FIG 3.

Inflammatory cytokine expression levels in HD-11 cells infected with R. anatipestifer strains. HD-11 cells were separately infected with Yb2, Yb2Δ02955, and cYb2Δ02955 strains. IL-1β (A), IL-6 (B), IL-8 (C), and TNF-α (D) transcription levels were significantly decreased in HD-11 cells infected with the Yb2Δ02955 mutant strain compared with the wild-type strain Yb2 at 3, 6, and 9 hpi. Statistical significance was assessed using two-way analysis of variance *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, P > 0.05.