Increased growth of Mtb-LT strains in macrophages is linked to increased lipid droplet accumulation.

MH-S cells were infected in triplicate with Mtb-HT and Mtb-LT strains at an MOI of 10. A total of 10 Mtb-HT and 10 Mtb-LT strains were analyzed, and it included the three Mtb-HT and three Mtb-LT strains described previously. Two days post-infection, cells were fixed in 4% paraformaldehyde, following which they were incubated with HCS LipidTOX Red dye. Mean Fluorescence intensity (MFI) is represented for LipidTOX Red. The average data for each strain is presented as a dot and the cumulative data as interquartile range with median. The data are representative of 1 of 2 individual experiments. Unpaired t-test was used to calculate the significant differences between cells infected with Mtb-HT and Mtb-LT strains (**p<0.01) (A). MH-S cells were grown on coverslips, infected with either Mtb-HT1 or Mtb-LT1. 48 hours later cells were processed for confocal imaging. The data is a representative confocal imaging showing cell nuclei stained with DAPI (blue) and presence of neutral lipids detected through HCS LipidTOX Red dye (B). BMDMs were differentiated for 7 days in D-10 containing 20% L-cell. Cells were infected using 3 MOI of the indicated strains (5 replicate wells for each condition). Data presented are day 7 CFU with and without MPN (final concentration of 100nM) (C) and are representative of one of three individual experiments. Data is represented as mean +/- SEM and significant differences in intracellular bacterial growth were calculated using one way ANOVA (*p <0.05 and ****p <0.0001).