Research shows H1N1 swine flu can infect cells situated deeper in the lungs
11 September 2009
Researchers from Imperial College London and colleagues say this may explain why those infected with H1N1 influenza are more likely to suffer severe symptoms.
Influenza viruses infect cells by attaching to specific receptors on the outside of the cell. Seasonal influenza viruses attach to receptors found on cells in the nose, throat and upper airway.
The new research, published in 'Nature Biotechnology', shows that H1N1 swine flu can attach to those receptors, but also a receptor found on cells deep inside the lungs, which can result in a more severe lung infection.
The researchers say this may explain why H1N1 replicates and spreads between cells more quickly. If a flu virus is able to bind to more than one type of receptor, it can attach itself to a larger area of the respiratory tract, infecting more cells and causing a more serious infection.
"Receptor binding determines how well a virus spreads between cells and causes an infection," said Professor Ten Feizi, one of the researchers from Imperial College London.
"Our new study adds to our understanding of how the swine-origin influenza H1N1 virus is behaving in the current pandemic, and shows us changes we need to look out for."
The researchers compared the binding qualities of two samples of the H1N1 virus with a sample of a seasonal flu virus using a microarray (a glass surface with a variety of different cell receptors attached to it).
They found that the binding of the H1N1 virus to the lung receptors was weaker than that between H1N1 and receptors located in the upper respiratory tract, which may explain why most H1N1 swine flu patients experience mild symptoms. Consequently, the researchers are wary of what could happen in the future.
"If the flu virus mutates, it may attach to the receptors deep inside the lungs more strongly, and this could mean that more people would experience serious symptoms," said Professor Feizi.
"We think scientists should be on the lookout for these kinds of changes in the virus so we can try to find ways of minimising their impact."
The research was part-funded by the Wellcome Trust.
Image: A representation of the influenza virus. Credit: Anna Tanczos, Wellcome Images
Reference
Childs RA et al. Receptor-binding specificity of pandemic influenza A (H1N1) 2009 virus determined by carbohydrate microarray. Nat Biotechnol 2009;27(9):797-9.