Fig. 1

Airborne transmission experiment for ferrets infected with the clade 2.3.4.4b influenza A(H5N1) virus A/Emu372-E627K. At 0 dpi, donor ferrets (n = 3 per dose) were inoculated with 4.7, 3.7, 2.7 and 1.7 lg EID₅₀ of A(H5N1) virus. On the second dpi, groups of naïve ferrets were placed in separate cages of the TIEGEL ELC 04–60 dynamic aerobiology chamber (with directed airflow from donor to recipient ferrets) which were positioned at a distance from the cages of groups of donor ferrets to prevent direct contact. Joint exposure of the animals lasted 5 h daily for 5 days, starting on the second and ending on the sixth dpi. Clinical course of infection was monitored, and nasal wash samples were taken at indicated time points from both inoculated and contact ferrets. Blood was taken from all survived contact ferrets to check for seroconversion on 22 and 30 dpc.