Molecular Signature of Biological Pathogens

Peripheral blood mononuclear cells (PBMCs) were infected in vitro to develop a model for studying infections of high interest with regards to bioterrorism threats. PBMCs were infected with E.coli B. subtilis and B. cereus, and gene expression analyzed by DNA micro-array technology. Each group had clearly different genetic expression profiles. Random Forest Predictor classified Control, E.coli, B. subtilis and B. cereus groups with only one misclassification in 34 samples (test set accuracy=97%). A list of the 20 most important predictor genes was developed using stepwise linear discriminant analysis. In vivo responses to initial Anthrax vaccinations and E. coli urinary tract infections were compared to in vitro responses to B. cereus and to E. coli, respectively. E. coli urinary tract infections differed from controls, but did not group with in vitro infections, suggesting a limited systemic response. Anthrax vaccinations produced a distinct response, different from controls but similar to the in vitro responses from B. cereus infections. These findings suggest that this model will predict systemic infection responses to bioterrorism pathogens of interest. Analysis of proteomic responses to identify key markers for specific infections provided critical information to guide in vivo analyses that will be expanded to a larger group of subjects with systemic infections in Phase II. The original document contains color images. All DTIC reproductions will be in black and white.