TABLE 1.

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

Inoculum and doseNo. of biopsies positive/total no. of ear biopsies conducted at postinoculation weekb:No. of cultures positive/total no. of specimens examinedNo. of mice infected/total no. of mice inoculatedID50 (no. of organisms)
23456HeartJointSkinAll sites
Expt I
    13A/E22/C18
        1053/3NDNDNDND3/33/33/39/93/3
        1043/3NDNDNDND3/33/33/39/93/3
        1033/3NDNDNDND3/33/33/39/93/3
        1022/33/3NDNDND3/33/33/39/93/3
        1010/31/31/31/31/31/31/31/33/91/3
    13A/E22/D32
        1053/3NDNDNDND3/33/33/39/93/3
        1043/3NDNDNDND3/33/33/39/93/3
        1033/3NDNDNDND3/33/33/39/93/3
        1021/33/3NDNDND3/33/33/39/93/3
        1010/30/30/30/30/30/30/30/30/90/3
    13A/dbpA′/A3
        1050/32/33/3NDND3/33/33/39/93/3
        1040/33/3NDNDND3/33/33/39/93/3
        1030/31/33/3NDND3/33/33/39/93/3
        1020/30/32/33/3ND3/33/33/39/93/3
        1010/30/31/33/3ND3/32/33/38/93/3
    13A/dbpA′/B6
        1050/32/33/3NDND3/33/33/39/93/3
        1040/31/32/33/3ND3/33/33/39/93/3
        1030/32/33/3NDND3/33/33/39/93/3
        1020/30/32/33/3ND3/33/33/38/93/3
        1010/30/30/32/32/32/33/32/36/92/3
Expt II
    13A/E22/C32
        102NDNDNDNDND3/33/33/39/93/3
        101NDNDNDNDND0/30/30/30/90/3
    13A/E22/D18
        102NDNDNDNDND3/33/33/39/93/3
        101NDNDNDNDND1/31/31/33/91/3
    13A/dbpA′/A3
        102NDNDNDNDND3/32/33/38/93/3
        101NDNDNDNDND3/33/33/39/93/3
    13A/dbpA′/B6
        102NDNDNDNDND3/33/33/39/93/3
        101NDNDNDNDND2/32/32/36/92/3
  • 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 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).

  • b ND, not determined.