CFU recovered after 2-h adherence and invasion assays with Bp340, the Bp340ΔbcaA strain (A), the Bp340ΔbcaB strain (B), and the respective complementation strains. Assays were performed three times in duplicate, and the results were combined. Data are means ± SEM. ***, P < 0.0001 (by one-way ANOVA with Tukey's posttest at a 95% confidence interval).