AFTER a bioterrorist attack, every second counts. Doctors need to find out exactly which pathogen has been released and quickly so that they can treat thousands of potential victims before it鈥檚 too late.
Now a biotech firm claims to have built a machine that might help do just that. The company has cranked up the PCR technique, which amplifies DNA segments, so that it can help spot bugs such as anthrax more quickly. One test churned out DNA within 78 seconds. 鈥淭hat is the fastest PCR ever performed in the world,鈥� says Hendrik Viljoen from the University of Nebraska, who is working with the company.
In the past, the only way to identify a suspect bug was to culture it in the lab, which can take days. Modern PCR machines have cut the wait to a few hours, but even that may not be fast enough to save victims who need immediate treatment, or to contain an outbreak of an infectious disease.
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PCR machines take time because DNA fragments must be exposed to wildly different temperatures through each amplification cycle. This is usually done by automated thermocyclers, which use heating and cooling elements to slowly warm and cool the air surrounding the DNA.
The new PCR machine, devised by Megabase Research Products, based in Lincoln, Nebraska, uses pressurised helium and carbon dioxide instead of air. Heat transfers more quickly in helium than in other gases. And when pressurised carbon dioxide is released it instantly cools its surroundings. The pressurisation also increases the speed at which the gases move in the machine, causing even faster heat transfer.
Viljoen says he has already tested the new machine in over 600 experiments with DNA samples from 20 different organisms, including Bacillus anthracis, the bacterium that causes anthrax. But Kurt Peterson at PCR manufacturer Cepheid, in California, says there is a trade-off between speed and sensitivity. A superfast machine may not be sensitive enough to detect the small number of pathogens found at an attack sight.