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Infect Immun 2007 Nov;75(11):5233-9

Bacillus anthracis Exosporium Protein BclA Affects Spore Germination, Interaction with Extracellular Matrix Proteins, and Hydrophobicity.

Brahmbhatt TN, Janes BK, Stibitz ES, Darnell SC, Sanz P, Rasmussen SB, O'brien AD


The bacillus collagen like protein of anthracis (BclA) is the immunodominant glycoprotein on the exosporium of Bacillus anthracis spores. Here, we sought to assess the impact of BclA on spore germination in vitro and in vivo, surface charge, and interaction with host matrix proteins. For that purpose, we constructed a marker-less bclA null mutant in B. anthracis Sterne 34F2 strain. The growth and sporulation rates of the DeltabclA and parent strains were nearly indistinguishable, but germination of mutant spores occurred more rapidly than wild-type spores in vitro and was more complete by 60 minutes. Additionally, the mean time-to-death of A/J mice inoculated subcutaneously or intranasally with mutant spores was lower than for the wild-type spores even though the 50% lethal doses of the two strains were similar. We speculated that these in vitro and in vivo differences between mutant and wild-type spores might reflect ease of access of germinants to their receptors in the absence of BclA. We also compared the hydrophobic and adhesive properties of DeltabclA and wild-type spores. The DeltabclA spores were markedly less water-repellent than wild type spores and, probably as a consequence, the extracellular matrix proteins laminin and fibronectin bound significantly better to mutant than to wild type spores. These studies suggest that BclA acts as a shield to not only reduce the ease with which spores germinate but also to change the surface properties of the spore which, in turn, may impede the interaction of the spore with host matrix substances.

Category: Journal Article
PubMed ID: #17709408
Includes FDA Authors from Scientific Area(s): Biologics
Entry Created: 2011-10-04 Entry Last Modified: 2012-08-29