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Application of Biological and Molecular Techniques to the Diagnosis and Control of Avian Influenza and other Emerging Poultry Pathogens


The project plan for this CRIS project has four general objectives that are designed to increase our basic understanding of avian influenza virus (AIV) and to develop improved control measures.<P>

The specific objectives are listed below. <ol>
<li> Identify determinants of virulence, tissue tropism and host range of AIV.
<li> Develop vaccines that effectively stop outbreaks, allow differentiation from natural infection and can be administered in a cost effective manner.
<li> Improve existing diagnostic tests and develop new diagnostic tests that are rapid, sensitive, and improve the detection of avian influenza.
<li> Use molecular epidemiologic techniques and viral genomics to understand virus transmission and spread of AI outbreaks in poultry and wild birds.</ol> These objectives include a mixture of basic and applied research to give us the additional knowledge and tools to help control AI. This virus remains a difficult target because it can naturally infect a number of wild bird species, which provides numerous exposure opportunities for poultry and other domestic animal species. Additionally, avian influenza virus is highly variable because of both a high mutation rate and the ability to reassort gene segments, which has resulted in many unexpected phenotypes of the virus. The first objective includes the characterization of new or unusual avian influenza viruses in multiple species to provide improved risk assessment of isolates and increase our understanding of the pathogenesis of AIV. Sequence analysis and molecular epidemiology, objective 4, are also an important part of this characterization. The ultimate goal is to understand which specific amino acid changes are correlated to virulence, tissue tropism, and host range. The applied aspect of this project is the development of improved control tools for avian influenza in poultry, objectives 2 and 3. This includes the development and evaluation of new vaccines for use in poultry. Current vaccines, in general, provide solid protection from disease but have serious limitations in how they are applied and their ability to be used in a DIVA (differentiate infected from vaccinated animals) vaccination program. Many vaccine technologies are available that may be mass applied and are DIVA compatible, but more research needs to be done to determine if these technologies can be modified for avian influenza and are cost effective in the poultry industry. The remaining objective is to improve current diagnostic tests and develop new testing technologies. The continued development of existing technologies like real-time RT-PCR will provide increased performance or utility for testing different sample types, and to increase throughput and reliability of the test technology. Alternative technologies will also be explored with collaborative partners to achieve faster, more sensitive and economical testing. Additionally, improved serologic diagnostic tests and procedures will be examined, particularly as allied tests for DIVA vaccines.

More information

A multidisciplinary approach will be used to study avian influenza virus (AIV) in poultry with particular emphasis on highly pathogenic avian influenza. The use of molecular biological techniques including RT-PCR, cloning, and sequencing will be used for molecular epidemiology, development of an influenza sequence database, and the use of reverse genetics to engineer influenza viruses to examine an individual viral genes role in virulence. For studying the pathogenesis of influenza, gross and clinical pathology, histology, immunohistochemistry, and quantitative RT-PCR will be used to examine the effect of infection with different viral strains and protection in vaccine trials. Cellular biology, immunology, and host genetics will be used to determine the role of host resistance to influenza infection. Improved diagnostic tests, emphasizing rapid detection, will be developed. Continued surveillance of wild bird isolates will continue with collaborators from several different institutions. These efforts should provide better control measures. BL-2 and BSL-3AG; 05/23/2003.

Pantin-Jackwood, Mary; Suarez, David
USDA - Agricultural Research Service
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