A key gene that governs the severity of influenza infections has been identified. Scientists predict that this finding might lead to a new class of antiviral drugs capable of targeting a range of different infections, the British Science Festival heard last week.
By studying samples from the 2009 swine flu outbreak, researchers noticed a strong relationship between severity of influenza symptoms and variants in a gene called IFIT3. Around one in 400 people carries a variant named rs12552, which makes them more likely to experience severe, and sometimes fatal, illness when they are infected with the influenza virus.
Professor Paul Kellam of the Wellcome Trust Sanger Institute near Cambridge said: 'When you have this variant you have a four- to five-fold increased chance of severe influenza when exposed to a virus that is otherwise causing mild or no disease in the wider population.'
IFIT3 works by strengthening cell walls to prevent viruses from entering and infecting the cell. This defence is impaired in people who carry the rs12552 gene variant. Early signs are that drugs that increase the activity of IFIT3 may be effective treatments for other viral diseases as well.
'By understanding genetic variants like this we can start to think about broad-spectrum antivirals that hit a whole range of viruses, from flu to dengue and Ebola,' commented Professor Kellam.
'We have broad-spectrum antibiotics that work against a range of bacteria... This could lead to a broad-spectrum antiviral, though it would work by altering human cells rather than targeting the virus directly,' he added.
Although such treatments are an estimated five to ten years away, the discovery of the IFIT3 gene variant has more immediate implications for health. During flu epidemics, rapid testing for the rs12252 variant in hospital emergency departments could help to identify people at risk of developing severe influenza and prioritise them for treatment.
Using the test in healthy people could also lead to a personalised approach to influenza vaccination. At present, an annual flu vaccine is recommended for groups such as the over- 65s, pregnant women and people with chronic medical conditions, who are believed to be at greater risk of influenza complications. Identifying those who are genetically susceptible could help doctors to decide more accurately who should receive influenza vaccination.