Figure 5.

Mutation of P66 affects the ability of B orrelia burgdorferi to cross an endothelial monolayer of cells. HMEC‐1 human microvascular endothelial cells were plated in 3 μm pore size Transwell inserts and grown to confluence in antibiotic free medium. B31‐A3 (wild‐type), Δp66, p66^cc, BD 205 A , D 207 A or BD el202–208 bacteria were added to the insert at an MOI of 20 and the ability of bacteria to cross the monolayer of cells was assessed over 48 h by taking an aliquot from the insert and from the well below. Bacteria were counted manually using a Petroff‐Hausser counting chamber under dark‐field microscopy, and the percentage of bacteria that crossed the cell monolayer was calculated. Inserts without a cell monolayer were assessed as controls for bacterial crossing of the membrane alone. A two‐way repeated measures ANOVA with Bonferroni's post‐test was performed. Asterisks indicate comparison to wild‐type bacteria, plus signs indicate comparison to p66^cc bacteria. **/⁺⁺ P < 0.01, ***P < 0.001, n = 5.