The 2009 pandemic swine flu virus is causing different symptoms and affecting different risk groups compared to seasonal flu strains.
One of the reasons may be the receptor cells where this virus attaches.
The seasonal influenza viruses attach to receptor cells in the upper respiratory system, including the nose, throat, and upper respiratory tract.
A new study has shown that this 2009 H1N1 strain can attach to lower respiratory membranes, something that our regular seasonal strains cannot do.
Using a carbohydrate microarray (a glass surface with different receptor cells), researchers added viruses and recorded the number of receptor cells that showed attached viruses.
Seasonal strains only attached to alpha 2-6 upper respiratory receptors while the 2009 pandemic strain could attach strongly to alpha 2-6 and weakly to alpha 2-3 lower respiratory receptors (Childs, Receptor-binding specificity of pandemic influenza A (H1N1) 2009 virus determined by carbohydrate microarray, Nature Biotechnology, September 2009).
Infections in the lower respiratory system can be much more serious and difficult to treat. Once viruses have have attached to those receptors and infected those cells, they replicate and spread easily.
People with symptoms of swine flu infections should consult their health care provider for treatment.