Quicker Turnaround for Flu Tests

CU-Boulder Professors Robert Kuchta and Kathy Rowlen

CU-Boulder Professors Robert Kuchta and Kathy Rowlen display a scanner and the Flu Chip, which is inserted and read by the scanner to determine specific genetic subtypes of flu viruses. University of Colorado at Boulder, Office of News Services hide caption

itoggle caption University of Colorado at Boulder, Office of News Services

A new test can analyze the genetic makeup of a flu virus in just 12 hours. That's a lot faster than traditional lab tests, which take three or four days to identify a flu strain. The development could make it easier for health officials to identify and contain an emerging flu that has the potential to start a pandemic.

In Depth

NPR's Joe Neel answers questions about the risk of pandemic flu, and the status of vaccines and treatments.

The new device is called the Flu Chip, and it was developed by biochemists Robert Kuchta and Kathy Rowlen at the University of Colorado at Boulder. It's a glass slide coated with snippets of DNA that represent variants of three important flu genes.

To run the test, a doctor first takes a nose swab from a patient. A lab then extracts the genetic material and applies it to the chip. Different strains of flu make the chip light up in unique patterns of green. "So we just glance at the chip and it takes 10 seconds of looking at it, if that long, and then you have your answer," says Kuchta.

The chip's design allows it to detect both known flu strains and newly emerging strains. "It would be virtually impossible for the flu to mutate so that we wouldn't be able to detect it," says Kuchta. "Because a new flu strain would give a very different signature on a chip, we could say, ‘You have a flu, and it is new and it is weird.'"

Being able to quickly identify weird new flu strains is important for public health officials, who are closely tracking a bird virus called H5N1 that has killed at least 60 people in South Asia. The fear is that this virus could someday mutate into a form that spreads easily between humans. That could start a global flu pandemic like the one in 1918 that killed millions of people. Officials want to use vaccines and anti-viral drugs to contain a new virus before it can spread widely. To do that, they'll need to catch an emerging virus as quickly as possible.

Doctors already have some quick tests that can diagnose a case of flu in just 30 minutes or so. But these rapid tests can only say if a patient is infected with influenza. They can't provide detailed information about what strain of virus the patient has, says David Cho with the National Institute of Allergy and Infectious Diseases in Bethesda, Md. "Right now, we can't say with certainty that it is the bird flu strain or just a normal case of flu," Cho says.

To answer that question, doctors currently have to turn to a lab that's equipped to grow the flu virus and analyze its genes. But that takes days, and the delay can mean false alarms and public uncertainty. And public health officials would like to be able to mobilize their stores of vaccines and drugs more rapidly.

Designing a faster, more reliable test has been difficult because of some serious technical obstacles.

One problem is that, at any given moment, many different flu strains are circulating, and the differences between them are subtle but important. What's more, the viruses are constantly mutating and changing. "And so it's kind of a moving target and a little bit harder to design a test to detect that moving target," says Niranjan Bhat, who works on flu with the Centers for Disease Control and Prevention in Atlanta.

Still, the CDC has been collaborating with scientists to find faster ways to analyze flu genes. It helped Kuchta and Rowlen test their Flu Chip's accuracy, by providing samples of different flu strains, including H5N1. Kuchta says the chip seems highly accurate: "It just worked spectacularly well, with greater than 90 percent accuracy."

The device will undergo additional testing next month, when technicians at the CDC will run the chip "side by side" with the routine tests done on flu samples that come into the lab each winter. These tests are used to monitor and track flu strains, in order to decide what strains should go into next year's flu vaccine.

If everything goes well, the Flu Chip could be ready for wider use in six months. The team also is experimenting with improvements to the chip that could cut the testing time from 12 hours to two. They're also hoping to make the chip small and simple enough that health workers could take it into small villages, or other places that currently have no ability to identify flu strains.



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