Transmission and Pathogenesis of Swine-Origin 2009 A(H1N1) Influenza Viruses in Ferrets and Mice

TLDR

The clinical spectrum and transmissibility of swine‑origin 2009 A(H1N1) influenza virus remain incompletely understood. Ferrets were used to assess pathogenesis and transmissibility of selected 2009 A(H1N1) isolates versus seasonal H1N1 strains. The study found atypical gastrointestinal symptoms and suggested that 2009 A(H1N1) transmits less efficiently via respiratory droplets than seasonal H1N1, indicating a need for further mammalian adaptation. References: Munster et al.

Abstract

“Swine Flu” Pathology The clinical spectrum of disease caused by the swine-origin 2009 A(H1N1) influenza virus and its transmissibility are not completely understood. Munster et al. (p. 481 ; published online 2 July) and Maines et al. (p. 484 ; published online 2 July) used ferrets, an established model for human influenza, to evaluate the pathogenesis and transmissibility of a selection of 2009 A(H1N1) virus isolates compared with representative seasonal H1N1 viruses. The results help explain the atypical symptoms seen so far, including the gastrointestinal distress and vomiting observed in many patients. Although results were variable, it seems that the 2009 A(H1N1) virus may be less efficiently transmitted by respiratory droplets in comparison to the highly transmissible seasonal H1N1 virus, suggesting that additional virus adaptation in mammals may be required before we see phenotypes observed in earlier pandemics.