A POLYMORPHISM OBSERVED IN THE EXPERIMENTALLY SUCCESSFUL PEPTIDE VACCINE SEQUENCE DERIVED FROM THEILERIA-SERGENTI PIROPLASM MAJOR SURFACE-ANTIGEN (P-33)

A polymorphism in the experimentally successful peptide vaccine sequen ce (EVVWKEKKEVKDLDA, amino acids 134-148) derived from the 33 kDa piro plasm 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 th e 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 applica tion of the two major peptide sequences as cocktailed vaccine should b e evaluated for a practical use of this strategy to controlling ?: ser genti infection in Japan.