New way to target flu viruses found

Washington D.C: Researchers have found a new way to target flu viruses. There is a hitch in the swing of a protein that delivers the flu virus. Rice University and Baylor College of Medicine researchers believe this mechanism may be a useful target to stop the virus from infecting cells.

The paper begins to define the mechanism that allows the protein to unfold and refold in a snap, changing its form to expose a peptide that attaches the virus to a cell and begins infection.

The researchers believe therapeutic drugs can use this mechanism to shut the virus down. "This protein starts in a folded state and goes through a global transformation, refolding in a completely different state, But there's a small part in the center that evolution has conserved," said Onuchic, co-director of Rice`s Center for Theoretical Biological Physics (CTBP). 

That single conserved amino acid residue is the hitch that makes the protein pause in the process of refolding. It allows a fusion peptide buried inside to bind to the target cell and begin infecting it. Without the pause, the refolding would be too quick for binding to take place. said Onuchic.

He added, "We figured out there's a bunch of energy that makes the final state of HA2 much more stable than the initial state. But with the spring-loaded mechanism, most of the energy would already be wasted by the time it forms the coiled-coil and binds the cell and viral membranes."

The conserved hydrophilic (water-attracting) residue, known as Thr59, is of particular interest to the researchers not only for the way it disrupts folding and allows the virus to attack, but also because it has a twin.

Lead author and Rice postdoctoral researcher, Xingcheng Lin said, " The current research focused on the group that incorporates Thr59 and causes the H3N2 strain responsible for the Hong Kong flu."