ORIGINAL PAPER Identification and characterization of Theileria ovis surface protein (ToSp) resembled TaSp in Theileria annulata P. Shayan 1 & S. Jafari 1 & R. Fattahi 1 & E. Ebrahimzade 1 & N. Amininia 1 & E. Changizi 2 Received: 22 November 2015 /Accepted: 19 January 2016 /Published online: 2 February 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract Ovine theileriosis is an important hemoprotozoal disease of sheep and goats in tropical and subtropical regions which caused high economic loses in the livestock industry. Theileria annulata surface protein (TaSp) was used previously as a tool for serological analysis in live- stock. Since the amino acid sequences of TaSp is, at least, in part very conserved in T. annulata , Theileria lestoquardi and Theileria china I and II, it is very impor- tant to determine the amino acid sequence of this protein in Theileria ovis as well, to avoid false interpretation of serological data based on this protein in small animal. In the present study, the nucleotide sequence and amino acid sequence of T. ovis surface protein (ToSp) were deter- mined. The comparison of the nucleotide sequence of ToSp showed 96, 96, 99, and 86 % homology to the corresponding nucleotide sequence of TaSp genes by T. annulata, T. China I, T. China II and T. lestoquardi, previously registered in GenBank under accession nos. AJ316260.1, AY274329.1, DQ120058.1, and EF092924.1 respectively. The amino acid sequence analysis showed 95, 81, 98 and 70 % homology to the corresponding amino acid sequence of T. annulata, T chinaI, T china II and T. lestoquardi, registered in GenBank under accession nos. CAC87478.1, AAP36993.1, AAZ30365.1 and AAP36999.11, respectively. Interestingly, in contrast to the C terminus, a significant difference in amino acid se- quence in the N teminus of the ToSp protein could be determined compared to the other known corresponding TaSp sequences, which make this region attractive for de- signing of a suitable tool for serological diagnosis. Keywords Theileriosis . TaSp gene . PCR . Sequencing . ToSp gene Introduction Ovine theileriosis is an important hemoprotozoal disease of sheep and goats in tropical and subtropical regions which is caused at least by T. lestoquardi (Theileria hirci), T. china ,I and T. china II. T. ovis is reported as must probably not a pathogen (Ahmed et al., 2006; Nagore et al., 2004; Niu et al., 2009; Zaeemi et al., 2011). T. lestoquardi, which is a causal agent of malignant ovine theileriosis is distributed in the south half of Iran, and T. ovis causing subclinical infections in small ruminants is wide- spread all over the country (Jalali et al., 2014; Hashemi- Fesharaki, 1997; Hooshmand-Rad and Hawa, 1973). The diagnosis of small ruminant theileriosis is based on clinical symptoms, blood smears (Giemsa staining), serologic tests, and molecular biology methods (Inci et al., 2010). Giemsa staining cannot be used as a reliable method for diagnosis of theileriosis because this method is unspecific and can be accompanied with some technical problems and ,in some cases, needs special experiences especially by low parasitemia (Shayan & Rahbari, 2005). * P. Shayan pshayan@ut.ac.ir 1 Center for Ticks and Tick-borne Diseases, Department of Parasitology, Faculty of Veterinary Medicine, University Of Tehran, Tehran, Iran 2 Department of Parasitology, Faculty of Veterinary Medicine, University of Semnan, Semnan, Iran Parasitol Res (2016) 115:1893–1899 DOI 10.1007/s00436-016-4929-1