Toxins of Bacillus anthracis.

Bacillus anthracis, a gram positive bacterium, is the causative agent of anthrax. This organism is capsulogen and toxinogenic. It secretes two toxins which are composed of three proteins: the protective antigen (PA), the lethal factor (LF) and the edema factor (EF). The lethal toxin (PA+LF) provokes a subit death in animals, the edema toxin (PA+EF) induces edema. The edema and the lethal factors are internalised into the eukaryotic target cells via the protective antigen. EF and LF exert a calmoduline dependent adenylate cyclase and a metalloprotease activity respectively. Progress in the structure-function relationship of these three proteins, their regulation mechanisms and their roles in pathogenesis and immunoprotection will be exposed.