In Vitro Studies on Theileria-Infected Lymphoblastoid Cell Lines

A review of literature of the history of the development of Theileria-cell culture and studies on Theileria-infected lymphoblasts was carried out. A need for a systematic study of characteristics that might help identification of Theileria cell-lines as well as the relationship between Theileria and the host-cell in vitro was noted. As a result, a study of the characteristics of Theileria- infected cell-lines and the relationship between Theileria and the host lymphoblast cell was undertaken. Five celllines isolated by the author in Kenya (one infected with T. lawrencei in buffalo cells; three infected with T. lawrencei and one with T. parva in cattle cells) together with four cell-lines (one with T. narva and three with T. annulata in cattle cells) previously isolated by workers in East Africa and Iran were used in the study. Electron microscopic studies on the relationship of T. annulata, T. parva and T. lawrencei with the host-cell revealed a close association of the parasite with the hostcell in that the host-cell treated the parasite in a way similar to its own nucleus by forming nucleopore-1 ike structures with the parasite membrane, and during host-cell division the parasite was aligned along the mitotic spindle fibrils very much in the same way as the host-cell chromosomes were. A very active Golgi apparatus was observed in all Theileria-infected lymphoblasts. No ultrastructural differentiating features between T. parva, T. lawrencei and T. annulata parasites could be found in the Theilerla- infected lymphoblasts maintained in vitro. Studies on isoenzyme variants between the various Theileria-infected cell-lines revealed only two enzymes that could be distinguished on a Theileria-species basis. These were glucose phosphate isomerase and glyceraldehyde phosphate dehydrogenase. The importance of the isoenzyme results is discussed. There were no significant differences between all cattle Theileria-infected cell-lines with regard to percentages of cells parasitized, cells in mitosis and multinucleate cells or the mean schizont nuclear number. There were, however, significant differences between cattle Theileria-infected cells and buffalo Theileria-infected cells. The significance of these findings in relation to characterization of cell-lines is discussed.