1918 influenza was an avian flu virus
Just in case you were wondering if all this talk about avian flu wasn't a bit overblown, we now find out that the virus that caused the 1918 influenza pandemic, which killed 50 million people, "more humans than any other disease in a similar duration in the history of the world," was a mutated form of an avian flu virus.
Two teams of federal and university scientists announced today that they had resurrected the 1918 influenza virus, the cause of one of history's most deadly epidemics, and had found that unlike the viruses that caused more recent flu pandemics of 1957 and 1968, the 1918 virus was actually a bird flu that jumped directly to humans.The studies are not published yet, but I'll post links when they're up.
The work, being published in the journals Nature and Science, involved getting the complete genetic sequence of the 1918 virus, using techniques of molecular biology to synthesize it, and then using it to infect mice and human lung cells in a specially equipped, secure lab at the Centers for Disease Control and Prevention in Atlanta.
The findings, the scientists say, reveal a small number of genetic changes that may explain why this virus was so lethal. The work also confirms the legitimacy of worries about the bird flu viruses that are now emerging in Asia.
The new research indicates that the 1918 virus, unlike more recent flu pandemics of 1957 and 1968, was actually a bird flu that jumped directly to humans. The new studies find that today's bird flu viruses share a few of the crucial genetic changes that occurred in the 1918 flu. The scientists suspect that with the 1918 flu, changes in just 25 to 30 out of about 4,400 amino acids in the viral proteins turned the virus into a killer. The bird flus, known as H5N1 viruses, have a few, but not all, of those changes.
Update 6 Oct: The Nature article is online now: Characterization of the 1918 influenza virus polymerase genes.
Update 7 Oct: Science article now online as well: Characterization of the Reconstructed 1918 Spanish Influenza Pandemic Virus.