Another H7N9-in-ferrets paper.

This was on my "to read" pile and got moved to the "forgot to read" pile.

Kreijtz and colleagues from the Osterhaus group described inoculating ferrets intratracheally with 10⁵-10⁸ 50% tissue culture infective doses influenza A(H7N9) virus A/Anhui/1/2013. Some interesting results include...

• Ferrets showed much more pathology than in the studies below; from 2-days onwards ferrets had breathing difficulties as well as fever and weight-loss and some animals died on day-3 post inoculation. Perhaps due to the instillation of virus into the lower airways rather than intranasally?
• Infectious virus and viral RNA could be identified from the upper (nasal turbinates, pharynx, tonsils) and lower respiratory tract (trachea, bronchus, bronchial lymph nodes, lungs). It was most interesting to note that virus came back up the airways to replicate in the upper respiratory tract.
• The authors note that Anhui/1 can bind both α2,3 & α2,6 sialoside molecules (supporting Tumpey's findings below). It's α2,6 (human-like) sialoside preference explains the upper respiratory tract findings, while the human deep lung's expression of α2,3 explains the virus causing pneumonia in the ferrets.