12 October 2001 News Update

SCANNER TO "LISTEN" FOR VIRAL INFECTIONS

Doctors may soon be able to "listen'' for infection using a new kind of virus detector. The United Kingdom system uses a quartz crystal ''microphone'' which picks up the sound of a captured virus breaking free from an antibody. The device is so sensitive that it can detect a single virus particle in a drop of fluid.

The scientists who developed the "rupture-event scanning'' (REVS) method believe it will greatly improve the early detection of viral diseases. It should also allow far more sensitive monitoring of the effectiveness of anti-viral drugs and vaccines used to treat the human immunodeficiency virus (HIV), influenza and other infections.

Their concept relies on the way that quartz crystals vibrate when placed in an electric field. Dr David Klenerman and his team at Cambridge University reasoned that if an object was attached to a vibrating quartz crystal, at a certain frequency it might be thrown off by the force of the vibration. They used this principle to devise the detector.

A crystal disk was coated in an antibody protein which binds to the herpes simplex virus. Subjected to an electric field, the crystal with the virus attached began to vibrate.

Then at a certain point, as the frequency was increased, the virus broke free. Acting as a miniature microphone, the crystal picked up the "tearing'' sound of the rupture and sent a signal to a computer which could be read by the researchers.

The results of the REVS experiment have been published in the journal Nature Biotechnology. The scientists said the system could be used to detect a range of diseases and to monitor viral loads of many millions of viruses as well as spotting the earliest stages of infection.

Antibodies specific to different viruses or strains of viruses could be used to identify an infection accurately. Work is under way to develop a detector which could be taken and used anywhere. "We are in the process of simplifying and miniaturising our instrument electronics to allow development of a portable device,'' said the Cambridge University team.

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