Phylogeny of benign Theileria species from cattle in Thailand, China and the U.S.A. based on the major piroplasm surface protein and small subunit ribosomal RNA genes.

The major piroplasm surface protein and small subunit ribosomal RNA genes of benign Theileria species isolated from cattle in China, Thailand and the U.S.A. were amplified by polymerase chain reaction, cloned and sequenced. The major piroplasm surface protein genes of these three isolates were more than 89% identical at amino-acid level. Several deletions in the gene from the Thai isolate led to considerable structural change through frame shifts of the major piroplasm surface protein. Phylogenetic analyses based on both of the major piroplasm surface protein and small subunit ribosomal RNA genes suggest that there may be a second cosmopolitan benign Theileria species infecting cattle in addition to the Theileria sergenti/buffeli/orientalis complex.