Figure 4.

Figure 4. Salmonella hindbrain ventricle (HBV) infection induces hyper-accumulation of macrophages harboring persistent bacteria at late time point of infection.

(A) Tg(mfap4:mCherry-F) larvae were injected with either PBS or Sal-GFP-int in HBV. Representative maximum projections of fluorescent confocal images, showing accumulation of macrophages (red) that co-localize with persistent Salmonella (green) at 4 dpi. Scale bar: 50 μm. (B) 3D reconstruction of persistent Salmonella residing inside a macrophage at 4 dpi. Scale bar: 5 μm. (C) Tg(mpx:GFP) larvae injected with either PBS or Sal-DsRed in HBV. Representative maximum projections of fluorescent confocal images showing that Salmonella (red) do not co-localize with neutrophils (green) at 4 dpi. Scale bar: 50 μm. (D) 3D reconstruction of neutrophils and persistent Salmonella at 4 dpi. Scale bar: 30 μm. (E–G) Tg(mfap4:mCherry-F/mpx:GFP) larvae were injected with either PBS or Sal-E2Crimson in HBV. (E) Representative maximum projections of fluorescent confocal images showing macrophage clusters (red), persistent Salmonella (magenta) and neutrophils (green) at 4 dpi. Scale bar: 50 μm. (F) Quantification of the total volume of recruited cells (mfap4⁺ or mpx⁺ cells) at 4 dpi. Data of three replicates pooled (mean volume/larva ± SEM, n_Sal = 20, n_PBS = 8, Mann–Whitney test, two-tailed, *p < 0.05, ****p < 0.0001). (G) 3D reconstruction of the HBV (middle panel) showing macrophage clusters (red) in which Salmonella (gray) persist, surrounded by neutrophils (green) at 4 dpi. Right and left panels are zooms of regions boxed by dotted lines. Scale bar: 30 μm. Scale bar zooms: 10 μm.