2007 Annual Report 1a.Objectives (from AD-416) • 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. 1b.Approach (from AD-416) 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. 3.Progress Report None. 4.Accomplishments Development of a quantitative real-time RT-PCR (qRRT-PCR) test to measure turkey cytokine expression. Few tools are available for evaluating the turkey immune response therefore this assay, which measures changes in the expression of immune system genes was developed. The turkey cytokine qRRT-PCR test will allow for researchers to look at the immune system of turkeys in more depth and to understand the effect of viruses on the immune system. Since viral immunosuppression can impact vaccine efficacy and may be a factor in causing enteric disease, this will help to elucidate the mechanism of disease. This accomplishment is in the National Program 103 Animal Health (100%), Component 6 - Countermeasures to Prevent and Control Enteric Diseases. Problem statement 6B: Enteric Diseases of Poultry. The pathogenesis of recent isolates of turkey astrovirus type-2 (TAstV-2)was evaluated in poults at hatch. Previous work has shown that nearly 100% of turkey flocks in the U.S. are exposed to TAstV-2. It was also shown that there are genetic variants of TAstV-2 which differ substantially from viruses characterized in the 1990’s. Although, there was variation among the isolates in disease severity, these studies revealed that these genetic variants all caused weight depression, which the most critical aspect of enteric disease for the turkey industry. Understanding which viruses are important for disease aids control and identification of the genetic elements of the viruses which are related to disease will elucidate the mechanism of disease. This accomplishment is in the National Program 103 Animal Health (100%), Component 6 - Countermeasures to Prevent and Control Enteric Diseases. Problem statement 6B: Enteric Diseases of Poultry. 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Review Publications Pantin Jackwood, M.J., Spackman, E., Woolcock, P.R. 2006. Molecular characterization and typing of chicken and turkey astroviruses circulating in the United States: Implications for diagnostics. Avian Diseases. 50:397-404. Pantin Jackwood, M.J., Spackman, E., Day, J.M. 2007. Pathology and virus tissue distribution of turkey origin reoviruses in experimentally infected turkey poults. Veterinary Pathology. 44:185-195.