FIG 3.

Candida filaments breach the tissue barrier, leading to death. At 4 dpf, AB and mpo:Rac2-D57N zebrafish were injected in the swim bladder with 4 nl of Caf2-dTom (A and B) (the data are the same as those used for Fig. 2A to E) or 10⁷ CFU/ml (C) and 3 × 10⁷ CFU/ml (D and E) of tet-T21-dTomato (tet-T21) or tet-UME6-dTomato (tet-UME6). The fish were immediately screened, and only fish with 15 to 30 (C) or 50 to 100 (D and E) yeast cells were selected. Fish were imaged by confocal microscopy every 24 h for 3 days. (A to C) Death is due to filament breaching of the epithelial barrier. (A and B) Diagrams representing the findings of the retrospective analysis of the burden status at 24 hpi of fish dead (A) or alive (B) at 48 hpi. (C) Average percentage of fish alive at 48 hpi from each infection level at 24 hpi. The regression line (red), the R² value, and the P value obtained by the Pearson correlation test are shown. Data from three independent experiments were pooled (the data are the same as those used for Fig. 2A to E). (D to F) Active filamentation is involved in breaching of the epithelial barrier. (D and E) Percentage of fish receiving a low infection dose (D) and a high infection dose (E) with barrier breach by filaments (high-plus-breach status) after 72 h of infection with tet-T21 and tet-UME6. Data from three independent experiments were pooled (for the low infection dose, n = 35 and 39 tet-T21 and tet-UME6 fish, respectively; for the high infection dose, n = 56 and 53 tet-T21 and tet-UME6 fish, respectively); the differences in the overall percentages were evaluated by Fisher's exact test (P = 0.0123 and P = 0.0002 in panels D and E, respectively). (F) The survival of fish injected with PVP, tet-T21, and tet-UME6 (50 to 100 yeast cells) over 72 h is represented (Kaplan-Meier test). Data from three independent experiments were pooled (n = 56, 56, and 53 for mock-infected fish and fish infected with tet-T21 and tet-UME6, respectively). *, P < 0.05; ***, P < 0.001.