Intracellular localization of the E. coli clones carrying vtaA8 and vtaA9 from H. parasuis within the endosomal network of PAM at different times post-infection (30 min and 1 h). E. coli (pACYC184 pEGFP) (Control, first column) and the clones with vtaA8 (pMCH-vtaA8 pEGFP; vtaA8, second column) or vtaA9 (pMCH-vtaA9 pEGFP; vtaA9, third column) were expressing GFP (green signal). Nuclei were counterstained with DAPI (blue signal). Upper panels show the co-localization (arrows) between control, vtaA8 or vtaA9 and the early endosomal marker EEA1 (red signal). Lower panels show the co-localization (arrows) between the control, vtaA8 or vtaA9 and the acidic lysosomes stained with LysoTracker Red DND-99 (red signal). Percentages of co-localization are indicated in each panel. Scale bars, 5 μm. Individual images for each fluorescence are presented in the Additional file 2: Figure S2A and Figure S2B.