Department of Pathogenic Biology, College of Basic Medicine, Chengde Medical University, Chengde, Hebei, China.
College of Hetao, Bayannur, Inner Mongolia, China.
Ticks Tick Borne Dis. 2020 Sep;11(5):101477. doi: 10.1016/j.ttbdis.2020.101477. Epub 2020 May 29.
Anaplasma bovis is an organism significant to cattle and buffalo since it is one of the causative agents of bovine anaplasmosis. Previous studies have shown the worldwide distribution of A. bovis. However, most of these studies about its genetic diversity only focused on the rrs gene. In this study, DNA of A. bovis was detected in blood samples of cattle and goats in Xi'an city, China by nested-PCR. Near full-length rrs, groEL, and gltA genes were amplified successfully from the positive samples. Genetic analysis showed that specific genetic marker (an insertion and a deletion) was found in the rrs sequences in some strains, as well as clone 88 from monkeys in previous study. Phylogenetic analysis based on the rrs, groEL, and gltA genes revealed that A. bovis circulating in Xi'an exhibited great genetic diversity. Our results also indicated that variants outside China presented geographic clustering, and all A. bovis isolates based on the groEL or gltA gene also showed a host origin clustering. Also of note was that the phylogenetic analyses of the groEL and gltA genes suggested that both frequent dispersals over long distances in recent years and local adaptation over long evolutionary timescales played important roles in the distribution and evolution of A. bovis in China. Finally, a potential recombination event in the genome of Zhouzhi-cattle-10 based on inconsistent positions in the groEL and gltA trees was also observed. These results also reinforce the need for assessing the pathogenicity to humans of A. bovis variants with specific marker in the rrs gene.
牛无浆体是一种对牛和水牛具有重要意义的生物体，因为它是牛无浆体病的病原体之一。先前的研究表明，牛无浆体在世界范围内分布。然而，这些关于其遗传多样性的研究大多数仅集中在 rrs 基因上。在本研究中，通过巢式 PCR 从中国西安市牛和山羊的血液样本中检测到牛无浆体 DNA。从阳性样本中成功扩增了近全长 rrs、groEL 和 gltA 基因。遗传分析表明，一些菌株的 rrs 序列中发现了特定的遗传标记（插入和缺失），以及之前研究中来自猴子的克隆 88。基于 rrs、groEL 和 gltA 基因的系统发育分析表明，西安流行的牛无浆体表现出很大的遗传多样性。我们的结果还表明，中国以外的变异存在地理聚类，并且基于 groEL 或 gltA 基因的所有牛无浆体分离株也显示出宿主起源聚类。值得注意的是，groEL 和 gltA 基因的系统发育分析表明，近年来频繁的长距离传播和长期的局部适应在牛无浆体在中国的分布和进化中都发挥了重要作用。最后，还观察到基于 groEL 和 gltA 树中不一致位置的周至牛 10 号基因组中的潜在重组事件。这些结果也强调了需要评估 rrs 基因中具有特定标记的牛无浆体变异对人类的致病性。
