Fig. 5.

fmOMV provide broad and potent protection against diverse influenza A viruses. a Mice (n = 8–9) were injected with fmOMV and challenged with 10 LD₅₀ of PR8, H5N2, and highly pathogenic H5N1 influenza viruses at the indicated time points. The vaccinated group was immunized intramuscularly with the trivalent split influenza vaccine containing pH1N1 antigen twice at a 2-week interval (n = 8). Two weeks after the second injection, the mice were challenged with each virus. b Mice (n = 8) were intranasally injected with each indicated TLR ligand (3 µg) and challenged with 10 LD₅₀ of the pH1N1 virus. a, b The survival rates were monitored for 2 weeks after the viral challenge. These data are representative of two or three independent experiments. *** p < 0.001, ** p < 0.01, * p < 0.05.