MIT finds key to avian flu in humans( CAMBRIDGE Mass.--MIT researchers hav...)

CAMBRIDGE, Mass.--MIT researchers have uncovered a critical difference between flu viruses that infect birds and humans, a discovery that could help scientists monitor the evolution of avian flu strains and aid in the development of vaccines against a deadly flu pandemic.

The researchers found that a virus's ability to infect humans depends on whether it can bind to one specific shape of receptor on the surface of human respiratory cells.

Now that we know what to look for, this could help us not only monitor the bird flu virus, but it can aid in the development of potentially improved therapeutic interventions for both avian and seasonal flu, said Ram Sasisekharan, MIT Underwood Prescott Professor of Biological Engineering and Health Sciences and Technology, and the senior author of a paper on the work that will appear in the Jan. 6 issue of Nature Biotechnology.

Flu viruses come in many strains, and not all of them can infect humans. Strains known as H1 or H3 have jumped from birds to humans and hence are tailored to attack cells of the human upper respiratory tract. H5 strains are usually confined to birds, but when they do infect humans they can have very high fatality rates.

In the past decade, isolated outbreaks of avian flu (H5N1) in humans have raised concerns that a deadly pandemic could arise if the avian flu evolves to a form that can easily infect humans and pass from person to person. Some scientists believe such an outbreak could rival the 1918 Spanish flu that killed 50 million to 100 million people worldwide.

Scientists already knew that whether an influenza virus infects humans depends on whether its hemagglutinin, a protein found on the virus surface, can bind to sugar (or glycan) receptors in the respiratory tract. Human respiratory cells have glycan receptors classified as alpha 2-6; avian respiratory cells' glycan receptors are known as alpha 2-3. This classification is based on how the sugars are
'/>"/>