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

农业中的疾病是农民面临的一个问题，因为它会对农民的收入产生负面影响，还会减少他们牲畜的福利。禽类副结核分枝杆菌(MAP)是绵羊约翰氏病的病原体，在牛和山羊等其他经济相关的反刍动物中也有发现。这种疾病的特征是由于肠壁增厚而导致的消瘦，降低了营养吸收，并导致动物在看起来吃得正常的情况下挨饿。已知MAP还与寄生线虫共生，如圆锥线虫和柱状食道线虫，这些线虫对疾病具有协同或机械媒介作用。农民在试图控制地图或阻止地图进入他们的羊群时面临着许多挑战。MAP通过粪便-口腔途径传播，并从粪便中的受感染动物排泄到周围环境，在那里它可以存活一年以上。传播也可能通过野生动物宿主，包括野鹿、狐狸和兔子。绵羊在出生的头几个月经常会感染MAP，要么是因为受到粪便污染的土壤、水、表面，要么是因为它们母亲的乳汁脱落。这种感染可能不会被发现，因为许多病例都是亚临床的；诊断检测的问题也可能导致约翰氏病被低估。MAP还与人类克罗恩病有争议，因此代表着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区系发生变化，特别是未解决的线虫感染会导致潜在有益的放线杆菌水平下降。在该项目之前的其他工作中，从安古斯农场饲养的一群患有线虫和MAP感染的绵羊身上收集了粪便样本，在三年的时间里，提供了单个绵羊和整个羊群内微生物区系变化的纵向轮廓。这些基线数据将成为评估蠕虫治疗和约翰氏病疫苗接种效果的参考。通过研究肠道微生物区系的波动，将研究驱虫治疗对农场饲养绵羊MAP疫苗接种效果的影响。该项目的目标是：使用元分类DNA测序来表征农场饲养绵羊肠道微生物区系的原核成分。利用定量聚合酶链式反应和培养技术调查MAP在研究农场不同地点土壤中的持久性，并将其与土壤条件、其他土壤微生物区系和放牧绵羊的疾病联系起来。调查MAP感染、寄生虫感染与农场饲养绵羊肠道微生物群的关系。使用诊断测试和微生物区系分析评估针对约翰氏病的疫苗效力。评估驱虫治疗对疫苗效果的影响。这些信息将被用作改进MAP和线虫感染的诊断和治疗策略的基础，以改善动物的健康和福利。(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)