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Research Project: Intervention Strategies to Control and Prevent Disease Outbreaks Caused by Avian Influenza and Other Emerging Poultry Pathogens

Location: Exotic & Emerging Avian Viral Diseases Research

2015 Annual Report


1a. Objectives (from AD-416):
1. Characterize variant and emerging avian influenza viruses in live poultry markets and commercial production systems. 2. Identify genetic and biological determinants of virulence, tissue tropism and host range of avian influenza virus. 3. Identify genetic and biological determinants of avian influenza virus susceptibility and resistance in avian species. 4. Improve existing diagnostic tests and testing strategies for avian influenza virus surveillance, detection, and recovery from disease outbreaks. 5. Develop new vaccine platforms designed to control and prevent avian influenza virus outbreaks.


1b. Approach (from AD-416):
These objectives include a combination of basic and applied research to give us the knowledge and tools to effectively control avian influenza virus (AIV). The first objective focuses on characterizing new and emerging strains of AIV, initially by genome sequencing and analysis, then by pathogenesis and transmission studies, and finally by antigenic characterization. The second objective will elucidate specific viral factors involved in pathogenesis and virulence at a molecular level including utilizaiton of variant isolates initially characterized under objective 1. The third objective will investigate the viral factors involved in transmission and host adaptation of AIV among avian species with reverse genetics and pathogensis studies. Under objective 4 diagnostic tests will be improved by characterizing novel isolates to assure specificity and by adapting novel technologies to improve sentivity and specificity. New vaccines will be developed and evaluated through a variety of approaches including antigenic and molecular characterization for objective 5.


3. Progress Report:
In late 2014 through June 2015, there were several outbreaks of H5 highly pathogenic avian influenza virus (HPAIV) in commercial poultry, back-yard poultry, and wild birds in the United States (U.S.). Research efforts were directed to support control and mitigation of these outbreaks to provide immediate and needed data to the poultry industry and United States Department of Agriculture (USDA) agencies involved in the outbreak response. Research accomplishments included the development of a diagnostic assay specific for the strains of virus causing the outbreak. This has helped the National Veterinary Services Laboratories and National Animal Health Laboratory Network labs triage samples and to more rapidly diagnose the HPAIV. The biology of this virus, which has turned out to be novel, was evaluated for its effect on turkeys, chickens, game birds, and waterfowl. This data informed field veterinarians of what signs to watch for in the field and provided information on the optimal specimens to collect for diagnosis. Work with the waterfowl demonstrated that some species are good carriers; they produce high levels of virus and do not become sick. Data on numerous vaccines was developed to provide regulatory groups and the industry with information on how well different vaccines protect chickens and turkeys from this virus. This information has been communicated to the poultry industry and regulators. Low pathogenic avian influenza of the H9 subtype is endemic in much of the world. Vaccine is used to control the virus in chickens and turkeys in some countries. Since influenza can mutate, the vaccines must be changed periodically so they work. Selecting a new vaccine strain can be difficult and often requires extensive testing in vivo. In order to reduce the need for in vivo vaccine testing, a novel method to characterize the relationships among isolates was tested with H9 avian influenza virus. Testing showed that using this new method with other information on the vaccine candidate strains could help inform decisions about selecting the best isolate to use when producing vaccine.


4. Accomplishments
1. Intercontinental movement of H5 high pathogenicity avian influenza (HPAI) was documented by sequence analysis by U.S.D.A. scientists. The deadly H5N8 HPAI virus emerged in China during November 2013 and was spread by wild birds to South Korea and Japan by early 2014. The virus moved to summer breeding grounds in Siberia and Alaska by migratory birds. Two distinct subgroups emerged in late 2014 with one subgroup spreading to Russia and Europe, and the other to North America. Viruses from both subgroups reappeared in Japan. These results indicated that the deadly H5N8 virus was spread by wild birds from Asia to the U.S.A.

2. Co-infection of domestic ducks with Newcastle disease virus (NDV) and avian influenza virus (AIV) affects shedding and transmission of these viruses. Simultaneous infections with AIV and NDV are commonly reported in domestic ducks in many parts of the world; however, it’s not clear if co-infections with these viruses affects the severity of disease, the amount of virus they produce, or the transmission of the viruses. Domestic ducks were infected with NDV and either a low or highly pathogenic AIV by giving the viruses individually, simultaneously, or sequentially two days apart. Although there was no observed effect on disease, ducks exposed to both viruses produced more virus and were more susceptible to infection. Surveillance and control programs will be more efficient with data from these studies because they have demonstrated the effect on virus production.

3. Vaccination prevents H5N1 high pathogenicity avian influenza virus contaminated eggs. High pathogenicity avian influenza virus (HPAIV) infections in chickens decrease egg production, and eggs that are laid contain HPAIV. Eighty-three percent (83%) of hens without vaccination died within 3 days after HPAIV challenge; laid soft and thin-shelled eggs; and virus was recovered from eggshell, inside eggs, and from the oviduct and ovary. By comparison, once or twice vaccinated hens survived, continued laying eggs, and had fewer HPAIV contaminated eggs and such eggs had less virus. The current study demonstrated that H5N1 HPAIV infections can be effectively controlled by either single or double vaccination.

4. Characterization of chickens as reservoirs of the human infectious H7N9. A novel low pathogenicity avian influenza virus of the H7N9 strain, which causes disease in humans, but not chickens, has been circulating in Asia since 2013. ARS researchers in Athens, Georgia, characterized chickens as possible reservoirs of the virus by determining how much virus they could release into the environment and the best diagnostic samples to collect. This data was used to develop optimal sample collection and surveillance strategies in U.S. labs which conduct surveillance for the virus.

5. Characterization of vaccines for H7N3 strain highly pathogenic avian influenza virus from Mexico. The H7N3 highly pathogenic avian influenza virus emerged in Mexico in 2012 and has continued to sporadically cause outbreaks in poultry. Critical parameters for developing an effective vaccine were evaluated. The amount of virus and the strain of virus which would produce the optimal vaccine were determined by ARS researchers in Athens, Georgia. This information will allow for the production of a quality vaccine in Mexico, and provide assurance of an acceptable vaccine in the U.S. if we experience a related outbreak.

6. Risk of highly pathogenic avian influenza virus in liquid egg product from flocks with undetected infection. Movement of poultry and egg products, such as liquid egg product during a disease outbreak, is critical for business continuity. A modeling approach was used with data produced by ARS scientists in Athens, Georgia, to determine the risk that highly pathogenic avian influenza virus could spread if liquid egg product was shipped. The models predicted that it would be very unlikely that the concentration of virus could exceed the limit of inactivation used in the international standards for pasteurization. Therefore, liquid egg product which will be pasteurized can be shipped with an expectation that it is safe. This information will enable the decision to be made to move liquid egg product during a highly pathogenic avian influenza virus outbreak when certain risk based parameters are met and will allow for better business continuity.

7. Understanding avian influenza virus transmission in wild birds in South America. Avian influenza virus is primarily disseminated around the world through wild bird migrations, which can lead to infection of poultry. However, occurrences of avian influenza in poultry in South America are more rare than on any other continents. ARS researchers in Athens, Georgia, in collaboration with other groups, evaluated a species of duck, which migrates between North and South America, for their role in dissemination of the virus between continents, and showed that habitat and migration ecology are key factors, which may limit the spread of avian influenza. Knowledge of avian influenza virus movement with wild birds allows better prediction of risk to domestic birds based on exposure to wild birds.


Review Publications
Weaver, J., Malladi, S., Spackman, E., Swayne, D.E. 2015. Risk reduction modeling of high pathogenicity avian influenza virus titers in non-pasteurized liquid egg obtained from infected but undetected chicken flocks. Risk Analysis. doi: 10.1111/risa.12374.

Spackman, E., Wan, X., Kapczynski, D.R., Xu, Y., Pantin Jackwood, M.J., Suarez, D.L., Swayne, D.E. 2014. Potency, efficacy, and antigenic mapping of H7 avian influenza virus vaccines against the 2012 H7N3 highly pathogenic avian influenza virus from Mexico. Avian Diseases. 58:359-366.

Russell, C.A., Kasson, P.M., Donis, R.O., Riley, S., Dunbar, J., Rambaut, A., Asher, J., Burke, S., Davis, C., Garten, R.J., Gnanakaran, S., Hay, S.I., Herfst, S., Lewis, N.S., Lloyd-Smith, J.O., Macken, C.A., Maurer-Stroh, S., Neuhaus, E., Parrish, C.R., Pepin, K.M., Shepard, S., Smith, D.L., Suarez, D.L., Trock, S.C., Widdowson, M., George, D., Lipsitch, M., Bloom, J.D. 2014. Improving pandemic influenza risk assessment. eLife. doi: 10.7554/eLife.03883.

Spackman, E., Pantin Jackwood, M.J. 2014. Practical aspects of vaccination of poultry against avian influenza virus. The Veterinary Journal. 202(3):408-415. doi: 10.1016/j.tvjl.2014.09.017.

Bertran, K., Moresco, K.A., Swayne, D.E. 2015. Impact of vaccination on infection with Vietnam H5N1 high pathogenicity avian influenza virus in hens and the eggs they lay. Vaccine. 33(11):1324-1330.

Spackman, E., Pantin Jackwood, M.J., Swayne, D.E., Suarez, D.L., Kapczynski, D.R. 2015. Impact of route of exposure and challenge dose on the pathogenesis of H7N9 low pathogenicity avian influenza virus in chickens. Virology. 477:72-81.

Pantin Jackwood, M.J., Costa-Hurtado, M., Miller, P.J., Afonso, C.L., Spackman, E., Kapczynski, D.R., Shepherd, E.M., Smith, D.M., Swayne, D.E. 2015. Experimental co-infections of domestic ducks with a virulent Newcastle disease virus and low or highly pathogenic avian influenza viruses. Veterinary Microbiology. 177:7-17.

Ramey, A., Walther, P., Link, P., Poulson, R., Wilcox, B., Newsome, G., Spackman, E., Brown, J., Stallknecht, D. 2014. Optimizing surveillance for South American origin influenza A viruses along the United States Gulf Coast through genomic characterization of isolates from blue-winged teal (Anas discors) . Transboundary and Emerging Diseases. doi: 10.1111/tbed.12244.

Morrison, J., Josset, L., Tchitchek, N., Chang, J., Belser, J., Swayne, D.E., Pantin Jackwood, M.J., Tumpey, T., Katze, M. 2014. H7N9 and other pathogenic avian influenza viruses elicit a three-pronged transcriptomic signature that is reminiscent of 1918 influenza virus and is associated with lethal outcome in mice. Journal of Virology. 88(18):10556-10568. doi: 10.1128/JVI.00570-14.

Lee, D., Torchetti, M., Winker, K., Ip, H.S., Song, C., Swayne, D.E. 2015. Intercontinental spread of Asian-origin H5N8 to North America through Beringia by migratory birds. Journal of Virology. 89(12):6521-6524. doi: 10.1128/JVI.00728-15.

Machalaba, C.M., Elwood, S., Forcella, S., Smith, K., Hamilton, K., Jabara, K., Swayne, D.E., Webby, R.J., Mumford, E., Mazet, J., Gaidet, N., Daszak, P., Karesh, W.B. 2015. Global avian influenza surveillance in wild birds: A strategy to capture viral diversity. Emerging Infectious Diseases. 21(4):e1-7.