Comparing 'Swine' and Seasonal Flu in Ferrets

	Schematic presentation (A) and a photograph (B) of transmission cages. The ferrets are housed in clear Perspex transmission cages, in which each inoculated animal was housed individually with a naive... Click here for more information.

Compared to seasonal influenza, the 2009 A(H1N1) flu virus causes a slightly more severe illness in ferret models, a pair of studies reports in the July 3 issue of Science. These findings may help explain why the new H1N1 pandemic has included symptoms not generally associated with influenza, such as gastrointestinal distress and vomiting. Ferrets are considered a good model for studying influenza because they are affected by flu viruses in a similar way that humans are. Both studies analyzed ferrets infected with 2009 A(H1N1) and compared them with animals infected with seasonal flu. The two teams, one from the Netherlands and one from the United States, both found that 2009 A(H1N1) replicated more extensively in the respiratory tract, reaching down to the lungs, whereas the seasonal flu virus stayed in the ferrets' nasal cavity. The U.S. team also found the virus in the animals' intestinal tract. When the researchers investigated transmissibility, their results were mixed. Vincent Munster and colleagues in the Netherlands, report that both types of flu virus were equally good at infecting new individuals via respiratory droplets. In contrast, Taronna Maines and colleagues in the United States found that the 2009 A(H1N1) virus may be less transmissible than seasonal H1N1.

Article #18: "Transmission and Pathogenesis of Swine Origin 2009 A(H1N1) Influenza Viruses in Ferrets and Mice," by T.R. Maines; J.A. Belser; D.A. Wadford; C. Pappas; H. Zeng; K.M. Gustin; M.B. Pearce; N.J. Cox; J.M. Katz; T.M. Tumpey at Centers for Disease Control and Prevention in Atlanta, GA; A. Jayaraman; K. Viswanathan; Z.H. Shriver; R. Raman; R. Sasisekharan at Harvard-MIT Division of Health Sciences & Technology in Cambridge, MA; A. Jayaraman; K. Viswanathan; Z.H. Shriver; R. Raman; R. Sasisekharan at Massachusetts Institute of Technology in Cambridge, MA