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Anthrax |
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Anthrax is a disease caused by the bacterium called Bacillus anthracis, which can be used as a lethal biological weapon. Anthrax may occur in three forms:
The spore of Bacillus anthracis is quite stable. It can exist in soil for many years. However, naturally occurring anthrax is very rare. In the US, only 235 cases were reported between 1955 and 1994, with 11 cases inhalational, which is often fatal. The bacterial spores usually clump together and hard to suspend in the air. To make them a deadly weapon, they have to be separated and combined with fine dust particles to increase the time of floating in the air. Pathogenesis of Anthrax Bacillus anthracis is a Gram-positive bacterium which contains two major virulence factors: poly-D-glutamic acid capsule and anthrax toxin. The poly-D-glutamic acid capsule is nontoxic by itself, but plays an important role in protecting the organism from being killed by phagocytes. Anthrax toxin consists of three distinct proteins: lethal factor, edema (oedema in British spelling) factor, and protective antigen. The lethal factor is a protease that cleaves members of the mitogen-activated protein kinase kinase (MAPKK) family, thereby interrupting the signaling pathways. The edema factor is an adenylate cyclase. The protective antigen mediates the delivery of these two enzymatic components by binding to a cellular receptor.
Anthrax Vaccines The anthrax vaccine being used in the US is made from the protective antigen of the avirulent, nonencapsulated strain of Bacillus anthracis. Although the vaccine has over 90% of efficacy, it requires a series of injections and annual boosters. Researchers are actively developing more effective vaccines. Web Links:
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