FIG 4.

Neutrophils respond to A. fumigatus hyphae and mediate host survival. (A and B) Immunocompetent larvae with fluorescent neutrophils [Tg(mpx:dendra2)] injected with A. fumigatus (gpdA::mCherry::his2A) and screened at 1 day postinfection (dpi) for the presence of hyphae. (A) Time lapse imaging reveals a persistent neutrophil response around A. fumigatus hyphae characterized by both tight colocalization with the mycelium and migration toward and adherence to hyphal filaments (gray arrow) by individual neutrophils (see also Movie S6 in the supplemental material). (B) Representative images from daily imaging of hypha-containing fish demonstrate host clearance of hyphae at 2 dpi. (C) Larvae expressing the inhibitory Rac2D57N mutation specifically in neutrophils [Tg(mpx:mCherry-2A-Rac2D57N)] are highly susceptible (P < 0.001) to A. fumigatus (gpdA::GFP::his2A) infection. Survival data were pooled from five independent experimental replicates, and the P value was calculated by Cox proportional-hazard regression analysis. Scale bar, 100 μm.