FIG 2 .

M. tuberculosis proliferation within microspheres is intracellular (A, B). PBMCs were infected with luminescent M. tuberculosis and incorporated into microspheres. Cells were released by decapsulation, and extracellular and cell-associated bacteria were separated by differential centrifugation. Open bars; extracellular mycobacteria; checkered bars; cell-associated mycobacteria. Mycobacterial location determined by luminescence and colony counting on 7H11 agar demonstrated that bacterial proliferation was principally cell associated (C). PBMCs were infected with GFP-expressing M. tuberculosis and incorporated into microspheres. Microspheres were decapsulated, and M. tuberculosis localization was analyzed by flow cytometry (i) Uninfected cells. GFP-expressing M. tuberculosis cells at time zero (ii), day 1 (iii), day 4 (iv), day 7 (v), and day 15 (vi) show progressive intracellular proliferation. Data are from a representative experiment performed on two occasions in triplicate (D). M. tuberculosis infection does not reduce cell viability within microspheres. Cellular survival was measured by the CellTiter-Glo 3D Cell Viability Assay. Data are the mean ± the standard error of the mean of an experiment performed in triplicate on two occasions. *, P < 0.05; ***, P < 0.001; ****, P < 0.0001.