PARIS — Scientists in Singapore say they have devised a mini-lab capable of identifying the H5N1 bird flu virus in less than 30 minutes, in what they believe could be a breakthrough in efforts to shore up defenses against any flu pandemic.
Other commercially available tests take from several hours to a matter of days to deliver results and are many times more expensive, the inventors report in the journal Nature Medicine.
One of the big tasks in a putative pandemic of bird flu would be to identify and isolate infected people to stop them spreading the virus to others.
In the best-case scenarios, an outbreak can be halted if it does not spread beyond the first 20 cases or if it is contained within three weeks after the first case emerges.
So the ability to screen people swiftly at the point of outbreak and at migratory centers such as airports is vital — and can only be achieved if cheap, accurate, handheld testers are available.
A team led by Juergen Pipper at the Institute of Bioengineering and Nanotechnology in Singapore drew on parts of a standard CD-ROM drive for the design of their prototype tester.
It works by taking a throat-swab sample, which is then immersed in a droplet containing so-called superparamagnetic particles, which are silica compounds that respond to a directed magnetic field.
The droplet is then placed on a tiny platform covered with a hydrophobic film. A magnet directs — like an invisible hand — the particles to move, mix and merge with the liquid, eventually pulling out the virus’ RNA genetic code.
The genetic material is then corralled into an off-the-shelf tester, a “lab-on-a-chip.”
There, the sample is washed four times to remove residual contaminants and copied many times over by polymerase chain reaction (PCR) to make it large enough to be identified accurately as a pathogen.
Compared to commercially available tests, which take a long time to isolate the virus and typically use antigens to get a telltale response, this technique “is equally sensitive and is 440 percent faster and 2,000-5,000 percent cheaper,” the paper says.
The prototype has delivered accurate results within 28 minutes when tested on samples of highly pathogenic H5N1 virus.
The technique could be used to detect the viruses that cause AIDS, hepatitis B and Severe Acute Respiratory Syndrome (SARs) by extracting their RNA from blood, urine and saliva, the authors believe.
In its current form, H5N1 bird flu is highly contagious among birds but is difficult to transmit to humans, unless the individual happens to be in close proximity to sick fowl.
The worry is that the present strain will pick up genes from conventional flu viruses that will make it highly contagious among humans in addition to being lethal.