Molecular epidemiological investigation on Theileria in yellow cattle from Xiangxi Autonomous Prefecture of Hunan Province

Abstract

To investigate the prevalence and genetic variation of Theileria in yellow cattle in Xiangxi Autonomous Prefecture of Hunan Province. A total of 184 blood specimens were collected from Fenghuang, Huanyuan and Baojing counties of Xiangxi Autonomous Prefecture during the period from August 2018 through August 2019, and were detect using PCR assay with the specific 18S ribosomal rRNA (18S rRNA) gene targeting Theileria. The gene sequences of positive specimens were aligned with the sequences recorded in GenBank, and a phylogenetic tree was created with Plasmodium ovale 18S rRNA as an outgroup. A total of 143 blood samples were positive for Theileria, with a mean detection rate of 77.7%. Theileria was prevalent in the blood samples from yellow cattle in all three counties, with detection rates of 85.0% in Fenghuang County, 88.3% in Huayuan County and 61.0% in Baojing County, respectively. There was no significant difference in the detection rate of Theileria between Xiangxi yellow cattle and normal yellow cattle (77.2% vs. 79.5%; χ2 = 0.08, P > 0.05), while the detection of Theileria was significantly lower in the housed yellow cattle than in free-range cattle (68.9% vs. 89.7%; χ2 = 22.36, P < 0.01). A total of 18 PCR positive samples were randomly selected for sequencing and analysis, and all samples showed more than 99.0% homology with T. luwenshuni isolates. Phylogenetic analysis showed that the 18 positive samples were clustered into the same branch with T. luwenshuni, but were far away from other isolates. The prevalence of Theileria is high in yellow cattle from Xiangxi Autonomous Prefecture of Hunan Province, and T. luwenshuni may be the dominant parasite species.