A novel "Flu Chip" has been developed to determine the genetic signatures of specific influenza strains from patient samples within hours, US scientists reported on Monday.

This achievement, expected to be in use in laboratories within a year, may help world health officials combat the predicted flu epidemics by making it easier for more laboratories to swiftly identify severe flu strains, the researchers said.

Scientists from the University of Colorado at Boulder, who invented this Flu Chip, also planned to make the genetic sequences of different flu strains freely available to interested researchers.

Tests by US Centers for Disease Control and Prevention (CDC) showed this Flu Chip can determine the genetic make-up of types and subtypes of the flu virus in about 11 hours, while current methods for characterizing flu subtypes take about four days, said Kathy Rowlen, a professor who led this research.

Strain identification is critical for tracking emerging strains and in determining which flu strains are most likely to infect people the following year in order to develop annual vaccines, but currently no more than 200 facilities worldwide can provide detailed strain analysis of influenza, she said.

Current laboratory culturing techniques by the CDC and World Health Organization (WHO) take four to five days to determine flu strains afflicting patients. Commercial tests like rapid antigen testing can detect influenza in less than an hour, but can't provide genetic information about various flu subtypes, the researchers said.

The chip, which can be configured to test for all known flu virus strains as well as new variant strains, was evaluated for three primary subtypes of flu, including the highly pathogenic avian flu strain H5N1, and two of the most common human flu types worldwide in recent winters, H1N1 and H3N2.

The chip was more than 90 percent accurate and will be tested again "side by side" with standard flu-virus culturing methods for accuracy and speed at the CDC next month, Rowlen said.

"This was the first time a version of the Flu Chip was tested outside of our lab, and it exceeded our expectations," she said in a statement.

The Flu Chip fits on a microscope slide and contains an array of microscopic spots. Genetic bits of information that are complimentary to known, individual influenza strains are "spotted" robotically in an array, where each row of three spots contains a specific sequence of "capture" DNA.

The microarray is then immersed in a wash of influenza gene fragments obtained from the fluid of an infected individual. RNA fragments from the infected fluid bind to specific DNA segments on the microarray like a key in a lock, indicating both a match and that the virus signature is present, Rowlen said.

Then the captured RNA is labeled with another complimentary sequence that also contains a fluorescent dye, and such "hits" light up like a pinball machine when the chip is inserted into a laser scanner.

The chip is able to recognize mutations that might occur in avian flu H5N1, which has been spreading rapidly Asia and parts of Europe. While the avian virus does not now spread effectively from person to person, health officials are fearful the strain will mutate and become transmittable between humans, possibly triggering a worldwide pandemic.

The technology could be downsized to fit into a hand-held portable device the size of a cell phone or PDA within a few years, making spot test in remote areas around the world feasible, according to the researchers. They also hope to make the identification process more rapid.

Source: Xinhua