Genotyper could identify new flu in less than two hours

Updated 8:00 PM September 2, 2005

Genotyper could identify new flu in less than two hours

By Laura Bailey
News Service

With the threat of a flu pandemic looming, researchers are racing to develop tools that will help them diagnose and identify new flu strains quickly.

The Genotyper, a portable lab-on-a-chip developed by a multidisciplinary team at the University, eventually could make it possible for doctors to decode the genetic makeup of flu viruses in less than two hours.

Two images of the influenza genotyper chip. Above: Various reagents paths and locations. Below: A top view of the chip. (Images courtesy Prof. Ronald Larson).

Ultimately, the Genotyper will be fully portable and could be connected wirelessly to track the spread of existing or emerging flu strains around the globe, says Ron Larson, professor of chemical engineering and member of the team developing the technology. The device would be about as the size of a television remote control, he says.

The technology originated in the laboratories of Mark Burns, professor of biomedical and chemical engineering, and David Burke, associate professor of human genetics, who sought to develop fast, inexpensive methods for deriving genetic information from humans. It is being applied to genotyping influenza virus by a team that also includes Larson, Michael Solomon, associate professor of chemical engineering, and A. Oveta Fuller, associate professor of microbiology and immunology in the Medical School.

Their findings are outlined in a paper, "Microfluidic Integrated Device for Genetic Analysis," whose primary authors include Larson, Burns, Burke and Fuller.

The process for identifying the flu type is similar to genetic fingerprinting used in deoxyribonucleic acid (DNA) identification, team members say.

First, the influenza RNA, or ribonucleic acid, is converted to DNA using the same biological processes that the HIV virus uses to convert RNA to DNA to replicate itself and elude the immune system, according to the paper.

Then, a segment of the DNA is reproduced in a process called polymerase chain reaction, or PCR, and enzymes are released that digest, or cut, the DNA at certain points.

"The way the gene is cut or not cut depends on which flu gene you have," Larson says. The pattern of fragment sizes tells scientists the locations of the cuts in the DNA, and this provides a fingerprint that distinguishes the type of flu, he says.

During the process, the DNA fragments are filtered though a gel, which, when it is electrically charged, causes them to move at certain speeds, depending on their size. The short fragments squirt through quickly; the longer ones more slowly, Larson says. They are stained with fluorescent tags, which allow scientists to distinguish one flu strain from the next, or tell if a new strain has emerged.

Different types of DNA strands can be tested and identified using the same device by using different reagents. To demonstrate the Genotyper's versatility, researchers conducted tests on DNA from a human, a mouse and from a strain of influenza.

Genotyper could identify new flu in less than two hours

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