State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Xujiaping 1, Lanzhou, Gansu, 730046, People's Republic of China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, People's Republic of China.
Parasit Vectors. 2017 Nov 13;10(1):565. doi: 10.1186/s13071-017-2485-x.
Anaplasma marginale is an important tick-transmitted rickettsial pathogen of cattle, with worldwide distribution and an important economic impact. The genetic diversity of A. marginale strains has been extensively characterized in different geographical regions throughout the world, while information is limited on studies in China. This study was carried out to determine the prevalence and genetic diversity of A. marginale strains in cattle from ten provinces of China.
A total of 557 blood samples from cattle were collected and screened for the occurrence of A. marginale by PCR based on the msp4 gene. The partial msp1a gene containing tandem repeat sequences was further amplified from msp4 positive samples. The Msp1a amino acid repeats were identified, and genetic variation of A. marginale strains was characterized based on the variation in the repeated portion of Msp1a.
Our results showed that 31.6% of 557 cattle were positive for A. marginale. The infection rates of A. marginale varied considerably from 0 to 96.9% in different sampling regions. Sequence analysis revealed that two msp4 sequence variants of A. marginale exist in cattle. One hundred and three msp1a sequences were obtained and permitted to identify 42 Msp1a tandem repeats, 21 of which were not previously published for A. marginale. Moreover, 61 A. marginale genotypes were identified based on the structure of Msp1a tandem repeats.
Anaplasma marginale is widely distributed in China and a high prevalence of infection was observed in cattle. The geographical strains of A. marginale were molecularly characterized based on the structure of Msp1a tandem repeats. Forty-two Msp1a tandem repeats and 61 genotypes of A. marginale were identified. This study, for the first time, revealed the genetic diversity of A. marginale strains in cattle in China.
边缘无浆体（Anaplasma marginale）是一种重要的蜱传立克次体病原体，分布广泛，对牛具有重要的经济影响。在全球不同地理区域，已广泛对边缘无浆体菌株的遗传多样性进行了描述，而在中国的研究信息有限。本研究旨在确定来自中国十个省份的牛中边缘无浆体菌株的流行情况和遗传多样性。
共采集了 557 份来自牛的血液样本，通过基于 msp4 基因的 PCR 检测来筛查边缘无浆体的发生情况。从 msp4 阳性样本中进一步扩增了包含串联重复序列的部分 msp1a 基因。鉴定了 Msp1a 氨基酸重复序列，并根据 Msp1a 重复部分的变异特征来描述边缘无浆体菌株的遗传变异。
结果显示，557 头牛中有 31.6%为边缘无浆体阳性。不同采样区域的边缘无浆体感染率从 0 到 96.9%不等，差异很大。序列分析显示，牛中存在两种边缘无浆体 msp4 序列变体。获得了 103 个 msp1a 序列，可以识别 42 个 Msp1a 串联重复，其中 21 个是以前未发表过的边缘无浆体序列。此外，基于 Msp1a 串联重复结构，鉴定了 61 种边缘无浆体基因型。
边缘无浆体在中国广泛分布，牛中观察到高感染率。基于 Msp1a 串联重复结构对地理株边缘无浆体进行了分子特征描述。鉴定了 42 个 Msp1a 串联重复和 61 种边缘无浆体基因型。本研究首次揭示了中国牛中边缘无浆体菌株的遗传多样性。
