FIG 3.

Assessment of wild-type and T2SS mutant L. pneumophila strains trafficking to lysosomes. A. castellanii amoebae were pulsed with fluorescent dextran red for 1 h and then infected with GFP-positive wild-type strain 130b (WT), lspF mutant NU275 (lspF), or dotA mutant NU428 (dotA). The infected amoebae were immediately imaged by confocal microscopy, and the percentage of intracellular bacteria colocalizing with dextran red-positive lysosomes was enumerated. Results presented show representative images on the left (green, bacteria; red, dextran red-containing lysosomes; scale bar, 1 μm) and the percentage of colocalization on the right. Quantified data are presented as means with standard errors from three independent experiments. The asterisk indicates a significant difference between results for the lspF mutant and those for the dotA mutant (Student's t test; *, P < 0.05), whereas the lspF mutant was not significantly (ns) different from the wild-type strain.