Molecular sleuthing by military pathologists has exhumed the first fragments of the genetic blueprint of the virus behind the flu pandemic of 1918, which killed 20 million to 40 million people worldwide. The genetic mug shot, described in today's issue of Science,* could help health officials spot a reemergence of the deadly virus and suggests that pig populations--the source of the virus--be closely monitored.
The breakthrough came from the preserved tissues of a 21-year-old Army private who died in the 1918 pandemic. Looking for the culprit, pathologist Jeffery Taubenberger, molecular biologist Ann Reid, and their colleagues at the Armed Forces Institute of Pathology in Washington, D.C., examined several dozen samples of lung tissues taken from soldiers and preserved in their institute's archives. The flu virus stores its genetic information on single strands of RNA, which is very susceptible to degradation. "So you have to look for little pieces," Taubenberger says. Only in the lungs of the private did they find pieces of viral RNA. They amplified the RNA with the polymerase chain reaction, which provided enough to sequence parts of the virus's genetic code.
So far, the killer virus looks like a run-of-the-mill swine flu, not an avian virus as some virologists had suspected--leaving scientists to wonder why the strain was so deadly. As he continues to probe the viral RNA, Taubenberger wants to solve another mystery: why young adults, usually the most resistant to flu infections, were the hardest hit in 1918 by the swine flu.
"What this says is we had better watch what's happening in the pig populations of the world," says Robert Webster, a virologist at St. Jude Children's Research Hospital in Memphis, Tennessee. He notes that the ever-changing flu viruses in those animals are the source of new flu viruses in humans. Currently, both the Centers for Disease Control and Prevention and the World Health Organization devote most of their flu-surveillance efforts to monitoring for new flu strains in people, not animals.
Meanwhile, Taubenberger hopes that other researchers will comb their archives for more samples of the 1918 flu virus. He may get his wish: A Canadian-led team hopes to dig up seven miners who are thought to have died in the epidemic and have been preserved in their graves in the frozen ground near Spitzbergen, Norway. "We want to know what killed these people," adds Webster. "The potential is there for this kind of virus to return."