Applying recombinant technologies to define the secretome of M.a. paratuberculosis for the discovery of potential immunogens and diagnostic reagents

约翰氏病（JD）是一种影响反刍动物如牛、山羊、绵羊、麋鹿和鹿的不可治愈的慢性消耗性疾病。动物通过食用食物、水或牛奶中的活的鸟分枝杆菌副结核亚种（或MAP）细菌而感染。 JD影响加拿大所有地区的牛群，多达40%的奶牛群报告感染动物。受感染牲畜的畜群由于产奶量、生育力下降和对患病牲畜的扑杀增加而遭受非常重大的经济损失。也有人担心MAP与人类克罗恩病的某些病例之间可能存在关联。这些关注将继续下去，直到有明确的证据反对这种联系，但如果这种联系被确定，这将是毁灭性的养牛业。目前还没有保护动物免受感染的疫苗，也没有预防或减少粪便和牛奶中MAP脱落的治疗方法。然而，JD可以通过阻止MAP在奶牛之间的传播来控制，这一目标可以通过在受感染的动物开始脱落细菌之前识别和清除它们来实现。然而，目前的诊断测试缺乏检测具有早期阶段（或亚临床）疾病的动物的灵敏度和特异性。为了开发这样的测试，需要研究工作来建立我们对MAP细菌的生物学和遗传学的理解，并发现可用于设计MAP特异性诊断测定和可能的疫苗的MAP组分。迄今为止，只有少数MAP蛋白已被确定和充分表征。我们的研究目的是利用目前的重组技术来表征MAP分泌的蛋白。分泌的蛋白质首先与宿主接触，决定感染的过程，并含有宿主免疫系统识别的抗原，以诱导抗体和细胞介导的应答。表征分泌蛋白在发现用于分析宿主免疫应答、诊断感染以及区分接种疫苗和感染宿主的新型试剂方面也具有实际应用。

Johne's disease (JD) is an incurable chronic and wasting disease affecting ruminant animals such as cows, goats, sheep elk and deer. Animals become infected by eating live Mycobacterium avium subspecies paratuberculosis (or MAP) bacteria in food, water or milk. JD affects herds in all regions of Canada with up to 40% of dairy herds reporting an infected animal. Herds with infected animals suffer very significant economic looses from decrease in milk production, fertility and increased culling of sick animals. There is also concern regarding the possible association between MAP and some cases of Crohn's disease in humans. These concerns will continue until there is definitive proof against such a link but it would be devastating to the cattle industry if such link were established. Currently there are no vaccines that protect animals against infection and no treatments that prevent or reduce MAP shedding in feces and milk. However, JD can be controlled by stopping the cow-to-cow spread of MAP and this goal can achieved by identifying and removing infected animals before they start shedding the bacterium. However, the current diagnostic tests lack the sensitivity and specificity to detect animals with early stage (or subclinical) disease. To develop such tests, research effort is needed to build on our understanding of the biology and genetics of MAP bacteria and to discover MAP components that can be used to design MAP-specific diagnostic assays and possibly vaccines. To date only a few MAP proteins have been identified and fully characterized. The purpose of our study is to use current recombinant technologies to characterize the proteins secreted by MAP. Secreted proteins make first contact with the host, determine the course of infection and contain the antigens recognized by the host immune system to induce antibody and cell mediated responses. Characterizing secreted proteins also has practical application in the discovery of novel reagents for profiling host immune responses, diagnosis of infection, and differentiation between vaccinated and infected hosts.