FIG. 3.

In vitro adherence to immobilized fibrinogen and fibronectin and internalization into cultured endothelial cells. L. lactis expressing various FnBPA fragments were tested first for in vitro adherence to immobilized fibrinogen (upper panel) and fibronectin (middle panel) and second for internalization into cultured BAEC (lower panel). S. aureus Cowan and 8325-4 were used as wild-type controls, L. lactis 0 (i.e., expressing only the signal sequence and cell wall-anchoring domain) served as a negative control, and L. lactis FnBPA+ was used as a positive control. Binding titers were defined as the inverse of the highest dilution of ligand demonstrating adherence by optical density. Internalization results are expressed as the percentage of surviving bacteria compared to the initial inoculum. All data represent the median of three or more separate experiments. Intra- and interrun variations were ≤20%. For all L. lactis strains expressing truncated FnBPA or A⁺¹⁶ subdomains, significant differences (analysis of variance and Fisher's post hoc PLSD test, P < 0.05) from L. lactis 0 (*) and L. lactis FnBPA+ (§) are indicated.