Isolation of Theileria lestoquardi infected cells and using for immunization of sheep without attenuation

Theileria lestoquardi is the causative agent of malignant theileriosis of sheep and goats. T. lestoquardi is the main cause of theileriosis of sheep in the south of Iran. In this experiment, theileria infected cell line was isolated from the prescapular lymph node of an adult ewe. Molecular study confirmed this cell line of ovine lymphocyte has been transformed by the T. lestoquardi. This isolate of T. lestoquardi was designated Booket (Isolation place). Long-term culture or high passage of T. lestoquardi infected lymphoplastoid cells was shown to result in attenuation of their virulence. In this study sheep inoculated with low passage (without attenuation) of this isolate showed no clinical signs of theileriosis, which shows the significance of this cell line to develop a tissue-culture vaccine against malignant ovine theileriosis.