Molecular Characterization and Phylogenetic Analysis of Pathogenic Theileria spp. Isolated from Cattle and Sheep based on Cytochrome b Gene in Iran

The present study investigated the phylogenetic relationship based on cytochrome b gene sequences among pathogenic Theileria species (spp.) in Iran, including Theileria annulata and Theileria lestoquardi, along with other data available in GenBank. A total of 136 (cattle) and 80 (sheep) blood samples suspected of piroplasm infection were obtained from six different provinces of Iran. Both microscopic and molecular methods using species-specific primers were used for screening T. annulata and T. lestoquardi positive samples. Finally, the partial cytochrome b gene of 30 T. annulata and 5 T .lestoquardi were amplified, sequenced, and deposited in GenBank. The results indicated that there were 12 different genotypes among T. annulata isolates, while only one genotype was observed among T. lestoquardi isolates. T. lestoquardi infection in cattle was detected in one sample, and no T. annulata and T. lestoquardi coinfection were detected in sheep and cattle. In the phylogenetic tree, different Theileria spp. were placed in separate clades, and the reliability of depicted tree and monophyly of T. annulata and T. lestoquardi ingroups were supported by the bootstrap value of 94% which significantly indicated that these two species evolved from a common ancestor. The tree also showed that these two pathogenic spp. shared a more recent common ancestor, compared to another species of Theileria parasites. To the best of our knowledge, this study is the first phylogenic analysis of pathogenic Theileria spp. in Iran based on the cytochrome b gene sequences. In addition, the first T. lestoquardi cytochrome b gene was sequenced and deposited in GenBank.