Wang Ye, Wang Bo, Zhang Qingxun, Li Ying, Yang Ziwen, Han Shuyi, Yuan Guohui, Wang Shuangling, He Hongxuan
National Research Center for Wildlife Borne Diseases, Institute of Zoology, Chinese Academy of Sciences, Beichen West Road, Chaoyang District, Beijing, 100101, China.
College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
Acta Parasitol. 2021 Dec;66(4):1177-1185. doi: 10.1007/s11686-021-00381-9. Epub 2021 Apr 11.
The tick-borne protozoa piroplasms, including Theileria and Babesia, are the cause of substantial economic losses to the livestock industry. However, in southern Qinghai province, China, there are limited information on the molecular characteristics of piroplasms. This study therefore aimed at determining the prevalence and genetic diversity of piroplasms.
In order to detect piroplasms, we examined 330 yaks and 236 Tibetan sheep blood samples by nested PCR. The differences in piroplasms prevalence in relation to different risk factors was analyzed using SPSS 26. Phylogenetic analysis based on 18S rRNA sequences was inferred using MEGA 7.
During this study, Theileria spp. were detected in 33.6% (111/330) of yaks and 94.1% (222/236) of Tibetan sheep, but no Babesia was identified. Importantly, a comparison study revealed that T. ovis infection was highly prevalent in sheep (94.1%) but infrequent in yaks (6.1%), while T. sinensis was host-specific to yaks with an infection rate of 27.6%. In addition, male animals were more likely to be infected by T. sinensis and female animals were more likely to be infected by T. ovis. And animals below 4000 m areas reported a higher infection rate with T. sinensis (26.1% vs. 2.9%, p < 0.001). Alongside these differences in prevalence, we found a significantly higher T. sinensis infection rate in separated-grazing livestock (22.2% vs. 3.7%, p < 0.001), while mixed-grazing ruminants had a higher T. ovis infection rate (50.0% vs. 39.0%, p = 0.014). Furthermore, sequence analysis revealed that the 18S rRNA sequences obtained in this study shared 86.9-100.0% identities with each other and they were clustered into T. sinensis or T. ovis.
To our knowledge, this is the first report of T. sinensis in Qinghai region. In addition, high prevalence of the generally sub-clinical T. ovis in sheep indicates extensive exposure to ticks and transmission of tick-borne pathogens with a significant economic impact. This study provides insights into the distribution and genetic diversity of Theileria in China.
蜱传播的原生动物梨形虫，包括泰勒虫属和巴贝斯虫属，给畜牧业造成了巨大的经济损失。然而，在中国青海省南部，关于梨形虫分子特征的信息有限。因此，本研究旨在确定梨形虫的流行率和遗传多样性。
为了检测梨形虫，我们通过巢式PCR检测了330份牦牛和236份藏绵羊的血液样本。使用SPSS 26分析梨形虫流行率与不同风险因素之间的差异。基于18S rRNA序列，使用MEGA 7进行系统发育分析。
在本研究中，在33.6%（111/330）的牦牛和94.1%（222/236）的藏绵羊中检测到泰勒虫属，但未发现巴贝斯虫。重要的是，一项比较研究表明，绵羊中绵羊泰勒虫感染率很高（94.1%），而牦牛中则很少见（6.1%），而中华泰勒虫对牦牛具有宿主特异性，感染率为27.6%。此外，雄性动物更易感染中华泰勒虫，雌性动物更易感染绵羊泰勒虫。海拔4000米以下地区的动物中华泰勒虫感染率较高（26.1%对2.9%，p<0.001）。除了流行率的这些差异外，我们发现散养牲畜的中华泰勒虫感染率显著更高（22.2%对3.7%，p<0.001），而混养反刍动物的绵羊泰勒虫感染率更高（50.0%对39.0%，p=0.014）。此外，序列分析表明，本研究获得的18S rRNA序列彼此之间的同源性为86.9%-100.0%，它们被聚类为中华泰勒虫或绵羊泰勒虫。
据我们所知，这是青海地区中华泰勒虫的首次报道。此外，绵羊中通常为亚临床感染的绵羊泰勒虫的高流行率表明蜱的广泛暴露以及蜱传播病原体的传播，具有重大经济影响。本研究为中国泰勒虫的分布和遗传多样性提供了见解。
