1a. Objectives (from AD-416):
Objective 1: Develop bacteriophage as an alternative to antibiotics to prevent and treat pertinent poultry diseases such as turkey coryza. Sub-objective 1A: Isolate bacteriophage with activity to clinically relevant Bordetella avium isolates. Sub-objective 1B: Establish a model to study turkey coryza. Sub-objective 1C: Determine the efficacy of bacteriophage to prevent Bordetella avium induced turkey coryza. Sub-objective 1D: Determine the efficacy of bacteriophage to treat Bordetella avium induced turkey coryza. Objective 2: Determine the role of stress-induced immunosuppression in the pathogenesis of Clostridial dermatitis (CD) in turkeys and runting stunting syndrome (RSS) in chickens, and the efficacy of immunomodulation in reducing their incidence and severity. Sub-objective 2A: Develop an experimental model for CD in turkeys using dexamethasone (Dex) immunosuppression, transport stress, and Escherichia coli respiratory challenge and evaluate herbal immunomodulators for their efficacy in decreasing CD incidence. Sub-objective 2B: Evaluate the efficacy of adaptogenic herbal immunomodulators in early feeding as a management strategy for the prevention of RSS. Objective 3: Develop diagnostic tools to evaluate the role of antimicrobial peptides in stress-induced immunosuppression.
1b. Approach (from AD-416):
Bacteriophage targeted to the bacteria Bordetella avium, the cause of turkey coryza, will be isolated from environmental sources. We will develop a model to study the effects of bacteriophage to both prevent and treat turkey coryza by spray administration and environmental augmentation of bacteriophage. We will use our stress response model to evaluate the role stress plays in Clostridial dermatitis (CD) in turkeys and runting stunting syndrome (RSS) in chickens. Using this model we will evaluate the efficacy of feed and /or water delivered adaptogenic herbal immunomodulators as a management strategy for the prevention of these costly diseases. We will also develop tools to evaluate the role of antimicrobial peptides in stress-induced immunosuppression. These approaches are an effort to find practical alternatives to antibiotics to reduce the impact diseases have on poultry production.
3. Progress Report:
We have not been able to develop a practical method to administer bacteriophage in the hatchery that would prevent colibacillosis. Therefore, we believe these data suggest that the most practical way to administer bacteriophage to prevent colibacillosis in poultry would be to introduce bacteriophage to the environment, which could reduce the infectious levels of the targeted pathogen. We have been unable to initiate the study of turkey Clostridial Dermatitis due to the high cost of turkeys and turkey feed. We have instead continued work on our 36-month and 48-month milestones, developing an experimental model for runting-stunting syndrome (RSS) in broiler chickens and optimizing herbal treatments for RSS. Broiler chicks from ascites-resistant and ascites-susceptible genetic lines have been bred, hatched, and orally challenged with E. coli in a cold–stress model that results in significant reduction in body weight in both lines of birds. Commercial chicks have also been studied, and the model is reproducible. Two abstracts describing this model will be presented at the 2013 Meeting of the American Association of Avian Pathologists. The adaptogen, Rhodiola rosea, has been used in two studies as a feed supplement to decrease mortality and improve production values of cold-stressed and E. coli challenged birds in the RSS model. Work is continuing on optimization of this treatment. Antimicrobial peptides such as beta defensins play an important role in innate immunity and thus have potential to decrease susceptibility to infection. Immunoassays of these peptides that are applicable to several different species of poultry are desirable if the peptides are homologous and have conserved regions. We examined the peptide sequences of avian beta defensin-2 (AvBD2) of chicken, turkey, pheasant, and quail, and found >80% identities. Because AvBD2 is produced in large amounts due to its production by heterophils and epithelial cells, it may be possible to develop common reagents to measure aAvBD2 production for diagnostic applications involving stress in several species of poultry to achieve our projected milestone. Developing antibodies to conserved regions of peptides is waiting for additional fund availability.
1. Stress can result in Clostridial dermatitis of turkeys. Clostridial dermatitis of turkeys has recently been ranked by producers as the most important disease affecting turkey production. An analysis of multiple studies spanning a number of years of research from our laboratory at Fayetteville, Arkansas, quantitated turkey Clostridial dermatitis incidence as the result of dexamethasone immunosuppression. This work was related to a stress model developed by our scientists and was published in the journal Avian Diseases. This publication is the first to establish the role of stress in this important turkey disease and should lead to production methods to minimize stress such as single house production and decreased density.