FIG 4 .

HtrA-overexpressing strain A3HtrAOE displayed a motility defect in comparison to WT B31A3, as demonstrated by plate swarm assay. The abilities of B. burgdorferi B31A3 and A3HtrAOE to swarm were analyzed in plate assays consisting of semisolid BSK medium diluted 1:10 in 0.35% agarose. (A) Following incubation (7 days, 35°C, 2.5% CO₂), swarm diameters in individual plates for WT B31A3 (n = 12) and A3HtrAOE (n = 18) were measured and compared. Statistically relevant differences between the medians were determined by use of the Mann-Whitney test for nonparametric data where P is ≤0.0001. The error bars represent the standard deviations. (B) Images from representative experiments showing wild-type B31A3, A3HtrAOE, and ΔflaB strains as well as a no-inoculum control are shown.