Biologists recreated a virus responsible for the 1918 flu pandemic (also called the Spanish Flu) [wiki], which caused some 50 to 100 million
people deaths in just two years, from tissue samples gathered from corpses.
Now, they've found that the reconstructed virus is terrifyingly lethal in monkeys:
Some scientists question the wisdom of reconstructing such a deadly virus. Do the benefits outweigh the risks?
Those who carried out the macaque study say yes, as a better understanding of how it acts in a system similar to humans' will help scientists treat future pandemics. The study was carried out in the biohazard level 4 labs of the Public Health Agency of Canada in Winnipeg. Yoshihiro Kawaoka of the University of Wisconsin-Madison and his colleagues infected macaques with the 1918 virus or a contemporary flu strain3. Whereas the contemporary virus caused mild symptoms in the lungs, the 1918 flu spread quickly throughout the respiratory system and the monkeys died within days. The damage parallels reports of human patients in 1918.
The team reports that the 1918 virus caused the monkeys' immune systems to go into overdrive, causing immune proteins to be expressed at abnormally high levels and attack the body — what immunologists call a cytokine storm.
By the way, when they sequenced the Spanish Flu virus, the scientists proposed that the virus was derived from an avian source. Bird flu [wiki], anyone?