We euthanized all remaining birds and inspected them for gross pathologic lesions, collecting samples for histologic analysis (spleens, livers, kidneys, hearts, and bursa Fabricii) and qRT-PCR (spleens and kidneys from all; hearts, livers, bursa Fabricii, and cecal tonsils from a few).
The most consistent lesions were tubulonephrosis with occasional tubular epithelium necrosis; intraglomerular urolithiasis and multifocal interstitial lympho-histiocytic infiltration (Figure 7, panel A); vacuolic degeneration and disintegration of liver cells with signs of hepatitis (Figure 7, panel B); acute serous myocarditis; and depletion of lymphocytes with scattered lymphocyte necrosis in the lymphoid organs (spleen, bursa Fabricii, and thymus) (Figure 7, panels C and D).
D) Bursa Fabricii, showing atrophy of bursal follicles with marked lymphoid depletion in the medullary region (arrow).