In vivo bioluminescence imaging of B. burgdorferi infection and inflammatory phagocytes: (a) Representative images of a control mouse and Bb-infected mice at day 1 followed by 1, 2, 3, 4, 5, 6 and 8 weeks after intradermal inoculation with B. burgdorferi strain ML23 pBBE22luc. Images were acquired following ip. injection of D-luciferin. (b) Geometrical mean of total flux (p/s) of mice after ip. injection of D-luciferin. In vivo imaging was performed on Bb-infected (n = 6–26/group) and control (n = 4–10/group) mice at day 1 followed by week 1, 2, 3, 4, 5, 6 and 8 after intradermal inoculation. All values are derived from ROI analysis of carpal and tarsal joints. Data are presented as mean ± SEM. (c) Quantitative representation of lucigenin bioluminescence from the ROI analysis of the carpal and tarsal joints after ip. injection of lucigenin (12.5 mg/kg) in Bb-infected (n = 18) and control (n = 6) mice on week 3 after inoculation. Data are presented as mean ± SEM. All images were acquired with a delay of 10 min post-injection (p.i.) of substrate before imaging was completed. The significance level is indicated by asterisks (*). p < 0.0001 (****).