The P. aeruginosa ΔoprF mutant is attenuated in zebrafish embryos in a macrophage-dependent manner. (A) Diagram of 50 h post-fertilization (hpf) zebrafish embryo showing the caudal vein injection site (green arrow). (B) Survival curves of embryos infected with PAO1 wild-type stain or PAO1 ΔoprF mutant. Non infected embryos (NI) were used as control. Embryos were either treated with LipoPBS (left panel) or with LipoCld (right panel) to deplete macrophages. Approximately 3500 CFU P. aeruginosa were microinjected into the caudal vein (n = 50–70 for infected embryos and n = 30 for NI embryos, pool of three independent experiments). Results are expressed as the percentage of surviving embryos at different times post-infection. (C) Representative fluorescence images of embryos infected by either wild-type or ΔoprF P. aeruginosa (at 20 hpi) in the context of LipoPBS or LipoCld treatment. The efficiency of macrophages depletion is shown in the upper panels with the visualization of red macrophages. Scale bar 400 µm. (D) Quantification of bacterial loads (fluorescence pixel counts) from two independent experiments. Each symbol represents individual embryo (n = 18–20) and horizontal lines indicate the median values. Statistical significance was determined by log-rank test (B) or one-tailed Mann–Whitney’s test (D).
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