US scientists claim development of new test to detect H5N1 virus

Washington, Nov 16 (UNI) In a major breakthrough, scientists from the University of Colorado at Boulder and the Center for Disease Control and Prevention (CDC) said they have developed a new and inexpensive ''gene chip'' test based on a single influenza virus gene that could allow them to quickly identify flu viruses, including avian influenza H5N1.

The researchers used the MChip to detect H5N1 in samples collected over a three-year period from people and animals in geographically diverse locales, according to a release from the National Institute of Allergy and Infectious Diseases (NIAID), part of the US National Institutes of Health.

In tests on 24 H5N1 viral isolates, the chip provided complete information about virus type and subtype in 21 cases and gave no false positive results, the scientists claimed.

They said the MChip could provide a significant advantage over available tests because it is based on a single gene segment that mutates less often than the flu genes typically used in diagnostic tests.

As a result, the MChip may not need to be updated as frequently to keep up with the changing virus.

The research was led by University of Colorado scientist Kathy L Rowlen and funded by the NIAID. A paper describing the work is scheduled to appear in the December 15 issue of the American Chemical Society's journal Analytical Chemistry.

''Concerns about a possible influenza pandemic make it imperative that we continue to devise reliable and easy-to-use diagnostic tests for H5N1 that can be employed on-site where outbreaks are suspected,'' NIAID Director Anthony S Fauci said.

''The MChip developed by Dr Rowlen and her colleagues performed extremely well in initial tests and has the potential to be a valuable tool in global influenza surveillance efforts.'' The MChip has several advantages over the FluChip, a flu diagnostic previously developed by the same research team, Dr Rowlen said.

While the FluChip is based on three influenza genes -- hemagglutinin (HA), neuraminidase (NA) and matrix (M) -- the MChip is based on one gene segment. Unlike HA and NA, which mutate constantly and thus are technically difficult to use to develop gene chip diagnostic tests, the M gene segment mutates much less rapidly, she explained.

''The M gene segment is much less of a moving target than the HA or NA gene.'' ''We believe that a test based on this relatively unchanging gene segment will be more robust because it will continue to provide accurate results even as the HA and NA genes mutate over time. The work summarized in our paper strongly supports that idea,'' she said.

Another potential advantage is that the MChip would, for the first time, create a way to simultaneously screen large numbers of flu samples to learn both the type and subtype of virus present.

Current real-time tests provide information about the type of virus (type A or B) in a sample, but additional tests must be run to determine the virus subtype (for example, H5N1 subtype).

UNI XC PDS VP0645