Production of interferon by Theileria annulata- and T. parva-infected bovine lymphoid cell lines.

Theileria annulata and T. parva-infected lymphoblastoid cells were examined for their capacity to produce interferon (IFN). Supernatants of such cells were tested in biological assay for their antiviral activity. Only T. parva-infected cells of T-cell origin were capable of producing IFN-gamma. Supernatants of some but not all T. annulata-infected cells showed also antiviral activity, which was greatly reduced after exposure to a pH of 2. Northern-blot analysis of the cells using an IFN-gamma cDNA probe confirmed the results obtained for T. parva-infected cells in a biological assay. No IFN-gamma mRNA was detected in T. annulata-infected cells. The importance of IFN for the pathogenesis of theileriosis is discussed.