FIG 6 .

Peptide uptake is essential for viability, morphogenesis, and virulence within the mammalian host. (A) Dark-field microscopy (magnification, ×400) demonstrates cell morphology of the conditional NBD mutant compared with wild-type spirochetes in DMC chambers. (B) Silver stain of SDS-PAGE gel for the wild-type strain and the conditional NBD mutant (with and without IPTG) from DMC explants. (C) Immunoblotting of B. burgdorferi whole lysate using sera from mice with and without IPTG supplementation at 2 weeks after needle inoculation with the NBD mutant. An immunoblot of serum from a mouse two weeks after inoculation with wild-type spirochetes is shown alongside. Blots represent two independent experiments, each performed with two cohorts of 4 mice each (Exp 1, M1 to M4; Exp 2, M5 to M8). Molecular markers are shown for the gel and Western blot in kilodaltons.