Figure 1. Y. enterocolitica O:3 interaction with epithelial cells.

Ten different Y. enterocolitica serotype O:3 isolates from human patients or pigs, Y. enterocolitica O:8 strain 8081v, Y. enterocolitica O:9 strain 4620 and Y. enterocolitica O:5,27 strain 3056 were grown at 25°C overnight in LB medium. About 5·10⁴ HEp-2 cells were infected with 5·10⁵ bacteria and incubated at 22–25°C to monitor cell association or 37°C to determine the internalization efficiency of the bacteria by the gentamicin protection assay. E. coli K-12 was used as negative control. Data are presented as means ± standard deviations of three independent experiments performed in duplicate.