Invasion of the Brain by Is Mediated by InlF and Host Cell Vimentin.

is a facultative intracellular bacterial pathogen that is frequently associated with food-borne infection. Of particular concern is the ability of to breach the blood-brain barrier, leading to life-threatening meningitis and encephalitis. The mechanisms used by bacterial pathogens to infect the brain are not fully understood. Here we show that is able to utilize vimentin for invasion of host cells. Vimentin is a type III intermediate filament protein within the cytosol but is also expressed on the host cell surface. We found that interaction with surface-localized vimentin promoted bacterial uptake. Furthermore, in the absence of vimentin, colonization of the brain was severely compromised in mice. The virulence factor InlF was found to bind vimentin and was necessary for optimal bacterial colonization of the brain. These studies reveal a novel receptor-ligand interaction that enhances infection of the brain by and highlights the importance of surface vimentin in host-pathogen interactions. is an intracellular bacterial pathogen that is capable of invading numerous host cells during infection. can cross the blood-brain barrier, leading to life-threatening meningitis. Here we show that an surface protein, InlF, is necessary for optimal colonization of the brain in mice. Furthermore, in the absence of vimentin, a cytosolic intermediate filament protein that is also present on the surface of brain endothelial cells, colonization of the brain was significantly impaired. We further show that InlF binds vimentin to mediate invasion of host cells. This work identifies InlF as a bacterial surface protein with specific relevance for infection of the brain and underscores the significance of host cell surface vimentin interactions in microbial pathogenesis.