Assessment of the pathogenicity of Mycoplasma gallisepticum and the immunogenicity of its membrane proteins in geese

Introduction Mycoplasma gallisepticum (MG) imposes heavy losses on the goose industry in China, yet its goose-specific biology is poorly understood. In elucidation of the biology, the pathogenicity and immunogenicity of MG in geese were analysed. Material and Methods Goslings were divided into three groups and either infected with the goose isolate MG-GD01/22, infected with chicken-derived MG R(low) or left untreated as controls. Clinical scores were recorded, and morbidity/mortality, air-sac lesions and tracheal and lung histopathology evaluated. Isolate membrane proteins were separated by SDS-PAGE and screened by Western blot with goose hyper-immune sera. Results Both MG-GD01/22 and MG R(low) established infection, with morbidity rates of 90% and 80% and qPCR positivity of 100% and 80%, respectively. The MG-GD01/22 isolate caused 20% mortality and more severe respiratory signs, whereas MG R(low) induced milder disease without deaths. Both strains produced airsacculitis and interstitial pneumonia, but MG-GD01/22 caused more marked pulmonary haemorrhage. Gel electrophoresis showed similar bands at 50–130 kDa with differences at 25–50 kDa. Western blot revealed strong immune responses to conserved 75 kDa and 67 kDa proteins, particularly those of MG-GD01/22. Conclusion Both strains are pathogenic in geese, with MG-GD01/22 exhibiting higher virulence. The conserved 75 kDa and 67 kDa proteins represent promising targets for the development of diagnostic assays and vaccines against Mycoplasma gallisepticum infection in geese.