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Scientists at the Centers for Disease Control and Prevention (CDC) have successfully reconstructed the influenza virus strain responsible for the 1918 pandemic, a project that greatly advances preparedness efforts for the next pandemic.
"This groundbreaking research helps unlock the mystery of the 1918 flu pandemic and is critically important in our efforts to prepare for pandemic influenza," said CDC Director Julie Gerberding, MD, MPH. "We need to know much more about pandemic influenza viruses. Research such as this helps us understand what makes some influenza viruses more harmful than others. It also provides us information that may help us identify, early on, influenza viruses that could cause a pandemic."
The work, done in collaboration with Mount Sinai School of Medicine, the Armed Forces Institute of Pathology and Southeast Poultry Research Laboratory, determined the set of genes in the 1918 virus that made it so harmful. Prior to this study, which will be published in the Oct. 7, 2005 issue of Science, flu experts had little knowledge of what made the 1918 pandemic so much more deadly than the 1957 and 1968 pandemics. This week's issue of Nature also includes a related article titled, "Characterization of the 1918 Influenza Virus Polymerase Genes" which describes the final three gene sequences of the 1918 influenza virus. The work reported in the Nature article was done by scientists at the Armed Forces Institute of Pathology.
The 1918 pandemic killed an estimated 20-50 million people worldwide, including 675,000 in the United States. The pandemic's most striking feature was its unusually high death rate among otherwise healthy people aged 15-34. During normal seasonal flu outbreaks, severe complications and death are most common among the elderly and young children.
Influenza pandemics occur when a new strain emerges to which people have little or no immunity. Most experts believe another pandemic will occur, but it is impossible to predict which strain will emerge as the next pandemic strain, when it will occur or how severe it will be.
"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 Dr. Terrence Tumpey, the CDC senior microbiologist who recreated the virus. "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."
In reconstructing the 1918 influenza virus, researchers learned which genes were responsible for making the virus so harmful. This is an important advance for preparedness efforts because knowing which genes are responsible for causing severe illness helps scientists develop new drugs and vaccines (e.g., they can focus their research on those genes).
The CDC employed stringent biosafety and biosecurity precautions during research on the 1918 influenza virus. The work was done in a high-containment Biosafety Level 3 lab with enhancements that include special provisions to protect both laboratory workers and the public from exposure to the virus. Currently available antiviral drugs have been shown to be effective against influenza viruses similar to the 1918 influenza virus.
All laboratory work was conducted at the CDC. The work was supported in part with funding from the U.S. Department of Agriculture and the National Institutes of Health.