Study On The Relationship Between Pathological Changes Of Main Organs Of SPF Chicks Infected With REV And The Viral Load

Reticuloendotheliosis(RE)is a serious immunosuppressive neoplastic disease that is ubiquitous in poultry populations today.Widespread epidemics of this disease results in the severe economic losses in poultry farming.At present,the research of it is limited,especially the research on the immunosuppressive mechanism is not comprehensive and systematic.In this study,120 1-day-old SPF chicks were randomly divided into two groups,REV-infected group(group I)and control group(group C).As for the chicks infected with REV,102 TCID50 REV dilution was infected intraperitoneally at age of 1 day,and the control chicks were given the same amount of sterile PBS by the same way.The chicks were strictly isolated and managed separately.On the 1st,3rd,7th,14 th,21st,28 th,35th and 42 th day after the infection,6 chicks were randomly selected from each group.The chicks were sacrificed by drawing-out all the blood in their hearts,the immune organs such as spleen,thymus,bursa,Hader’s gland,cecal tonsil,and non-immune organs such as heart,liver,lung and kidney were quickly taken.The viral load in the main organ tissues,histopathological and ultrastructural pathological changes were systematically studied by using molecular biology and transmission electron microscopy combined with traditional pathological methods.The main results of the study are as follows:(1)The virus can be detected in different organs of 1-day-old SPF chicks infected with REV,and the viral load in the spleen is the highest.The viral load in the thymus and spleen peaked on the 14 th day after infection,and in the bursa of Fabricius peaked on the 7th day;the viral load in the liver and kidney both peaked on the 14 th day after infection,and in the heart and lung reached a peak on the 3rd and 7th day respectively;(2)Different degrees of pathological damaged to the main organs of 1-day-old SPF chicks infected with REV,including hyperemia,hemorrhage,lymphocytic infiltration,reticuloendothelial cell proliferation,cell degeneration,necrosis or apoptosis,etc.Severe thymus,bursa,spleen,liver,kidney,followed by heart and lungs.Histopathological changes mainly include immune organs,thymus corpuscles and bursal follicle atrophy,cell degeneration,focal necrosis in the red medulla of the spleen;myocardial cell granular degeneration,hepatic steatosis,pulmonary interstitial pneumonia,glomerular atrophy,tubular epithelial cells swelling and luminal occlusion;(3)The ultrastructural changes of the main organs of 1-day-old SPF chicks infected with REV were significant,which showed nucleus malformation,pyknosis,and inclusion of nuclear inclusion bodies,and chromatin edge collection was obvious.Mitochondrial swelling,rupture,emptying of endoplasmic reticulum in smooth surface,degranulation of rough endoplasmic reticulum,reticuloendothelial cell proliferation;myocardial fiber rupture,widening of sarcomere,fat droplets in hepatocytes,alveolar epithelium swelling,and the tubular epithelial cells degeneration and necrosis;(4)The damage in organs of 1-day-old SPF chicks infected with REV was more serious.The pathological changes of immune organs were more obvious,such as cell degeneration,necrosis or apoptosis,the number of cells was significantly reduced,and the organ atrophy was obvious.The non-immune organs like lung appeared tumor-like lesion,lymphocytes and fibroblasts increased,alveolar epithelial cells disintegrated.The large-scale focal necrosis and cell lysis are characterized in ultra-microscopic lesions.The changes of pathological damage to main organs of 1-day-old SPF chicks infected with REV were closely related to viral load.The viral load of immune organs was significantly higher than that of non-immune organs,and the damage of non-immune organs in the later stage of virus infection lasted longer than that of immune organs,and the extent was more serious.This subject has studied the relationship between pathological damage and viral load of REVinfected SPF chicks in a comprehensive and systematic way through the detection of the above indicators,which provided a very important scientific experimental basis for control of RE and further elucidating the immune pathogenesis of REV.