Figure 3
The progression and severity of L. donovani infection of mice is dependent upon the initial inoculum size. (A) Groups of three mice were infected intravenously with different doses of day-seven stationary-phase L. donovani promastigotes and infections were monitored over 20 weeks by in vivo imaging. To quantify the parasite load, the bioluminescence (total flux, photon/sec) associated with the liver (B) and spleen (C) was measured. Mice were infected with 0.10 × 108 (white circles), 0.25 × 108 (blue circles), 0.50 × 108 (red circles) or 1.00 × 108 (green circles) parasites, respectively. Liver-associated bioluminescence increased linearly during the initial 1–3 weeks, analysed using linear regression in GraFit and plotted as dashed lines. The progression of infection of the liver during the initial three weeks was also analysed using linear regression and increases in bioluminescence were found to be directly proportional to the parasite dose for weeks 1 (black circles), 2 (blue circles) and 3 (green circles), respectively (D). The parasites’ rapid localisation and clearance in the liver within first 24 h of infection were determined in mice challenged with 1 × 108 parasites (n = 5) (E). Liver bioluminescence was normalised using measurements at 1 hour post infection as control for 100%. Data points represent means ± S.E.M. (n = 3 for B, C and D) or (n = 5 for E).
