Figure 2.

Analysis of N. meningitidis adhesion on endothelial cells in the presence of liquid flow using in a laminar flow chamber. (A) Endothelial cells forming a confluent monolayer on a glass slide are placed in the flow chamber and observed by phase contrast microscopy with a 20x lens. A typical sequence of three videoframes illustrates bacterial adhesion under various flow conditions: (B) before the introduction of bacteria into the chamber; (C) fluorescent bacteria flowing over the cells appear as short bright lines; and (D) bacteria adherent on the cell monolayer appear as still bright spots. Quantitative image analysis with the Quia software package allows automated identification of attached bacteria, which are then marked with colored squares. (E) Number of adherent bacteria determined as a function of time with the Quia software package shows bacteria accumulating with time in a linear fashion (circles). As a reference, results of a similar experiment performed in static conditions are also presented (squares). (F) The number of adherent bacteria plotted as a function of the concentration of bacteria introduced in the chamber shows a linear relationship between the inoculum and the number of adhering bacteria.