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Abstract：
BACKGROUND: Epidemiological surveys in Oman have revealed a high prevalence of the co-occurrence of the pathogenic Theileria lestoquardi and the non-pathogenic Theileria ovis among sheep in the Barka region, Oman. Our most recent data illustrated an interaction and reduced mortality risk in animals co-infected with T. lestoquardi and T. ovis, suggesting that the latter confers protection against pathogenicity of T. lestoquardi. The present study extends the above findings and examines disease outcomes; clinical markers, hematological parameters, and parasite density in mixed and single T. lestoquardi infections.
METHODS: A total of 390 blood samples were collected from 16 sheep pens located in Barka, Oman between July and November 2019. Theileria spp. were detected and quantified using qPCR assay targeting 18S rRNA, and the extent of genetic diversity was estimated by a panel of T. lestoquardi specific micro- and mini-satellites. The association of some disease markers with the presence of Theileria spp. and genetic diversity was tested.
RESULTS: Theileria spp. were detected in 75 (19.2%) sheep; of these 65 (86.7%) had mixed infections (T. lestoquardi plus T. ovis), 8 (10.6%) were infected with T. lestoquardi alone, and 2 (2.7%) with only T. ovis. Exotic breeds had a higher risk for Theileria spp. infection. The density (18S rRNA gene copies) of both parasites was higher in single infection against mixed infection, and there was a relatively lower density of T. lestoquardi in mixed infections. However, there was no difference in hematological indices between single T. lestoquardi and mixed infections. High genetic diversity was observed among T. lestoquardi in Barka, with no differences of T. lestoquardi in single and mixed infections. The extent of diversity seen in Barka was higher (He = 0.772) than that reported in Oman in 2019 (He = 0.582), with distinct T. lestoquardi genotypes.
CONCLUSIONS: The lower density of T. lestoquardi as mixed infection with T. ovis compared to single infection supports the hypothesis that T. ovis confers protection against lethal T. lestoquardi infection. However, there were no differences in disease correlations (clinical markers, hematological parameters, and density of parasites) or the extent of diversity of T. lestoquardi between the two types of infection. The presence of distinct T. lestoquardi genotypes in Barka, compared to that reported earlier in Oman, likely reflects movement of carrier animals and highlights the need for further analysis of the parasite populations to inform novel approaches for controlling malignant ovine theileriosis.
METHODS: A total of 390 blood samples were collected from 16 sheep pens located in Barka, Oman between July and November 2019. Theileria spp. were detected and quantified using qPCR assay targeting 18S rRNA, and the extent of genetic diversity was estimated by a panel of T. lestoquardi specific micro- and mini-satellites. The association of some disease markers with the presence of Theileria spp. and genetic diversity was tested.
RESULTS: Theileria spp. were detected in 75 (19.2%) sheep; of these 65 (86.7%) had mixed infections (T. lestoquardi plus T. ovis), 8 (10.6%) were infected with T. lestoquardi alone, and 2 (2.7%) with only T. ovis. Exotic breeds had a higher risk for Theileria spp. infection. The density (18S rRNA gene copies) of both parasites was higher in single infection against mixed infection, and there was a relatively lower density of T. lestoquardi in mixed infections. However, there was no difference in hematological indices between single T. lestoquardi and mixed infections. High genetic diversity was observed among T. lestoquardi in Barka, with no differences of T. lestoquardi in single and mixed infections. The extent of diversity seen in Barka was higher (He = 0.772) than that reported in Oman in 2019 (He = 0.582), with distinct T. lestoquardi genotypes.
CONCLUSIONS: The lower density of T. lestoquardi as mixed infection with T. ovis compared to single infection supports the hypothesis that T. ovis confers protection against lethal T. lestoquardi infection. However, there were no differences in disease correlations (clinical markers, hematological parameters, and density of parasites) or the extent of diversity of T. lestoquardi between the two types of infection. The presence of distinct T. lestoquardi genotypes in Barka, compared to that reported earlier in Oman, likely reflects movement of carrier animals and highlights the need for further analysis of the parasite populations to inform novel approaches for controlling malignant ovine theileriosis.
摘要：
背景：在阿曼进行的流行病学调查显示，在Barka地区的绵羊中，致病性泰利氏菌和非致病性泰利氏菌的并发患病率很高，阿曼。我们最近的数据说明了一种相互作用和降低的死亡风险在动物中共同感染的T.lestoquardi和T.Ovis，这表明后者赋予了对麻黄杆菌致病性的保护作用。本研究扩展了上述发现，并检查了疾病结果；临床标志物，血液学参数,和寄生虫密度在混合和单一的麻黄杆菌感染。
方法：从位于Barka的16个羊圈中收集了390份血液样本，2019年7月至11月之间的阿曼。Theileriaspp.使用靶向18SrRNA的qPCR检测和定量，遗传多样性的程度是由一组特定的Lestoquardi微型和微型卫星来估计的。某些疾病标志物与Theileriaspp的存在的关联。并对遗传多样性进行了测试。
结果：Theileriaspp。在75只(19.2%)绵羊中检测到；这65只(86.7%)患有混合感染(T。lestoquardi加T.ovis)，8例（10.6%）单独感染了利去夸迪，和2（2.7％），只有T.Ovis。外来品种对Theileriaspp的风险较高。感染。两种寄生虫的密度（18SrRNA基因拷贝）在单次感染中相对于混合感染较高，混合感染中的麻黄杆菌密度相对较低。然而,单一利去夸地T.single感染和混合感染之间的血液学指标没有差异。在Barka的列氏夸迪中观察到了高度的遗传多样性，在单一感染和混合感染中，麻黄病菌的含量没有差异。Barka的多样性程度（He=0.772）高于2019年阿曼的多样性程度（He=0.582），具有不同的莱氏夸脱菌基因型。
结论：与T.Ovis混合感染时，与单一感染相比，T.Ovis的密度较低，支持T.Ovis赋予针对致死性T.lestoquardi感染的保护作用的假设。然而,疾病相关性没有差异(临床标志物，血液学参数,和寄生虫的密度）或两种类型感染之间的麻黄酵母的多样性程度。Barka中存在明显的列氏夸脱菌基因型，与之前在阿曼报道的相比，可能反映了携带者动物的运动，并强调需要进一步分析寄生虫种群，以提供控制恶性绵羊theileriosis的新方法。
方法：从位于Barka的16个羊圈中收集了390份血液样本，2019年7月至11月之间的阿曼。Theileriaspp.使用靶向18SrRNA的qPCR检测和定量，遗传多样性的程度是由一组特定的Lestoquardi微型和微型卫星来估计的。某些疾病标志物与Theileriaspp的存在的关联。并对遗传多样性进行了测试。
结果：Theileriaspp。在75只(19.2%)绵羊中检测到；这65只(86.7%)患有混合感染(T。lestoquardi加T.ovis)，8例（10.6%）单独感染了利去夸迪，和2（2.7％），只有T.Ovis。外来品种对Theileriaspp的风险较高。感染。两种寄生虫的密度（18SrRNA基因拷贝）在单次感染中相对于混合感染较高，混合感染中的麻黄杆菌密度相对较低。然而,单一利去夸地T.single感染和混合感染之间的血液学指标没有差异。在Barka的列氏夸迪中观察到了高度的遗传多样性，在单一感染和混合感染中，麻黄病菌的含量没有差异。Barka的多样性程度（He=0.772）高于2019年阿曼的多样性程度（He=0.582），具有不同的莱氏夸脱菌基因型。
结论：与T.Ovis混合感染时，与单一感染相比，T.Ovis的密度较低，支持T.Ovis赋予针对致死性T.lestoquardi感染的保护作用的假设。然而,疾病相关性没有差异(临床标志物，血液学参数,和寄生虫的密度）或两种类型感染之间的麻黄酵母的多样性程度。Barka中存在明显的列氏夸脱菌基因型，与之前在阿曼报道的相比，可能反映了携带者动物的运动，并强调需要进一步分析寄生虫种群，以提供控制恶性绵羊theileriosis的新方法。
