Control of Emerging and Re-Emerging Poultry Respiratory Diseases in the United States

NON-TECHNICAL SUMMARY: Respiratory bacterial and viral diseases are the major group of diseases affecting poultry. Many endemic respiratory infectious diseases in the U.S. continue to decrease the profitability of commercial poultry production. Furthermore, chickens immunosuppressed by IBDV infection are more susceptible to respiratory infections. It is, therefore, critical to control and prevent the merging and re-emerging poultry respiratory diseases in the United States. Such challenges posed by the number of different disease etiologies and their complexities require a collaborative multistate research effort. Indiana will identify reservoirs of infectious respiratory disease agents (AIV and APV) in wild birds and poultry in Indiana and Midwestern US, study the pathogenesis of IBD regarding the interaction of IBDV with the host tissues/cells, study the genotypes, pathogenicity, and immunogenicity of IBDV strains and isolates obtained from US and Asia in chickens and turkeys, determine the effect of IBDV infection on the pathogenicity of avian respiratory infectious diseases (avain influenza and avian mycoplasmosis), and optimize DNA vaccination to confer protection of chickens against IBDV infection. The overall impact of a successful outcome from the proposed project will be the advancement of diagnostics, development of vaccine, and implementation of eradication protocols for poultry respiratory diseases and related immunosuppressive diseases that will benefit the poultry industry.

<P>
APPROACH: Objective 1: Indiana will conduct surveillance of avian influenza virus (AIV) in wild birds, backyard poultry, and commercial poultry in Indiana. Surveillance will be performed in commercial poultry, backyard poultry, live bird markets and auctions, wild aquatic birds, and swine. AIV will be detected by virus isolation and real-time RT-PCR. Indiana will participate in studying the prevalence of avian pneumovirus (APV) in commercial turkeys and wild birds in the Midwestern US. Sero-surveillance studies for APV will be conducted in hunter-killed waterfowl, trapped wild birds, and in commercial turkeys. Objective 3: Indiana will study the pathogenesis of infectious bursal disease (IBD) regarding the interaction of infectious bursal disease virus (IBDV) with the host tissues/cells. Chickens will be orally inoculated with reverse genetically engineered IBDV with mutations in structural and/or non-structural protein genes. Bursal histopathology, immune responses, and bursal cytokine mRNA profiles will be evaluated. Indiana will study the genotypes, pathogenicity, and immunogenicity of IBDV strains and isolates obtained from US and Asia in chickens and turkeys. Hypervariable region of VP2 gene will be amplified and the amplicons will be sequenced and analyzed. Chicken embryos, chickens, or turkey poults will be challenged with various IBDV strains and isolates to evaluate bursal histopathology and immune responses. Indiana will determine the effect of IBDV infection on the pathogenicity of avian respiratory infectious diseases (avain influenza and avian mycoplasmosis) by oral inoculation of SPF or commercial chickens with IBDV followed by intra-nasal or intra-tracheal challenge of chickens with the respiratory pathogens. Objective 4: Indiana will optimize DNA vaccination for IBD. Chickens or IBDV-maternally-derived broiler chickens will be in ovo or intramuscularly injected with a chimeric DNA plasmid (carrying VP2 gene of IBDV and chicken cytokine gene) and challenged with homologous or heterologous IBDV. ELISA and virus neutralization tests as well as bursal pathology will be performed to determine the immune response and protection efficacy. Efforts will be made to provide research updates via presentations at regional, national , and international meetings (e.g. Transmissible Disease of Poultry Committee meeting at United State Animal Health Association Meeting and American Association of Avian Pathologists-sponsored meetings) to ensure information dissemination to all stake holders. The outputs will be evaluated by reducing poultry mortality and condemnation through the use of improved diagnostic tools, vaccines, and bio-security measures and by producing safe and competitively priced eggs and poultry meat products for the consumers.