Take a zebrafish larva injected with fungal spores in the hindbrain ventricle.
Macrophages are recruited to the site of injection, forming a tight cluster around the spores.
The spores undergo phagocytic engulfment by macrophages.
These spores have the ability to resist degradation inside the phagosome, allowing them to germinate into hyphae and induce necrotic cell death of the macrophage.
The hyphae possess exposed pathogen-associated molecular patterns, or PAMPs, on their surface.
Neutrophils recruited to the site of infection, recognize and bind PAMPs. Contact with neutrophils triggers a complex hyper-branching phenotype in hyphae, thereby hindering their engulfment by neutrophils and facilitating immune evasion.
Homogenize the larva, releasing the viable fungal spores and hyphae. Centrifuge to remove cellular debris and plate the supernatant on a growth medium.
Upon incubation, count the fungal colony-forming units or CFUs.
CFU counts represent the number of viable fungal spores that evaded the host immune defenses.
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