Much has been discovered about Bacillus anthracis infection but the exact pathogenesis is still not fully understood. The new heightened awareness of the use of anthrax as a potential bioterrorist agent has spawned new research into the pathophysiology of the disease. Recent studies have shown the fatal outcome to B. anthracis infection is associated with the host’s septic response which is mediated by a number of host defense mechanisms and the activation of many blood homeostatic systems. The research objectives of this study are four-fold: (1) to assess the blood coagulation and fibrinolysis caused by B. anthracis pathogenesis in relation to septic shock, (2) to investigate the proteolysis of antithrombin by neutrophil elastase (3) to investigate the proteolysis of antithrombin by anthrax proteases (4) to determine the markers of inflammation and acute phase response in B. anthracis infection. Mice will be challenged intraperitoneally with spores of non-encapsulated B. anthracis Sterne strain [pXO1⁺, pXO2^-] and non-toxigenic delta-Sterne strain [pXO1^-, pXO2^- ] to evaluate the toxigenic role during anthrax pathogenesis. Both blood and liver tissue will be analyzed to determine the physiological and biochemical mechanisms that occur during anthrax pathogenesis. From this data, we will propose a novel pathologic mechanism contributing to the host septic response during B. anthracis infection which will provide insight to new therapeutic and detection strategies to decrease mortality in anthrax patients.