Fig. 5

Intracellular burden of Mtb lacking PDIM is severely reduced in human lymphatic endothelial cells. a Representative images of human lymphatic endothelial cells infected with Mtb WT, Mtb ΔPDIM or Mtb ΔPDIM::PDIM at each time point. In addition, Mtb ΔPDIM was infected at 10 times the usual MOI to overcompensate for the reduced phagocytic uptake of this strain. b The phagocytic uptake for each strain was measured using ImageJ by plotting the total GFP signal (called the RAWIntDen) per cell at 5 + 2 hpi. At least six fields of view were analysed per replicate with three independent replicates performed. The overall average GFP per cell is shown with error bars representing the standard error of the mean. Differences between the mean for each strain were tested using one-way ANOVA with Tukey’s post-test. c The GFP per cell was measured in the same way as described in (b) except each time point for each strain is compared (i.e. for bacterial replication). GFP green fluorescent protein, hpi hours post-infection, MOI multiplicity of infection, Mtb Mycobacterium tuberculosis, ns not significant, PDIM phthiocerol dimycocerosate, WT wild type, *** p < 0.001, * p < 0.05