Figure 3. The vmp expression site is required for B. hermsii to relapse in mice following needle-inoculation.

RML mice were injected ip with 500 spirochetes of the wild-type (WT), Vmp⁻ mutant (Vmp⁻), or reconstituted (Vmp⁺R) strains. Mice 1–4 were sampled on days 1–14 and mice 5–8 sampled on days 2–14 post-infection and the numbers of spirochetes per ml of blood were determined by QPCR. Each plot represents the data from an individual mouse. The lack of a detectable relapse spirochetemia in the mice infected with the Vmp⁻ mutant compared to the WT and Vmp+R strains was statistically significant (Fisher’s Exact Test, P = 0.0001).