Clostridium tetani
They may exert their effect locally or produce systemic effects. Well-known exotoxins include: botulinum toxin produced by "Clostridium botulinum"; "Corynebacterium diphtheriae" toxin, produced during life-threatening symptoms of diphtheria; tetanospasmin produced by Clostridium tetani. The toxic properties of most exotoxins can be inactivated by heat or chemical treatment to produce a toxoid. These retain their antigenic specificity and can be used to produce antitoxins and, in the case of diphtheria and tetanus toxoids, are used as vaccines.