Molecular characterization of Theileria annulata in large ruminants from Khyber Pakhtunkhwa, Pakistan

Abstract

Background: Theileria annulata a vector borne haemoprotozoan is responsible for tropical theileriosis. Theileriosis causes substantial economic losses to the livestock sector in Pakistan. For treatment and control purpose accurate identification of Theileria species infesting livestock are required. Very little is known about the genetic variation of Theileria species. Objectives: The aim of the present study was genetic characterization of Theileria species infecting the cattle based on 18S ribosomal RNA region from Khyber Pakhtunkhwa, Pakistan. The phylogenetic association of Theileria species based on localities was determined. Materials and Methods: Total of 362 samples were collected from the blood of cattle. Information regarding age, sex, locality, tick infestation was noted. DNA was extracted from blood samples, primers were designed and PCR was performed. The PCR products were sequenced and compared with reference sequences downloaded from GenBank. Results: PCR results showed the prevalence of Theileria annulata in the cattle population was 9.9%. The animals belonged to 3-4 years age group (5.24%), females (7.7%) and Cross breed (7.4%) showed high infestation rate. Theileria annulata was more prevalent 6.62% in Peshawar as compared to Abbottabad (3.31%). Two genotypes of Theileria annulata were identified in present study. The total sequenced length of identified genotypes was 388 base pairs. The identified Theileria annulata sequences showed 96% homology, while the 97.87% homology was recorded with isolates reported from other countries. The sequence formed a monophyletic clade with isolates from China, India, Iran, Iraq and Europe. Conclusion: The results showed the existence of two genotypes of Theileria annulata in cattle of KP, Pakistan. Further studies on genetic diversity of Theileria species in other agro ecological zones of country are needed to explore.