Anthrax is an infectious disease due to Bacillus anthracis, a gram-positive, spore-forming bacterium. Among bioterrorist agents, anthrax is considered as one of the most potent and dangerous bio-agent and has been classifi ed in the A list of the Centers of Disease Control. The pathogenic power of this bacteria is due to an exotoxin, which is secreted into the host’s system when three nontoxic proteins link together to form a toxin complex. The three parts of the pathogen complex are protective antigen (PA), lethal factor (LF) and edema factor (EF).At molecular level, the PA binds to cell receptors where it is cleaved into PA20 and PA63. PA63 can competitively bind EF or LF or both. The PA-LF complex forms the lethal toxin (LTx) and the PA-EF complex forms the edema toxin (ETx). Once ETx is endocytosed, EF is released in cytosole. EF is a calmoduline and Ca2+ dependent adenylyl cyclase which catalyses the conversion of cytosolic adenosine triphosphate into cyclic adenosine monophosphate (cAMP) leading to edema.
