Molecular detection and phylogenetic characterization of Theileria species from sheep in central part of Tamil Nadu

To determine the prevalence of Theileria species in sheep, a total of 150 sheep belonging to 33 smallholder flocks from three three districts in Tamil Nadu were examined from September 2015 to February 2016. Whole blood samples, peripheral blood smears and lymph node smears were collected and analysed for the presence of Theileria spp. by employing staining and molecular techniques. The major tick species identified in sheep were Haemaphysalis intermedia, Rhipicephalus haemaphysaloides, Hyalomma anatolicum and Hyalomma marginatum. On examination of blood smears, piroplasms of Theileria species were detected in 42 (28.00%) samples, whereas schizonts could be detected in lymph node smears collected from sheep infected with T. lestoquardi. Polymerase chain reaction (PCR) was performed and amplified 464 and 863 bp18S rRNAgene ofT. ovis and T. lestoquardi, respectively. OnPCR analysis, T. oviswas detected in 64 (42.67%) samples, while T. lestoquardi was detected only in four samples (2.67%) in Karur district. Among the three districts, high prevalence of Theileria was recorded in Karur. Sequencing and phylogenetic analysis of PCR positive products showed 100% homology with sequences available in Gene Bank. The results of the present study revealed that sheep flocks of the study area were infected with both T. ovisand T. lestoquardi.