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Scientists: 1918 Killer Flu Was a Bird Flu

Ominous Changes in Current Bird Flu Echo 1918 Virus

How Much Time Do We Have?

How long does this process take? Nobody knows. Taubenberger says the 1918 bird virus appeared in humans "a couple of years" before 1918. But how long it took the virus to jump species from birds to humans is unknown.

There is one ominous sign. It's in a flu gene protein called PB2. A single change in this gene makes H5N1 extremely deadly to mice. The same single change helps bird flu to adapt to mammals.

For example, the change in PB2 was seen in six of the seven H5N1 viruses spreading among captive tigers in Thailand. The same change popped up in the only human to die during an outbreak of another bird flu, H7N7, in the Netherlands. And it's present in recent H5N1 viruses from humans in Vietnam and Thailand and from wild birds in China.

"The fact that [gene] changes identified in the 1918 analysis are also seen in highly pathogenic avian influenza strains of H5N1 and H7N7 is intriguing, and suggests that these changes may facilitate virus replication in human cells and increase pathogenicity," Taubenberger and colleagues write in their Nature paper.

New Information to Help Fight Flu

Scary as it is to take a close-up look at killer flu bugs, it's a good thing to do. Knowing the enemy helps us find ways to defeat it, says Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases.

"There are a number of ways one needs to prepare for a flu pandemic. And there is no better way than understanding the issues described here -- particularly the adaptability of the virus in a sense of efficient person-to-person spread and pathogenesis," Fauci said at the news conference.

CDC Director Julie Gerberding, MD, MPH, says the 1918 virus has a lot to teach us.

"We have been able to unmask the 1918 virus and it is revealing to us some of the secrets that will help us prepare for the next pandemic," Gerberding said at the news conference. "Some of those secrets are what led to efficient transmission in people -- and what made it so deadly. This important science does create new information and clues that will ... accelerate development of our antiviral drug stockpile and vaccines to protect against H5N1 or another virus."

Mount Sinai researcher Adolfo Garcia-Sastre, PhD, is one of the developers of the reverse genetic technique used to reconstruct the 1918 virus. He says the genetic changes that help flu bugs adapt to humans appear to be common to all type A flu viruses.

"What is interesting is these genes seem to be involved in the virulence of other flu viruses, not just bird flu," Garcia-Sastre said at the news conference. "So there are common themes involved in the virulence of flu viruses. Now we have good clues for the development of new drugs against flu disease."

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