Examination of immunomodulatory effects of gut microbiota manipulations in the chicken

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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.