Fig. 5.

Quantification of adhesion to human umbilical vein endothelial cells (HUVEC) of PilW variants constructed in this study. The WT strain and the pilW mutant were included as positive and negative controls, respectively. After a 30-min contact, during which standardized numbers of bacteria were incubated with standardized numbers of cells, nonadherent bacteria were removed by replacing the medium. After a further 4 h of incubation (the medium being replaced every hour), cells were washed, and adherent bacteria were recovered and plated. Results are expressed as CFU of adhering bacteria normalized for an inoculum of 10⁷ CFU and are the means ± standard deviations from 4 to 6 independent experiments. Results statistically significantly different from the WT strain (P ≤ 0.01), as assessed by two-tailed Student's t test, are indicated by an asterisk.