxin directly targets human peripheral monocytes and causes multiple aberrant gene responses that would be expected to result in defects in human monocyte’s normal signaling transduction pathways and nction. This study provides further insights into the mechanisms associated with the host immune system collapse during an anthrax infection, and suggests that anthrax LT may have additional targets outside the well-known MAPK pathway.
Project description:The goal of this project was to screen soil samples for bacteria that may harbor B. anthracis virulence-associated genes (VAGs). There is currently no information about the prevalence of these types of organisms in the environment. Due to increased environmental monitoring of select agents by programs such as BioWatch and biodetection systems in place at the United States Post Offices and Department of State locations, it has become critical that we not only better understand the natural range of B. anthracis but also how widespread B. anthracis virulence genes are in environmental communities. Naturally occurring isolates containing the B. anthracis virulence genes could generate false-positive results in tests that detect the anthrax toxins, capsule or their associated genes. Understanding the true diversity and pathogenic potential of Bacillus spp. and particularly the B. cereus group is crucial not only in terms of understanding data from environmental monitoring but also diagnosing patients with clinical presentations similar to anthrax in the future. Severe and fatal disease caused by strains similar to B. anthracis could unnecessarily initiate emergency responses if anthrax was incorrectly suspected. Conversely, these strains may be used as bioterror agents requiring science-based responses; presently our limited understanding of these organisms does not permit data-driven decision making. We have investigated 700 aerobic sporoform soil isolates obtained from two areas in the Southwest of the US. Soil samples from the first site had been taken from public access land approximately 50 meters across from the work site of a fatal pneumonia case in a welding factory. This took place in year 2003 when B. cereus was isolated from a metal worker. The second site was targeted because of a recent case involving a deceased mule suspected to have died of a B. anthracis infection. Soil samples were initially analyzed at the CDC. Isolates were obtained by heating the soil at 65 degrees Celcius for 30 minutes followed by plating on agar media. All isolates were screened by PCR for the presence of B. anthracis genomic traits such as toxin genes (cya, lef and pag) as well as chromosomal markers. All isolates were also tested for their hemolytic activity as well as phage sensitivity.