Examination of immunomodulatory effects of gut microbiota manipulations in the chicken

食源性致病菌，尤其是沙门氏菌。和空肠弯曲杆菌，会导致人类严重疾病。这两种病原体占全球食物中毒病例的90%以上，加拿大每年至少有17,000例报告感染这两种细菌的病例。然而，这可能低估了问题的严重程度，因为许多病例仍未上报。据估计，美国每年发生超过400万例沙门氏菌病或弯曲杆菌病。鸡的肠道中可能藏有这些病原体，因此，在将这些病原体传播给人类的过程中发挥了重要作用。目前，有几种策略可以控制鸡的食源性病原体，包括使用益生菌。这些细菌通常是肠道细菌群落的成员，它们可以发挥广泛的功能，减少致病细菌在肠道的定植，改善肠道健康，并增强系统和局部的免疫反应。重要的是，在家禽生产中使用抗生素作为生长促进剂正受到越来越多的限制，最终将被完全禁止。这意味着需要确定抗生素替代策略，如益生菌，并扩大我们对其作用模式的理解。对益生元免疫学特性的仔细研究将为发现预防鸡传染性疾病的新策略提供平台。因此，本研究旨在阐明益生菌影响鸡免疫系统的机制。这些研究将强调预防沙门氏菌在鸡体内肠道定植的免疫学机制。拟议的研究结果预计将通过减少家禽的食源性病原体负担和脱落，促进建立和维持安全的食物链。此外，预计还会带来其他好处，如减少抗生素的使用及其对出现抗药性细菌株的影响，以及人类食物中存在抗生素残留。

Food-borne pathogens, especially Salmonella spp. and Campylobacter jejuni, cause serious illness in humans. These two pathogens account for over 90% of all food poisoning cases worldwide and there are at least 17,000 reported cases of infections with these two bacteria in Canada every year. However, this might be an underestimate of the extent of the problem, as many cases remain unreported. It is estimated that each year, over 4 million cases of salmonellosis or campylobacteriosis occur in the US. Chickens may harbour these pathogens in their intestines and, as a result, play an important role in transmission of these pathogens to humans. Currently, several strategies exist for control of food-borne pathogens in chickens, including the use of probiotic bacteria. These bacteria are usually members of the gut bacterial community, which could exert a wide array of functions leading to reduction of gut colonization by disease causing bacteria, improved gut health, and enhancement of systemic and local immune responsiveness. Importantly, the use of antibiotics in poultry production as growth promotants is becoming increasingly restricted and will be eventually banned altogether. This signifies the need to identify antibiotic replacement strategies, such as probiotics, and to expand our understanding of their mode of action. Careful examination of immunological attributes of prebiotics will provide a platform for discovering novel prophylactic strategies against infectious diseases in chicken. Thus, the proposed studies are aimed at elucidating the mechanisms through which probiotics influence the chicken immune system. These studies will emphasize the immunological mechanisms of protection against gut colonization by Salmonella in the chicken. Findings of the proposed studies are expected to facilitate the establishment and maintenance of a safe food chain by reducing food-borne pathogen burden and shedding in poultry. In addition, other benefits such as reduction in the use of antibiotics and its ensuing effects on emergence of antibiotic-resistant strains of bacteria and presence of antibiotic residues in human food are expected.