Protein 'tubules' free avian flu virus from immune r...( A protein found in the virulent avia...)

A protein found in the virulent avian influenza virus strain called H5N1 forms tiny tubules in which it "hides" the pieces of double-stranded RNA formed during viral infection, which otherwise would prompt an antiviral immune response from infected cells, said Baylor College of Medicine researchers in an online report in the journal Nature.

Two domains or portions of the protein NS1 combine to form tiny tubules where double-stranded RNA is hidden from the immune system, said Dr. B. V. Venkataram Prasad, professor of biochemistry and molecular biology, molecular virology and microbiology at BCM and his student, Dr. Zachary A. Bornholdt (now of the Scripps Research Institute in La Jolla, California).

"Once we confirm the importance of this structural information, we should be able to design drugs to block this action," said Prasad. "There are other things the protein could do to interfere with different immune mechanisms. We don't know if this is the only mechanism or if there are others that also come into play during influenza virus infection."

The two researchers had already recognized the importance of the protein NS1 in the virulence of influenza viruses and particularly, H5N1, a form of avian flu associated with more than half the deaths in a 2004 "bird flu" outbreak that resulted in 50 human cases and 36 deaths in Vietnam, China and Thailand. In all but one case, experts ruled out human-to-human spread of the virus. In a previous report, Prasad and Bornholdt described the structure of an area of the protein called the effector domain. In this report, a series of elegant experiments designed and carried out over eight months by Bornholdt allowed the two scientists to "crystallize" the entire protein.

By doing this, they were able to determine its structure using a technique called X-ray crystallography. This technique enables scientists to determine the three-dimensional structure of proteins and other bio-molecu
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