Fig 6.

RFP-expressing Histoplasma yeast cells replicate and traffic in macrophages similarly to wild-type cells. (A and B) Intramacrophage growth of Histoplasma yeast cells. Yeast growth was measured by quantitative plating of macrophage lysates for viable yeast CFU (A) or measurement of RFP fluorescence (B). P388D1 macrophages were infected with Histoplasma G217B or OSU76 yeast cells at an MOI of 0.5:1 (A) or 2.5:1 (B) (yeast cells to macrophages). At 2, 21, 46, and 69 h postinfection, macrophages were lysed, and yeast cells were recovered and plated onto solid medium to determine CFU (A). At 27, 48, 73, and 103 h postinfection, RFP fluorescence from macrophages infected with OSU76 yeast cells was determined (B). Data points represent means ± standard deviations of yeast CFU counts or fluorescence (n = 3 replicates). (C) Characterization of the intracellular Histoplasma-containing compartment. At 2 h postinfection, macrophages were fixed and stained. Infected macrophages were visualized by differential interference contrast (DIC) microscopy and fluorescent markers for yeasts (Uvitex), RFP, and lysosome-associated membrane protein 1 (LAMP-1). Representative images are shown.