Scientists from the Mount Sinai School of Medicine injected mice with a reconstructed 1918 influenza virus and found an unusually fierce activation of the immune system, probably the main factor in making this virus particularly deadly.
From BBC News:
Scientists in the US have reconstructed the H1N1 virus in a bid to better understand how it became such an effective killer – and to also bolster knowledge in the face of current H5N1 bird flu threat.
The researchers infected mice with the recreated influenza virus.
Through functional genomic analysis they discovered that the mice’s immune systems responded fiercely to the infection and remained active until the animals’ deaths several days later.
At the same time, the animals also suffered the severe lung disease that is characteristic of the virus.
Dr John Kash, lead author of the study and assistant professor of microbiology at the University of Washington, said: “What we think is happening is that the host’s inflammatory response is being highly activated by the virus, and that response is making the virus much more damaging to the host.
“The host’s immune system may be overreacting and killing off too many cells, and that may be a key contributor to what makes this virus more pathogenic.”