A natural model of immunomodulation for necrotic enteritis in poultry

  • Author / Creator
    He, Wanwei
  • Necrotic enteritis (NE) is an economically important disease in poultry, caused by the opportunistic pathogen Clostridium perfringens. Well-known as a multifactorial disease, NE development is under the influence of a wide range of environmental risk factors. Current in vivo NE challenge models typically incorporate pre-exposure to disease risk factors, in combination to inoculation of C. perfringens culture to obtain a clinical NE outcome. My first goal was to establish a model based on the natural uptake of C. perfringens from the barn environment to produce subclinical infection. We incorporated access to litter, coccidial exposure, feed composition, and feed withdrawal stress to achieve the commonly observed subclinical NE infection peak at 3 weeks post hatch.
    Antibiotics were traditionally used to control infectious diseases in poultry but has aroused public concern with the emergence of resistant microbes. As reduction and removal of antibiotics become the trend in poultry farming, my second goal was to understand the impact of antibiotic removal during a naturally-occuring NE condition. My data shows that drug-free animals showed short-term body weight decline during NE induction, though the overall feed intake, weight gain, feed conversion, and carcass traits were not affected. Surprisingly, medication treatment increased ileal pH and cecal pathogenic C. perfringens load. These findings suggest an urgent need for drug-free alternatives to combat NE infection as the industry is moving away from antibiotic use.
    Colonization by C. perfringens occurs early after hatch and induces host immune tolerance that allows it to persist as part of the bird's commensal flora. β-glucan, a yeast cell wall component, is well characterized for its immunomodulation capacity and has recently been identified as a primary driver of trained immunity. The last goal of the project was to assess if the context of early-life exposure to C. perfringens may affect NE infection outcomes. β-glucan was co-administered with C. perfringens and the impact on disease severity and bird performance was subsequently determined. Intra-abdominal injection of β-glucan post-hatch improved ileal morphology, prevented organ weight decline, and avoided NE-induced increase in feed conversion ratio. Further analysis revealed metabolic and functional changes of abdominal leukocytes following the initial stimulation, including increased glycolysis, proinflammatory cytokine expression, and ROS production. These results suggest that β-glucan can reduce the negative impacts of NE by influencing the context in which C. perfringens is first encountered.

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.