Fig. 1.

BrdU incorporation assay demonstrates persistent parasite replication in situ. (A) Labeling of log-phase promastigotes with BrdU. (B) Parasite density and extent of BrdU labeling of log-phase promastigotes cultured for 24 h in the presence of BrdU. Dark-shaded diamonds, parasite number; light-shaded squares, percent BrdU⁺. (C) The effect of increasing the number of BrdU doses (simultaneous local and systematic injection) on the percent BrdU⁺ parasites during acute mouse footpad infections where parasites are growing logarithmically. n = 3 mice; >1,000 total parasites. (D) Confocal microscopic analysis of BrdU incorporation of footpad PIPs. (E) Comparison of the percent BrdU⁺ intracellular parasites in AIPS versus PIPs. Data points, mean percent BrdU labeling for individual mice. Horizontal bars, mean for all mice. (F) Analysis of the BrdU-labeling intensity of parasite nuclei. n = 20 parasites per category. Graph shows mean ± SEM; *P < 0.05; n.s., not significant by Student’s t test or ANOVA. Arrowheads, BrdU-labeled nuclei; arrows, BrdU-labeled kinetoplast (mitochondrial) DNA. (Scale bar, 5 µM.)