TABLE 1.
Increasing DbpA expression severely impairs dissemination and significantly reduces ID50 of B. burgdorferi in SCID micea
| Inoculum and dose | No. of biopsies positive/total no. of ear biopsies conducted at postinoculation weekb:
|
No. of cultures positive/total no. of specimens examined
|
No. of mice infected/total no. of mice inoculated | ID50 (no. of organisms) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2 | 3 | 4 | 5 | 6 | Heart | Joint | Skin | All sites | |||
| Expt I | |||||||||||
| 13A/E22/C | 18 | ||||||||||
| 105 | 3/3 | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 104 | 3/3 | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 103 | 3/3 | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 102 | 2/3 | 3/3 | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 101 | 0/3 | 1/3 | 1/3 | 1/3 | 1/3 | 1/3 | 1/3 | 1/3 | 3/9 | 1/3 | |
| 13A/E22/D | 32 | ||||||||||
| 105 | 3/3 | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 104 | 3/3 | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 103 | 3/3 | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 102 | 1/3 | 3/3 | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 101 | 0/3 | 0/3 | 0/3 | 0/3 | 0/3 | 0/3 | 0/3 | 0/3 | 0/9 | 0/3 | |
| 13A/dbpA′/A | 3 | ||||||||||
| 105 | 0/3 | 2/3 | 3/3 | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 104 | 0/3 | 3/3 | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 103 | 0/3 | 1/3 | 3/3 | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 102 | 0/3 | 0/3 | 2/3 | 3/3 | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 101 | 0/3 | 0/3 | 1/3 | 3/3 | ND | 3/3 | 2/3 | 3/3 | 8/9 | 3/3 | |
| 13A/dbpA′/B | 6 | ||||||||||
| 105 | 0/3 | 2/3 | 3/3 | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 104 | 0/3 | 1/3 | 2/3 | 3/3 | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 103 | 0/3 | 2/3 | 3/3 | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 102 | 0/3 | 0/3 | 2/3 | 3/3 | ND | 3/3 | 3/3 | 3/3 | 8/9 | 3/3 | |
| 101 | 0/3 | 0/3 | 0/3 | 2/3 | 2/3 | 2/3 | 3/3 | 2/3 | 6/9 | 2/3 | |
| Expt II | |||||||||||
| 13A/E22/C | 32 | ||||||||||
| 102 | ND | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 101 | ND | ND | ND | ND | ND | 0/3 | 0/3 | 0/3 | 0/9 | 0/3 | |
| 13A/E22/D | 18 | ||||||||||
| 102 | ND | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 101 | ND | ND | ND | ND | ND | 1/3 | 1/3 | 1/3 | 3/9 | 1/3 | |
| 13A/dbpA′/A | 3 | ||||||||||
| 102 | ND | ND | ND | ND | ND | 3/3 | 2/3 | 3/3 | 8/9 | 3/3 | |
| 101 | ND | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 13A/dbpA′/B | 6 | ||||||||||
| 102 | ND | ND | ND | ND | ND | 3/3 | 3/3 | 3/3 | 9/9 | 3/3 | |
| 101 | ND | ND | ND | ND | ND | 2/3 | 2/3 | 2/3 | 6/9 | 2/3 | |
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 SCID mice each received a single intradermal/subcutaneous dose of 100 μl of bacterial suspension; ear biopsies were performed up to 6 weeks postinoculation, 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).
ND, not determined.