A comparative phylogenetic analysis of Theileria spp. by using two two \"۱۸S ribosomal RNA\" and \"Theileria annulata merozoite surface antigen\" gene sequences

More than ۱۸۵ species, strains and unclassified Theileria parasites are categorized in the Entrez Taxonomy. The accurate diagnosis and proper identification of the causative agents are important for understanding the epidemiology, prevention and appropriate treatment. This study aims to discuss the importance of two genes of Theileria annulata ۱۸S ribosomal RNA (۱۸S rRNA) and Theileria annulata merozoite surface antigen (Tams۱) for phylogenetic analysis of molecular data. Eight Theileria annulata isolates including S۱۵ Iran vaccine strain, six T. annulata field isolates and one Iraq T. annulata field isolate were studied in this study. The ۱۸S rRNA and Tams۱ gene sequences were investigated by phylogenetic analysis after DNA extraction, PCR, and DNA sequencing. Sequence fragments of about ۱۴۱۰ to ۱۴۱۲ bp of the complete ۱۸S rRNA gene and ۷۷۸ nucleotides of Tams۱ gene sequences were used in the analysis of nucleotide diversity. Sequence alignment and phylogenetic analysis were performed by constructing the phylogenetic tree and identity matrix based on two above genes. The results of the study revealed, the ۱۸S rRNA is informative in estimation of relationships among Theileria species and strains, but the Tams۱ seems to be appropriate for analysis of the molecular antigenicity in vaccine development.

Keywords:

Theileria annulata , Tams۱ , ۱۸S rRNA , Taxonomy , Phylogenetic analysis