Gene Chip Test Identifies Influenza Viruses

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 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.

Following exposure to a viral isolate, the MChip displays results as a pattern of fluorescent spots. To automate the process of interpreting this pattern, thus eliminating the possibility of human error, scientists developed an artificial neural network trained to recognize the distinctive pattern indicative of H5N1. Automating the interpretation of MChip results could allow it to be used more readily by health workers at the site of possible flu outbreaks.

The MChip was developed by Professor Kathy L. Rowlen of the University of Colorado (Boulder, CO, USA) and colleagues. Results of the MChip study are now available online and are scheduled to appear in the December 15, 2006, issue of the journal Analytical Chemistry.

The MChip has several advantages over the FluChip, a flu diagnostic previously developed by the same research team, said Dr. Rowlen. 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.

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.)



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