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Abstract：
BACKGROUND: Treponeme-Associated Hoof Disease (TAHD) is a polybacterial, multifactorial disease affecting free-ranging wild elk (Cervus canadensis) in the Pacific Northwest. Previous studies have indicated a bacterial etiology similar to digital dermatitis in livestock, including isolation of Treponema species from lesions. The lesions appear to progress rapidly from ulcerative areas in the interdigital space or along the coronary band to severe, ulcerative, necrotic, proliferative lesions under-running the hoof wall, perforating the sole, and contributing to hoof elongation, deformity, and overgrowth. Eventually the lesions undermine the laminal structure leading to sloughing of the hoof horn capsule. The objective of this study was to characterize the bacterial communities associated with hoof lesions, which were categorized into 5 stages or disease grade severities, with 0 being unaffected tissue and 4 being sloughed hoof capsule. We also wanted to determine if the etiology of TAHD through morphological changes was dominated by Treponema, as observed in hoof diseases in livestock.
RESULTS: The bacterial 16S rRNA gene was sequenced from 66 hoof skin biopsy samples representing 5 lesion grades from samples collected by Washington Department of Fish and Wildlife as part of a voluntary hunter program. Analysis of the relative abundance of bacterial sequences showed that lesions were dominated by members of the bacterial phyla Proteobacteria, Firmicutes, Spirochaetes, Bacteroidetes and Actinobacteria. In lesion samples, members of the genus Treponema, Porphyromonas, and Mycoplasma increased with lesion severity. Association analysis indicated frequent identification of Treponema with Porphyromonas, Bacteroides and other anaerobic Gram-positive cocci.
CONCLUSIONS: The bacterial 16S rRNA gene sequencing confirmed the presence of Treponema species at all stages of TAHD lesions, treponeme specie-specific PCR and histopathology, indicating that the morphological changes are a continual progression of disease severity with similar bacterial communities. Association and abundance of these other pathogenic genera within lesions may mean synergistic role with Treponema in hoof disease pathogenesis. Characterizing bacteria involved in lesion development, and their persistence during disease progression, provides evidence for science-based management decisions in TAHD infected elk populations.
RESULTS: The bacterial 16S rRNA gene was sequenced from 66 hoof skin biopsy samples representing 5 lesion grades from samples collected by Washington Department of Fish and Wildlife as part of a voluntary hunter program. Analysis of the relative abundance of bacterial sequences showed that lesions were dominated by members of the bacterial phyla Proteobacteria, Firmicutes, Spirochaetes, Bacteroidetes and Actinobacteria. In lesion samples, members of the genus Treponema, Porphyromonas, and Mycoplasma increased with lesion severity. Association analysis indicated frequent identification of Treponema with Porphyromonas, Bacteroides and other anaerobic Gram-positive cocci.
CONCLUSIONS: The bacterial 16S rRNA gene sequencing confirmed the presence of Treponema species at all stages of TAHD lesions, treponeme specie-specific PCR and histopathology, indicating that the morphological changes are a continual progression of disease severity with similar bacterial communities. Association and abundance of these other pathogenic genera within lesions may mean synergistic role with Treponema in hoof disease pathogenesis. Characterizing bacteria involved in lesion development, and their persistence during disease progression, provides evidence for science-based management decisions in TAHD infected elk populations.
摘要：
背景：密螺旋体相关蹄病（TAHD）是一种多细菌，影响西北太平洋自由放养的野生麋鹿（Cervuscanadensis）的多因素疾病。先前的研究表明，家畜中的细菌病因类似于数字皮炎，包括从病变中分离密螺旋体。病变似乎从指间空间或沿冠状动脉带的溃疡性区域迅速发展到严重，溃疡性,坏死,增生性病变在蹄壁下运行，在鞋底穿孔，有助于蹄伸长，畸形,和过度生长。最终，病变破坏了椎板结构，导致蹄角囊脱落。这项研究的目的是表征与蹄病变相关的细菌群落，分为5个阶段或疾病等级，其中0为未受影响的组织，4为脱落的蹄囊。我们还想通过形态学变化确定TAHD的病因是否由密螺旋体病主导，正如在牲畜蹄病中观察到的那样。
结果：从66个蹄皮肤活检样本中对细菌16SrRNA基因进行了测序，这些样本代表了华盛顿鱼类和野生动物部收集的5个病变等级，这是自愿猎人计划的一部分。对细菌序列的相对丰度的分析表明，病变由细菌门变形杆菌的成员主导，Firmicutes,螺旋藻,拟杆菌和放线菌。在病变样本中，密螺旋体属的成员，卟啉单胞菌,支原体随病变严重程度增加。关联分析提示与卟啉单胞菌频繁鉴别密螺旋体，拟杆菌和其他厌氧革兰氏阳性球菌。
结论：细菌16SrRNA基因测序证实在TAHD病变的所有阶段都存在密螺旋体物种，螺旋体物种特异性PCR和组织病理学，表明形态学变化是疾病严重程度的持续发展，细菌群落相似。病变内这些其他病原属的关联和丰度可能意味着与密螺旋体在蹄病发病机理中的协同作用。表征与病变发展有关的细菌，以及它们在疾病进展过程中的持久性，为TAHD感染麋鹿种群的科学管理决策提供了证据。
结果：从66个蹄皮肤活检样本中对细菌16SrRNA基因进行了测序，这些样本代表了华盛顿鱼类和野生动物部收集的5个病变等级，这是自愿猎人计划的一部分。对细菌序列的相对丰度的分析表明，病变由细菌门变形杆菌的成员主导，Firmicutes,螺旋藻,拟杆菌和放线菌。在病变样本中，密螺旋体属的成员，卟啉单胞菌,支原体随病变严重程度增加。关联分析提示与卟啉单胞菌频繁鉴别密螺旋体，拟杆菌和其他厌氧革兰氏阳性球菌。
结论：细菌16SrRNA基因测序证实在TAHD病变的所有阶段都存在密螺旋体物种，螺旋体物种特异性PCR和组织病理学，表明形态学变化是疾病严重程度的持续发展，细菌群落相似。病变内这些其他病原属的关联和丰度可能意味着与密螺旋体在蹄病发病机理中的协同作用。表征与病变发展有关的细菌，以及它们在疾病进展过程中的持久性，为TAHD感染麋鹿种群的科学管理决策提供了证据。
