A new recombinant protein-based ELISA for the diagnosis of malignant theileriosis of sheep and goats.

Tick-borne diseases of small ruminants are of highly economic importance in many countries. Malignant theileriosis of sheep and goats caused by Theileria lestoquardi is considered among the most important of these diseases and constitutes an obstacle to the sheep industry in countries like the Sudan. Here the application of a newly discovered surface protein of T. lestoquardi (Clone-5) in an enzyme-linked immunosorbent assay (ELISA) and the potentials of the application of the test in epidemiological surveys and diagnosis are described. Clone-5 contains a predicted number of 20 antigenic determinant sites and two polypeptides derived from the protein were recombinantly produced, purified and tested with control serum samples in both ELISA and Western Blot. One of the polypeptides was further used in validation experiments that involved the testing of negative and positive field serum samples collected from an area that had witnessed an outbreak of malignant theileriosis in Northern Sudan. ELISA, based on this recombinant protein, demonstrated a satisfactory performance with a calculated sensitivity and specificity of 94.6 and 88%, respectively, when countertested with a standard indirect fluorescent antibody test (IFAT). Moreover, no cross-reactions could be demonstrated against Theileria species (China) nor Cowdria spp. This test is recommended for further field validation experiments.