Location: Exotic & Emerging Avian Viral Diseases Research
Project Number: 6040-32000-066-023-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jun 1, 2016
End Date: Sep 30, 2021
Objective:
A highly pathogenic avian influenza virus has caused widespread outbreaks in the United States resulting in major losses to the poultry industries. The Objectives of this research are to: 1) identify molecular determinates of infectivity and transmission of these viruses for gallinaceous poultry; 2) determine if the high pathogenicity phenotype has longer or shorter environmental persistence than low pathogenicity phenotype; 3) determine the role of inadequate immunity in antigenic drift of field viruses; 4) identify changes in virulence, infectivity and transmissibility of new H5Nx high pathogenicity avian influenza viruses for gallinaceous poultry; 5) assess the role of airborne dispersion in farm-to-farm spread and examine mitigation strategies; 6) develop and optimize new methods for recover and identifying the virus in litter; 7) assess new air sampler technology for improved recovery of airborne virus; and 8) assess new H5Nx viruses for ability to infect and transmit among wild birds.
Approach:
1. Reverse genetics approach to understand why the wild bird origin high pathogenicity avian influenza viruses (HPAIV) infect and transmit so poorly in gallinaceous poultry. In addition identify the amino acid changes that increased infectivity and transmission in the more poultry adapted viruses.
2. Using a reverse genetics approach, make representative field viruses that differ only by the hemagglutinin gene cleavage site. Using a virus with a high pathogenicity avian influenza (HPAI) phenotype and a low pathogenicity avian influenza (LPAI) phenotype, compare these viruses for their ability to persist under different environmental conditions. This will address the question of whether the LPAI phenotype is more resistant to environmental conditions which may explain why HPAI viruses are not normally found in wild birds.
3. Study antigenic drift in an in ovo and in vivo models, birds or in eggs, will have different levels of closely matched and poorly matched antibody, and using a deep sequencing approach, antigenic variants will be analyzed for how quickly changes occur and if a pattern of changes occur. This project will test the theory that matched vaccines have slower antigenic drift than poorly matched vaccines.
4. Do additional pathogenesis, infectivity, and transmission studies on chickens and turkeys looking both at breed, different ages and times in the production cycle (i.e. layers vs pullets) to look for differences in susceptibility to infection and transmission.
5. Assessment of airborne transmission of HPAI virus over short and long distances, and analysis and preliminary evaluation of housing and biosecurity interventions to reduce risks. The initial steps would be working with The USDA-Center for Epidemiology and Animal Health (CEAH) on assessing wind dispersion models against genetic network analysis to confirm the wind spread between farms, and which activities are high risk. If such is found, look at initial modelling of dust dispersal in plume models and experimental non-infectious dust studies for dispersion in various housing models. If these models demonstrate potential virus dispersion on dust, available materials to remove dust and other air borne fomites or negative air ionization as means for removal and destruction of virus will be examined.
6. Develop and optimize the method for extracting the virus from the litter and to optimize the new Qiagen internal positive control for real-time reverse transcriptase polymerase chain reaction.
7. Dust sampling during any future HPAIV outbreaks with newly developed high efficiency air samplers and tie results in with air plume and dust models and field studies.
8. Infectivity and transmission studies in captive bred or wild ducks, geese and swans with newer H5 HPAIV to assess if they are more adapted to waterfowl and/or poultry.
