Study uncovers a lethal secret of 1918 influenza virus

In the new study, conducted in a high-level biosafety laboratory (BSL 4) at the Public Health Agency of Canada's National Microbiology Laboratory, seven primates were infected with the reconstructed 1918 virus. Clinical signs of disease were apparent within 24 hours of infection and within eight days euthanization was necessary. The rapid course of the disease mirrors how quickly the disease ran its course in its human victims in 1918.

Upon infection, the virus grew rapidly in the infected animals, suggesting the agent somehow sets the stage for virulent infection: "Somehow, early in infection, this virus does something to the host that allows it to grow really well," says Kawaoka. "But we don't know what that is."

Knowing that the virus does something early in infection to trigger such a devastating immune response may provide biomedical researchers with clues about how to intervene and stop or mitigate the virus' potentially lethal effects, Kawaoka says.

"Things may be happening at an early time point (in infection), but we may be able to step in and stop that reaction."

In addition to Kawaoka, authors of the new Nature paper include Darwyn Kobasa, Steven M. Jones, Hideki Ebihara, Friederike Feldman, Judie B. Alimonti, Lisa Fernando, Yan Li and Heinz Feldman of Canada's National Microbiology Laboratory; Kyoko Shinya of Japan's Tottori University; John C. Kash and Michael G. Katze of the University of Washington; John Copps of the Canadian Food Inspection Agency's National Centre for Foreign Animal Disease; and Yasuko Hatta, Jin Hyun Kim, Peter Halfmann and Masato Hatta of UW-Madison.

The new study was supported by the Public Health Agency of Canada, the Japanese Ministries of Education, Culture, Sports, Science and Technology, and private grants to Kawaoka. - Terry Devitt, (608) 262-8282,

HOLD FOR 1 P.M. EASTERN TIME RELEASE WEDNESDAY, JAN. 17, 2007

EDITOR'S NOTE: Authors Darwyn Kobasa and Michael G. Katze can be reached through their respective press officers: Kelly Keith (204) 789-5028, of the Public Health Agency of Canada; and Justin Reedy (206) 685-0382, of the University of Washington.