FDA clears single test for 12 respiratory viruses

Editor's note: This story was revised Jan 8 to correct information about the location of the test's manufacturer.

Jan 7, 2008 (CIDRAP News) – A single test that can identify up to 12 different respiratory viruses, including three kinds of influenza, from one sample has won the Food and Drug Administration's (FDA's) approval.

The test, called the xTAG Respiratory Viral Panel (RVP), is the first that can detect and distinguish influenza A subtypes H1 and H3 and also detect influenza B, the FDA said in announcing the approval on Jan 3. Influenza A is the most severe type of flu in humans and has been the cause of pandemics, the agency noted.

The new test panel is also the first test for human metapneumovirus (hMPV), which was first identified in 2001, the FDA said.

The test is made by Toronto-based Luminex Molecular Diagnostics, part of Luminex Corp, headquartered in Austin, Tex. In a news release, the company called the xTAG RVP "a ground breaking test that, with a single patient sample, can assess the presence or absence of 12 viral targets and provide qualitative results in a few hours."

Conventional testing for the same viruses requires a number of separate tests and can take several days, the company said. The new product will help physicians provide appropriate treatment and prevent inappropriate antibiotic use that has helped spawn resistant microbes, the statement said.

The FDA said, "The xTAG panel is the first FDA-cleared test for infectious respiratory disease viruses that uses a multiplex platform, allowing several tests to be processed using the same sample."

The test uses polymerase chain reaction (PCR) to amplify viral genetic material in samples from patients, according to Jeremy Bridge-Cook, vice president of Luminex Molecular Diagnostics. The FDA said the test uses secretions from the back of the throat.

The test uses tiny color-coded beads, or microspheres, that are coated with reagents specific to material from particular viruses, according to information on the Luminex Web site.

"There's a different color-coded bead for each virus in the test," Bridge-Cook told CIDRAP News. "The Luminex instrument can identify the different color-coded beads and whether the viral target was amplified. If any of the beads is positive, that indicates whether the viral target was present in the sample."

The use of PCR to reproduce viral material "speeds up the usual process of detecting and identifying respiratory viruses, which can take up to a week," Daniel D. Schultz, MD, director of the FDA's Center for Devices and Radiological Health, said in the news release.

The FDA said viruses identified by the xTAG RVP, in addition to the three forms of influenza and human metapneumovirus, include:

  • Respiratory syncytial virus subtypes A and B, both of which are leading causes of infant pneumonia and bronchiolitis and often contribute to the development of long-term lung disease
  • Parainfluenza 1, 2, and 3—all leading factors in croup and the common cold
  • Rhinovirus, the most common viral infective agent in humans and another cause of the common cold
  • Adenovirus, a cause of respiratory tract infections often similar to strep throat or tonsillitis

The 12 viruses covered by the test account for more than 85% of respiratory viral infections, the Luminex statement said.

The company said the test's ability to identify influenza subtypes H1 and H3 will be important in efforts to detect quickly any emerging pandemic flu virus. The test will make it possible to sort H1 and H3 viruses, which make up the vast majority of influenza A subtypes, from rare forms of influenza A. "This way, the few samples that do test positive for influenza A but cannot be identified as H1 or H3 subtypes can be flagged for further investigation by the CDC or local public health labs," the company said.

Bridge-Cook said the time needed to run the test will vary, but "I'd say maybe 6 hours might be a typical time."

As for the cost, he said he couldn't give a specific figure, but added, "From a ballpark standpoint, basically the number is in the low hundreds [of dollars], as opposed to thousands of dollars, with respect to what it costs the healthcare system as a whole when the test is run."

Bridge-Cook said the test requires specially trained personnel, so it's likely to be used mainly in hospital laboratories. But he said many hospital labs take samples from outpatient clinics, so the test would not be limited to use on inpatients.

The FDA said that because the test is specific to the 12 viruses listed, it should be used with other diagnostic information, such as patient data, bacterial or viral cultures, and x-rays.

See also:

Jan 3 FDA news release
http://www.fda.gov/bbs/topics/NEWS/2008/NEW01770.html

Jan 3 Luminex news release
http://phx.corporate-ir.net/phoenix.zhtml?c=79403&p=irol-newsArticle&ID=1091216&highlight=

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