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Handheld labs, DNA chips could speed flu response one day

  • Story Highlights
  • Scientists working on tests that could rapidly test for bird flu
  • Current tests must be conducted in special labs
  • Researchers hope to create portable devices that could be used anywhere
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By David E. Williams
CNN
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(CNN) -- Researchers are working on new, faster ways to diagnosis bird flu and other dangerous influenza strains before they can erupt into a full-fledged pandemic.

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Technology examining the flu virus' genetic makeup may help speed diagnosis, essential for containing an outbreak.

Avian flu, or H5N1, does not spread easily to humans, but when it does the results are often deadly. The World Health Organization has reported 332 human cases of the disease since 2003 -- 204 of those patients died.

Early detection could help contain an outbreak, but current tests are expensive, can only be performed in special labs and can take about a week.

A team at the University of Michigan is working to shrink the laboratory full of equipment needed to test for various flu strains into a device the size of a television remote control.

The process converts the virus' genetic material, or RNA, into DNA and then uses special enzymes to cut the DNA, said Ronald Larson, the chemical engineering professor leading the project.

"These enzymes are amazing, they look for a tract of DNA, say six spaces that they match, and then they'll cut right there," Larson said. "So it's like very discriminating scissors that only cuts at certain genetic locations."

There are enzymes that only cut the bird flu virus and others that only cut human strains, Larson said. So scientists, or a machine, can determine which virus is present by looking for the cut strands. Explainer: Bird flu vs. human flu »

The test, known as the Genotyper, uses a small piece of etched glass that is sandwiched with a silicon chip, like the kind used to make electronic circuit boards.

The test currently takes more than an hour and requires a lot of "operator intervention," he said.

"We have a prototype, it's not really fast," Larson said. "This device is not ready to be commercialized."

He said the most time consuming part of the process is amplifying the DNA, or making millions of copies of the sample, so there is enough genetic material to observe.

Scientists at the University of Colorado are working on a different method, called a microarray, to create their test, the Flu Chip.

The chip is basically a glass slide covered with tiny dots of DNA that match different parts of the virus' genetic material. The slide is then dipped into solution containing genetic fragments from a patient's sample, said Kathy Rowlen.

Matching fragments will stick together like the teeth of a zipper.

"Then you look at the pattern of which little bits caught which other little bits and that pattern tells you essentially what kind of virus you have," she said.

She said the test can check for various strains of the flu, as well as other viruses that cause similar symptoms.

"There is so much information on these microarrays because you can put lots and lots of little bits of DNA down that are going to serve as the little capture sites," she said. "And the beauty is that it can provide you with a tremendous amount of information in one test."

She said the test takes about seven hours, "which sounds like a long time but when you consider that the standard test takes about a week, seven hours doesn't sound too bad."

Larson predicted that it would be five to 10 years before portable influenza tests hit the market.

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He said scientists understand the technology needed for the tests, and even know how to miniaturize it, but getting consistent results, without false positives or negatives is the hard part.

"It's actually pretty complicated," he said. "You're doing several steps that are usually done with test tubes in a laboratory involving centrifuges and heavy equipment, and you're trying to eliminate all of that equipment, and carry out a sequence of processes that all have to be automated and done in a miniature format, and still have a signal, or result, that's dependable enough that you can rely on it." E-mail to a friend E-mail to a friend

All About InfluenzaContagious and Infectious DiseasesVaccines

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