By BLOOMBERG NEWS
Published: January 18, 2007
Scientists infected monkeys with a virus that caused the 1918-19 influenza pandemic and said in the Jan. 18 issue of the journal Nature that it caused an illness like that suffered by patients with the bird flu now spreading in Asia.
Infection with a reconstructed version of the 1918 virus, known as the Spanish flu, incited a deadly chemical reaction in the laboratory animals, a group of scientists said in the magazine.
The group was led by Darwyn Kobasa, a researcher for the Public Health Agency of Canada in Winnipeg, Manitoba. Both the Spanish flu and H5N1 bird flu in Asia appear able to set off the reaction, the researchers said. Studying the Spanish flu virus’s interaction with monkeys may help health officials prepare for a possible pandemic caused by H5N1.
“We see responses that are similar between humans infected with H5N1 and nonhuman primates infected with the 1918 virus,” said Yoshihiro Kawaoka, a virologist at the University of Wisconsin in Madison. “By studying this model in detail, we may learn to cope with those immune responses.”
The 1918 flu may have killed as many as 50 million people, about 2 percent of those infected. Researchers say the outbreak started as a bird virus, until genetic changes enabled it to spread in people.
Similar mutations may allow H5N1 to set off a pandemic, researchers say. The bird flu has infected 267 people, mostly poultry workers or keepers in Asia, and killed 161 of them since late 2003, according to data compiled by the World Health Organization.
While the study points to an immune response as a probable cause for the destructiveness of the 1918 flu, researchers are still learning about the virus, said Michael Katze, a microbiologist at the National Primate Research Center at the University of Washington in Seattle.
“We know very little about why these viruses are so lethal,” Dr. Katze said.
Research has shown that H5N1 kills mice, causing the same kind of chemical reaction, called a cytokine storm, seen in the monkeys. Many other flu viruses are also fatal in mice, and the researchers said it was important to conduct studies in primates.
In 2005, Army scientists reported that they had reconstructed the Spanish flu virus by extracting genetic fragments from the bodies of victims exhumed from the Alaskan permafrost. American and Canadian researchers compared the effects of the virus on monkeys with those of seasonal flus.
The 1918 virus grew faster and spread more widely in the monkeys than the other viruses. While the immune reaction to the seasonal viruses abated after a few days, the response in monkeys with Spanish flu persisted, damaging tissues and impairing lung function, the study said.
