Several bacterial pathogens are associated with the formation of non-cancerous or even cancerous tumor lesions, while the underlying mechanisms of bacteria-triggered tumorigenesis remain elusive. Here, I propose to study the molecular mechanism of vasoproliferative tumor-formation by the emerging pathogen Bartonella henselae. My laboratory will analyze bacterial pathogenicity factors mediating vascular endothelial cell proliferation and remodeling in vitro and vascular tumor formation in vivo. We will focus our analysis on (i) the anti-apoptotic protein BepA and other effector proteins (BepB-G) translocated via a type IV secretion system into endothelial cells, and (ii) a yet unidentified vasoproliferative factor in the bacterial outer membrane. While these factors directly activate endothelial cells, we will also study virulence factors triggering the paracrine release of the vasoproliferative host factor VEGF from infected macrophages and epithelial cells.