Figure 2
Pathological evaluation of the duck brain and BBB after R. anatipestifer infection. Fourteen-day-old Cherry Valley ducks were intravenously injected with 2.5 × 108 CFU of R. anatipestifer Yb2, Yb2ΔsspA, or cYb2ΔsspA. Histopathological changes in the brain and changes in the BBB ultrastructure were examined by H&E staining and transmission electron microscopy, respectively, at the indicated time points after infection. A–H Brain samples from control ducks and Yb2-, Yb2ΔsspA-, or cYb2ΔsspA-infected ducks were stained with H&E 24 h (A–D) and 48 h (E to H) post-infection. Blue arrow, inflammatory cell infiltration; orange arrow, meningeal thickening; green arrow, microglial proliferation. I–L The ultrastructure of the impaired duckling BBB observed by transmission electron microscopy. I Normal duck brain control; J duck brain with Yb2 infection. The intercellular junctions (TJs) were altered, and the basement membrane (black arrow) was disrupted. K The brain of a Yb2ΔsspA-infected duck was similar to that of a normal control duck brain; the TJs were integrated, and the basement membrane was intact. L Duck brain with cYb2ΔsspA infection. The TJs were altered, and the basement membrane (black arrow) was disrupted.