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UMD alum resurrects and studies killer flu virus
By Cheryl Reitan
December 22, 2005
The possibility of an avian flu pandemic has been a hot topic in the news for much of the past year. And Terrence Tumpey, a 1986 University of Minnesota, Duluth (UMD) biology graduate and senior microbiologist at the Influenza Branch of the Centers for Disease Control and Prevention, is at the forefront of research on the avian flu.
"Studying the influenza virus is a challenge," Tumpey said. "We're always trying to stay one step ahead. We're amazed at how it can adapt if you give it time."
Tumpey and his colleagues are studying the lethal 1918 virus that killed 50 million people worldwide and half a million in the United States. Their work, as reported in the October, 2005, issue of Science, has used a technique called reverse genetics to re-create a living 1918 virus. To do that, they gathered viral DNA from the preserved tissues of people who died in 1918 and 1919--including a woman whose body was frozen in the Alaskan permafrost.
Tumpey's research has determined that avian flu is genetically similar to the Spanish flu of 1918. The virus began with bird flu genes but then mutated to become infectious to humans. The research team also found that the 1918 flu was a purely avian virus, not a hybrid. It appeared to have passed directly from birds to humans and mutated on its own. Scientists say this is one mode of viral infection and the possible cause of the rapid spread of the 1918 pandemic.
"Influenza viruses are constantly evolving, and that means our science needs to evolve if we want to protect as many people as possible from pandemic influenza," said Tumpey.
The Spanish flu began with mild outbreaks in the spring of 1918 but then swept the globe by the fall. Nearly half of those who died were young, healthy adults, rather than the usual flu victims--young children and the elderly. Soldiers returning from World War I also brought the virus home with them. Poor hygiene and uninformed medical practice helped spread the pandemic.
Tumpey's tests revealed that the 1918 flu had a unique function. It targeted deeper areas of the lungs than standard viruses. It affected the delicate tissues where oxygen and carbon dioxide are exchanged, creating inflammation deep in the lungs and blocking the airways.
Since his work is extremely dangerous, the precautions are meticulous. All viruses are handled inside a biosafety cabinet. Researchers wear a half-body suit with a respirator, and all the air they breathe is filtered. Rigorous security requirements include fingerprinting pads and retina scanning, and guarantee the virus doesn't fall into the wrong hands.
Three worldwide outbreaks of flu occurred in this century--in 1918, 1957, and 1968. The 1957 pandemic killed about 70,000 Americans and the 1968 "Hong Kong flu'' killed about 34,000. The milder pandemic flu bugs of 1957 and 1968 also had bird flu genes. But they picked up the ability to spread in humans by swapping genes with a human flu virus. While all three flus may have been caused at least partially by viruses from animals, the 1918 flu, by far the most deadly, may have started when a bird virus acquired genetic changes allowing for human-to-human spread. The presence of genes from the human virus gave the human immune system some ability to recognize the flu and fight it off.
Researchers downplayed the risk of bringing back to life a virus that killed millions of people 87 years ago. People who survived the initial 1918 outbreak gained immunity to the virus, and milder versions of the Spanish flu have been circulating among people for decades.
"By identifying the characteristics that made the 1918 influenza virus so harmful, we have information that will help us develop new vaccines and treatments," said Tumpey. "Influenza viruses are constantly evolving, and that means our science needs to evolve if we want to protect as many people as possible from pandemic influenza."