Increasing DbpA expression severely impairs dissemination and significantly reduces ID50 of B. burgdorferi in immunocompetent micea

Inoculum and doseNo. of biopsies positive/total no. of ear biopsies conducted at postinoculation week:No. of cultures positive/total no. of specimens examinedNo. of mice infected/total no. of mice inoculatedID50 (no. of organisms)
23456HeartJointSkinAll sites
Expt I
Expt II
  • a The 13A/E22/C, 13A/E22/D, 13A/dbpA′/A, and 13A/dbpA′/B spirochetes were grown to late log phase (108 cells per ml) and 10-fold serially diluted with BSK-H medium. Groups of three BALB/c mice each received a single intradermal/subcutaneous dose of 100 μl of bacterial suspension; ear biopsies were performed up to 6 weeks post-inoculation, starting at week 2. Once all three animals of a dose group became positive, biopsies were no longer performed on the group. All animals were sacrificed immediately after the last biopsy; heart, tibiotarsal joint, and skin specimens were harvested for bacterial isolation. Experiment II was designed to assess ID50 values only, so a biopsy was not conducted. The ID50 values were calculated by the method of Reed and Muench (35).

  • b ND, not determined.