FIGURE 6.

Escaping A. fumigatus germlings are surrounded by a non-acidic phagosomal compartment. Alveolar monolayers were challenged with A. fumigatus (green) for 18 h at 37°C, 5% CO₂. Following incubation times, cells were stained with Cell Mask Deep Red (magenta) and LysoTracker (red). (A) Time lapse (min) of an internalised spore surrounded by an acidic phagosome. (B) LysoTracker channel shown in A. Arrowheads highlight the site of lysosome fusion with the phagosome. (C) Acidification rate of spores internalised by either alveolar or bronchial cells. r.a.u estates for relative abundance units. (D) Time-lapse quantification of the percentage of germlings surrounded by acidified and non-acidified phagosomes. (E) Merged images of an internalised young germling. The arrow highlights the acidic compartment that surrounds A. fumigatus. The arrowhead highlights the fusion site of the acidic compartments. (F) Merged images of an internalised mature germling. The asterisk highlights the initial interaction between the mature germling tip and the protrusion of the host plasma membrane. Note there is no fusion of acidic compartments surrounding A. fumigatus. (G) Relative fluorescence of LysoTracker in internalised spores and germlings. Measurements were performed three times on three biological samples (average ± standard deviation [SD]) (**P < 0.01 and ****P < 0.0001). Scale bars: 5 μm.