To: MEDICAL EDITORS

Contact: Carrie Strehlau, Public Relations, +1-901-495-2295, carrie.strehlau@stjude.org, Summer Freeman, Public Relations, +1-901-495-3061, summer.freeman@stjude.org, or Marc Kusinitz, Ph.D., Scientific Communications, +1-901-495-5020, marc.kusinitz@stjude.org, all of St. Jude Children"e;s Research Hospital

MEMPHIS, Tenn., Aug. 20 /PRNewswire-USNewswire/ -- Scientists at St. JudeChildren"e;s Research Hospital have found key features that distinguishinfluenza viruses found in birds from those that infect humans.

The St. Jude team used a mathematical technique to identify specific aminoacid building blocks that are statistically more likely to appear in avianinfluenza virus proteins and those that are more likely to be in humaninfluenza virus proteins. The differences in these amino acids can be used asmarkers to track changes in H5N1 avian influenza strains that threaten humans."Influenza mutates rapidly, so that any marker that is not the same in birdflu but remains stable in human flu is likely to be important," said DavidFinkelstein, Ph.D., research associate at the St. Jude Hartwell Center forBioinformatics and Biotechnology. "If human specific markers startaccumulating in bird flu viruses that infect humans, that suggests that thebird flu may be adapting to humans and could spread."

The researchers also found that various strains of H5N1 that have infectedhumans are more likely to contain human markers than are H5N1 strains thathave not infected humans. Only occasionally have H5N1 samples obtained fromhuman patients shown any of these markers, and no H5N1 strain has permanentlyacquired any of them.

A report on this work appears in the advanced online edition of "Journalof Virology."

The investigators cautioned that there is no proof yet that the humanmarkers in H5N1 and other bird flu viruses directly contribute to the abilityof these viruses to cause pandemics among humans; and H5N1 is not any moreadapted to humans today than in the past. However, the fact that the birdviruses accumulate and retain these markers after infecting humans suggeststhat these changes are important. Therefore, scientists should monitor avianinfluenza viruses to see if they are acquiring human markers.

"While we can"e;t directly estimate how long it would take an avian virussuch as H5N1 to acquire these traits, we can use these markers to roughlymeasure the distance between an avian influenza and a pandemic," said ClaytonNaeve, Ph.D., St. Jude Hartwell Center director and the paper"e;s senior author.

The other authors of this paper include Suraj Mukatira, Perdeep Mehta,John Obenauer, Xiaoping Su and Robert Webster.

This work was supported with funding by ALSAC.

St. Jude Children"e;s Research Hospital

St. Jude Children"e;s Research Hospital is internationally recognized forits pioneering work in finding cures and saving children with cancer and othercatastrophic diseases. Founded by late entertainer Danny Thomas and based inMemphis, Tenn., St. Jude freely shares its discoveries with scientific andmedical communities around the world. No family ever pays for treatments notcovered by insurance, and families without insurance are never asked to pay.St. Jude is financially supported by ALSAC, its fundraising organization. Formore information, please visit http://www.stjude.org.

SOURCE St. Jude Children"e;s Research Hospital

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