The LmjF-LUC-SAT and LmjF-PHLEO strains show comparable virulence in infections of resistant mice.

<p>C57BL/6 mice (5 per group) were infected with 10⁵ metacyclic stage LmjF-LUC-SAT or LmjF-PHLEO <i>L</i>. <i>major</i>. (A) Measurements of lesion pathology (increase in footpad thickness). Error bars show the standard deviation. (B) Persistent parasites numbers were determined by limiting dilution assay from footpad tissue 130 days post infection. Horizontal bars show the geometric mean. †, <i>P</i> > 0.05.</p

Mice persistently infected with LmjF-LUC-SAT show protection from disease pathology by secondary challenge with LmjF-PHLEO parasites.

<p>Mice (4-5/group) were inoculated with 10⁵ metacyclic LmjF-LUC-SAT parasites in the left hind footpad (primary site), after which they developed lesions and then went on to heal (similar to that shown in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004811#pntd.0004811.g001" target="_blank">Fig 1A</a>). (A) At least one month after resolution of the primary lesions, each mouse was inoculated in the right hind footpad (secondary site) with 10⁵ metacyclic LmjF-PHLEO parasites, and lesion progression is shown in the figure. The dashed line represents the average of the data presented in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004811#pntd.0004811.g001" target="_blank">Fig 1A</a> for infections of naïve mice with LmjF LUC-SAT and LmjF-PHLEO for comparison. In these experiments “time 0” is when the secondary inoculation was performed unless otherwise indicated. For all plots, error bars show the standard deviation (n = 4 or 5 in expt. 1 or 2 respectively). (B) Footpad thickness at the primary injection site (left foot). (C) Monitoring of reactivation of the primary LmjF-LUC-SAT parasites at the primary (♦,■) or secondary (◊,□) infection sites site by bioluminescent imaging of luciferase expression <i>in vivo</i>; experiment 1 (♦,◊); experiment 2 (■,□). The gray circle (upper right) shows the luminescence profile of LmjF-LUC-SAT parasites infecting naïve mice at the peak of infection, included for comparison only. Error bars depict the standard deviation.</p

Retention of both primary and secondary infecting parasites following secondary challenge despite protection from disease pathology.

<p>The graph plots the number of persistent parasites present in sites of primary and secondary <i>Leishmania</i> infections >10 weeks post secondary challenge as assessed by limiting dilution analysis in unselective (white bar), nourseothricin-containing (gray bars; resistance mediated by <i>SAT</i> marker) or phleomycin-containing (black bars; resistance mediated by <i>PHLEO</i> marker) as described in the methods. The number of parasites in the primary infection site (LmjF-LUC-SAT inocula) is displayed in the top graph, and the number of parasites in secondary infection site (LmjF-PHLEO inocula) foot is displayed in the bottom graph. The numbers between the two graphs represent the mouse identification number (experiment number-mouse number). “Avg.” represents the mean for all mice.</p