FluChip shows promise in diagnosing A(H5N1) avian flu, and others including pandemic flu

The New York Times reports on a new test for A(H5N1) avian influenza (commonly called bird flu) which is undergoing further research. The FluChip was designed by Robert D. Kuchta and Kathy L. Rowlen, a University of Colorado chemistry professor who led the team that developed the test. Current tests for A(H5N1) require culturing the virus in eggs to get enough genetic material to test and identify the virus, taking up to 5 days not including transport to these specialty labs. The FluChip cuts that time down to less than 12 hours.

The technology used by the FluChip is called a microarray, or gene chip, which uses genetic principles to identify what kind of flu it is. The chip has genetic material, RNA, from 5,000 samples of different animal and human flu virus which help differentiate the flu in question, since the DNA of that flu will stick to the RNA on the chip.

To get enough DNA of the flu you're trying to identify, scientists use polymerase chain reaction amplification (PCR) to duplicate the virus DNA so that it can be used with the chip. This is great for flu viruses that we already have the DNA of, such as avian influenza A(H5N1), but points out a significant problem when thinking of pandemic flu.

Pandemic flu is anticipated to be an entirely new virus that the world has not been exposed to before, which would assist it's spread since we will not have had any possible way to develop antibodies against it yet. It will take time for scientists to identify and isolate the DNA of this new virus to be able to use to make tests like the FluChip useful, so don't expect the CDC to whip this out at the start of a pandemic.

This is promising, but won't be helpful at the outset of pandemic flu. It's helpful for A(H5N1) but with the success in controlling the spread in Vietnam & Thailand, and improvement in control in Indonesia, avian influenza A(H5N1) isn't expected to become a pandemic, in part because it has not been able to spread between humans, only from birds to humans.

It's still a big step ahead of my currently available test for influenza. It's a dipstick test I can run in my own office that identifies influenza A within minutes. My problem is that I can't tell what strain of influenza A it is, so the presumptive diagnosis of A(H5N1) is still by details of the patient's history and physical exam.

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