Scientific Publications by FDA Staff

Cell Microbiol 2012 Aug;14(8):1219-1230

Bacillus anthracis protease InhA regulates BslA-mediated adhesion in human endothelial cells.

Tonry JH, McNichol BA, Ramarao N, Chertow DS, Kim KS, Stibitz S, Schneewind O, Kashanchi F, Bailey CL, Popov S, Chung MC

To achieve widespread dissemination in the host, Bacillus anthracis cells regulate their attachment to host endothelium during infection. Previous studies identified BslA (Bacillus anthracisS-layer Protein A), a virulence factor of B. anthracis, as necessary and sufficient for adhesion of vegetative cells to human endothelial cells. While some factors have been identified, bacteria-specific contributions to BslA mediated adhesion remain unclear. Using the attenuated vaccine Sterne 7702 strain of B. anthracis, we tested the hypothesis that InhA (immune inhibitor A), a B. anthracis protease, regulates BslA levels affecting the bacteria's ability to bind to endothelium. To test this, a combination of inhA mutant and complementation analysis in adhesion and invasion assays, Western Blot and InhA inhibitor assays was employed. Results show InhA down-regulates BslA activity reducing B. anthracis adhesion and invasion in human brain endothelial cells. BslA protein levels in DeltainhA bacteria were significantly higher than wild-type and complemented strains showing InhA levels and BslA expression are inversely related. BslA was sensitive to purified InhA degradation in a concentration- and time-dependent manner. Taken together these data support the role of InhA regulation of BslA-mediated vegetative cell adhesion and invasion.