الفهرس 
Review of Literature
Material & MethodsOnly 14 pages are availabe for public view
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Abstract
In this study DHV has been isolated from different organs; liver, kidney, bile duct, spleen, and pancreas and feces of these ducklings (96 samples). The virus was isolated via AC route (1500 eggs) of 8-10 days old ECE. Two egg passages were carried out for each sample. The isolated DHV was identified using AGPT, VNT, HAT, PHAT, RPHAT, and IFAT beside histopathological examinations and Acridine Orange staining. Experimental infection of isolated DHV in 100 susceptible ducklings was done and identified by IFAT and histopathological examinations. Preparation of specific hyperimmune serum against standard DHV was done by inoculation of the vaccinal DHV S/C into 5 baladi 5 months-old rabbits and collection of the serum and then purified. The obtained results were as follows: 1- Bacterial examinations were done to each collected sample. 2- DHV field isolate was isolated directly from the collected samples in which 13 liver samples, 13 bile duct samples, 13 pancreas samples, 13 spleen samples, 13 kidney samples, and 13 fecal samples into AC route of ECE giving the same lesions of DVH. The causative agent of 2 samples (No.8&10) was Salmonella, and the causative agent of one sample (No.16) was unknown (suspected parvovirus). 3- DHV field isolate titer was estimated in ECE, and EID50/ml was measured by Reed and Muench, 1938. 4- The viral nucleic acid of DHV field isolate was identified by using 0.01% Acridine Orange pH 4.0 and examined under fluorescent microscope; it showed red color that reveals the single stranded genome. 5-DHV field isolate was identified using AGPT, VNT “Alpha method”, HAT, PHAT, RPHAT, and IFAT beside histopathological examinations. 6- The hemagglutination ability of the DHV field isolate was estimated by HAT using 1% sheep RBCs showed no hemagglutination activity of the isolate like the standard DHV and also the sample No.16. 7- Experimental infection of the isolated virus was inoculated IM into 5 days-old susceptible ducklings after assurance that ducklings were free from maternal immunity, it gave DVH clinical signs; 24-48 hrs. PI. The DHV field isolate was re-isolated from liver, kidney, feces, bile duct, spleen, and pancreas of experimentally infected ducklings then, IFAT was used for detection of DHV field isolate in both natural and experimental infections in different organs (liver, kidney, spleen, and pancreas) by cryostat methods. IFAT detection for the experimental infection was applied every day PI for 7 days and histopathological findings of DHV field isolate of both natural and experimental infections were the same findings of DVH. 8- The sample No.16 after it showed –ve result of both DHV and salmonella, no hemagglutination activity, it was injected IM in 7 days-old Muscovy ducklings and showed clinical signs and PM lesions. The results revealed that DHV causes nervous manifestations with diarrhea in young ducklings less than one month of age; the virus was isolated from liver, bile duct, pancreas, spleen, and kidney, and also feces of ducklings suffering from these signs. Also DHV may be found alone in natural infections or in mixed infection with Salmonella causing high mortalities in young ducklings. IFAT is the most rapid definitive diagnostic tool for DHV. We found an agent affecting young Muscovy ducklings (9-days old) causing nervous manifestations with ascetic fluid accumulation in the abdomen causing “penguin like posture” and high mortality (30-40%), this agent is non hemagglutinating agent and did not show the lesions of DVH in ECE, but the clinical signs and PM lesions were similar to that of Derzsy’s disease that will need further study.