This web page was produced as an assignment for an undergraduate course at Davidson College.
Bacillus Anthracis


Life Cycle
Innate Immunity
Humoral Immunity
Cell Mediated Immunity

Anthrax responds fairly well to treatment with antibiotics. Cuetaneous anthrax sores are rendered sterile within 24 hours of treatment with oral penicillin, and other antibiotics are as effective. However, because of the rapid progression of disease during inhalational and gastrointestinal anthrax, antibiotic treatment is usually still futile. In some cases, corticosteroid therapy is given in conjunction with antibiotics to reduce edema. Therapy is also given to offset the possibility of septic shock (1).

A study on anthrax ecology published in 1971 suggested that an effective means of controlling the disease was vaccinating livestock in order to cut off the disease’s likely host (3). However, recently anthrax has entered the post 9/11 world’s consciousness as a potential biological weapon. One report claims that 50 kg of aerosolized B. anthracis spores dispersed by airplane two kilometers upwind of  a major population center would kill over 95,000 people (2). For this reason, human prophylaxies are increasingly sought after.

Luckily, human vaccines do exist. Anthrax was actually the first disease in which a bacterial vaccine was found to be effective. This was a live, attenuated vaccine, obtained by Louis Pasteur. While still used for veterinary purposes, though not considered safe for humans due to residual virulence. The most common current vaccine is chemical, and consists mostly of purified protective antigen coupled with an adjuvant. However, the therapy has its drawbacks, as several boosters are required, and cases reactogenicities. Live spore vaccines appear to provide more protection against lethal challenges in animal models (4).

Future Directions
The consensus that anthrax is essentially caused by poisoning by anthrax toxins points in the direction of an anti-toxin therapy that could be useful either as a vaccine or as a therapy after infection. In most cases, animals with protective immunity against anthrax lethal toxin (LeTx) affords protection from spore challenge, and animals injected with large doses of LeTx die in a manner very similar to those challenged with live endospores. Fortunately, the discovery that LeTx acts a zinc metalloprotease is fairly recent, and may pave the way for therapies that can directly counteract the effects of the toxin in vivo (1).