Microchip-Based Test Distinguishes Flu Strains

The new test successfully distinguished among 72 flu strains--including the H5N1 avian flu strain--in less than 12 hours. The newly developed technology can be used in lower level biosafety facilities, and therefore will expand flu diagnostic capacity by allowing more labs to determine the geographic origin of a newly emergent virus and whether its source is human or nonhuman, learn how closely related a new virus is to ones that circulated previously, and detect genetic changes that may signal the virus is becoming more virulent.

The FluChip is a type of microarray, commonly called a gene chip. It was developed by scientists from the University of Colorado at Boulder (Boulder, CO, USA) and the Centers for Disease Control and Prevention (CDC, Atlanta, GA, USA). Microarrays are made by using a robotic arm to drop hundreds or thousands of spots of genetic material, DNA or RNA, of known sequence onto a microscope slide. The spots, called probes, are then exposed to a sample of unknown composition such as material taken from a person with an undiagnosed illness. Probes that match gene sequences of viruses present in the sample result in capture of the target gene. By analyzing the pattern of captured targets, doctors can diagnose the cause of infection.

The CDC provided flu isolates to the University of Colorado scientists to identify using the FluChip. The samples included strains that infect humans, horses, birds, and swine. CDC shared its technical expertise on flu and worked alongside University of Colorado staff in CDC laboratories to process the flu samples, test the FluChip technology, and analyze the results. Correct information about both type and subtype was obtained from 72% of the samples. It took about 11 hours to conduct the tests and learn the identities of the strains. The results appeared in the August 2006 issue of the Journal of Clinical Microbiology.

"This state-of-the-art research is vital to our efforts to protect the nation's health, and it may provide a new tool in our toolbox in the fight against flu,” said CDC director Julie Gerberding, M.D. "This is an excellent example of the advances we can achieve when governmental and academic researchers work together, and we look forward to future collaboration.”

Developing improved gene chips for flu diagnosis depends, in part, on the ready public availability of genomic sequence data, noted Karen Lacourciere, Ph.D., (U.S.) National Institute of Allergy and Infectious Disease (NIAID, Bethesda, MD, USA) flu program officer. In addition to flu genome sequence databases housed at the Los Alamos National Laboratory (Los Alamos, NM, USA) and the CDC, the scientists also used information from the NIAID-supported Influenza Genome Sequencing Project.



Related Links:
University of Colorado at Boulder
Centers for Disease Control and Prevention