Posted: February 4, 2008

Bird flu testing on the cheap

(Nanowerk News) Rapid identification of bird flu infection will be the key to controlling a pandemic should the virus learn how to transmit between humans. A new lab-on-a-chip could provide diagnosis in as little as 30 minutes.
The bird flu virus H5N1 and all its variants represent a worldwide threat that could be the cause of a pandemic - the likes of which have not been seen since the 'Spanish flu' outbreak following the end of World War I which had a mortality estimated at between 20 and 50 million across the world.
Of course the H5N1 virus has not made the vital jump where it can be passed from human to human, but it can pass from bird to human and is a potentially lethal condition. With this in mind, one of the problems when an outbreak is suspected is the ability to rapidly and accurately detect the virus in biological samples taken from the scene of the infection.
Conventional lab-based methods could take hours or even sometimes days to confirm an outbreak of the disease. Research has concentrated on assay methods including the use of genotyping and polymerase chain reaction (PCR) methods.
New discovery
However one method has been developed by the Institute of Bioengineering and Nanotechnology in Singapore (Institute of Molecular and Cell Biology and Genome Institute of Singapore) that fits the criteria perfectly in that it can detect the virus in samples taken in the field using a lab-on-a-chip methodology (although this should really be described as 'droplet-on-a-chip' technology).
The group that has developed the device is headed by Dr Juergen Pipper, who commented: "With our device, medical or humanitarian aid workers would be able to detect the presence of the H5N1 virus directly from throat swab samples on-site in less than half an hour."
The technology
The chip can detect the virus using real-time PCR technology, which has been seen in other detection kits. The chip is really a miniature PCR laboratory that can concentrate the RNA from the virus in droplets that can be manipulated with tiny magnetic particles into undergoing several cycles of PCR. The single droplet becomes the centre of the workflow carrying out viral RNA isolation, purification, preconcentration, and detection.
Pipper said: "The novelty of our method lies in the way that the droplet itself becomes a pump, valve, mixer, solid-phase extractor and real-time thermocycler. Complex biochemical tasks can thus be processed in a fashion similar to that of a traditional biological laboratory on a miniature scale."
He explained how the chip is made and how it works. "The miniaturised thermocycler is made by conventional silicon micromachining in a cleanroom. However, the (bio)assay itself is carried out on a Teflon-coated glass substrate. PCR requires several rounds of thermocycling between 95°C, 55°C, and 72°C, which is accomplished by resistance heating of a thin gold metal layer."
It has been suggested that the technology could be used to detect other pathogens and even distinguish between different variants of the H5N1 virus.
In addition the method is estimated to be 10 times faster than conventional assay methods and could potentially be (with commercial development of the chip) 40 times cheaper. Watch this space, as this technology looks set to go far.
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