Grant: Operating Grant

Blood-borne spread (dissemination) of pathogens is a critical step in the development of serious infectious disease, and is responsible for most of the mortality due to bacterial infection. The dissemination mechanisms of many bacterial pathogens are largely unknown. A key event in dissemination is pathogen adhesion to vascular endothelium, an event which permits circulating microbes to marginate from the bloodstream and decelerate sufficiently to transmigrate through the vasculature into target tissues. My research focuses on the mechanisms used by the Lyme disease bacterium Borrelia burgdorferi (Bb) to disseminate in the bloodstream of its vertebrate host, a process which we can observe in real time and 3D space in living animals by intravital microscopy. Using intravital microscopy, we determined that Bb vascular adhesion is regulated by host fibronectin (Fn), glycosaminoglycans (GAGs) and Fn- and GAG-binding sequences of the Bb adhesion protein BBK32. BBK32 is the only bacterial protein known to mediate vascular adhesion in vivo, and is conserved in other disseminating bacterial pathogens. The aim of my funding proposal is to investigate the biochemical and biophysical properties of the Bb vascular adhesion mechanism, by investigating the contributions of BBK32, host Fn and glycosylated endothelial receptors to shear force-regulated vascular adhesion and dissemination into joints and other target tissues. These studies will provide the first direct insight into the novel vascular adhesion mechanism of a bacterial pathogen in real-time and space, and will identify adhesion mechanisms and molecules with potential for development as novel clinical drug targets.