Figure 9. Exhaled viral RNA from donors infected with either NC/99 (A and B) or Cal/04 (C and D) virus.

RNA was measured in each filter sample by two RT-qPCR-based assays, detecting a single genomic RNA segment (LRRI assay, solid bar) or six segments (Ibis T5000 assay, checkered bar), and expressed as genome equivalents/1-hour filter collection. Donors were infected intranasally with 10⁶ FFU of either virus 24 hours prior to recipient exposure at a time when all donor nasal washes contained 10⁴–10⁵ FFU/mL. Each donor exposed three recipient ferrets and each of their corresponding collections (F1, F2, and F3) were the mean RNA levels from three filters each collecting airborne particles for 1 hour during the 3-hour exposure period.