ABSTRACT
INTRODUCTION Natural infection of humans by Bacillus anthracis, the etiological agent of anthrax, generally results from contact with infected animals or spore-contaminated animal products. Because of the rarity of human anthrax, the only interest for developing anthrax vaccines for humans is to protect against the use of B. anthracis as a bioweapon to intentionally cause disease. The outbreak of inhalational anthrax in the former Soviet Union in 1979 from the accidental release of spores (1), the admission that Iraq had produced anthrax spores as weapons (2), and the recent successful use of B. anthracis to cause disease in the autumn of 2001 (3) have highlighted the need for improved anthrax vaccines.
