1a. Objectives (from AD-416):
To improve control of avian influenza virus (AIV) by better understanding vaccine failure, immunity and transmission in avian species: a) evaluate AIV transmission and spread in ducks and peri-domestic species of birds; b) determine the conditions that lead to vaccine failure in chickens and ducks; c) and to elucidate the immune response of ducks to AIV.
1b. Approach (from AD-416):
Using a team approach we will address each sub-objective individually. AIV transmission will be evaluated by comparing routes of inoculation and by using several different species of bird to see they are susceptible to selected strains of AIV including the Asian highly pathogenic H5N1 lineage. Transmission to contact birds and measure of virus shed will also be tested. The approach to vaccine failure will be to vaccinate chickens with different immune statuses and after exposure to other common vaccines and pathogens to see the effect on vaccine efficacy. A further component will be to include challenge viruses which are not related to the vaccine strain. The immune response of ducks to AIV will be assessed by measuring the cell mediated immune response and other immunological and genetic factors in ducks which are exposed to the virus.
3. Progress Report:
This project is related to objective 1 and 2 of this in-house project: 1-characterize variant and emerging avian influenza viruses in live poultry markets and commercial production systems. 2-Identify genetic and biologicl determinants of virulence, tissue tropism and host range of avian influenza virus. Work on this project was initiated during October of 2011. Progress for FY2012 include completing: 1) Quality control testing of diagnostic labs; 2) an evaluation of the effect of duck species on disease caused by H5N1 highly pathogenic avian influenza virus; and 3) and evaluation of the effect of Newcastle disease virus on avian influenza virus infection in chickens. A quality control panel (36 sets) for the diagnostic detection of avian influenza virus genetic material was developed and distributed to 25 laboratories in the U.S. and abroad. This testing ensured that diagnostic laboratories involved in veterinary diagnostics could detect the virus with adequate sensitivity. Because of their role in spreading H5N1 Highly Pathogenic Avian Influenza (HPAI) virus, it is of vital importance to control highly pathogenic avian influenza virus in domestic ducks. We determined that the disease varies between the two common farmed duck species, with Muscovy ducks (Cairina moschata) presenting more severe disease than various other breeds of domestic ducks (Anas platyrhynchos). This information helps support the planning and implementation of surveillance and control measures in countries with large domestic duck populations. Co-infections of poultry with Newcastle disease virus, a very common respiratory virus of poultry, and avian influenza virus present a problem both from the clinical and the diagnostic aspects of these viruses. The goal of this study was to examine the interaction between Newcastle disease virus and avian influenza virus in infected poultry species. Experiments were conducted where chickens, turkeys or domestic ducks were exposed to Newcastle disease virus and to avian influenza virus. We found that co-infection can affect the replication dynamics and the disease caused by these viruses in poultry. The information obtained from these studies helps in understanding the interaction of these viruses in the field and improves the diagnosis of these viruses.