Characterization of bioluminescent <i>Leptospira</i> transformants.

<p>(A) Growth curves of <i>L. interrogans</i> Manilae wild-type and MFlum1 strains in EMJH medium at 28°C (Left Y axis) and corresponding bioluminescence of MFlum1 (Right Y axis). (B) Comparison of bioluminescence according to known numbers of MFlum1, grown to mid-log phase or to old stationary phase (four months). Measures were done with the IVIS Spectrum machine after addition of D-luciferin, in the presence or absence of ATP. Panels A and B are representative of 6 and 2 experiments, respectively. (C) Live imaging tracking over time of 2×10⁸ MFlum1 or bioluminescent <i>L. biflexa</i> Patoc PFlum7 injected intra-peritoneally (IP) into albino C57BL/6J mice (Left Y axis) and corresponding weight losses (Right Y axis) of MFlum1 infected mice. All bioluminescence analyses were carried out after the IP administration of D-luciferin. Data are expressed as the mean ± SEM of average radiance of light measured in photons/second/cm² in mice and imaged in the ventral view. This panel represents 3 experiments with a total of n = 12 mice infected with MFlum1, n = 4 mice infected with PFlum7, and n = 8 naïve mice. <i>p</i> values (*<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001) between infected and uninfected group. The cross indicates that the mice died or were sacrificed because of acute leptospirosis. Below are shown images of the tracking of one mouse photographed at different time post infection. (D) Live imaging tracking over time of 50 µl of blood collected from the 2×10⁸ MFlum1 infected mice at different time points from the experiment shown in panel 1C (Left Y axis) and corresponding number of leptospires measured by q-PCR (Right Y axis). Data are expressed as the mean ± SEM of average radiance of light measured in photons/second/cm² in 50 µL of blood. <i>p</i> values (*<i>p</i><0.05), between groups. This panel represents 2 experiments with a total of n = 6 mice. Below are shown the corresponding images at different dpi in the presence or the absence of ATP. Below D0 are shown images of the MFLum1 in PBS imaged just before IP injection.