Molecular Phylogenetic Analysis of Theileria Annulata in Hard Ticks of Cattle

Abstract

The current study was aimed to detect the prevalence T. annulata in bovine ticks molecularly using the polymerase chain reaction (PCR) assay, with phylogenetic analysis of local strains to estimate their identity with the global NCBI-GenBank strains. A total of 109 cattle existed at different areas in Al-Qadisiyah province (Iraq) were subjected to clinical examination to detect and collection of ticks during December (2021) to August (2022). An overall 50 samples of tick were subjected for molecular examination using the conventional PCR assay. Targeting the Cytochrom b gene, a total of 26% positive samples for T. annulata were detected in study ticks using the conventional PCR assay. The genomic DNAs of 10 positive samples were subjected for phylogenetic analysis based on the primer of Cytochrom b gene. However, sequencing findings for T. annulata isolates were named as T. annulata voucher IQ1-10, and recorded in NCBI under an accession numbers of OR125071, OR125072, OR125073, OR125074, OR125075, OR125076, OR125077, OR125078, OR125079 and OR125080. Comparative analysis for Cytochrom b-nucleotides sequence of study samples with the numbers of T. annulata isolates existed in GenBank database was constructed, and the results showed nucleotide alignment similarities and substitution mutations in Cytochrom b gene. Comparative identity between the local T. annulata IQ-isolates and NCBI-BLAST T. annulata of Cytochrom b gene revealed a significant association with Tunisian isolates at 98% similarity and 0.0-0.2% total genetic changes. In conclusion, the molecular diagnosis of T. annulata in the prevalent tick species of the region has demonstrated the prevalence of bovine Theileria parasites in ticks, and the risk of cattle to contract theileriosis. Although only a limited number of ticks were studied, these preliminary data suggest that specific parasite genotypes may be selected during tick transmission from a carrier animal. Given its enormous burden on livestock farming in Iraq, further investigations are needed to better understand its epidemiology, vector transmission and potential clinical significance in cattle from neighboring countries.