Chicken Amyloid Arthropathy Caused by Mycoplasma Synoviae Infection in Japan

Chicken Amyloid Arthropathy Caused by Mycoplasma Synoviae Infection in Japan

Chicken amyloid A (AA) amyloidosis is a fatal disease in adult birds with chronic inflammatory disorders. In white chickens, AA amyloidoses are observed as vaccine-associated amyloidosis. Meanwhile, in colored chickens, AA amyloidoses are generally known as amyloid arthropathy. Chicken amyloid arthropathy is typically caused by infection with Enterococcus faecalis. Mycoplasma synoviae was rarely reported as a causative agent for amyloid arthropathy. In this study, 36 brown layers that showed severe leg joint swelling and remarkable growth delay were examined by using histopathology, immunohistochemistry, ultrastructural morphology, bacteriology, and molecular biology. Histologically, severe amyloid deposits were observed in the leg joint synovium, and mild to moderate amyloid deposits were observed in the liver and spleen. In the synovium, amyloid deposits were observed at the same site as the orange area observed on gross examination. On ultramicroscopy, amyloid fibrils density in the synovium was observed to be higher than that in the liver. Polymerase chain reaction test revealed an M. synoviae infection in lesions, but not E. faecalis. This is the first report of chicken amyloid arthropathy by single infection of M. synoviae in Asia.