Abstract: To establish a PCR detection method of Theileria equi, the 18S rRNA gene recently discovered was shown to be species-specific. A pair of primers was designed to specifically amplify a 531 bp fragment. And the T.equi, T.equi and B.caballi mixture, B.caballi, T.uilenbergi, T.sinensis, T.annulata, T.ovis, T.luwenshun, T.sergenti are tested by PCR. While T.equi genome templates were amplified that different concentrations diluted in order to determine the sensitivity of the experiment. 45 equine blood samples were detected by the PCR and microscopic. The PCR result of specificity assay showed that one references T.equi and mixed with B.caballi could be detected by the PCR test, but no amplification was observed when other 7 bacterial species B.caballi, T.uilenbergi, T.sinensis, T.annulata, T.ovis, T.luwenshuni, T.sergenti tissue were detected. And the sensitivity result showed that the minimum dose of T.equi that could be detected by PCR assay was 10^-13, 45 clinical samples, from horses farm in China, doubtedly infected with T.equi were tested by PCR. Relevance ratio of T.equi was 17.78% (8/45) by PCR and microscopic examination found that only 8.89% (4/45). Between the coincidence rate was 100%. This research established T.equi PCR detection method is definitely a good detection method.

Key words: Theileria equi; PCR diagnosis method; development; application