Anthrax Research Today is a free monthly online journal that collates and summarizes the latest research about Anthrax, including details on bacillus anthracis, contagiousness, exposure, effects.

Treatment of experimental anthrax with recombinant capsule depolymerase.

Scorpio A, Tobery SA, Ribot WJ, Friedlander AM

USAMRIID, 1425 Porter Street, Frederick, MD 21702. angelo.scorpio@amedd.army.mil.

Bacillus anthracis produces an antiphagocytic gamma-linked poly-d-glutamic acid capsule that is required for virulence. Capsule depolymerase (CapD) is a membrane-associated poly-gamma-glutamate-specific depolymerase encoded on the B. anthracis capsule plasmid, pX02, that is reported to contribute to virulence by anchoring the capsule to the peptidoglycan and partially degrading high-molecular-weight capsule from the bacterial surface. We previously demonstrated that treatment with CapD effectively removes the capsule from anthrax bacilli, rendering them susceptible to phagocytic killing in vitro. Here we report that CapD promoted in vivo phagocytic killing of B. anthracis bacilli by mouse peritoneal neutrophils and that parenteral administration of CapD protected mice in two models of anthrax infection. CapD conferred significant protection compared with controls when coinjected with encapsulated bacilli from fully virulent B. anthracis Ames or the nontoxigenic encapsulated strain DeltaAmes and when injected 10 min after infection with encapsulated bacilli from B. anthracis Ames. Protection was also observed when CapD was administered 30 h after infection with B. anthracis DeltaAmes spores, while significant protection could not be demonstrated following challenge with B. anthracis Ames spores. These data support the proposed role of capsule in B. anthracis virulence and suggest that strategies to target anthrax bacilli for neutrophil killing may lead to novel postexposure therapies.

Published 26 February 2008 in Antimicrob Agents Chemother, 52(3): 1014-20.
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