Experimental Sheep immunization With bovine Theileria annulata Vaccine.

Theileriosis is a tick-borne hemoprotozoan disease that affects domestic and wild ruminants in tropical and subtropical regions, and resulting in high economic losses . Pervious studies reveals a high dgree of similarity between theileria lestoquardi and theileria annulata , which the first is the causative agent of malignant theileriosis of sheep and goats, and the second causes tropical theileriosis in cattle .Extensive similarities between these two theileria species revealing a close evolutionary relationship and suggest that these species evolved very recently from a common ancestor . Therefore the aim of this study was to examine the possibility of sheep immunization using bovine theileria vaccine . For this purpose, research was conducted in three stages: 1 - In the first experiment 30 sheep divided into two treatment groups (12) and one group (6) as control, groups 1and 2 immunized with theileria lestoquardi and annulata respectively and countrol group were received cell culture medium then all groups were challenged with homogenized spleen and liver of sheep suffering from acute Theileriosis . 2 - In the second experiment 12 sheep divided into three groups of four sheep , groups 1and 2 immunized with theileria lestoquardi and annulata respectively and countrol group were received cell culture medium then all groups were challenged with homogenized of infected ticks . 3 - The third experiment as the field test was performed by immunized a flock of 600 sheep in a region with the highest reported incidence of sheep theileriosis with theileria annulata vaccine at the time of vaccination (late February). Results of clinical and paraclinical trials sugested that there were no statistically significant difference between the sheep and bovine theileriosis vaccines either to produce immunity or to creat side effects .Under field conditions no mortality was reported in immunized fluck by theileria annulata vaccine only one case showed mild symptoms of theileriosis , while that in the control herd 6 dead , 15 cases of serious disease and 30 cases of mild disease was reported . The results of this study indicate that the bovine theileria vaccine is safe and could create protective immunity in sheep.