Molecular Study of Sheep Malignant Theileriosis at Barka Region in the Sultanate of Oman

Background: We used the PCR technique based on the abovementioned primer pair and sequenc­ing to demonstrate the Theileria infection in the sheep samples collected from Sultanate of Oman. Methods: According to the frame work of "integrated control of ticks and tick borne diseases in global­ized world managed by EU-ICTTD-3 project, the samples from blood, liver, spleen, lymph node and lung were sent to the laboratory of Iranian Research Center for Ticks and Tick-borne Diseases (IRCTTD). Sam­ples from blood smear and impression smears from liver, spleen, lymph node, and lung were analyzed by Geimsa staining. The DNA was extracted from the abovemen­tioned samples and analyzed by PCR tech­nique using specific primers derived from the nucleo­tide sequences of 18S rRNA gene of T. lestoquardi , which can amplify the common region in other Theileria and Babesia spp.  Subsequently the amplified DNA was sequenced. Results: The analysis of blood smears of the sheep was negative for piroplasmosis performed through the Giemsa staining. The impression smears prepared from liver, spleen, lymph node, and lung showed suspi­cious structures mimicking Theileria schizonts in some cells.   The results showed an expected PCR prod­uct of 428 bp in length, which is specific for Theileria spp . The PCR products were subsequently se­quenced. The corresponding nucleotide sequence is registered under accession number JF309152 in Gen­Bank. The sequence alignment in GenBank showed that the PCR products had 99% homology to the known T. lestoquardi registered under accession number AF081135 in the GenBank. Conclusion: Oman sheep are highly susceptible for Theileria infection and the infected sheep mostly die before the microschizonts or erythrocytic form of Theileria appears in the nucleated or ery­trocytic cells respectively.