The bacterium Bacillus anthracis causes the disease anthrax. This disease primarily affects herbivores in tropical regions of the world. Humans can also contract anthrax, either by accidental exposure to B. anthracis or as a consequence of bioterrorist activities.
The most important factors that determine the capacity to cause disease of B. anthracis are the anthrax toxin and a capsule. By producing these so-called virulence factors B. anthracis can evade the immune system of the host, thereby allowing the proliferation of the bacteria in the body.
This study aimed to elucidate the mechanisms which govern the production of the virulence factors in B. anthracis. In general, production of virulence factors in bacteria is tightly controlled as it is a waste of valuable energy to produce virulence factors under conditions when they are not needed, for example outside the host’s body. In B. anthracis it was already known that the anthrax toxin and capsule are maximally produced at 37°C and in the presence of carbon dioxide. Both these conditions occur in mammalian hosts. Previous research by a number of groups has shown that a protein, called AtxA, controls the production of both anthrax toxin and capsule.
In this study we have found that another protein, CodY, controls the production of B. anthracis toxins but not of capsule. The CodY protein was found to  respond to the presence of several metabolites in the bacterial cell. This indicates that CodY is an important link between the metabolic state of the cell and the production of virulence factors by B. anthracis. We also found that CodY acts independent of AtxA, thereby creating an additional level of complexity in the regulation of the production of virulence factors in B. anthracis. All these findings broaden our knowledge of B. anthracis and may provide clues for the development of novel treatment strategies against anthrax. Â
