Bacillus cereus strains harboring a pXO1-like virulence plasmid cause respiratory
anthrax-like disease in humans, particularly in welders. We developed mouse models for intraperitoneal as well as
aerosol challenge with spores of B. cereus G9241, harboring pBCXO1 and pBC218 virulence plasmids. Compared to wild-type B. cereus G9241, spores with a deletion of the pBCXO1-carried protective
antigen gene (pagA1) were severely attenuated, whereas spores with a deletion of the pBC218-carried protective
antigen homologue (pagA2) were not.
Anthrax vaccine adsorbed (AVA) immunization raised
antibodies that bound and neutralized the pagA1-encoded protective
antigen (PA1) but not the PA2 orthologue encoded by pagA2. AVA immunization protected mice against a lethal challenge with spores from B. cereus G9241 or B. cereus Elc4, a strain that had been isolated from a fatal case of
anthrax-like disease. As the pathogenesis of B. cereus
anthrax-like disease in mice is dependent on pagA1 and PA-
neutralizing antibodies provide protection, AVA immunization may also protect humans from respiratory
anthrax-like death.