Fig 1. Efficient transmission of seasonal H1N1 and H3N2 influenza viruses to naïve animals under short or periodic exposures.

(A) Schematic of experimental procedure. Shaded gray bars depict exposure times. Three to four donor ferrets were infected with A/CA/07/2009 (H1N1) (B-D) or A/Perth/16/2009 (H3N2) (E-G) and a naïve recipient ferret was placed in the adjacent cage at 24 hour post-infection for 7 (B and E) or 2 (C and F) continuous days, or 8 hours a day for 5 consecutive days (D and G). Nasal washes were collected from all ferrets on the indicated days and each bar indicates an individual ferret. Limit of detection is indicated by dashed line. Viral titers for donor animals in part G have previously been published in [45].