Respiratory Pathogen Studies in Chickens with IBDV Induced Immune Suppression.

PI: Daral J. Jackwood

Objective 2. Investigate the multifactorial etiology involving poultry respiratory diseases.

Activity 2.1:
Studies on the interactions of respiratory pathogens in broilers and layers should consider the effect of IBDV on the clinical outcomes and transmission patterns of the respiratory pathogens being examined. Some combinations of respiratory pathogens may cause mild or subclinical disease that would be economically inconsequential. These pathogens may be naturally attenuated or in some cases, live-attenuated vaccine strains. Combining these infectious agents with IBDV induced immune suppression may dramatically alter the clinical outcome of the respiratory disease.

Research Plan:
Combinations of respiratory pathogens that cause little or no clinical disease in broiler and layer chickens will be targeted. These combinations will be repeated in chickens that have been given a previous or concurrent inoculation of IBDV. The strain of IBDV selected for these studies is an antigenic variant (T1) that has been proven to cause immune suppression in the presence of maternal immunity to classic and variant vaccine strains of IBDV.

The experiments described for the co-infection of SPF broiler and layer chickens with LPAIV, IBV and/or Mycoplasma are described (Pantin-Jackwood, USDA). These experiments will be repeated using SPF broilers and layers that have been inoculated with IBDV at one-week pre-challenge or simultaneously with the respiratory agents. The metrics of clinical disease previously described will be compared to that observed for these respiratory pathogens given in the absence of IBD.

Yearly Goals:

Year 1:
Co-infection of SPF and commercial broiler chickens with H5N2 LPAIV, IBV (vaccine strain) and MS. (see Mary J. Pantin-Jackwood Project).

Year 2:
Inoculate 1 week old SPF and commercial broilers with IBDV (T1) then 1 week later repeat the co-infection of these birds with H5N2 LPAIV, IBV (vaccine strain) and MS.

Year 3:
Inoculate 1 week old SPF and commercial broilers with IBDV (T1) and simultaneously co-infect them with H5N2 LPAIV, IBV (vaccine strain) and MS.

Potential Impact and Expected Outcomes:
These studies will help define the role of immune suppression on respiratory disease in chickens. Previous studies on the co-infection of IBDV and respiratory pathogens have shown an increase in the severity of respiratory lesions. Our studies will be on combinations of respiratory pathogens that produce little or no clinical disease alone. The role of IBDV induced immune suppression on these respiratory agents will provide practical information on when and how IBD should be controlled to prevent respiratory disease in chickens.

wpadminProject Jackwood