St. Jude Influenza Survey Uncovers Key Differences Between Bird Flu and Human Flu

Specific mutations linked to immune suppression and viral replications

differ between bird and human flu viruses could be used to monitor emerging

pandemics



20 Aug, 2007, 01:00 ET from St. Jude Children's Research Hospital

    MEMPHIS, Tenn., Aug. 20 /PRNewswire-USNewswire/ -- Scientists at St.
 Jude Children's Research Hospital have found key features that distinguish
 influenza viruses found in birds from those that infect humans.
     The St. Jude team used a mathematical technique to identify specific
 amino acid building blocks that are statistically more likely to appear in
 avian influenza virus proteins and those that are more likely to be in
 human influenza virus proteins. The differences in these amino acids can be
 used as markers to track changes in H5N1 avian influenza strains that
 threaten humans. "Influenza mutates rapidly, so that any marker that is not
 the same in bird flu but remains stable in human flu is likely to be
 important," said David Finkelstein, Ph.D., research associate at the St.
 Jude Hartwell Center for Bioinformatics and Biotechnology. "If human
 specific markers start accumulating in bird flu viruses that infect humans,
 that suggests that the bird flu may be adapting to humans and could
 spread."
     The researchers also found that various strains of H5N1 that have
 infected humans are more likely to contain human markers than are H5N1
 strains that have not infected humans. Only occasionally have H5N1 samples
 obtained from human patients shown any of these markers, and no H5N1 strain
 has permanently acquired any of them.
     A report on this work appears in the advanced online edition of
 "Journal of Virology."
     The investigators cautioned that there is no proof yet that the human
 markers in H5N1 and other bird flu viruses directly contribute to the
 ability of these viruses to cause pandemics among humans; and H5N1 is not
 any more adapted to humans today than in the past. However, the fact that
 the bird viruses accumulate and retain these markers after infecting humans
 suggests that these changes are important. Therefore, scientists should
 monitor avian influenza viruses to see if they are acquiring human markers.
     "While we can't directly estimate how long it would take an avian virus
 such as H5N1 to acquire these traits, we can use these markers to roughly
 measure the distance between an avian influenza and a pandemic," said
 Clayton Naeve, Ph.D., St. Jude Hartwell Center director and the paper'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's Research Hospital
     St. Jude Children's Research Hospital is internationally recognized for
 its pioneering work in finding cures and saving children with cancer and
 other catastrophic diseases. Founded by late entertainer Danny Thomas and
 based in Memphis, Tenn., St. Jude freely shares its discoveries with
 scientific and medical communities around the world. No family ever pays
 for treatments not covered by insurance, and families without insurance are
 never asked to pay. St. Jude is financially supported by ALSAC, its
 fundraising organization. For more information, please visit
 http://www.stjude.org.
 
 

SOURCE St. Jude Children's Research Hospital
    MEMPHIS, Tenn., Aug. 20 /PRNewswire-USNewswire/ -- Scientists at St.
 Jude Children's Research Hospital have found key features that distinguish
 influenza viruses found in birds from those that infect humans.
     The St. Jude team used a mathematical technique to identify specific
 amino acid building blocks that are statistically more likely to appear in
 avian influenza virus proteins and those that are more likely to be in
 human influenza virus proteins. The differences in these amino acids can be
 used as markers to track changes in H5N1 avian influenza strains that
 threaten humans. "Influenza mutates rapidly, so that any marker that is not
 the same in bird flu but remains stable in human flu is likely to be
 important," said David Finkelstein, Ph.D., research associate at the St.
 Jude Hartwell Center for Bioinformatics and Biotechnology. "If human
 specific markers start accumulating in bird flu viruses that infect humans,
 that suggests that the bird flu may be adapting to humans and could
 spread."
     The researchers also found that various strains of H5N1 that have
 infected humans are more likely to contain human markers than are H5N1
 strains that have not infected humans. Only occasionally have H5N1 samples
 obtained from human patients shown any of these markers, and no H5N1 strain
 has permanently acquired any of them.
     A report on this work appears in the advanced online edition of
 "Journal of Virology."
     The investigators cautioned that there is no proof yet that the human
 markers in H5N1 and other bird flu viruses directly contribute to the
 ability of these viruses to cause pandemics among humans; and H5N1 is not
 any more adapted to humans today than in the past. However, the fact that
 the bird viruses accumulate and retain these markers after infecting humans
 suggests that these changes are important. Therefore, scientists should
 monitor avian influenza viruses to see if they are acquiring human markers.
     "While we can't directly estimate how long it would take an avian virus
 such as H5N1 to acquire these traits, we can use these markers to roughly
 measure the distance between an avian influenza and a pandemic," said
 Clayton Naeve, Ph.D., St. Jude Hartwell Center director and the paper'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's Research Hospital
     St. Jude Children's Research Hospital is internationally recognized for
 its pioneering work in finding cures and saving children with cancer and
 other catastrophic diseases. Founded by late entertainer Danny Thomas and
 based in Memphis, Tenn., St. Jude freely shares its discoveries with
 scientific and medical communities around the world. No family ever pays
 for treatments not covered by insurance, and families without insurance are
 never asked to pay. St. Jude is financially supported by ALSAC, its
 fundraising organization. For more information, please visit
 http://www.stjude.org.
 
 SOURCE St. Jude Children's Research Hospital