Figure 1

Deletion of the proQ gene attenuated the virulence of the APEC strain FY26 in vivo. A Western blotting analysis of ProQ expression in WT FY26, the mutant FY26ΔproQ, and the complemented strain FY26CproQ. OmpA and CRP served as reference proteins for this analysis. B Mortality rates of WT FY26, FY26ΔproQ, and FY26CproQ in a chicken colibacillosis model, with survival rates determined at 7 dpi. A two-way ANOVA was used to ascertain the statistical significance (*P < 0.01). C In vivo impact of proQ gene deletion on APEC colonization. A systemic infection experiment was performed in a chicken model to assess APEC proliferation in chicken lungs, liver, and spleen at 24 hpi. In addition, the proliferation of WT FY26, FY26ΔproQ, and FY26CproQ in chicken blood samples was observed. Statistical significance was determined using the nonparametric Mann‒Whitney U test. D Histological examination of chicken lungs following intratracheal infection with WT FY26, FY26ΔproQ, or FY26CproQ was performed. Lungs, retrieved at 24 hpi, underwent HE staining and were visualized under a light microscope to identify pathological changes. Illustrated lung lesions: a WT FY26, b FY26ΔproQ, and c FY26CproQ. Control: d PBS-inoculated chicken lung.