Feb. 2, 2007 — Making a small change in the outer coating of the lethal 1918 flu virus was enough to stop it from spreading, a discovery that may help scientists monitor today's bird flu and other influenza strains for signs of the next pandemic.
The 1918 pandemic was triggered by a bird virus that mutated into one that could attack humans, going on to kill a staggering 50 million people worldwide in a matter of months.
To learn what caused that catastrophic bird-to-human transformation, scientists with the Centers for Disease Control and Prevention turned back the clock: They worked with recreated batches of the actual H1N1 flu strain that spawned the 1918 pandemic, but they altered two spots in a key protein to make that virus a little more birdlike again.
Then the researchers dripped the altered virus into the noses of ferrets, who catch and spread influenza like humans do.
The infected ferrets still sickened and died as the flu ravaged their lungs. But remarkably, they didn't infect healthy ferrets caged right next to them, the CDC team reports in Friday's edition of the journal Science.
Why not? Most flu spreads when an infected person coughs or sneezes out droplets of virus. Ferrets infected with the altered 1918 virus didn't sneeze at all.
The research suggests that for a new flu strain to become a pandemic threat, a protein called hemagglutinin that coats the virus' surface must prefer attaching to cells found mostly in the human nose and windpipe, where it can be sneezed easily.
