FIGURE 3.

Model of internalization of A. fumigatus conidia by airway epithelial cells. Once conidia swell, β-glucan in the conidial cell wall is recognized by dectin-1, activating PLD-1 and PLD-2 (isoforms of phospholipase D) and promoting actin polymerization. Another, as yet uncharacterized signal results in the phosphorylation of cofilin-1, causing it to release actin. Conidia are then internalized through actin and microtubule polymerization and phagocytosis. Upon internalization, they are trafficked through the endosomal system where they are degraded and cleared from the host or alternatively, small numbers may persist, germinate and escape.