676 Proliferation and Cytokine Profile of T. annulata-Infected Ovine, Caprine, and Bovine Lymphoblastoid Cells L. SCHNITTGER, C. HOLLMANN, U. DIEMER, K. BOGUSLAWSKI, AND J.S. AHMED a Forschungszentrum Borstel, 23845 Borstel, Germany ABSTRACT: T. annulata, the causative agent of tropical theileriosis in cattle, can also infect ovine and caprine leukocytes in vitro. In vivo studies showed that this parasite causes a mild infection in both these animal species, and in sheep merozoite stage development seems to be inhibited. Since the nature of T. annulata infected caprine and ovine cells is not known, all three cell lines were karyotyped and phenotypically characterized by flow cytometry. They all express mRNA of cytokines IL-1, IL-1, IL-8, and TNF-, but not of IFN-, IL-2, and IL-4. In contrast, IL-6 mRNA was expressed in the cattle cell line only, while mRNA of IL-10 was exclusively produced by the sheep cell line. The observed differences in cytokine mRNA expression may be responsible for the different pathogenesis of T. annulata infection in cattle and sheep. INTRODUCTION Tropical theileriosis is a disease of cattle caused by the tick-borne protozoan parasite Theileria annulata. After being inoculated by Hyalomma ticks, the sporozoi- tes of this parasite invade bovine leukocytes, in which they subsequently develop into macro- and microschizonts. The latter differentiate to merozoites giving rise to piro- plasms. Phenotypic and cytokine analysis revealed that B-lymphocytes and macrophages are the main targets of T. annulata sporozoites in cattle. 1–3 Apart from cattle, sheep and goat can also be infected by T. annulata causing the transformation of their leukocytes. 4–6 Like T. annulata-infected cattle cells, T. annulata-infected sheep and goat cells can be propagated in vitro as cell lines. Since T. annulata-infected ovine and caprine leukocytes have not yet been characterized, we investigated the phe- notype of infected cells and examined their cytokine profile. MATERIAL AND METHODS Preparation of T. annulata Sporozoites and Establishment of Theileria-Infected Cell Lines T. annulata sporozoites were prepared from the salivary glands of infected Hyalomma ticks 7 and then used for in vitro infection of bovine peripheral blood a Address for correspondence: J.S. Ahmed, Forschungszentrum Borstel Parkallee 22, 23845 Borstel, Germany. Voice: 494537188428; fax: 494537188404. jahmed@fz-borstel.de