Fig. 2

Kinetics of host-adapted Borrelia spp. in the blood of immunodeficient NOD-SCID mice over a course of 17 days. Mice were injected intradermally with cultured 1.0 × 10⁵Bp (a) or 1.0 × 10⁶Bbss (b) per animal. aBp was detectable on day 1 pi, with an increasing hematogenous spirochete burden over time. On day 12 pi, an average of 5.6 ± 1.2 × 10⁶ cells were detected per ml blood among six NOD-SCID mice. In five additional NOD-SCID mice, 7.2 × 10⁶Bp/ml blood was detected on day 12 pi. b The first Bbss in blood were detectable on day 2 (8.5 ± 1.4 × 10³ cells/ml), and concentrations climaxed at 4.9 ± 3.3 × 10⁴ cells/ml blood on day 7, plateauing at ~ 3.0 × 10⁴ until day 17 pi. On day 10 pi, the average borrelial load was 3.9 ± 1.3 × 10⁴ organisms per ml blood among six NOD-SCID mice. In two additional groups of five NOD-SCID mice, 3.5 × 10⁴ and 2.8 × 10⁴Bbss/ml blood were detected on day 10 pi