Influence of Strain of Mycoplasma synoviae

SUMMARY Two strains of Mycoplasma synoviae (WVU 1853 and F10-2AS) were compared for their relative pathogenicity in terms of airsacculitis and synovitis. Both strains produced air-sac lesions after aerosol exposure of chickens vaccinated against Newcastle disease and infectious bronchitis; both produced synovitis when inoculated into the foot pad. The WVU 1853 strain was more likely to result in synovitis, whereas the F10-2AS strain was more apt to produce air-sac lesions.