Live bioluminescence imaging of Swiss Webster mice infected with increasing doses of TcCOL-Nluc parasites during the acute phase.

(A) Image of a 96-well plate containing 100 μl of 2-fold serial dilutions of TcCOL-NLuc trypomastigotes. After addition of the Nano-Glo^® Luciferase Assay, the plate was transferred to the IVIS 200 system camera chamber and imaged with an exposure time of 30 seconds and medium binning. (B) Linear regression plot generated using luminescence values (total flux expressed as photons/second) recorded for each well. Data represent means ± s. d. of three replicate wells. The dotted line indicates the background luminescence of the control wells. (C) Ventral view images of mice infected with increasing numbers of TcCOL-Nluc tissue culture-derived trypomastigotes (10 to 10⁴ parasites per dose) taken at 7, 14, 21 and 28 dpi. (D) Bioluminescence signal (total flux) measured over time for each animal in the regions of interest indicated by red rectangles in A, and expressed as total flux (photons/sec). Grey lines indicate the detection threshold determined as the mean (solid line) and mean ±2 s.d. (dashed lines) of background luminescence of the control uninfected mouse. (E) Blood parasitemia (trypomastigotes/ml) quantified by microscopy at the indicated times post-infection. Grey dotted line represents the limit of detection (1.58 x10⁴ parasites/ml blood). Log ₁₀ heat-map scales represent bioluminescence intensity (blue: low; red: high). NI: non-infected mouse.