Gut protease treated yersiniae are less invasive in vitro. Y. enterocolitica WA-C or the invasin mutant WA-C-inv (Δinv) were digested with the supernatant of small intestinal luminal fluid (SI) or trypsin or mock digested with trypsin digestion buffer. Invasion (a) and adhesion (b) assays were performed using HeLa cells. Invasion assay was performed at 37°C, adhesion assay at 20°C. Percent yersiniae surviving gentamicin treatment is shown in (a), Percent yersiniae adhering to cells and SD is shown in (b). Statistical analysis was performed using Mann-Whitney test at the 0.05 significance level. Asteriks indicate a significant difference from WA-C.