Georgia Tech's Research Horizons magazine - Spring/Summer 2005
A Pandemic Upon Us
Researchers battle avian flu threats to poultry industry and humans
by Jane M. Sanders
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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.
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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.
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.”
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."
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.
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.”
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 |
