A genetic variant which explains why Chinese populations may be more vulnerable to H1N1 swine flu has been found by researchers at the University of Oxford and Beijing Capital Medical University.
This finding could help identify those at high risk of severe infection and help prioritise those in highest need of treatment.
The study led by Dr Tao Dong of the University of Oxford showed that people with a specific genetic variant are six times more likely to suffer from severe influenza infection than those without.
The particular variant rs12252-C is occasionally found in Caucasian populations and was already known to be associated with more severe influenza disease. However, the research teams in the UK and China showed that this variant was present in 69% of Chinese patients with severe pandemic (swine) influenza in 2009 compared with 25% who only had a mild version of the infection.
The results are published today in the journal Nature Communications. The study was part-funded by the Medical Research Council.
Dr Tao Dong of the Weatherall Institute of Molecular Medicine at Oxford University says: 'Understanding why some people may be worse affected than others is crucial in improving our ability to manage flu epidemics and to prevent people dying from the virus. It's vital that we continue to fund research that examines flu from the smallest details of our genetic code, in the populations around the world that continue to be vulnerable to infection.'
The results suggest that the gene variant increases the severity of, rather than susceptibility to, influenza infections.
It is thought that the DNA change increases risk of severe infection by limiting the effectiveness of a protein which helps to defend against influenza and similar viruses. This protein, known as IFITM3, has been previously shown to slow down virus replication in mice.
Professor Andrew McMichael, co-author of the study at the University of Oxford, says: 'The apparent effect of this gene variant on the severity of influenza is of great interest. It remains to be seen how this gene affects the whole picture of influenza in South East Asia but it might help explain why new influenza viruses often first appear in this region of the world.'