Fig 6.
Loss of PilU increases serum resistance. (A) Survival of the wild-type strain (WT), the ΔpilU mutant, the ΔpilU_C mutant, the ΔpilT mutant, the ΔpilT ΔpilU double mutant, and the ΔpilT ΔpilU_C mutant after 60 min of incubation in 35% NHS. Bacterial survival is expressed as the percentage of CFU remaining from the initial inoculum of 107 CFU in 1 ml of medium, which was set to 100%. Error bars show standard deviations. Statistically significant differences from the wild type are indicated with asterisks (P < 0.001; Tukey's range test). (B) Measurement of capsular polysaccharide by ELISA. A capsule-negative mutant (SiaD−) was used as the negative control. Purified capsule (P.C.) was used as the positive control.