As a rule, I normally defer to the brilliant Dr. Niman, but the new work by Dr. Taubenberg seems to be definitive.
http://www.businessweek.com/technology/content/oct2005/tc2005106_4568_tc057.htm
Scientist Jeffery Taubenberger says studies of the virus behind a deadly 1918 epidemic boost concerns about the danger of today's avian strains
In 1918, a devastating flu epidemic swept the world, killing more than 50 million people, including an estimated 675,000 in the U.S. The disease was deadlier than previous flu outbreaks, killing more than 2% of those infected. Some people died within hours, and many families lost at least one member.
Why was the virus so dangerous? Could such a pandemic happen again? Could the strains of avian flu now destroying poultry in Asia and spreading from Russia toward Europe turn into deadly human viruses?
CUTTING-EDGE METHODS. The urgency of those questions inspired scientists to embark on a several-year quest to unearth lung tissue from victims of the 1918 flu and to analyze the viruses' genes. The task has been challenging. Some samples came from tissue saved from long-ago autopsies. Others came from people buried in Alaska and frozen by the permafrost.
In both types of samples, however, the amounts of virus were tiny -- usually just a single copy of DNA fragments. As a result, researchers had to use cutting-edge molecular biology methods to read the genetic codes.
Now they have succeeded. In an Oct. 6 paper in Nature, scientists, led by Jeffery K. Taubenberger of the Armed Forces Institute of Pathology, report that they have read the full genetic sequence of the 1918 virus, along with the codes of scores of other influenza strains, including the avian flu.
DEADLY QUALITIES. Simultaneously, a team at the Centers for Disease Control & Prevention wrote in a paper in the Oct. 7 issue of Science that they used the genetic information to recreate the deadly 1918 strain. They proved how virulent the virus was by giving it to mice. The mice quickly died.
The work of these two teams is more than just a scientific tour-de-force. It also opens the door to understanding why some flu strains are deadlier than others -- and to figuring out how a virus that originally infects only birds is able to evolve to target humans.
Soon it should be possible to use this information to learn if today's flu strains are mutating in ways that could bring another pandemic.
...........(snip)
That seems to raise a key point, since one huge question is whether epidemics are likely to be caused by a bird flu virus that suddenly mutates so that it can infect humans, or whether a bird virus and a human flu virus get together and mix genes, creating an even more dangerous strain. What is the story for the 1918 virus?
This is the biggest surprise, we think. The data support the conclusion that this was an entirely avian virus that adapted for humans. It was not an assortment or mix of bird and human virus, as in the last two pandemics [in 1957 and 1968].
MA