Location: Endemic Poultry Viral Diseases Research
Project Number: 6040-32000-084-002-A
Project Type: Cooperative Agreement
Start Date: Aug 28, 2025
End Date: Aug 27, 2028
Objective:
Objective 1: Develop and validate ARV infection models for avian reovirus (ARV) that mimic natural infections with ARV more closely than footpad inoculation in both chickens and turkeys
Objective 2: Test how single and mixed infections, including infections with (apparently) non-pathogenic viruses, affect the immune response, intestinal microbiota and metabolome, and, in the case of mixed infections act synergistically in causing clinical signs and pathological lesions.
Objective 3: Discover and characterize the baseline, gut microorganism composition in commercial broiler flocks, and determine which gut microbiota components are correlated with good health, economically important weight gain and disease resistance.
Objective 4: Determine the genetic basis of virulence in the avian reoviruses, as a basis for attenuation of candidate vaccine strains when the reverse genetics system becomes available.
Approach:
Objective 1: (1) Compare oral inoculation with footpad and occulonasal inoculation. (2) Infect young chickens orally with ARV and test for effects on the immune response, intestinal microbiota and metabolome as well as pathological lesions. (3) Inoculate embryonated chicken eggs with ARV pre-incubation and test for effects on hatchability, infection rates after hatch and development of clinical signs and pathological lesions.
Objective 2: Several animal trials will be conducted to investigate how infection with avian reovirus (ARV), either alone or in combination with Eimeria spp., as well as chicken anemia virus (CAV) influence the immune response in bursa and thymus as well as the intestinal microbiome and metabolome. Immune profiling and immunohistochemistry of relevant tissues will evaluate pathogen-specific immune responses and their modulation during co-infections. In-vitro experiments will investigate the effect of inoculation with ARV on the metabolome in various cell types.
Objective 3: Samples of intestines, Bursa Fabricii and thymus will be collected from clinically healthy flocks to establish a baseline for the prevalence of various pathogens that may or may not cause disease, depending on the environment and the presence of other microorganisms. These include ARV, Eimeria spp., fowl adenovirus, CAV, and infectious bursal disease virus. In addition, the intestinal microbiota will be characterized. Detected pathogens will be genotyped. Isolated ARV will be sent to US National Poultry Research Center for genotyping and use in animal trials.
Objective 4: (1) Inoculate virulent ARV into a variety of cell types (liver/LMH, myoblast/QM5, myeloid/HD11) and passage until attenuation. (2) Subject a variety of S1133-derrived strains of ARV to whole-genome sequencing. (3) Using the data from objectives 4.1 and 4.2, determine which genetic changes resulted in reduced virulence.