Multilocus Sequence Typing of Pathogenic Treponemes Isolated from Cloven-Hoofed Animals and Comparison to Treponemes Isolated from Humans.
Multilocus Sequence Typing of Pathogenic Treponemes Isolated from Cloven-Hoofed Animals and Comparison to Treponemes Isolated from Humans.
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DOI：
10.1128/aem.00025-16
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发表时间：
2016-08-01
影响因子：
4.4
通讯作者：
Evans NJ
中科院分区：
文献类型：
--
作者：
Clegg SR;Carter SD;Birtles RJ;Brown JM;Hart CA;Evans NJ
密螺旋体与人类和动物的许多疾病有关。据报道，数字化皮炎(DD)密螺旋体可引起牛、绵羊、猪、山羊和野生麋鹿的严重病变，造成重大的全球动物福利问题和经济损失。这些螺旋体的挑剔之前排除了研究系统群内遗传多样性的可能性。我们分离的密螺旋体档案使多位点序列分型能够量化DD密螺旋体的多样性和种群结构。分离自三大洲9个国家不同动物宿主的菌株(n=121)。本文对目前分离的7个看家基因座位上的DD密螺旋体的分析证实了先前指定的三个系统群的分类：中型密螺旋体、噬菌密螺旋体和足密螺旋体。对7个DD密螺旋体管家基因的序列分析表明，每个系统群内的菌株之间的多样性水平普遍较低，不需要以前使用的“-like”后缀。令人惊讶的是，每个系统群中的所有分离物都聚集在一起，而不考虑宿主或地理来源，这表明相同的序列类型(STS)可以感染不同的动物。一些STS来自同一农场的多只动物，突出了可能在农场内的传播。几个STS感染了来自相似地理区域的多个主机，识别了可能频繁的主机间传播。有趣的是，足弓形虫通过形成两个独特的ST复合体，似乎比中型弓形虫或吞噬锥虫DD密螺旋体进化得更快。从不同宿主或地理区域分离的密螺旋体之间缺乏系统发育区分，这与其他临床相关螺旋体的数据形成了很大的对比。重要性最近数字皮炎(DD)密螺旋体的宿主范围从牛扩大到绵羊、山羊、猪和野生麋鹿，再加上不同宿主之间和与人类密螺旋体的16S rRNA基因序列高度相似，这表明相同的细菌种类可以在多个不同的宿主中引起疾病。这项多位点序列分型(MLST)研究进一步表明，从不同宿主分离的这些细菌确实非常相似，增加了跨物种传播的可能性。这项研究还表明，感染传播频繁，无论是在当地还是全球，这表明传播途径不只是动物之间的传播。这些结果表明，农场生物安全对于控制疾病在驯化物种中的传播是重要的。持续的监测和警觉对于确定这些重要病原体的进化和跟踪这些重要病原体的任何进一步的寄主范围的扩大是重要的。
Treponema species are implicated in many diseases of humans and animals. Digital dermatitis (DD) treponemes are reported to cause severe lesions in cattle, sheep, pigs, goats, and wild elk, causing substantial global animal welfare issues and economic losses. The fastidiousness of these spirochetes has previously precluded studies investigating within-phylogroup genetic diversity. An archive of treponemes that we isolated enabled multilocus sequence typing to quantify the diversity and population structure of DD treponemes. Isolates (n = 121) were obtained from different animal hosts in nine countries on three continents. The analyses herein of currently isolated DD treponemes at seven housekeeping gene loci confirm the classification of the three previously designated phylogroups: the Treponema medium, Treponema phagedenis, and Treponema pedis phylogroups. Sequence analysis of seven DD treponeme housekeeping genes revealed a generally low level of diversity among the strains within each phylogroup, removing the need for the previously used “-like” suffix. Surprisingly, all isolates within each phylogroup clustered together, regardless of host or geographic origin, suggesting that the same sequence types (STs) can infect different animals. Some STs were derived from multiple animals from the same farm, highlighting probable within-farm transmissions. Several STs infected multiple hosts from similar geographic regions, identifying probable frequent between-host transmissions. Interestingly, T. pedis appears to be evolving more quickly than the T. medium or T. phagedenis DD treponeme phylogroup, by forming two unique ST complexes. The lack of phylogenetic discrimination between treponemes isolated from different hosts or geographic regions substantially contrasts with the data for other clinically relevant spirochetes. IMPORTANCE The recent expansion of the host range of digital dermatitis (DD) treponemes from cattle to sheep, goats, pigs, and wild elk, coupled with the high level of 16S rRNA gene sequence similarity across hosts and with human treponemes, suggests that the same bacterial species can cause disease in multiple different hosts. This multilocus sequence typing (MLST) study further demonstrates that these bacteria isolated from different hosts are indeed very similar, raising the potential for cross-species transmission. The study also shows that infection spread occurs frequently, both locally and globally, suggesting transmission by routes other than animal-animal transmission alone. These results indicate that on-farm biosecurity is important for controlling disease spread in domesticated species. Continued surveillance and vigilance are important for ascertaining the evolution and tracking any further host range expansion of these important pathogens.