Effect of Nematode and Mycobacterium avium subspecies paratuberculosis Infections on the Ovine Intestinal Microbiome

农业中的疾病对农民来说是一个问题，因为它对他们的收入产生了负面影响，并降低了他们牲畜的福利。鸟分枝杆菌副结核亚种（MAP）是绵羊约翰氏病的病原体，也存在于其他经济相关的反刍动物如牛和山羊中。这种疾病的特征是由于肠壁增厚而导致的消瘦，减少营养吸收，并导致动物饥饿，尽管看起来正常进食。还已知MAP与寄生蠕虫如Teladorsagia circumcincta和Oesophagostomum columbianum共同存在，其可对疾病具有协同或机械导向作用。农民在试图控制MAP或防止其进入羊群时面临许多挑战。MAP通过粪口途径传播，并从受感染动物的粪便中排出到周围环境中，在那里它可以存活一年以上。传播也可能通过野生动物水库发生，包括野鹿，狐狸和兔子。绵羊在出生后的头几个月里通常会感染MAP，无论是来自粪便污染的土壤、水、表面还是从母乳中脱落。这种感染可能未被发现，因为许多病例是亚临床的;诊断测试的问题也可能导致约翰氏病被诊断不足。MAP与人类克罗恩病的相关性也存在争议，因此代表了潜在的公共卫生威胁。我们小组进行的初步研究表明，用驱虫剂治疗绵羊会导致肠道微生物群的变化，特别是未解决的线虫感染会导致潜在有益放线菌的水平降低。在导致该项目的其他工作中，从安格斯的一群农场饲养的绵羊中收集了三年内同时发生线虫和MAP感染的粪便样本，提供了单个绵羊和整个羊群内微生物群变化的纵向概况。这些基线数据将作为评估蠕虫治疗和疫苗接种对约翰氏病影响的参考。通过研究肠道微生物群的波动，将研究驱虫治疗对农场饲养的绵羊接种MAP疫苗的效果。该项目的目标是：使用元染色体组DNA测序来表征农场饲养的绵羊群中肠道微生物群的原核成分。使用qPCR和培养技术调查研究农场不同地点土壤中MAP的持久性，并将其与土壤条件、其他土壤微生物群和放牧这些地区的绵羊疾病联系起来。调查农场饲养的绵羊群中MAP感染、寄生虫感染和肠道微生物群之间的关系。使用诊断测试和微生物群分析评估疫苗对约翰氏病的有效性。评价驱虫治疗对疫苗效力的影响。这些信息将作为改进MAP和线虫感染的诊断和治疗策略的基础，以改善动物健康和福利。（492）

Disease in the agricultural industry is a problem for farmers as it negatively impacts their income as well as reducing the welfare of their livestock. Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of Johne's disease in sheep and found in other economically relevant ruminants such as cattle and goats. The disease is characterised by emaciation as a result of thickening of the intestinal wall, reducing nutrient absorption and causing the animal to starve despite appearing to eat normally. MAP is also known to co-occur with parasitic nematode worms such as Teladorsagia circumcincta and Oesophagostomum columbianum which can have a synergistic or mechanical vectoring effect on the disease. Farmers face many challenges when trying to control MAP or prevent it from entering their flocks. MAP is transmitted via the faecal-oral route and shed from infected animals in faeces to the surrounding environment where it can survive for over a year. Transmission may also occur via wildlife reservoirs including wild deer, foxes and rabbits. Sheep will often become infected with MAP in their first few months of life either from faecally-contaminated soils, water, surfaces or shedding from their mother's milk. This infection can go undetected as many cases are sub-clinical; problems with diagnostic testing can also lead to Johne's disease being under-diagnosed. MAP is also controversially associated with Crohn's disease in humans and so represents a potential public health threat. Preliminary studies carried out by our group have shown that treating sheep with anthelmintic leads to changes in the intestinal microbiota, specifically that an unresolved nematode infection leads to reduced levels of the potentially-beneficial Actinobacteria. In other work leading up to this project, faecal samples have been collected from a flock of farm-raised sheep in Angus with co-occurring nematode and MAP infections over a three-year period, providing a longitudinal profile of the changes in the microbiota within individual sheep and the flock as a whole. These baseline data will form the reference against which the effects of worm treatment and vaccination against Johne's disease will be assessed. By studying the fluctuations in the intestinal microbiota, the effect of anthelmintic treatment on the efficacy of vaccination against MAP in farm-raised sheep will be investigated.The project will aim to:Characterise the prokaryotic component of the gut microbiota in a farm-raised sheep flock using metataxonomic DNA sequencing. Investigate the persistence of MAP in soils at different locations on the study farm using qPCR and culture techniques, and link this to soil conditions, other soil microbiota and disease in the sheep which graze these areas.Investigate the relationship between MAP infection, parasitic worm infection and intestinal microbiota in a farm-raised sheep flock. Assess vaccine efficacy against Johne's disease using diagnostic testing and microbiota profiling. Evaluate the impact of anthelmintic treatments on vaccine efficacy.This information will be used as a basis for improving diagnostic and treatment strategies for MAP and nematode infection to improve animal health and welfare. (492)