Science moves in mysterious ways, and sometimes what seems like the end of the story is really just the beginning. Or, at least, that is what some researchers are thinking as they scratch their heads over the weird genetic sequence of the 1918 flu virus.
Dr. Jeffery Taubenberger, a molecular pathologist at the Armed Forces Institute of Technology who led the research team that reconstructed the long-extinct virus, said that a few things seemed clear.
The 1918 virus appears to be a bird-flu virus. But if it is from a bird, it is not a bird anyone has studied before. It is not like the A(H5N1) strain of bird flus in Asia, which has sickened at least 116 people, and killed 60. It is not like the influenza viruses that infect fowl in North America.
Yet many researchers believe that the 1918 virus, which caused the worst infectious disease epidemic in human history, is a bird-flu virus. And if so, it is the only one that has ever been known to cause a human pandemic.
That, Taubenberger said, gives rise to a question. Are scientists looking for the next pandemic flu virus in all the wrong places?
"I can't even assign a hemisphere," he said. "It just came from somewhere else. Maybe it's in pigeons. Or in songbirds."
"It's weird, it's really weird," he added. "My view is to be undogmatic as possible and just try to follow the data. This is the result we get. The question is: What does it mean?"
Taubenberger's question emerged from the science fiction-like search for the 1918 virus that eventually led to its reconstruction.
A decade ago, Taubenberger and his colleagues found shards of the extinct virus in two fingernail-size snippets of formaldehyde-soaked lung tissue from two soldiers and from the frozen lung of an Inuit woman who died of the flu in 1918 and was buried in permafrost. Slowly and pain-stakingly, they fished out the tiny fragments of viral genes and began reconstructing them.
The first gene they sequenced was the one that codes for the hemagglutinin protein on the virus' surface. Immediately, Taubenberger and his colleagues were struck by an oddity: The chain of nucleotides that coded for the amino acids in the protein were arranged differently from those found in any other bird flu.
The genetic code is flexible; there is more than one way that a group of three nucleotides can be arranged to code for the same amino acid.
But every bird-flu virus ever studied used the same spellings for the hemagglutinin amino acids. Not the 1918 flu.
There were two possibilities, Taubenberger thought. One was that bird flus have evolved over the decades and that back in 1918, the amino acids in bird viruses were simply coded differently.
Another was that if the 1918 flu virus came from a bird, it was no bird that anyone had considered before.
"We decided there was no way to address this," Taubenberger said. After all, the birds from 1918 were long gone, and their viruses had died with them.
Then Dr. Thomas Fanning, a scientist in Taubenberger's group, mentioned that he had a friend at the Smithsonian who worked at the National Museum of Natural History in Washington. It had several thousand preserved birds from the early 20th century that were floating in Mason jars of alcohol.
From there, they reached James Dean, a supervisor in the division of birds at the museum, who sent Taubenberger a computer printout of the birds in the museum's collection -- hundreds of birds, with notes telling the species and the exact times and places where they were collected. But which to choose?
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