Exposure to 
All aerosol challenges occurred with a well-characterized, single lot of A modified type three-jet Collison nebulizer (BGI, Waltham, MA, USA) was used to generate a controlled delivery of aerosolized Rabbits were exposed muzzle-only to aerosol challenge, whereas each NHP was anesthetized prior to challenge, placed into a plethysmography chamber, and put in a Class III cabinet system for spore exposure. The targeted aerosol challenge dose was 200 LD