Fig. 1

Spirochete loads in unfed and fed nymphs infected with WT and A3/flaB _p::ospC. Nymphs artificially infected as larvae with WT B. burgdorferi or spirochetes engineered to constitutively produce OspC (A3/flaB _p::ospC), were homogenized and plated a before and b after feeding on naïve mice to determine spirochete loads in ticks. The mean number of spirochetes (± SD) was similar between groups (P > 0.05, Student’s t-test, unpaired, 2-tailed) and increased approximately 10-fold when nymphs fed