Figure 4. Y. enterocolitica O:3 and O:8 interaction with epithelial cells.

Y. enterocolitica O:3 strain Y1 was pregrown at 37°C and Y. enterocolitica O:8 strain 8081v was grown at 25°C. The bacteria were added to HEp-2 and incubated for 30 min at 37°C after centrifugation of the bacteria onto the monolayer. Different stages of the internalization process are shown (initial binding, filopodia and lamellipodia formation). Bars indicate 1 µm.