Protection of rhesus macaques against inhalational anthrax with a Bacillus anthracis capsule conjugate vaccine.

Abstract The efficacy of currently licensed anthrax vaccinesis largely attributable to a single Bacillus anthracisimmunogen, protective antigen. To broaden protection against possible strains resistant to protective antigen-based vaccines, we previously developed a vaccinein which the anthrax polyglutamic acidcapsule was covalently conjugated to the outer membrane protein complex of Neisseria meningitidisserotype B and demonstrated that two doses of 2.5 μg of this vaccineconferred partial protection of rhesus macaquesagainst inhalational anthrax. Here, we demonstrate complete protection of rhesus macaquesagainst inhalational anthraxwith a higher 50 μg dose of the same capsule conjugate vaccine. These results indicate that B. anthraciscapsule is a highly effective vaccinecomponent that should be considered for incorporation in future generation anthrax vaccines.