All ETDs from UAB

Advisory Committee Chair

John F Kearney

Advisory Committee Members

Charles L Turnbough Jr

David D Chaplin

David E Briles

William H Benjamin

Zdenek Hel

Document Type

Dissertation

Date of Award

2015

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Bacillus anthracis (Ba) is a Gram,-positive zoonotic bacterium that causes inhala- tional, cutaneous and intestinal Anthrax Disease. Although the infectious form of Ba is its endospore (spore), only the tripartite toxin-producing vegetative bacteria causes disease pathology. While current vaccination strategies target the Protective Antigen (PA) com- ponent of this toxin, vaccine-elicited immunity to the spore form of Ba is lacking. How- ever, vaccines targeting spore components of Ba have the potential to neutralize the in- fectious form of Ba. We sought to determine if antibodies elicited through immunization with the main antigenic component of the spore surface- Bacillus collagen-like protein of Anthracis (BclA)- can mediate immunity and protect against lethal Ba infection. The study of Ba is problematic due to its inherent virulence and bio-safety con- cerns. Many laboratories utilize the Sterne strain, which only require a BSL II facility, but limits researchers to the susceptible A/J or similar mouse strains. In our initial studies we confirm that C5 deficiency renders C57BL/6 mice susceptible to this strain. Because the majority of genetically manipulated mice are on the C57BL/6 background, the use of C5 deficient mice (C5-/-) in the C57BL/6 background broadens our ability to study Ba- host interactions under a variety of experimental conditions. Intranasal immunization with recombinant BclA and cholera toxin provided sig- nificant protection from lethal intratracheal Ba challenge to complement component 5- deficient (C5-/-) C57BL/6 mice. Importantly, passive transfer of BclA-specific monoclo- ii nal antibodies (mAbs) was similarly able to protect from lethal Ba challenge, and signifi- cantly increase spore uptake by macrophages and lead to enhanced spore-destruction in vitro. The effects of BclA-specific mAbs are mediated by Fc receptors, which promoted endo-lysosomal fusion, increased acidification of the endosomal compartment, and sub- sequently promoted spore destruction within macrophages. Collectively, these results indicate that vaccine-elicited antibodies targeting the Ba spore component BclA can lead to protection from infectious Ba spores by promoting their uptake and destruction. BclA-targeted immunity could be a major supplement to current toxin-based vaccines. Furthermore, BclA-specific mAbs represent an important addition to current antibiotic regimens used to treat Ba, and may be of highly significant value in the treatment of multiple antibiotic-resistant Ba strains or bioengineered strains.

Share

COinS