St. Jude influenza survey uncovers key differences between bird flu and...(m identified 32 specific locations in pr...)

Date:8/20/2007

m identified 32 specific locations in proteins where a gene mutation caused the existing amino acid to be substituted with a different amino acid. What made these 32 changes special was that influenza from birds differed from the influenza that was in humans. After the avian influenza infected humans, the amino acid changes are stable in the proteins and remain stable over time. Therefore, these markers can be used to distinguish influenza viruses that infect birds from those that infect humans.

The researchers discovered these markers by computationally surveying the sequence of amino acids in 10,671 proteins from avian influenza viruses and 13,757 proteins from human influenza viruses. The survey identified 32 persistent markers that exist in five bird and human virus proteins: PA, NP, M1, NS1 and PB2. These markers stand out as obvious differences between bird and human viruses, and many appear in regions where host protein and viral replication occur. The researchers did not determine what functional role the markers play in the life of the viruses.

For example, 26 of the 32 markers discovered are found in NP, PB2 and PA, which help to form a complex of proteins critical for the replication of virus genes. The other six persistent host markers are in M1 and NS1 proteins. M1 is known to bind to a protein in cells that enhances the replication of viruses; and NS1 plays a role in suppressing the host immune response. Therefore, the markers in M1 and NS1 might represent key mutations needed to improve the ability of the virus to suppress the immune system and enhance viral replication.

The St. Jude team also studied markers in influenza viruses that caused pandemics in 1918, 1957 and 1968outbreaks thought to have been caused by avian influenza viruses that adapted to humans. The study focused on the viruses isolated from humans early in each pandemic in order to determine which markers the viruses had recently acquired just before t
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Contact: Summer Freeman summer.freeman@stjude.org 901-495-3061 St. Jude Children's Research Hospital Source:Eurekalert

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