Wisconsin ? University of Wisconsin-Madison researchers have unveiled a critical protein that prevents influenza viruses from entering cells, a mechanism that could spark production of anti-viral medications to fight multiple flu strains, including the deadly strain of bird flu that’s circulating globally.

The authors said the findings provide a basic understanding of how to block replication in both seasonal flu strains and the avian influenza H5N1 virus inside cells, thus halting their ability to spread infection.

For the study, published this month in the Journal of Virology, UW researchers tested a small protein molecule, known as an entry blocker, in the presence of several influenza subtypes. An entry blocker is a fragment of a larger human protein that helps substances pass through membranes.

To the scientists’ surprise, the protein prevented each virus they tested – both seasonal strains and H5N1 – from attaching to the cell and from entering it, thus inhibiting the virus’ ability to replicate and infect more cells.

Furthermore, the protein improved survival among mice treated after exposure to the virus. Normally, infected mice die within a week, but all the animals given the protein survived.