phylogenetic study of theileria annulata isolates from alborz province by using 18s rrna gene and its regions sequences

tropical theileriosis is a tick-transmitted disease which caused by obligative intracellular protozoan theileria annulata. diagnosis is usually based on identification of parasite in giemsa stained smears of peripheral blood, spleen or lymph nodes. today, the molecular methods with high sensitivity and specificity are used for diagnosis of infected and carrier animals, epidemiological and phylogenetic studies. due to the presence of bovine theileriosis in iran, t. annulata phylogenetic analysis has been focused using 18s rrna gene and its region sequences (its1, 5.8s rrna, its2) for two alborz theileria annulata isolates and bovine theileriosis vaccine strain s15 cell line. the target sequences were amplified by pcr and further pcr product sequencing. the phylogenetic tree were constructed based on 18s rrna complete gene sequences and its region, then the sequences of iranian isolates and registered theileria sequences from other countries registered in genbank were compared. the obtained results showed that the 18s rrna gene and its sequence are valuable for detection and classification at the species and subspecies levels, respectively. other important finding obtained from the present study was the result from phylogenetic tree of complete 18s rrna gene sequences that revealed the highly pathogenic theileria spp. (lymphoproliferative theileria) including t. annulata, t. lestoquardi and t. parva were placed in a separate cluster away from the other theileria spp.