Ultrastructural Pathologic Observation on the Gut-Associated Lymphoid Tissues of Sacculus Rotundus of Rabbits Infected with Rabbit Haemorrhagic Disease Virus

Ultrastructural pathological changes in the gut-associated lymphoid tissues of sacculus rotundus (SR) of rabbits infected with rabbit haemorrhagic disease virus (RHDV) were first observed. There were numerous holes at the luminal and basement membrane surfaces of the dome epithelium (DE), consistently accompanied by necrosis of lymphocytes and M-cells, and pronounced depletion of lymphocytes in the domes and follicles, decrease of DE complex with formation of pseudomembranous structure on the surface of the dome epithelium. A specific finding in lymphocytes and macrophages was that severe destruction detraction of the membrane of rough endoplasmic reticulum(RER) was accompanied by conspicious increase of solitary, ribo-some-like particles in the cytoplasm, with appearances of intranuclear particles and intranuclear inclusions. It was found that there were many round and dense virion-like particles, with 26 nm in diameter, in the nuclei and cytoplasm of lymphoctes, plasma cells, macrophages and fibroblasts, or in degenerated cells and cellular debris. At the same time, another round virion-like particles about 34 nm in diameter were also seen in the cytoplasm of some cells and interstitium. The results indicated that the appearances of the ribosome-like particles, virion-like particles and inclusion bodies were related to the replication and assembly of RHDV. The present observations suggested that DE of sacculus rotundus could be a open pathway and a transporting route for the entry of antigens into hosts. While the antigen is profoundly deleterious, DE may be as a closed portal or a barrier preventing the foreign antigenic materials from invading.

Histopathology and Ultrastructural Pathology of Cyprinid Herpesvirus Ⅱ(CyHV-2) Infection in Gibel Carp, Carassius auratus gibelio

Cyprinid herpesvirus II （CyHV-2） infection is identi- fied in cultured gibel carp, Carassius auratus gibelio, with high mortality in China in recent years. Histological pathology includes acute hepatocellular necrosis, splenic necrosis, kidney necrosis, hyperplasia of the secondary lamellae with focal necrosis. Acute necrotic myocarditis and granulocytes are prominent within the cardiac lumen in infected fish. In addition, necrosis is observed in the submucosa and mucosa epithelium of intestinal tract. Edemas are observed in renal glomerulus, submucosa and mucosa epithe- lium of intestinal tract, myocardial cells and neurons. Transmis- sion electron microscopy indicates the cytoplasmic inclusions in splenocytes, glomerulus cells and hematopoietic tissue cells of kidney, epithelial cells of gills and brain cells. The histopathology and ultrastructural pathology in CyHV-2 infected gibel carp are characterized with extensive necrosis and cytoplasmic inclusions in spleen, kidney, gill and brain, which suggests that CyHV-2 may mainly infect the spleen, kidney, gill and brain of fish.