Evaluation of Theileria annulata recombinant immunodominant proteins for the development of ELISA.

A number of Theileria annulata genes have been cloned, sequenced and expressed, including TaSP, TaD, TaSE and TamtHSP70. Several recent publications document the suitability of the recombinant TaSP protein for use in the diagnosis of tropical theileriosis. To investigate whether TaD, TaSE or TamtHSP70 elicit a humoural immune response in the T. annulata-infected host and to assess the potential of these proteins for development of diagnostics, a total of 156 field sera from Sudan and 49 negative sera from Germany were investigated in ELISA for the presence of specific antibodies against these recombinant proteins in comparison to TaSP. Antibodies against TaD and TaSE were found to be present, whereas no antibody response could be detected against the recombinant TamtHSP70. Highest titres were found to be present against the TaSP protein, with antibody titres against TaD and TaSE being in general somewhat lower. Correlation analysis showed a significant correlation of TaSP and TaSE and of TaSE and TaD antibody titres, however not between TaSP and TaD. In conclusion, the infected bovine host was shown to produce antibodies against three of the four recombinant T. annulata proteins tested, all three having been described or predicted to be parasite membrane proteins. The outstanding performance of the TaSP protein for detection of T. annulata infection in indirect ELISA was confirmed.