# 1448
Ten days ago I wrote an essay on how RBDs (Receptor Binding Domains) determined what kind of receptor cells a virus could attach to.
New research now indicates that the shape of the sugar molecule on the surface of animal cell membranes is a determining factor in viral binding.
I prefer to think of this as augmenting my essay, not making it obsolete. Oh, Well. Science marches on.
This from The Times of India.
How humans catch bird flu: Study
6 Jan 2008, 1134 hrs IST
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PARIS: Scientists on Sunday said they had figured out how influenza viruses carried by birds latch on to humans, a discovery that may open the way to a vaccine against not just deadly avian flu but against all flu types.
There are many strains of flu virus, but only a few have succeeded in crossing the species barrier from animals to humans.
Strains known as H1 and H3 are the most common, and are especially efficient in attacking cells in the upper reaches of the respiratory system. Variants of the H5 virus, by contrast, usually remain confined to wild or domesticated fowl.
But when they do infect humans it is often with lethal results, as immune systems are unable to recognise and counter the novel pathogen.
<snip>
Up to now, scientists believed it was a genetic switch in the virus that allowed it to bind to human rather than bird receptors, thus making the much-feared "species jump" possible.
But the study, led by Massachusetts Institute of Technology (MIT) professor Ram Sasisekharan, says that the big factor is the shape of the sugar receptors in human lung cells.
The human alpha 2-6 receptors come in two shapes, one broadly resembling an umbrella, and the other a cone. To infect humans, flu viruses must bind to the umbrella-shaped receptors, the researchers found.
"This work enables researchers to look at flu viruses in an entirely new way," said Jeremy Berg, director of the National Institute for General Medical Sciences, which funded the research.
