Project Number: 6612-32000-054-00
Project Type: Appropriated

Start Date: Nov 15, 2006
End Date: Nov 14, 2011

Objective:
¿ Determine the role of avian astroviruses, avian reoviruses, avian rotaviruses and novel enteric viruses in inducing disease and production losses in poultry. ¿ Characterize the molecular, physico-chemical, and antigenic properties of viruses that induce enteric disease and production losses in poultry. ¿ Develop practical control strategies and diagnostic techniques for viruses causing enteric disease and production losses.

Approach:
Avian astroviruses, avian reoviruses and avian rotaviruses, among others, have been identified as the predominant virus families in specimens from commercial poultry flocks presenting with enteric disease. Initial work with each virus family shows a high level of genetic variation among isolates suggesting that: 1) disease induction is strain dependent, and 2) multiple serotypes of each virus are present in the field. Therefore, a minimum of 2 to 3 genetically variant isolates from enteric disease cases from each virus family will be evaluated for their pathogenesis. Pathogenesis studies will evaluate clinical, gross and microscopic lesions after exposure. Body weights will be used as a primary metric of disease severity. Virus shed times, immune dysfunction indicators and tissue tropism will also be evaluated. Once a virus is determined to be a cause of enteric disease as either a primary or pre-disposing agent, the isolate will be characterized further. Such characterization will include the development of specific antibody directed to the isolate and subsequent antigenic characterization by cross-neutralization assay. In depth genetic information will be collected and analyzed from target viruses by sequencing the entire genome and comparing with previously reported gene sequences from viruses of the same families in poultry and other species. With this information diagnostic tests that target virulent strains will be developed and bench validated. Two diagnostic test formats will be utilized, PCR based methods and micro-array based methods. Further characterization of the viruses will include evaluating: environmental stability, transmission characteristics, including age-related susceptibility to infection and disease.