Molecular Characterisation of Theileria orientalis in large ruminants from the northwestern region of Pakistan Pakistan

Abstract

Background and Objectives: Theileriosis is among the most serious illnesses present in both tropical and subtropical areas of the world and has a considerable economic effect on the cattle industry and Pakistan being in subtropical zone, is ideal for ticks and tick-borne diseases. Theileria orientalis is the emerging agent causing theileriosis and leads extensive loss of livestock. The present study aimed to find the prevalence and molecular characterization of Theileria orientalis infecting cattle. Methodology: The blood samples from 362 cattle were collected and examined microscopically for the presence of theileriosis. DNA was extracted from 27 positive cattle and polymerase chain reaction was done. Sequences were aligned and phylogenetic relationship was determined with maximum likelihood method. Results: the overall prevalence of Theileria orientalis was 7.46% and the presence of ticks ratio was 85.19% in positive animals. In females’ cattle the prevalence was highest 62.96% as compared to males. Crossbreeds showed highest infection rate of 75.08% followed by exotic and indigenous breeds. Age infection analysis revealed that highest infection rate was 59.25% in 2.1-4 years aged animals. A 376bp 18S rRNA sequence was amplified. The highest rate of transitional substitution possibility score was 14.8010 for substitution of T/U to C, A to G, C to T/U, and G to A. The current isolate Theileria orientalis from Pakistan showed 100% homology with T. orientalis from South Korea. The interspecific variation showed differences with isolated from Pakistan (MG585380, MG585380) at 24 base positions. Conclusion: The study recorded existence of Theileria orientalis in cattle population of Abbottabad, KPK based on 18S rRNA gene. However, further detailed studies on other genetic markers are required to confirm the genetic identity of T. orientalis. Moreover, studies on molecular identification of ticks are required for control of tick-borne diseases.