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 demonstrated that neither a coarse or fine bacteriophage spray was able to protect day-old chicks challenged with Escherichia coli by the intra-tracheal route. We have completed two studies on the ability of an in ovo administration of bacteriophage to prevent colibacillosis when the birds are challenged with E. coli at day of age. In ovo bacteriophage decreased both mortality and the isolation of the challenge strain of E. coli from the liver. These studies were conducted to find a practical way to administer bacteriophage at the hatchery to prevent colibacillosis. We have been unable to initiate a trial for turkey Clostridial Dermatitis due to the high cost of turkeys and turkey feed. We have instead begun our 36-month milestone, developing an experimental model for runting-stunting syndrome in broiler chickens. Broiler chickens from ascites-resistant and ascites-susceptible genetic lines have been bred, hatched, and orally challenged with two E. coli isolates. Both E. coli isolates have produced significant reduction in body weight in both lines of birds. We have designed an AvBD2 peptide; however, we have not yet outsourced it for antibody production. Chicken and turkey AvBD2 have been purified.
1. Complete amino acid sequences of pheasant and quail avian beta defensin 2 (AvBD2). We have been able to identify mature functional peptides in tissue extracts using mass spectrometry. Using this technology we have been working to identify and characterize AvBD2 in avian species where the genome is not yet known. We have determined the amino acid sequences of both pheasant and quail AvBD2. The AvBD2 from both species are 36 amino acids long and similar to chicken, turkey, duck, and ostrich AvBD2. The defensins are antimicrobial peptides and are an integral part of innate immunity. Because of its abundance, the concentration of AvBD2 in blood may be a useful indicator of pathogen exposure and the status of immunity. Besides immunoassay, mass spectrometry offers methods that can determine blood levels of AvBD2 in birds.
Durairaj, V., Clark, F.D., Coon, C., Huff, W.E., Okimoto, R., Huff, G.R., Rath, N.C. 2012. Effects of high fat diet and prednisolone treatment on femoral head separation in chickens. British Poultry Science. 53(2):198-203.