Helmholtz Center for Infection Research 1 article published in JoVE Immunology and Infection Pneumococcus Infection of Primary Human Endothelial Cells in Constant Flow Hilger Jagau1,2, Ina-Kristin Behrens1,3, Michael Steinert1,4, Simone Bergmann1 1Institut für Mikrobiologie, Technische Universität Braunschweig, 2Devision of Infection Medicine, Department of Clinical Science, Lund University, 3Medical Microbiology and Hospital Epidemiology, Max von Pettenkofer Institute, Ludwig Maximilians University, 4Department of Molecular Infection Biology, Helmholtz Center for Infection Research This study describes the microscopic monitoring of pneumococcus adherence to von Willebrand factor strings produced on the surface of differentiated human primary endothelial cells under shear stress in defined flow conditions. This protocol can be extended to detailed visualization of specific cell structures and quantification of bacteria by applying differential immunostaining procedures.