2.8 Challenge experiment with A. pleuropneumoniaeserotype 7
The A. pleuropneumoniae serotype 7 strain used in this study was provided by Tecon Biology Co., Ltd and was cultured in BHI medium supplemented with 10 mg/L β -nicotinamide adenine dinucleotide at 37 °C.[26] For the challenge experiment, forty mice were divided into four groups: Three experimental groups were immunized with 20 μg purified Oml1, Oml7, or ApxII, respectively. The control group was immunized with PBS. After 14 days of immunization, all mice were intraperitoneally injected with 0.5 mL of A. pleuropneumoniae serotype 7 (6×108 CFU). The survival of mice was counted in the following 7 days.