New sensor detects bird flu in minutes
17 October 2007
A new biosensor developed at the Georgia Tech Research
Institute (GTRI) can detect bird flu (avian influenza) in just minutes. The
biosensor is economical, field-deployable, sensitive to different viral
strains and requires no labels or reagents.
Quick identification of avian
influenza infection in poultry is critical to controlling outbreaks, but
current detection methods can require several days to produce results.
can do real-time monitoring of avian influenza infections on the farm, in
live-bird markets or in poultry processing facilities,” said Jie Xu, a
research scientist in GTRI’s Electro-Optical Systems Laboratory (EOSL).
Worldwide, there are many strains of avian influenza virus that cause
varying degrees of clinical symptoms and illness. In the United States,
outbreaks of the disease — primarily spread by migratory aquatic birds —
have plagued the poultry industry for decades with millions of dollars in
losses. The only way to stop the spread of the disease is to destroy all
poultry that may have been exposed to the virus.
A virulent strain of
avian influenza (H5N1) has begun to threaten not only birds but humans, with
more than 300 infections and 200 deaths reported to the World Health
Organization since 2003. Looming is the threat of a pandemic, such as the
1918 Spanish flu that killed about 40 million people, health officials say.
“With so many different virus subtypes, our biosensor’s ability to detect
multiple strains of avian influenza at the same time is critical,” noted Xu.
A study testing the sensor has been published in the journal Analytical and
“The technology that Georgia Tech developed with
our help has many advantages over commercially available tests — improved
sensitivity, rapid testing and the ability to identify different strains of
the influenza virus simultaneously,” said David Suarez, a collaborator on
the project and research leader of exotic and emerging avian viral diseases
in ARS’ Southeast Poultry Research Laboratory in Athens, Giorgia. Suarez is
providing antibodies and test samples for GTRI’s research.
Jie Xu, a research scientist in the Georgia Tech Research
Institute's Electro-Optical Systems Laboratory,
holds the optical waveguide sensor.
biosensor is coated with antibodies specifically designed to capture a
protein located on the surface of the viral particle. For this study, the
researchers evaluated the sensitivity of three unique antibodies to detect
avian influenza virus.
The sensor uses the interference of light waves, a
concept called interferometry, to precisely determine how many virus
particles attach to the sensor’s surface. More specifically, light from a
laser diode is coupled into an optical waveguide through a grating and
travels under one sensing channel and one reference channel.
Current methods of identifying infected birds include virus
isolation, real-time reverse transcriptase polymerase chain reaction
(RRT-PCR) and antigen capture immunoassays. Virus isolation is a sensitive
technique, but typically requires five to seven days for testing. RRT-PCR is
commonly available in veterinary diagnostic laboratories, but requires
expensive equipment and appropriate laboratory facilities. RRT-PCR can take
as little as three hours to get test results, but routine surveillance
samples are more often processed in 24 hours. The antigen capture
immunoassays can provide rapid test results, but suffer from low sensitivity
and high cost.
New sensor advantages
Beyond the waveguide sensor, the only
additional external components required for field-testing with GTRI’s
biosensor include a sample-delivery device (peristaltic pump), a data
collection laptop computer and a swab taken from a potentially infected
bird. Power is supplied by a nine volt battery and USB connection. The
waveguides can be cleaned and reused dozens of times, decreasing the
per-test cost of the chip fabrication.
Xu and Suarez are currently working
together to test new unique antibodies with the biosensor and to test
different strains. In addition, Xu is reducing the size of the prototype
device to be about the size of a lunchbox and making the computer analysis
software more user-friendly so that it can be field-tested in two years.
“We are continuing our collaboration and have provided additional money to
Georgia Tech to move the project along faster,” added Suarez. “Since this
technology is already set up so that you can use multiple antibodies to
detect different influenza subtypes, we are going to extend the work to
include the H5 subtype.”
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