The current anthrax vaccine has numerous side effects including headaches, fever and nausea and needs to be administered in regular booster doses to retain its protective ability. Rakesh Bhatnagar and colleagues at the Center for Biotechnology at the Jawaharlal Nehru University, New Delhi, India are to present three abstracts at the 41^st Annual Meeting of the American Society of Cell Biology — on 11 December 2001 in Washington DC — revealing a potential vaccine for anthrax that doesn't have these side effects.

Bhatnagar begin looking for a suitable vaccine seven years ago following a major animal anthrax epidemic in West Bengal. The anthrax-causing bacterium, Bacillus anthracis, derives its toxicity from three proteins; protective antigen (PA), lethal factor (LF) and oedemal factor (OF). The proteins are harmless on their own but PA binds to LF to produce lethal toxin and to OF to form oedema toxin, which then affect the host. PA is the most important of the three since it binds to host cell walls and mediates the entry of the other proteins into the cell. It also forms the basis of the existing vaccine although trace amounts of LF and OF are present to increase its efficacy and it is these components that are responsible for the vaccine's side effects.

The team produced non-toxic mutant forms of all three proteins that retained their antigenicity to enable an effective immune response to be initiated. The altered genes were introduced into safe host organisms, which were then fermented in a 5-liter fermenter, producing up to 5g of PA per liter (1g of PA can supply millions of individual vaccine shots).

Bhatnagar said that the laboratory tests had been completed and that appropriate testing in animals and subsequent clinical trails were ready to be undertaken. A mass immunization programme with a safe and effective anthrax vaccine would effectively negate the threat of a concerted bioterrorist attack using this particular organism.

For an in depth description of the fundamental biology and basis of toxicity of anthrax and four other organisms most likely to be used as bioweapons, click through to:

Anatomy and actions of microscopic agents of terror