الفهرس 
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Abstract
Comprehensive studies were carried out to investigate a pathological and
ultrastructural studies of rabbits experimentally infected with RHDV. Moreover
to study the pathogenesis of the disease through studying the early stages of
RHDV infection parallel with viral detection in the different cells of different
infected organs. Different organs of experimentaly infected rabbits were
examined histopathologicaly and liver and lungs were examined for the presence
of the virus by Electron microscopy examination and correlation of the presence
of the virus with the histopathological observations. A total of 135 rabbits were
lm. inoculated by 1 ml. of liver suspeusion of estimated LDso and tissue samples
were taken from the liver, lung, kidney, spleen and thymus at different intervals
post-inoculation (2, 4, 6, 12, 18, 24, 30, 36, 48, 60 and 72 hours and 4, 5, 6, 8, 10,
12 and 14 days, 18 groups). Histopathological observations revealed that the
liver was the first organ to be injured, that the liver was the first organ to be
injured, exhibiting a severe hepatitis started 24 h pi and electron microscopy
studies revealed electron dense viral particles in both hepatic and Kupffer cells
in the liver and phagocytic cells in the lung at 24 h pi. and still present until 12 d
pi. The main pathological changes were severe generalized circulatory
dysfunction, hyperaemia, congestion and haemorrhages, marked degeneration of
parenchymatous tissues, prononnced haemorrhagic pneumonia and extensive
distuption of lymphoid tissues. The main hepatic lesions were coagulative
necrosis, parenchymal and portal haemorrhages and a constant features were
enlarged pale, tan, yellow brown or cooked like liver. Haemorrhages in different
organs, especially in lung and kidneys were constant and characteristics. Deaths
could be attributed to the general circulatory disorders, severe necrotic hepatitis
and extensive pulmonary haemorrhages.