A polymorphism observed in the experimentally successful peptide vaccine sequence derived from Theileria sergenti piroplasm major surface antigen (p33).

A polymorphism in the experimentally successful peptide vaccine sequence (EVVWKEKKEVKDLDA, amino acids 134-148) derived from the 33 kDa piroplasm major surface antigen (p33) of Theileria sergenti was examined. The vaccine sequences obtained by PCR amplification and sequencing of the p33 gene from a total of 15 parasite-infected cattle blood samples collected from 4 prefectures through Hokkaido to Kumamoto revealed the two major sequences (Ikeda and Chitose stock types) either of which was identified in all samples. Since the peptide vaccine develops the parasite species- or stock-specific immunity in the animals, an application of the two major peptide sequences as cocktailed vaccine should be evaluated for a practical use of this strategy to controlling T. sergenti infection in Japan.