WASHINGTON, Jan. 26 (Xinhuanet) -- U.S. scientists have found a unique gene carried by the H5N1 bird flu strain may be a key factor in making the virus so deadly, local media reported on Thursday.

    Researchers at St. Jude Children's Research Hospital in Memphis,Tenn. discovered the gene after a large analysis of samples of about 11,000 flu viruses that Dr. Robert Webster has gathered from around the world since 1976. The samples include about 7,000 bird flu viruses, from poultry, ducks, gulls and other flocks.

    Initial results from the genetic analysis showed that all the bird flu viruses studied had the unique gene and none of the human flu viruses did, researchers reported in the journal Science.

    They also said people infected with H5N1 flu virus in Vietnam and Thailand had the "avian" version of the flu virus, and so was the case with the 1918 flu pandemic, which killed tens of millions of people globally.

    The researchers have completed the first large genetic analysis of more than 300 bird flu viruses from the virus collection. They identified 2,196 bird flu genes and 160 complete genomes. The information are posted in a public genetic database for any scientist to mine it.

    The study suggests that two nonstructural proteins, NS1 and NS2,may be key in helping avian virus latch onto and disrupt certain important cellular processes. They are only made once the avian flu virus has infected a cell. However, more evidence are needed to confirm the finding.

    The H5N1 bird flu virus was first found to have spread to people in 1997. It resurfaced in 2003 and has since infected at least 152 people and killed 83, according to the World Health Organization.

    Scientists fear the virus would soon mutate to become easily transmissible among people and cause a global pandemic similar to the 1918 outbreak. Enditem