Volume 18 | Number 3 | Fall 2006 | Safety Issue

page 1
Researchers Explore Biosensor Technology for the Rapid Detection of Avian Influenza

page 2
Georgia Plans Avian Flu Response

page 3
Conference Highlights the Potential and Risks of Nanotechnology for the Food Industry

page 4
Two Pioneering Poultry Companies Set the Standard for Corporate Wellness Programs

page 5
Washington Update: OSHA Issues Final Standard on Hexavalent Chromium

page 6
Visit ATRP at the 2007 International Poultry Expo

page 7
2007 National Safety Conference for the Poultry Industry

 

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Researchers Explore Biosensor Technology for the Rapid Detection of Avian Influenza

Biosensor

Research Scientist Jie Xu tests Georgia Tech’s biosensor in a biosecurity cabinet. Xu is part of a team of researchers who are developing the device for the rapid detection of avian influenza.

Avian influenza virus (AIV) is a contagious disease that causes infection in wild birds. While chickens, turkeys, and other gallinaceous birds are not natural reservoirs, AIV has been isolated sporadically as the cause of infection in domestic poultry. Once infection occurs, the virus can spread quickly from bird to bird. Therefore, early identification of the infection is critical for aiding in the control of outbreaks.

Currently, three methods of direct identification of infected flocks are commonly used: virus isolation, real-time reverse-transcriptase polymerase chain reaction (RT-PCR), and antigen capture immunoassays. Although effective, each method has drawbacks ranging from the time and equipment needed to perform the tests to low sensitivity and high costs. The availability of a rapid, sensitive, and economical diagnostic test for on-site analysis would greatly aid in the control of AIV at the outset and during an outbreak.

Researchers with the Georgia Tech Research Institute (GTRI) are addressing this need using a planar optical waveguide interferometer biosensor (under development for biological and chemical detection). The device provides a direct measurement of antibody-antigen complex formation as well as other biological interactions. It consists of a laser diode light source, an optical waveguide, and an imaging camera. As molecules or microbes bind to capture antibodies on the waveguide surface, they alter the propagation speed of light within the waveguide. When that beam is optically combined with a reference beam, an interference pattern is generated and imaged. Small changes in that interference pattern allow the sensor to accurately measure the amount of binding taking place on the waveguide surface.

Biosensor response to avian influenza virus samples (in buffer solution) using a direct immunoassay with anti-H7 monoclonal antibody on the waveguide surface. The response was measured 20 minutes after sample injection.

For AIV detection, the team is developing and optimizing a simple and sensitive direct immunoassay for avian influenza subtypes H5 and H7 using polyclonal and monoclonal antibodies created by the U.S. Department of Agriculture’s (USDA) Southeast Poultry Research Laboratory (SEPRL) in Athens, Ga. Two monoclonal and one polyclonal antibody for a single H subtype (H7) of avian influenza virus have been coupled to the waveguide and examined to determine their sensitivity when used with the interferometer transducer. Four H7 strains (H7N1, H7N2, H7N3, and H7N7) and a control H8 strain (H8N4) have been tested so far.

According to Dr. David Gottfried, senior research scientist and project director, results to date indicate that the GTRI biosensor is more sensitive than a commercial dipstick immunoassay by at least 2 orders of magnitude, and provides discrimination of the H antigen subtype. This should allow earlier diagnosis of infection, before symptoms appear, within a poultry flock. Various parameters of the assay were examined in order to optimize the response, and the results of triplicate assays indicate good chip-to-chip reproducibility. Sandwich assays, in which a combination of two antibodies is used to boost sensitivity and selectivity, were also performed with positive results.

Researchers also have completed a new prototype sensor design optimized for field measurements. The new design, explains Gottfried, incorporates an easily changeable waveguide/flow cell module, and optical alignment using a single adjustment which translates both the laser light source and the imaging camera on a single mechanical mount. This design is in the final stages of review before machining of parts, assembly of the system, and laboratory testing.

Future plans for this project include additional testing of H7, as well as H5, virus samples with both monoclonal and polyclonal capture antibodies, using both direct and sandwich assay protocols to further assess the specificity and cross-reactivity of the assay. Comparison of the biosensor assay to other diagnostic methods (e.g., RT-PCR) using split samples (oropharyngeal swabs) collected from experimentally infected chickens will be done in collaboration with SEPRL under the direction of Dr. David Suarez.

The project is part of a three-year, $5 million program titled “Prevention and Control of Avian Influenza in the U.S.,” which is being funded by the USDA’s Cooperative State Research Education and Extension Service, National Research Initiative, Cooperative Agricultural Project in Animal and Plant Security. The grant is the largest ever given by USDA to study a single animal disease or health threat. Administered by the University of Maryland, the funded effort includes researchers and extension specialists in 17 states, and was initiated in January 2005. The biosensor development work has also received funding from the Georgia Research Alliance Innovation Fund.

 

PoultryTech is published by the Agricultural Technology Research Program (ATRP), Food Processing Technology Division (FPTD) of the Georgia Tech Research Institute. ATRP is conducted in cooperation with the Georgia Poutry Federation with funding from the Georgia Legislature.