绵羊肺炎支原体盘羊杂交羊感染模型的建立OA

To establish an infection model of Mycoplasma ovipneumoniae(MO)in argali crossbred sheep,strain MO-XJ15 isolated from lung tissues of diseased sheep was identified as a virulent strain via immunofluorescence assay and chicken embryo inoculation.The strain was serially passaged three times in lambs.Lesioned lung tissues from infected sheep were collected,homogenized and filtered to prepare tissue-derived virulent inoculum.The MO load in the inoculum was quantified by quantitative real-time PCR(qPCR).Twenty-four MO-susceptible argali crossbred sheep were randomly allocated into four groups(n=6 per group).Each animal received an intratracheal inoculation of 5 mL undiluted virulent inoculum,1:10 diluted inoculum,1:100 diluted inoculum,or phosphate-buffered saline(PBS),respectively.After inoculation,clinical signs were evaluated using a standardized scoring system,and thoracic fluoroscopy was conducted.All sheep were necropsied on day 29 post-infection.Gross pulmonary lesions were examined and scored with ImageJ software.Lung tissue samples were collected for hematoxylin-eosin(HE)staining and histopathological assessment.The MO load in the tissue-derived virulent inoculum was 1.8×105 copies/mL.Typical clinical manifestations and pathological lesions of ovine mycoplasmal pneumonia were observed in all sheep in the undiluted group and several animals in the 1:10 dilution group.In conclusion,intratracheal inoculation with tissue-derived virulent inoculum of strain MO-XJ5 containing MO at a load of≥1.8×105 copies/mL can successfully establish an ovine mycoplasmal pneumonia model in argali crossbred sheep.