Dissecting the molecular diversity of bovine digital dermatitis treponemes.

牛数字性皮炎（BDD）是一种跛足的牛存在于大多数奶牛群在英国和世界各地的报告。这种跛行是后脚后跟球茎之间发炎病变的结果。这种疾病特别重要，因为它对受影响的动物来说非常痛苦，导致动物福利不佳。尽管对常用抗生素有一些反应，但病变经常复发。该病是一个重要的全球粮食安全问题，因为它会导致奶牛产奶量减少和繁殖性能下降。此外，最近英国乳制品行业的成本可能高达每年2600万英镑，这对英国的经济竞争力产生了负面影响。目前已在绵羊中发现这种疾病，它被称为传染性羊数字性皮炎（CODD），其病变比经常报告完全失蹄的牛更严重。BDD已被确定为一种由细菌引起的传染病。大多数证据清楚地表明，被称为“密螺旋体”的细菌是BDD的常见病因。利物浦大学之前的研究已经澄清了这些细菌与BDD的关系，并将这些致病细菌分为三种不同的群体。这些研究已经允许从BDD病变中分离出70种梅毒体，比世界上从事该疾病研究的任何其他研究小组都要多。这种菌株收集是调查这些生物体如何在牛羊中产生如此严重疾病以及感染如何在动物之间如此容易传播的宝贵资源。在目前的拨款申请中，拟议的研究将利用这一大组分离物来调查这些有机体如何在牛中引起疾病，以及是否可以开发新的疫苗或治疗方法。这三种不同的细菌群（密螺旋体）在基因和实际特征方面彼此非常不同，但它们都能在牛蹄上定居并引起疾病。虽然不同的密螺旋体群可能相当多样化，但为了能够共享相同的“生态位”，它们可能仍然共享非常相似的机制，以便能够生长，生存和伤害奶牛。这种共同机制可能是细胞表面显示的蛋白质，负责结合或破坏宿主，如果在所有BDD三螺旋体中共享，则可能具有作为疫苗靶点的潜力。鉴定这些关键的细菌蛋白并确定它们是否与宿主免疫系统相互作用，有助于鉴定潜在的疫苗成分，从而实现在牛羊群体中预防疾病的战略。利物浦大学在基因组学和蛋白质组学的前沿技术上进行了大量投资，有了这些设备，现在可以进行以前不可能进行的大量实验。例如，这些密螺旋体的全基因组现在可以在相对较短的时间内生成。本研究拟利用这一前沿的测序技术，对该细菌所有可预测的致病特性进行大规模的研究。为了确认所鉴定的基因实际上是表达的，蛋白质组学方法将被用于鉴定所有的蛋白质，包括密螺旋体内部和表面的蛋白质。此外，牛血清将与细菌细胞表面蛋白一起孵育，以确定哪些细胞表面蛋白与抗体结合，从而确定哪些被牛的免疫系统检测到。这些研究将有助于确定致病细菌的特征，并进一步有助于潜在的疫苗设计。通过使用上述各种方法调查BDD，我们应该提高对这种疾病的了解，并为根除这种痛苦和昂贵的疾病做出贡献。

Bovine Digital Dermatitis (BDD) is a lameness of cattle present in the majority of dairy herds in the UK and reported throughout the world. This lameness is the result of inflamed lesions between the heel bulbs of the rear feet. The disease is of particular significance because it is very painful for the animal affected resulting in poor animal welfare. Despite some response to commonly used antibiotics, lesions frequently reappear. The disease is an important global food security issue because it causes reduction in milk production and poor reproductive performance in dairy cows. Furthermore, with the recent cost to the dairy industry in the UK likely to be as much as 26 million pounds per year, it has a negative effect the UK's economic competitiveness. The disease has now been identified in sheep, where it is known as Contagious Ovine Digital Dermatitis (CODD) with lesions more severe than seen in cattle with frequent reports of complete hoof loss. BDD has been identified as an infectious disease with a bacterial cause. The majority of evidence clearly identifies bacteria known as 'Treponema' as the common cause of BDD. Previous studies at the University of Liverpool have clarified the association of these bacteria with BDD and characterised these causal bacteria into three distinct groups. These studies have allowed for the isolation of 70 treponemes from BDD lesions, a greater number than any other research groups working on this disease worldwide. This strain collection is an invaluable resource for investigating how these organisms produce such severe disease in cattle and sheep and how the infection may so readily be transmitted between animals. The proposed research in this current grant application will use this large panel of isolates to investigate how these organisms cause the disease in cattle and whether novel vaccines or treatments can be developed. The three distinct groups of bacteria (treponemes) are very different from one another in terms of their genetics and their actual characteristics yet they are all able to colonise the bovine hoof and cause disease. Whilst the different treponeme groups may be quite diverse, to be able to share the same 'niche', they may still share very similar machinery to be able to grow, survive and damage the cow. This common machinery is likely to be proteins exhibited on the surface of the cell which are responsible for binding or damaging the host and if shared across all BDD treponemes may have potential as vaccine targets. Identification of these key bacterial proteins and determining whether they interact with the host immune system allows for identification of potential vaccine components and thus enable a strategy to prevent disease in cattle and sheep herds.At the University of Liverpool, there have been major investments in the current cutting edge technologies of genomics and proteomics and with these facilities it is now possible to perform substantial experiments not previously possible. For example, whole genomes of these treponemes can now be generated in a relatively short time. This study proposes to use this cutting edge sequencing technology to investigate, on a large scale all the predicted disease causing characteristics of the bacteria. To confirm that the genes identified are in fact expressed the proteomics approaches will be used to identify all the proteins both inside the treponemes and those on the surface. Furthermore cattle sera will be incubated with the bacterial cell surface proteins to identify which cell surface proteins are bound to by antibodies and therefore to actually identify which are detected by the cattle's immune system. These studies will help characterise the causal bacteria and further aid in potential vaccine design. By investigating BDD using the various methods described above, we should improve understanding of the disease and contribute towards the eradication of this painful and expensive disease.