الفهرس 
Materials and mithodsOnly 14 pages are availabe for public view
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Abstract
The presence of haernorrhagic enteritis(HE) in foreign and native strains of meat and parent turkeys was investigated in 12 flocks in Giza , 18 flocks in Kalyoubia , and 7 flocks in Gharbia Governorates .
All flocks were examined serologically for antibody to HE virus (HEV) by the agar gel precipitation (AGP) test and enzvm -linked - immunosorbant assay (ELISA) and only 7 flocks in giza and kalvoubia for viral antigen in spleen homogenates by the AGPtest . The obtained results revealed that the age of poults which have had history of clinical signs and gross lesions suggestiveof HEVinfection (12 flocks in Giza) varied between 56-190 days,and mortality ranged from 3.42 to 11.42% . The disease in these 12 flocks was faulty diagnosed and treated as coccidiosis .Only 1 flock aged 56 days out of 3 of these 12 flocks which were examined for HEV antigen in the spleen gave positive results. Serum samples from all 1.2 flocks revealed precipitative antibodies in varying percentage (15-100’,0 end have had mean ELISA antibody titers ranging from 7988 to 1 >919
indicating their previous exposure to infection,
Antigen detection in spleen samples from 4 flocks of native’ turkeys
in Kalyoubia gave negative results in AGP test. Of the 18 flocks of native
turkeys in Kalyoubia examined serologically only 5 flocks revealed mean positive F,I,ISA antibody titers (range 9720-15564) and 4 of these 5 flocks have had precipitating antibody in 100% of the examined serum samples . Sera collected from 7 native flocks in Gharbia governorate revealed high ELISA antibody titers in only 4 flocks, and 2 out of these- 4 flocks have era from ave had trains of tance of
had precipitating antibodies. The demonstration of antibodies in 9 out of 25 flocks in Kalyoubia and Gharbia governorates which no history of the disease suggested the presence of mild field HEV which infected the birds without notice ,or the relative resi native strains of turkeys.
Infectivity testing and propagation of HEV local isolate from one flock in Giza in 7 weeks old susceptible poults , r clinical signs and gross lesions specific for HE . Three blind p AGP test-positive pooled spleen homogenates were done to pro HEV for the other studies .Propagated HEV proved to have a tite 10 7 TID 50 / ml titration into susceptible poults.
Age susceptibility testing by oral inoculatuon of groups of s poults aged from 25- 80 days with 0.5 ml / bird of HE homogenate containing 107 TID50 / ml revealed that age group 46-58 days were the most susceptible days as judged devel clinical signs and gross lesions , and antigen detection by AGP-spleen , pancreas and intestine 6days post infection (PI), whil
other age-groups were less susceptible , mortality was abse infected age groups and was supposed to be due to residua immunity or the use of half the TID5O for infection.
Pathogenicity testing of HEV local isolate by oral inoculatio nirbird containing 107 TID50/m1 into 57 days old suscepti broad-breasted poults resulted in clinical signs including bloody depression, ruffled feathers and soiled vent , which started 2 d subsided on 7th day PI. Two out of 20 birds (tO%)died 5-6 d dead and sacrificed poults revealed characteristic gross 1
ecovered suited in
ssages of agate the
of
sceptible spleen between pment of est in the poults of
t in all maternal
of 0.2 le White iarrhaea, ys PI and ys PI and sions of
1 2
haemorrhagic enteritis with bloody intestinal contents and enlarged mottled spleen from 3-6 days PI; the later showed atrophy on the 7th day PI.
The sequenetial histopathological changes in different organs of infected poults sacrificed daily for 7 days Plwere described. The main lesions were necrosis of lymphoid cells and degeneration of the reticular cells of the spleen, accompanied by infiamatory cells and formation of the characteristic intranuclear inclusions; pronounced bursal lymphocytic necrosis with subepithelial and pelical edema; lymphocytie depletion in the medullary part of the thymus; proliferation of inflammatory cells in the lamina propria of the cecal tonsils and haemorrhages at the intestinal level; and degeneration of epithelil cells of the renal tubules and vacuolation of the glomeruli and the wall of the blood vessels with
endotheliosos.
Moreover.the value of spleen index (ST) was significantly hiller in Ihe inoculated birds than those of the uninoculated ones.
Detection of precipitinogen in spleen and pancreas of infected poults was successful from the 1st till the 7th day PI ,and from 1 up to 5 days PI in the intestine. However, • precipitinogen could demonstrated in the liver and bursa of Fabricius only from 4th to the 6th day PI. Fluorescent antibody(FA) and immunoperoxidase tests (IP) was helpful in domenstrating viral antigen in different organs experimentally infected poults on day 1 PI, but only spleen and pancreas were still postive up to day 4 PI. There was general agreement between the of results ofthe three antigen detection tests. Seroconversion was followed up in the infected birds by AGP and ELISA tests indicated that there was an increase in ELISAa tibody titers from the 4th day PI, peaked on day 21 PI. then declined to each zero at the 57 th day PI. Precipitating antibodies were first dete ted one day earlier (3rd day PI) and disappeared on day 57 PI.
Immune serum collected from convalescent turkeys ai d inoculated into susceptible poults in 0.5 nil dose / bird intramuscularly 1 5 days after oral infection with 0.2 ml of local HEV isolate containin 10A turkey median infective dose per ml succeeded to prevent clinical sings
mortalities or gross lesions which characterized HEV infection particularly when administered on the 2nd or 3 rd day aft r infection , and can be recommended to control outbreaks of the diseas besides the use of imported or locally prepared vaccines for prevention.