The course of a flu infection varies greatly from person to person. While many patients get mildly ill, the flu can be severe or even fatal in others. In a study, English researchers have now come across a gene that apparently plays a role in this.
Scientists at the Wellcome Trust Sanger Institute in Hinxton near Cambridge examined the IFITM3 gene in more detail as part of a study. It belongs to the immune system’s first line of defense and plays a role in fighting infections. As the researchers reported in the journal “Nature”, they switched off IFITM3 in an experiment with mice and then infected the animals with an influenza virus. Normally, mice with this virus show only a mild course of disease, symptoms of the flu usually subside after a few days. In the mice with the blocked gene, however, the researchers observed a significantly more severe course: after a week, the rodents had lost more than a quarter of their body weight and were fighting for their lives. And apparently IFITM3 doesn’t just play a role in mice. In studies of 53 people who were hospitalized for severe swine flu in 2009, the researchers found a mutation of IFITM3 in three patients. Usually this mutation is only found in 1 in 400 people. The researchers see this as a possible cause of the severe course of the flu. However, further studies are needed to support this assumption.