The new specimen was taken from the lung of one of 72 people buried in a mass grave after the flu swept through Brevig Mission, then known as Teller Mission, in 1918. The small town lost 85 percent of its population in a single week. Dr. Johan Hultin, a retired San Francisco pathologist, exhumed four bodies from the mass grave and found that one, an obese woman, was well-preserved. Tissue from her lung was later found to contain genes from the killer flu. The finding supports a widespread theory that flu viruses from swine are the most virulent for humans.
Most experts believe that flu viruses reside harmlessly in birds, where they are genetically stable.
Occasionally, a virus from birds will infect pigs. The swine immune system attacks the virus, forcing it to change genetically to survive. The result is a new virus. The 1918 flu genes were first isolated last year from the preserved lung tissue of an Army private who died at Fort Jackson, South Carolina. Army doctors in 1918 conducted autopsies on some of the 43,000 servicemen killed by the flu and preserved some specimens in formaldehyde and wax.