"Catch-tish-flu" - Researchers develop better bird flu-detecting tool

15 September 2007
Posted by Chris Smith.

Scientists at the Institute of Bioengineering and Nanotechnology in Singapore, writing in this month's Nature Medicine, have developed a novel technique that uses tiny magnetic silica-coated particles to purify and then diagnostically copy flu virus genetic material from a patient's throat swab.

A drop of water on a leaf.The entire process takes place inside a tiny oil-covered water-droplet, which is prepared from the patient's sample and placed on a teflon-coated glass slide.  The oil prevents the water in the droplet, which contains just one tenth of a millilitre of liquid, from evaporating.  Once the droplet is in situ the particles are added by stirring them into the droplet using a permanent magnet placed beneath the glass.  As the magnetic particles are stirred in the solution they soak up any viral RNA (the genetic material of flu) and are then withdrawn from the droplet.

Next they are passed across the glass slide, again using the magnet, through a series of smaller droplets containing a cleansing solution.  This washes away impurities clinging to the flu RNA or the particles.  After four washes the particles are dragged into a final droplet containing a chemical to release the RNA from the particles, and the ingredients for PCR (polymerase chain reaction), a process which copies or amplifies genetic material.

Once sufficient genetic material has been produced it can be analysed to pinpoint whether it contains the signature of H5N1.  Juergen Pipper, the lead author on the paper, points out that this approach yields 50,000% more RNA, is 50 times cheaper and 4 times faster than existing diagnostic methods, which might make a life or death difference when it comes to controlling the next pandemic.

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