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Prevention and Control of Avian Influenza in the U.S.

Investigators
Perez, Daniel
Institutions
University of Maryland - College Park
Start date
2005
End date
2007
Objective
Our long-term goal is to develop knowledge-based integrated approaches to detect, control and prevent the emergence of influenza viruses in avian species of economic importance. Aquatic birds are the primary reservoir of influenza A viruses. Often, some of these viruses cross the species barrier infecting non-natural hosts such as land-based poultry, without overt clinical signs. For reasons that are still poorly understood, influenza viruses circulating in land-based poultry can increase their virulence and cause important economic losses due to mortality and trade restrictions. The molecular mechanisms that lead to the emergence of influenza viruses in land-based poultry are poorly defined, however their consequences are well known by all, e.g. farmers, the poultry industry, government officials, and scientists. Poultry production in the US amounts to approximately 18% of total world production and poultry has become the most important source of meat protein in the human diet in many countries. Effective detection, control and prevention of avian influenza are of the utmost importance to maintain the US leadership in world poultry product markets and such efforts will make a significant contribution towards national food security. These goals cannot be accomplished without solid scientific knowledge of the molecular and epizootiological bases for the interspecies transmission of influenza A viruses including the factors contributing to high virulence in poultry. We propose to develop reagents, technologies, and human resources aimed at detection and eradication of influenza from economically important poultry species. Highly pathogenic avian influenza may pose a threat to public health, as evidenced by the transmission of avian influenza viruses from poultry to humans in Asia and the Netherlands. Thus, our efforts will also have a major impact on the prevention and control of zoonotic outbreaks of avian influenza.

In this application, the efforts of several institutions across the country will concentrate on three major aims:

Aim 1: 1) To determine the molecular basis for adaptation of influenza A viruses from wild aquatic birds and/or intermediate hosts to land-based poultry (chickens and turkeys). 2) To determine the molecular parameters for diagnosing avian influenza viruses in chickens and turkeys affected by co-infections by other respiratory and immunosuppressive viruses.

Aim 2: 3) To determine the dynamics and evolution of influenza A viruses in live bird market systems (LBMs) in three areas of the United States. 4) To determine the dynamics and evolution of influenza A viruses in waterfowl of the four major flyways of the U.S to understand the contribution of these species to the emergence and perpetuation of avian influenza in land-based poultry. 5) To build effective education and biosecurity programs. 6) To deliver an educational program on in house euthanasia and composting methods for use in the case of catastrophic mortality or depopulation.

Aim 3: 7) To develop critical diagnostic tests and, 8) vaccines for avian influenza control.

More information
NON-TECHNICAL SUMMARY:

Waterfowl are the natural reservoir of influenza A viruses. Often, some of these viruses cross the species barrier infecting non-natural hosts such as land-based poultry, where they can increase their virulence and cause important economic losses due to mortality and trade restrictions. The molecular mechanisms that lead to the emergence of influenza viruses in land-based poultry are poorly defined, however their consequences are well known by all, e.g. farmers, the poultry industry, government officials, and scientists.

Poultry production in the US amounts to approximately 18% of total world production and poultry has become the primary source of meat protein in the human diet in many countries. Effective detection and prevention of avian influenza are of the utmost importance to maintain the US leadership in world poultry product markets and such efforts will make a significant contribution towards national food security. These goals cannot be accomplished without solid scientific knowledge of the molecular and epizootiological bases for cross species transmission of influenza A viruses. To be useful this knowledge needs to be developed in the context of the actual production scenarios.

We propose to develop reagents, technologies, and human resources aimed at detection and eradication of influenza from economically important poultry species. Furthermore, highly pathogenic avian influenza may pose a threat to public health. Thus, our efforts will also have a major impact on the prevention and control of zoonotic outbreaks of avian influenza.

APPROACH: Aim 1: The critical first event in the development of HPAI is efficient replication of a LPAI. We will study the molecular basis that allows the transmission and perpetuation of AI from wild waterfowl to land-based poultry. We will use reverse genetics and classical virology to dissect the molecular events that take place for AI viruses to become endemic in land-based poultry. We propose to determine whether H5, H6, and H7 subtypes of influenza viruses present in wild aquatic birds can replicate in chickens and quail and whether quail enhance transmission to other bird species, particularly chickens and turkeys. We will determine the effect of other viral diseases such as NDV, IBDV, CIAV or HE viruses, on factors influencing the diagnosis of AI in poultry. Aim 2: We will investigate the risk factors associated with the emergence and perpetuation of AI in bird species in the LBM systems across the country. We will characterize AI circulating in wild waterfowl and their captive raised counterparts. Antigenic, molecular and in vivo characterizations will be performed to understand the movement of viruses across different bird species, the level of reassortment taking place and whether novel variants are generated. Surveillance activities will include collection of ground-truth data using GPS data collection systems. Educational programs and materials will be developed on avian influenza control including stand-up presentations, printed and on-line fact sheets, and CDs will be generated and delivered to targeted audiences including integrated and semi-integrated poultry meat and egg industry, allied industry representatives, independent poultry producers, poultry dealers and distributors, live bird market owners and workers, gamebird producers, poultry and waterfowl fanciers and 4-H club members. Aim 3: This objective addresses two key high priority needs: 1) Development of highly sensitive and rapid diagnostic tests for avian influenza during surveillance and outbreaks capable of discriminating between non-vaccinated and vaccinated birds as well as infected birds. 2) Development of alternative strategies for vaccination against avian influenza exploiting the latest molecular approaches available including reverse genetics and recombinant expression vectors. We propose to develop a rapid diagnostic test that is sensitive, inexpensive, and can be performed penside. The methods to be evaluated include an optical interferometric biosensor, serologic tests for different NA subtypes, a DNA microarray test, an Antibody-based Virus Concentrator, and microsphere -based multiplex immunoassays. Alternative vaccines strategies will include the evaluation of LPAI H5 and H7 strains as vaccine seeds for emergency vaccine stockpiles, the evaluation of antigenic drift in Mexican AI viruses using DNA vaccines, and the evaluation of six alternative strategies for vaccination against HPAI (and LPAI) using 1) a recombinant adenovirus vector, 2) a recombinant live lentogenic NDV vector, 3) a recombinant MDV vector, 4) a recombinant SFV suicide replicon, 5) a recombinant IBV vector, and 6) a whole RG AI vaccine.

PROGRESS: 2005/01 TO 2006/01 The program Prevention and Control of Avian Influenza in the US (AICAP) has developed a collective network research structure to establish the basis for a better understanding of AI; both the mechanisms that lead to the emergence of AI, and, more importantly, the prevention of AI in poultry. During the first year of funding we have established such a structure: through our research network, several of our groups have engaged in collaborative projects both within AICAP and outside the network. We have developed a website for our project (www.agnr.umd.edu/aicap), which serves as a portal for distribution of educational materials and details the projects that received funding during 2005. Given the size and broad scope of the project, coordination of the different project areas has been a major challenge. However, we are excited to note that major progress has been made in all areas of research, although due to space constraints we highlight only those with major advances during 2005. Drs. Benson, Alphin, and Malone (U. Delaware), and Tablante (U. Maryland): Environmental stability of AI and practical methods for mass euthanasia and viral inactivation on poultry premises.

Training sessions were organized and held at: Millsboro, DE; Moorefield, WV; Harrisonburg, VA; Statesville, NC; Lumberton, NC; Mt. Olive, NC; Lancaster, PA; Columbia, SC; APHIS/Riverdale, MD; Athens, GA; Montgomery, AL; Nashville, TN; Princeton, KY; Fayetteville, AR; Hope, AR; and Ruston, LA. Drs. Wallner-Pendleton, Dunn, and Lu (PSU): AI workshop training sessions for game bird producers. This project has been reaching out to game bird breeders with information on avian influenza, biosecurity steps to prevent infection and training in necropsy, serological sample taking and steps to becoming NPIP AI Clean according to subpart E. Game bird health workshops were held in South Carolina, Texas, California, Kansas and Minnesota with largely excellent attendance. Several presentations were added to the AI CAP website under education and were favorably reviewed. Dr. Gottfried, (GTRI): development of a cost-effective biosensor for the direct measurement of antibody-antigen complexes. AI subtype H7 was detected in both a direct antigen capture as well as a sandwich assay using surface attached antibodies, with sensitivity 2-3 orders of magnitude better than the Binax immunochromatographic assay.

Dr. Keeler (U. Delaware) subtyping AI by cDNA microarray met a major objective, which is the ability of one labeling reaction and one slide to identify both HA and NA subtypes. Drs. Vakharia and Perez (U. Maryland), baculovirus expressed NP AI antigen produced and licensed to Synbiotics, Inc., which has manufactured two AI diagnostic kits that have been approved for commercialization in domestic and international markets. Drs. Wan and Perez have recently provided evidence on the potential role of quail as an intermediate host in which AI viruses can acquire features typical of human viruses. Quail (and chickens) show abundant human-like receptors in the respiratory and intestinal tract, which explains in part how human flu-like viruses could emerge.

IMPACT: 2005/01 TO 2006/01

The input of all project participants, our interaction with members of the scientific advisory board (SAB), executive committee and stakeholders is highly valuable for the project. The interaction with members of APHIS (Dr. Tracy Duvernoy and others) has resulted in important exchange of ideas to improve the AICAP. These interactions will continue to make a major impact in the overall strategy to prevent and control AI in the US.

In 2006, a completely re-designed AICAP website will be more user-friendly for exchange of information among project participants and the poultry industry. We will create the opportunity for education of the general public and poultry producers on different aspects of AI. As the project starts to take the form of a cohesive unit, we will be making major contributions with our surveillance efforts, particularly through the work of the two umbrella projects on wild bird and live bird market surveillance (Drs. Slemons and Cardona). For 2006, 21 applications, four of them new, were submitted for consideration for funding. For 2006, the overall aims of the project will remain the same:

1) To establish the molecular basis for avian influenza interspecies transmission and pathogenesis

2) To continue expanding our wild bird surveillance capacity and characterize the population of AI viruses in wild birds in North America.

3) To continue our different education programs and analysis of risk factors in the emergence of AI

4) To continue exploring and validating alternative diagnostic tools and vaccines strategies

Funding Source
Nat'l. Inst. of Food and Agriculture
Project source
View this project
Project number
MD-VTMD-1130
Accession number
202495
Categories
Education and Training
Food Defense and Integrity
Commodities
Meat, Poultry, Game