KEY POINTS:
Scientists say they have identified a weakness in a protein in influenza viruses which could be targeted by new drugs to halt the spread of infection.
The protein's long tail appears to be its weak point. The tail loop is almost identical in different strains of influenza A - the most common form of the virus. New drugs that target it could be effective against multiple strains including the feared H5N1 bird flu.
"We have determined the atomic structure of the nucleoprotein from influenza A virus and found it contains a flexible tail loop," said Dr Yizhi Jane Tao, head of the research team from Rice University in Houston, Texas.
"This protein is important for virus replication. The tail structure gives us some hints about how to design antiviral drugs by using this protein as a target."
The scientists are now collaborating with other researchers to screen possible drug compounds that could inhibit virus replication.
The findings reported in the journal Nature could pave the way for a totally new approach to a virus that can kill.
Current treatment is centred on antiviral drugs such as Roche's Tamiflu, which Governments around the world have stockpiled against a potential pandemic. Some H5N1 viruses have shown resistance to the drug.
Health experts fear H5N1, which has infected 258 people and killed 154 since late 2003, could mutate into a form that could become highly infectious in humans, sparking a pandemic in which millions could die.
Regular seasonal influenza, type A and type B, kills between 250,000 and 500,000 people a year globally, says the World Health Organisation.
Dr Tao and scientists at the University of Texas at Austin grew nucleoprotein (NP) crystals on glass slides sealed in a jar.
NP has several important functions and is central to viral infection because after the virus has hijacked a cell, the protein forms columns that are needed for the virus to infect other cells.
The tail loop of NP has about 30 amino acids, which are the building blocks of proteins.
"We found that a mutation in only one residue out of 30 was enough to prevent the NPs from coming together to form the building blocks for the columns," Dr Tao said, "and without these columns the virus cannot make copies and infect other cells."
- REUTERS
