Figure 5.

CLSM acquired 3D image of W. chondrophila inclusions inside the swim bladder epithelium (A) after IF staining of Waddlia (red), mitochondria (green) and DAPI staining of host cell and bacterial DNA (blue). The image shows the formation of several bacteria containing vacuoles inside epithelial cells, accompanied by the recruitment and close association with host cell mitochondria. Close-ups of single inclusions with CLSM (B) and TEM (C) reveal typical features of the chlamydial life cycle, such as transformation from the smaller infectious EB with condensed DNA (arrow) to the larger and metabolically active RB form with finely distributed chromatin (arrow head), dividing inside the vacuole. TEM images show also the morphology of infected epithelial cells of the swim bladder (D) and endothelial cells of blood vessels (E), usually containing a single perinuclear inclusion (asterisks), strongly associated with host cell mitochondria. Scale bars (A) 2 μm, (B,C,E) 1 μm and (D) 5 μm.