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 research is directly related to inhouse objective 1 - Characterize variant and emerging avian influenza viruses in live poultry markets and commercial production systems; inhouse objective 2 - Identify genetic and biological determinants of virulence, tissue tropism and host range of avian influenza virus;inhouse objective 3 - Identify genetic and biological determinants of avian influenza virus susceptibility and resistance in avian species; inhouse objective 4 - Improve existing diagnostic tests and testing strategies for avian influenza virus surveillance, detection, and recovery from disease outbreaks; and inhouse objective 5 - Develop new vaccine platforms designed to control and prevent avian influenza virus outbreaks. Work on this project was initiated during October of 2011. Accomplishments for FY2013 include completing: 1) two rounds of quality control testing of surveillance labs in the National Institutes of Health Centers of Excellence in Influenza Research and Surveillance program; 2) an evaluation of the co-infection or prior exposure with Newcastle disease virus on disease caused by avian influenza virus; and 3) and evaluation of whether the novel H7N9 influenza could infect or cause disease in numerous avian species. A quality control panel (47 sets) for the diagnostic detection of avian influenza virus genetic material was developed and distributed to 37 laboratories in the US and abroad. This testing ensured that diagnostic laboratories involved in animal surveillance for influenza as part of the National Institutes of Health Centers of Excellence in Influenza Research and Surveillance program could detect the virus with adequate sensitivity. Work with H5N1 highly pathogenic avian influenza (HPAI) viruses continued as this strain remains a threat to poultry in many regions of the world. We examined the pathogenicity of H5N1 HPAI viruses in different species and breeds of domestic ducks and the effect of route of virus inoculation on the outcome of infection. We determined that the pathogenicity of H5N1 HPAI viruses varies between the two most common farmed duck species, Muscovy ducks (Cairina moschata) which presented a more severe disease than various breeds of Anas platyrhynchos var. domestica that includes the Pekin, Mallard-type, Black Runners, Rouen, and Khaki Campbell ducks. We also found that Pekin and Muscovy ducks inoculated could become infected by the intranasal, intracloacal, or intraocular routes. This information helps support the planning and implementation of H5N1 HPAI surveillance and control measures in countries with large domestic duck populations. Newcastle disease virus (also known as avian paramyxovirus type 1) is nearly ubiquitous in poultry worldwide and causes disease which is very similar to that of avian influenza virus (from respiratory disease to severe systemic disease). For example, one question is whether the widely used live Newcastle disease virus vaccine will make avian influenza infection more severe. Because of their similar presentation it is not clear how co-infection would present clinically. Experiments in domestic poultry were initiated in FY12 and were completed in FY13. The interaction between the two viruses was found to be complex and depended on the timing of exposure and the virulence of the strains. This data will aid the detection of each virus and the understanding of how they exacerbate or interfere with each other in the field. A novel avian influenza virus emerged in February 2013 and was first recognized for cause severe disease in people. It is recognized that this virus was being maintained in an animal reservoir. Since the virus was genetically consistent with being an avian influenza virus, numerous avian species were examined for whether they could be infected with the virus. Chickens, Pekin ducks, Muscovy ducks, Embden geese, Japanese quail and pigeons were tested. All species could be infected and no species presented with any clinical disease, therefore infection was effectively “silent”. Some species were more susceptible than others and shed more virus into the environment (for example chickens and quail), therefore are more likely to be the animal reservoirs. It was also shown that oral or tracheal samples were far superior to fecal samples for detecting the virus and should be the primary sample used in surveillance for the virus.