Fig 7.

41F5 inhibits the growth of intramacrophage yeast. Macrophages were infected with OSU76 at an MOI of 2.5:1 (yeast cells to macrophages). After internalization (4 h postinfection), concentrations of 41F5 (from 0.07 μM to 20 μM) or equivalent solvent control (DMSO) (0.002% to 0.5%) were added. (A) 41F5 inhibition of growth of yeast cells in culture (absorbance at 595 nm) and intramacrophage yeast cells (RFP fluorescence) after 4 days. (B) Quantitation of 41F5-based protection of infected macrophages. Shown is the survival of P388D1-lacZ macrophages after 4 days of infection with treatment with 41F5 or equivalent DMSO. Macrophage survival (relative to that of uninfected macrophages) was quantified by measuring the remaining macrophage-expressed LacZ activity. Bars represent means ± standard deviations (n = 3). Data are representative of 3 independent experiments. Statistically significant macrophage protection determined by Student's t test is indicated by an asterisk (P < 0.05). (C) Visualization of intramacrophage yeast growth in the absence (DMSO only) or presence of 41F5 (2 μM or 5 μM) at 1 day or 3 days postinfection. Infected macrophages (DIC image) and Histoplasma yeast cells (blue) were visualized by microscopy after staining with the fluorescent fungal cell wall stain Uvitex 3BSA. Representative images are shown.