I thought this was fairly interesting. I remember hearing about this when the experiment on mice took place, but this is further corroboration.
SEATTLE POST-INTELLIGENCER
http://seattlepi.nwsource.com/health/300109_flu18.html1918 flu ravaged body's defenses
Thursday, January 18, 2007
By TOM PAULSON
P-I REPORTER
Monkeys infected with a resurrected influenza virus responsible for history's deadliest pandemic have provided further evidence that the 1918 Spanish flu was so deadly because the virus somehow causes the immune system to overreact and attack the victim's body.
"It's still a mystery," said Dr. Michael Katze, a University of Washington virologist and one of the lead scientists on the research conducted at a high-security laboratory in Winnipeg, Manitoba. "We don't really know how or why this happens."
Katze and UW colleague John Kash were among a group of researchers who, last September, reported that mice infected with the 1918 flu virus caused a violent immune response. In today's article, published in the journal Nature, they and others have shown the response in infected macaque monkeys is just as rapid and violent.
"The guys in Winnipeg are used to dealing with things like ebola and they were still quite surprised at the extreme virulence of this virus in the macaques," Katze said. This is an important finding because monkeys are much closer to humans biologically, he said, and the observation of immune system overreaction in mice had to be confirmed in primates.
In 1918, the Spanish flu killed at least 50 million people worldwide and tended to hit healthy young adults hardest. Routine, seasonal flu tends to kill mostly the very young and the very old. In 1918, it was those with the healthiest immune system who died.
"Essentially, people are drowned by themselves," said University of Wisconsin virology Professor Yoshihiro Kawaoka, co-author of the study.
The Winnipeg experiment was supposed to last 21 days. But after eight days the monkeys were so sick -- feverish, in pain and having difficulty breathing -- that ethical guidelines forced the researchers to euthanize all seven of them ahead of schedule.
Katze and his colleagues did not handle the virus or the monkeys. The UW was involved because of its expertise in doing "functional genomic" analysis of tissue samples -- basically, looking for genetic clues that can explain what happens during infection.
"We still don't know why the host response was so violent, which viral genes are most important or what are the viral determinants of (the course of disease)," Katze said.
The 1918 virus, which was recovered from frozen corpses and reconstructed using reverse genetics, exists today only in two highly secure (known as Biosafety Level 4) labs where scientists are allowed to study it. This research was conducted at Public Health Agency of Canada's National Microbiology Laboratory in Winnipeg.
"This research provides an important piece in the puzzle of the 1918 virus, helping us to better understand influenza viruses and their potential to cause pandemics," said Dr. Darwyn Kobasa, lead author for this study and a researcher at the Canadian lab.
Kobasa and his colleagues said they were amazed by how rapidly and violently the virus attacked the macaques. The virus spread faster than a normal flu bug, he said, and triggered what some experts call a "storm" in the animal's immune systems.
Their bodies' defenses went haywire, not knowing when to stop, researchers said. The lungs became inflamed, filled with blood and fluids, threatening to drown the animals.
"It's a very good replicating virus and therefore it can affect more of the immune system," said Peter Palese, chairman of the microbiology department at Mount Sinai School of Medicine in New York. Palese wasn't part of the study but has worked on the 1918 virus.
The reason the scientific community today is especially interested in trying to figure out what exactly happened in 1918 is because the virus appears to have begun as a bird flu.
One strain of bird flu in circulation today, known as H5N1, is believed to have the potential to spark another human pandemic. It already has spread around the world in birds and killed a small number of people, but has yet to transmit easily from person to person. If it does, scientists think understanding the 1918 flu may give them clues about how to protect people from it.
The new work "gives us another tool," said Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, who was not part of the research. Fauci praised the study and said what it found in the effects on the body are stunning: "There aren't a lot of things that can induce that robust of an inflammatory response that quickly."
Material from The Associated Press is included in this report.
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