Molecular and Phylogenetic Analysis of the Partial Tamsl Gene Sequence of a Vaccine Strain of Theileria annulata

摘要

The polypeptide Tarns 1 is an immunodominant major merozoite piroplasm surface antigen of the protozoan parasite Theileria annulata and is highly variable. In this study, the partial nucleotide (nt) sequence of the Tamsl (522 nt) gene of Iranian vaccine strain (Vaccine-ir68) recovered from an outbreak of disease in Iran was determined and compared with the corresponding sequences of eighteen previously published Tamsl genes. According to sequencing result, a novel amino acid substitution at the Tamslregion (K—>Q) was found exclusively in isolate Vaccine-ir68. Genetic distance values, estimated from the sequence data, revealed striking sequence homology (approximately 99%) between Vaccine-ir68 isolate and Tunisian isolates, showing that they were same isolates of T. annulata which were spread in these areas. The phylogenetic tree constructed based on the sequence alignment of 19 Tamsl coding regions was distinctly divided into five lineages. There might be some unknown tick carrier birds immigrating to the different geographical regions. These birds have an effective role to distribute the T. annulata species in North Africa, Palestine and Iran.