Washington: Researchers have uncovered the Achilles heel of dreaded flu viruses, potentially opening the way for combating them and other virulent strains much more effectively.

"Our work uncovers an Achilles heel of influenza A viruses that cause human epidemics and high mortality pandemics," said Gaetano T. Montelione, professor of molecular biology and biochemistry at Rutgers University.

Working jointly with Texas University researchers, he determined the structure of a key site on an influenza A virus protein in 3D, that binds to one of its human protein targets, suppressing one's defences and helping the virus replicate.

This so-called NS1 virus protein is shared by all influenza A viruses isolated from humans - including avian influenza, or bird flu, and the 1918 pandemic influenza virus.

Previously, Robert M. Krug of Texas University discovered that the NS1 protein binds a human protein known as CPSF30, known to protect human cells from flu infection.

Once bound to NS1, the human protein can no longer generate molecules needed to suppress flu virus replication. Montelione and Krug of Rutgers identified the novel NS1 binding pocket that grasps the human CPSF30 protein.

The breakthrough was detailed in Proceedings of the National Academy of Sciences, Early Edition and is scheduled for publication in its forthcoming print edition.