A genetic analysis of mixed population in Theileria sergenti stocks and isolates using allele-specific polymerase chain reaction.

In order to differentiate parasite populations bearing two allelic forms of p33/32, an immunodominant piroplasm surface protein of Theileria sergenti, two sets of oligonucleotide primers were designed to amplify either of the two allele by the polymerase chain reaction (PCR). Each set of the primers differentially amplified either of Ikeda- or Chitose-type p33/32 genes. By using this allele-specific PCR and restriction enzyme digestion of amplified products, parasite populations within field isolates collected from different geographical regions in Japan were analyzed. Both of the allelic forms were detected in 13 samples out of 20 isolates and stocks by PCR. Either of Ikeda or Chitose type of p33/32 allele was detected in the other 7 samples. These results indicated that the majority of T. sergenti-infected calves (11/15) in Japan harbored mixed parasite populations bearing at least two different alleles of p33/32.