Effects of thymectomy and bursectomy on the systemic lesions of experimental Mycoplasma synoviae infection of the chicken

Abstract

The development of the systemic lesions of Mycoplasma synoviae infection was examined histo- and immuno-pathologically 2 and 4 weeks after the intraarticular inoculation of strain WVU 1853 in previously thymectomized or bursectomized and concomitantly X-irradiated (STx-X and SBx-X, respectively) chickens. The articular lesions in STx-X chickens showed chronic inflammatory changes 2 weeks after inoculation. In addition, in STx-X chickens, granular IgG deposition was detected at the sites of generalized vasculitis and glomerulonephritis by the fluorescent antibody technique. The bursa of Fabricius was atrophic and hyperplasia of plasma cells was observed in the thymus-dependent areas and red pulp of the spleen. The SBx-X chickens, on the other hand, showed acute inflammatory changes in articular tissues and no vasculitis or glomerulonephritis. These results suggest that M. synoviae infection in chickens could lead to an immune complex disease by impairment of the immune mechanism, presumably initiated by thymic dysfunction.