CHARACTERIZATION OF PROTECTIVE HOST RESPONSES TO AVIAN INFLUENZA VIRUS INFECTIONS IN AVIAN SPECIES
Location: Exotic and Emerging Avian Viral Diseases Research Unit
Project Number: 6612-32000-062-00
Start Date: Oct 01, 2011
End Date: Sep 30, 2016
1. Conduct comparative immunology studies of avian species to determine variations in protective innate defense mechanisms to avian influenza infections.
2. Characterize humoral and cellular immune responses to avian influenza viruses and identify epitopes associated with immunity.
3. Develop immunological reagents and methodologies to evaluate vaccine efficacy and protection.
The project plan has three interrelated objectives that are designed to increase our basic understanding of the immunological response to avian influenza virus (AIV) infection in different avian species and will result in improved vaccine development.
The first objectives initiate the characterization of host cytokine expression profiles from specific innate immune cells in vitro. These profiles will then be compared with cytokine profiles obtained from avian influenza (AI) infected tissues, in vivo, for a better understanding of the overall innate immune response to avian influenza viruses (AIV). Innate immune cells will be isolated or produced for in vitro analysis from multiple sources, including: specific pathogen-free (SPF) White Leghorn (egg laying-type), SPF White Plymouth Rock (meat-type) chickens, and SPF Small Beltsville White SPF turkeys from the Southeast Poultry Research Laboratory. In addition, some experiments will utilize commercial chickens, turkeys, geese, ducks or others as needed, as sources for primary cell culture. We have in-house supplies of SPF birds and eggs, which can be used for these studies. In addition, we also have access to major histocompatibility complex (MHC)-defined birds (Avian Disease Oncology Laboratory, East Lansing, MI) which can be used for immunogenetic comparison of cytokine responses within members of Gallus gallus species. Expected outcomes for this objective will be the determination of which cytokines and transcription factors contribute to a resistant phenotype of avian species to AIV. It may be likely that different profiles are determined for different bird species. Once innate immunity profiles have been established, the cellular and humoral immune responses that contribute to natural and vaccine-induced protection will be characterized. We will utilize chickens, turkeys, ducks and other bird species in these studies. Experiments in Objective 2 will determine antibody levels following infection and vaccination, identify cellular immune responses to homologous and heterologous AI isolates, and determine putative epitopes involved with immunity. We will specifically address: (1) the induction of anti-viral antibodies that correlates with protective efficacy, decreases in virus shedding, and provide cross-reactivity to homo- and heterosubtypic isolates, (2) the induction of cellular immunity in poultry and wild birds following infection or vaccination and challenge, (3) identify T-cell epitopes to the hemagglutinin and nucleoprotein proteins of AI. Finally, we will develop immunological reagents and methodologies to evaluate vaccine efficacy and protection. Besides the usual indicators of vaccine induced protection, including survival, or decreases in shedding, assays to determine why and how a particular vaccine induces immunological protection against challenge are lacking. By incorporating cytokines and toll-like receptor agonists into vaccine formulations, their contributions to humoral and cellular immunity can be evaluated. Finally, the extent of cross protective immunity developed in vaccinated birds will be examined by utilizing antigenic cartography.