Identification and pathogenic analysis of Mycoplasma synoviae isolated from a broiler farm in China

Mycoplasma synoviae (MS) is a pathogenic mycoplasma that infects poultry. In this study, MS strain YY (MS-YY) was isolated from a broiler farm. MS-YY was identified based on its colony morphology, biochemical characteristics, specific identification, infection route, and virulence. The experimental results demonstrated that pathogenic bacteria successfully infected SPF chickens, replicating the typical symptoms of MS. The colony morphology and biochemical characteristics of MS-YY were consistent with MS. The chicken erythrocyte agglutination test and erythrocyte adsorption test both yielded positive results. The metabolic inhibition test, growth inhibition test, and PCR identification collectively confirmed that MS-YY is indeed MS. In the infection route experiment, it was observed that although the dose used for inoculation via the paw pad route was relatively low, all inoculated chickens exhibited symptoms of MS infection, aligning with the results of the animal regression test. The virulence determination results indicated that the minimum morbidity dose concentration for 60-day-old chickens was 0.2 × 10⁴ CCU. In conclusion, a highly virulent strain of MS was successfully isolated, and a MS-YY infection model in SPF chickens was established. This study contributes to the development of a stable and standardized MS challenge model.