Feds say ferret research shows novel H1N1 flu more virulent

Research shows ferrets infected both with seasonal flu and with the novel H1N1 virus commonly called "swine flu" more readily transmitted the novel virus to other animals, the National Institutes of Health announced today.

Daniel Perez and colleagues at the University of Maryland conducted the study with support from the institutes' National Institute of Allergy and Infectious Diseases.

In announcing the results, authorities said "the novel 2009 H1N1 influenza virus may outcompete human seasonal influenza viruses.... Tests in animals showed that levels of the 2009 H1N1 virus rose more quickly than levels of the seasonal virus strains, and the new virus caused more severe disease.... University of Maryland researchers also observed that the novel H1N1 virus was transmitted more easily from infected to uninfected ferrets than either of the two seasonal influenza viruses."

Ferrets innoculated with 2009 H1N1 virus and with either seasonal H1N1 virus or seasonal H3N2 virus became "co-infected" with both viruses. But only the 2009 H1N1 virus was transmitted to uninfected ferrets. "The H1N1 pandemic virus has a clear biological advantage over the two main seasonal flu strains and all the makings of a virus fully adapted to humans," said Perez.

The research uncovered no evidence that the novel flu virus combined with the seasonal flu viruses to form "reassortant viruses," the feds said.

Said NIAID Director Anthony S. Fauci: "These new data, while preliminary, underscore the need for vaccinating against both seasonal influenza and the 2009 H1N1 influenza this fall and winter."

For more information visit www.flu.gov.

This story was originally published September 1, 2009 at 4:12 PM with the headline "Feds say ferret research shows novel H1N1 flu more virulent."