The transcription factor YbdO attenuates the pathogenicity of avian pathogenic Escherichia coli by regulating oxidative stress response.

Avian pathogenic Escherichia coli (APEC) is a significant pathogen infecting poultry that is responsible for high mortality, morbidity and severe economic losses to the poultry industry globally, posing a substantial risk to the health of poultry. APEC encounters reactive oxygen species (ROS) during the infection process and thus has evolved antioxidant defense mechanisms to protect against oxidative damage. The imbalance of ROS production and antioxidant defenses is known as oxidative stress, which results in oxidative damage to proteins, lipids and DNA, and even bacterial cell death. APEC uses transcription factors (TFs) to handle oxidative stress. While many TFs in E. coli have been well characterized, the mechanism of the YbdO TF on protecting against oxidative damage and regulating the virulence and pathogenicity of APEC has not been clarified. Here we focus on the regulatory mechanism of YbdO on the pathogenicity of APEC. The results from this study showed that YbdO attenuated the pathogenicity of APEC in chicks infection models by inhibiting the expression of virulence genes fepG and ycgV using quantitative real-time reverse transcription PCR (RT-qPCR) experiments. The electrophoretic mobility shift assays (EMSA) confirmed that YbdO specifically bound to the promoters of fepG and ycgV. Additionally, YbdO increases H