That structure revealed a previously unsuspected idiosyncrasy of NS1 in H5N1 that could explain the virus' virulence. In most cases, when an infected cell is exposed to a virus, double-stranded RNA molecules are formed triggering a potent anti-viral response that involves production of interferon.
However, the two domains of NS1 in this H5N1 interact to form tiny tubules. The double-stranded RNA is hidden or sequestered in these structures. The cell never sees a significant length of the RNA and does not marshal its immune forces to the fight the virus. Prasad and Bornholdt believe also that cellular factor binding sites found on the surface of the tubules also play a role in fooling the immune system.
"This is only one structure," said Prasad. "We need to see if this holds up with other NS1 structures from other influenza viruses."
Bornholdt's technique for crystallizing the protein will prove valuable in pursuing this work, said Prasad.
"Is this a common mechanism for eluding the immune system?" he said. He said hopes to build a library to NS1 structures to facilitate future studies designed to fight influenza worldwide.
While H5N1 is not usually transmitted from human-to-human at this point, a small change in its genetic structure perhaps an exchange of genes with a more easily transmitted flu virus could change that, he said. Developing drugs to fight the virus could prove life-saving in a pandemic.
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| Contact: Graciela Gutierrez ggutierr@bcm.edu 713-798-4710 Baylor College of Medicine Source:Eurekalert |