After just a couple of small changes to a single gene in a pandemic flu virus, it no longer passes efficiently between lab animals. That finding reveals a simple way in which avian-flu strains, such as the bird-flu strains now looming in Asia, could morph into strains that have pandemic-causing potential, say researchers.
The scientists, led by Terrence Tumpey of the Centers for Disease Control and Prevention in Atlanta, worked with a reconstructed version of the 1918-flu virus (SN: 10/8/05, p. 227: Killer Findings: Scientists piece together 1918-flu virus). The microbe caused a pandemic in 1918 and 1919. Researchers have concluded that the virus originated as an avian flu strain.