NEW YORK, Sept. 27 (UPI) -- U.S. scientists say they've found mice infected with the 1918 influenza virus show a strong immune system response that fails to protect against death.
The research team was led by John C. Kash, research assistant professor of microbiology at the University of Washington Medical School. The team wanted to determine why the virus, which killed up to 40 million people, was so lethal.
In the study, researchers infected one group of mice with a reconstructed 1918 influenza virus and a second group with benign human influenza. The mice infected with the 1918 virus showed a rapid and potent immune system response, yet the animals developed severe lung disease and died.
The mice infected with the more benign viruses developed a less strong immune response, but fewer animals died.
"When the body responds to infection, there are components of the immune system that can be beneficial and those that can be harmful," said Assistant Professor of Microbiology Christopher Basler of Mount Sinai Hospital in New York. "Our next step is to repeat these experiments, but deconstruct what the immune system is doing so that we can understand why it is reacting so strongly, yet failing to fight the infection."
The study appears online in the journal Nature.