S enteritidis strain cvcc3377

Jining Bairi chicken, a China local chicken breed with ability of disease and stress resistance, was used in the current study and provided by Shandong Bairi Chicken Breeding Co., Ltd. (Shandong, China). The S. Enteritidis strain (CVCC3377) used in the current study was purchased from the China Veterinary Culture Collection Center (Beijing, China). The animal trial was performed as described previously [82 (link)]. In brief, 168 two-day old SE negative Jining Bairi chickens with similar body weight (28.46 g–30.41 g) were randomly divided into two groups and raised in two separated isolators with the same condition. Each chicken in the inoculated group was orally inoculated with 0.3 ml 10⁹ colony-forming units (cfu)/ml SE inoculant, and each chicken in the control group inoculated with the same amount of sterile phosphate buffer saline (PBS). Twelve chickens from each of the inoculated group and control group were euthanized by cervical dislocation for sample collection at 1, 3, 7, 14, 21, 28, and 35 days post inoculation (dpi). The cecum samples were frozen in liquid nitrogen and stored at − 80 °C until further RNA isolation. All animal procedures were approved by Shandong Agricultural University Animal Care and Use Committee.

A total of 53 P. mirabilis isolates were used in this study. They were isolated from fox, raccoon, or mink farms in different cities of Shandong Province, China between October 2019 and November 2020 (Table 1). Detailed information on these P. mirabilis isolates is provided in Tables S1 and S2 in the Supplementary Materials. The standard Salmonella enterica serovar Enteritidis (S. Enteritidis) strain CVCC3377 was purchased from the China Veterinary Culture Collection Center (Beijing, China). All isolates were streaked on xylose lysine deoxycholate (XLD) agar plates at 37 °C for 16~24 h, and then colonies were inoculated in Luria–Bertani (LB) medium. Cultures were grown at 37 °C and 180 rpm to the stationary phase for subsequent experiments.