A team of researchers has discovered at least in part why some people infected with the swine flu H1N1 virus develop far more serious lung problems than those contracting seasonal H1N1 strains. Their studies also suggest that further mutations in the A/H1N1 virus could lead to a far higher proportion of infected people developing serious respiratory conditions.
The research is published in Nature Biotechnology in a paper titled “Receptor-binding specificity of pandemic influenza A (H1N1) 2009 virus determined by carbohydrate microarray.”
The scientists used carbohydrate arrays to compare seasonal and pandemic H1N1 flu strains in terms of their ability to bind to different receptors in the respiratory tract and lungs. They found that while seasonal strains only infected via binding to α2–6 receptors in the nose, throat, and upper airways, pandemic H1N1 flu could also bind, albeit weakly, to α2–3 receptors in the lungs. They suggest it is this ability of pandemic H1N1 to bind to cells in the lungs that leads some patients to develop serious respiratory symptoms.
Fortunately, because current pandemic H1N1 strains can only bind weakly to lung receptors, most people infected still only develop mild symptoms, the investigators state. As the paper’s co-author, Ten Feizi, points out, though, further mutations could allow the virus to cause more severe infection.
“If the flu virus mutates in the future, it may attach to the receptors deep inside the lungs more strongly, and this could mean that more people would experience serious symptoms. We think scientists should be on the lookout for these kinds of changes in the virus, so we can try to find ways of minimizing the impact of such changes.”