Researchers in Korea and the United States have discovered that an H1N2 influenza virus prevalent in pigs is highly lethal in ferrets, replicating well in the ferret upper and lower respiratory tracts and inducing severe viral pneumonia. It was also efficiently transmitted to other ferrets via respiratory droplets (Pascua PN et al. Proc Natl Acad Sci U S A. 2012;109:15900-15905). Ferrets are a recognized model of human influenza infection and transmissibility.
The lethal virus acquired simultaneous mutations in hemagglutinin and neuraminidase proteins during the single ferret passage, leading to greater virulence and transmissibility. The virus also demonstrated enhanced infectivity and growth in mice and human lung tissues. The authors noted that mutations in the 2 proteins that played an important role in the virus' pathogenicity and transmissibility could serve as potential virulence markers in mammals.
Hampton T. Pigs and Pandemic Influenza. JAMA. 2012;308(17):1729. doi:10.1001/jama.2012.28158