Spring/Summer 2005

AVIAN FLU A Pandemic Upon Us Industry Synergy In Brief

A Pandemic Upon Us
Researchers battle avian flu threats to poultry industry and humans.

by Jane M. Sanders

WITH POTENTIALLY DEVASTATING losses to the economy and new threats to human lives, avian influenza is the focus of research worldwide on ways to detect and control the disease.

photo by Gary Meek GTRI researchers led by senior research scientist David Gottfried are determining the feasibility of using their optical waveguide sensor – which can detect a variety of environmental, foodborne and terrorism-related agents – to find the avian influenza on poultry farms before it spreads. (300-dpi JPEG version - 764K)

In the United States, outbreaks of the disease – primarily spread by migratory aquatic birds – have plagued the poultry industry for decades with hundreds of millions of dollars in losses. The only way to stop the spread of the disease is to destroy millions of poultry farm birds that may have been exposed to the virus.

Recently, a virulent strain of avian influenza (H5N1) has begun to threaten not only birds but humans – this time in Asia. The continent has experienced widespread outbreaks in the poultry industry and some cases in humans, many of which were fatal. Looming is the threat of a pandemic – such as the 1918 Spanish flu that killed about 40 million people – health officials say.

In 2005, in response to the threats, the U.S. Department of Agriculture’s Cooperative State Research Education and Extension Service awarded its largest grant ever to study a single animal disease or health threat. That $5 million, multi-institutional study – headquartered at the University of Maryland (see www.aicap.umd.edu/) – is funding two years of biosensor research at the Georgia Tech Research Institute (GTRI), joined by a grant from the Georgia Research Alliance. Researchers are determining the feasibility of using GTRI’s optical waveguide sensor – which can detect a variety of environmental, foodborne and terrorism-related agents – to find the disease on farms before it spreads.

“Quicker detection is the key so infected flocks can be isolated and destroyed,” says J. Craig Wyvill, head of the GTRI Food Processing Technology Division. “If our low-cost, rapid-screening biosensor was used by the industry, it could help cut hours off the time it takes to get test results, thereby giving the industry a huge jump on controlling the spread of this disease. Our integrated-optics sensing platform is ideal for field application.”

photo courtesy GTRI J. Craig Wyvill is head of the Georgia Tech Research Institute Food Processing Technology Division.

The sensor consists of a laser light source, a planar waveguide (essentially a small piece of glass through which the light travels) and a detector for monitoring light output. Chemical reactions – in this case, the binding of an avian influenza antibody to the virus that causes the disease – on the waveguide surface alter the speed of light through the waveguide. This change is monitored with an interferometer by comparing a reference beam with another beam traveling under the sensing chemistry. Signal processing software interprets the sensor’s results and delivers information on the agents’ identity and quantity. The waveguide chip is small enough that it can accommodate several sensing channels designed to detect multiple agents.

With the grant, GTRI researchers are searching for the best-suited avian influenza antibodies to serve as the sensor’s receptor for binding the avian influenza virus to the sensor surface, explains lead researcher and GTRI senior research scientist David Gottfried. In contrast to most antibody assays that contain multiple chemical-binding steps, the GTRI sensor is a direct assay – meaning it directly detects the antibody binding to the target virus.

Researchers have conducted assays using the less-harmful H7 influenza strain, evaluating several different antibodies for their sensitivity and selectivity. Although researchers have a lot of additional work to do, they have already found that the GTRI biosensor is more sensitive than a commercial dipstick-type assay by at least two orders of magnitude. The biosensor is able to differentiate the H-antigen subtypes within a one-hour test window, Gottfried says.

"With continued development, this biosensor technology should be able to rival virus isolation and PCR (polymerase chain reaction) technologies in sensitivity with a more-rapid, lower-cost and field-usable assay," he notes. "The availability of this type of diagnostic test for an on-site analysis will be helpful in the control of avian influenza."

photo courtesy GTRI According to the U.S. Department of Agriculture, uncontrolled avian influenza in the United States could paralyze the industry and compromise the nation's position as the leading exporter of poultry in the world.

Gottfried and his colleagues are taking multiple approaches in determining the best antibodies to use in the sensor. “We can look for the entire virus or break the virus apart and look at its interior,” he explains. “There are a number of antigens associated with this virus that we can look at…. With this sensor, we can detect four to eight agents in one sample.”

Though the initial research has involved the less-harmful H7 strain of the virus as a sensing model, the researchers expect to extend their work to other more relevant strains, he adds.

Gottfried also notes that researchers are determining whether GTRI's sensing technology is competitive with other approaches in terms of cost, time, sensitivity and ease-of-use.

image courtesy CDC This colorized transmission electron micrograph of avian influenza (H5N1 strain) viruses (seen in gold) was grown in MDCK cells (seen in green). Avian influenza viruses do not usually infect humans, but several instances of human infections and outbreaks have been reported since 1997.

Though researchers expect this grant to cover development of a prototype device for further lab and field-testing, the system design of a commercial sensing device will come later.

“The bottom line is that we’ll be looking for simplicity in this application,” Wyvill says. “Will this sensor work easily in the field for detecting avian influenza?”

Most biosensors now offered commercially work only in a laboratory setting, and there is typically a 24-hour delay in getting test results. “In an avian influenza outbreak, time is valuable,” Wyvill notes. “Anything that can push the recognition point up has huge value. Our sensor is one of the few that offers portability and low cost. These aspects make it very promising.”

The sensing device will probably cost around $1,000, not including the costs for assay chips and antibodies, the researchers estimate. The whole package might be manufactured and marketed by pharmaceutical companies, Wyvill says. Typical users would likely be poultry farm service representatives and perhaps veterinarians, as well as government inspectors, he adds.

Field-based detection of avian influenza will likely follow faster laboratory diagnostic tests being developed by David Suarez at the USDA’s Southeast Poultry Research Laboratory, which is providing antibodies and test samples for GTRI’s research. For now, no field screening is occurring in the United States, and lab tests take at least four hours to complete.

“We want to be able to spot it in the field, isolate it and end it rather than dealing with the current time delays involved with sampling and lab tests,” Wyvill says. “With rapid field testing, we could isolate the disease and keep it from spreading to neighboring farms.”

-- Article updated May 5, 2006

For more information, contact Craig Wyvill at 404-894-3412 or craig.wyvill@gtri.gatech.edu – or David Gottfried at 404-407-8300 or david.gottfried@gtri.gatech.edu