Nuclear techniques in the study of East Coast fever (Theileria parva infection of cattle)

Nuclear techniques have been used in a variety of ways to study East Coast fever of cattle caused by the protozoan parasite Theileria parva. Macroschizonts, piroplasms and sporozoites have been radiolabelled by using different nucleic acid precursors, particularly 3H-hypoxanthine and 3H-thymidine. These studies have helped to elucidate cyclic changes occurring during parasite development in bovine lymphoid cells and in tick salivary glands. Attempts to attenuate parasites by irradiation have been partially successful in the case of sporozoites, and more attention should be given to an attempt to induce attenuation by irradiation of developing rather than mature sporozoites. Irradiation of macroschizont-infected cells does not appear to offer a means towards vaccine development but has proved a valuable technique in elucidating immunological mechanisms. The study of these mechanisms has also been greatly helped by nuclear techniques such as radioimmunoassay and 51Cr-release assays. Irradiation of laboratory mice, particularly athymic nude strains, has resulted in immunosuppression of the host so that macroschizont-infected bovine lymphoid cells will grow as tumours following subcutaneous inoculation. Schizonts do not transfer to mouse cells and, until this can be achieved, the use of an athymic mouse model for East Coast fever is limited. (author)