Researchers Complete Re-creation of 1918 Virus

Armed Forces Institute of Pathology (Washington, DC, USA), the U.S. Centers of Disease Control and Prevention (Atlanta, GA, USA), and Mount Sinai School of Medicine (New York, NY, USA). The findings have convinced the scientists that the 1918 virus began as an avian virus.

It has been difficult to study the 1918 virus since samples were not preserved at the time of the pandemic. Dr. Jeffery Taubenberger, chief of pathology at the U.S. Armed Forces Institute of Pathology, and his team have focused on publishing sequences for the genes of the virus, using materials preserved in the Alaskan permafrost and in the lungs of U.S. solders killed by the flu. They recently finished sequencing the three genes remaining. They have discovered 10 changes in amino acids that differ from other avian viruses, which suggest the virus might have mutated on its own to become transmissible in humans. The H5N1 avian virus that has so far claimed the lives of more than 50 people in Asia has already made five of these 10 changes. The team's work was published in the October 6, 2005, issue of Nature.

The other researchers, from Mount Sinai and the CDC, have reconstructed the virus by using reverse genetics, in order to learn what made it so lethal. The virus had the ability to enter cells deep in the lungs that flu viruses usually do not reach. The researchers focused on a gene in the re-created 1918 virus that allowed the virus to attach to cells and multiply. When that gene was removed, the virus lost its virulence. Moreover, certain genetic mutations of the virus have been found in the H5N1 strain, suggesting the new strain may follow a similar route. This team's work was published in the October 7, 2005, issue of Science.

According to Terrence Tumpey, a senior scientist at the CDC, the 1918 virus would be unlikely today to cause a pandemic. It is in the same family as those viruses many people have been exposed to over recent years, either by vaccination or natural infection, and thus they have developed some immune protection.

"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 Dr. Julie Gergerding.




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Armed Forces Institute of Pathology
CDC
Mount Sinai