Gene that stops killer flu viruses discovered

Some people may be at risk of a severe reaction to flu because they are not protected by a key gene, scientists in Scotland have found.

Researchers have for the first time identified a human gene responsible for susceptibility and response to flu and other viruses.

The gene – IFITM3 – produces a protein that protects cells against infections and is thought to be critical in the immune system’s response against viruses such as swine flu.

Scientists think when the protein produced by the normal IFITM3 gene is present in large quantities, the spread of flu in the lungs is hindered. When protein levels are lower, the virus can spread more easily causing severe symptoms.

The study found that patients who ended up in intensive care with potentially fatal complications after developing flu were much more likely to have a variant of this gene, that did not protect against the virus.

The research was led by the Wellcome Trust Sanger Institute, working in collaboration with scientists from The Roslin Institute, at the University of Edinburgh, and clinicians at NHS Lothian.

The study analysed DNA from patients treated in Scottish intensive care units during the 2009-10 swine flu pandemic.

Families were approached for permission to take blood samples from the patients, who had been previously fit and healthy but had developed life-threatening lung complications from flu.

Scientists found that 5.3 per cent of patients in intensive care with flu had a variant of IFITM3.

This was a significantly higher proportion of the gene variant than found in the general population, which was 0.3 per cent.

They said the findings “strongly suggest” that it plays a key role in flu susceptibility and reduced ability to fight the infection.

The study, called the Genetics of Influenza Susceptibility in Scotland (GenISIS) started when the swine flu pandemic hit Scotland. It was led by clinicians in NHS Lothian, with intensive care units across Scotland collaborating through the Scottish Critical Care Trials Group and funding from the Chief Scientist Office and the Wellcome Trust.

Dr Kenneth Baillie, of The Roslin Institute, said: “While most people who may contract flu during a pandemic will recover well and not experience serious symptoms, some develop a catastrophic and potentially fatal illness and need to be treated in intensive care. This happens to otherwise healthy, young people. This study shows for the first time it may be because they are more genetically susceptible to the virus.”

The studies of patients followed initial studies at the Wellcome Trust Sanger Institute that identified the IFITM3 gene in mice.

Professor Tim Walsh, professor of critical care medicine at the University of Edinburgh and consultant in critical care for NHS Lothian, said: “[This study] opens avenues for future research by clinicians and scientists to develop ways of predicting who might be at risk and where to focus efforts to find new treatments.”