Lipid Raft Aggregation in Epithelial Cells and Mtb Figure 2. Mtb strains induce time- and dose–dependent increase in LR aggregation. A549 type II alveolar epithelial cells were infected at three MOI’s, 1 (Fig. S1 A), 10 (A) and 100 (Fig. S1 B) and specimens prepared for confocal microscopy as described. A549 cells treated with Listeriolysin-O (LLO) as positive controls were assessed 15 and 30 min post treatment (data not shown) Images show that infections with strain CDC1551, HN878 and H37Rv produce substantial LR aggregation at 6 hpi (data not shown) and 24 hpi (A). Quantification of microscopic images at 6 PLOS ONE | www.plosone.org 4 September 2012 | Volume 7 | Issue 9 | e45028