Defining early entry mechanisms of Mycobacterium avium paratuberculosis into the host

约翰氏病（JD）是由鸟分枝杆菌亚种副结核（MAP）感染引起的反刍动物肠道常见病和慢性疾病。在感染后的早期阶段，动物几乎没有表现出该病的迹象，这使得很难发现该病，并且容易使感染在不被注意的情况下传播。JD对牛羊的健康和福利有重大影响，经济损失与生产力下降和慢性阶段的高死亡率有关。在英国和世界范围内，JD是一个潜在的和日益严重的问题，除了测试和屠宰之外，没有有效的控制措施。这部分是因为MAP能够隐藏和操纵免疫系统，但也反映了该领域研究人员的相对缺乏和整合，MAP的增长缓慢以及在目标宿主中进行实验研究的高成本。我们建议研究在感染不同毒力的MAP菌株后的早期阶段，MAP如何与肠道内的宿主细胞相互作用。我们将使用多种方法来确定MAP进入肠道的关键细胞类型和机制。这些包括可处理的小鼠模型，肠道样肠和外科肠环，提供了map -宿主相互作用的独特概述。此外，我们建议明确MAP基因在生存和复制中的作用。这些研究将弥补目前知识方面的根本差距，并将促进合理设计控制和治疗MAP感染的战略。我们的提议汇集了具有互补专业知识、已建立的感染模型和已证实的合作记录的研究人员。我们有三个相互关联的目标：1)使用小鼠模型确定MAP在肠道粘膜运输中涉及的细胞类型，以准确识别进入的细胞入口；2)使用肠样和外科肠环模型确定MAP在牛肠道运输的机制，以确定进入的关键途径和机制；3)使用靶向和随机诱变方法确定宿主组织入侵和生存所需的关键MAP基因在MAP，牛免疫学，粘膜免疫反应和细胞内细菌方面拥有独特的专业团队。主要成果将是确定控制进入的关键宿主和病原体因素，这些因素可能成为未来疾病控制干预战略的目标。

Johne's disease (JD) is a common and chronic disease of the gut of ruminants caused by infection with the pathogen Mycobacterium avium subspecies paratuberculosis (MAP). At early stages following infection animals show little evidence of the disease, making it difficult to detect and easy for infection to spread unnoticed. JD has a significant impact on the health and welfare of cattle and sheep, with economic losses associated with reduced productivity and high mortality in the chronic stage. JD is an insidious and increasing problem in the UK and world-wide, with no effective control measures in cattle other than test and slaughter. This is partly because MAP is able to hide from and manipulate the immune system but also reflects the relative paucity and integration of researchers in the area, slow growth of MAP and high cost of experimental studies in target hosts.We propose to investigate how MAP interacts with host cells in the gut at early stages following infection with strains of MAP of varying virulence. We will use a combination of methods to determine the critical cell types and mechanisms utilised by MAP for entry into the gut. These include tractable murine models, gut enteroids and surgical gut loops providing a unique overview of the MAP-host interaction. Moreover, we propose to define the role of MAP genes in survival and replication. These studies will address fundamental gaps in current knowledge and will facilitate the rational design of strategies to control and treat MAP infections.Our proposal brings together researchers with complimentary expertise, established models of infection and a proven record of collaboration. We have three inter-linked objectives:1) Define the cell types involved in transit of MAP across the gut mucosa using mouse models to accurately identify the cellular portal of entry2) Characterise the mechanisms by which MAP transits the bovine gut using enteroids and surgical gut loop models to identify critical pathways and mechanisms of entry3) Identify critical MAP genes required for host tissue invasion and survival using targeted and random mutagenesis approaches This project brings together a unique team with expertise in MAP, bovine immunology, mucosal immune responses and intracellular bacteria. The major output will be the definition of key host, and pathogen factors that control entry and that could be targets for future intervention strategies for disease control.