Fig. 5
Protective immunity against lethal challenge with H5N6 or H5N1 virus. At day 30 after the first immunization, chickens were challenged intranasally with 20 μl of 5 × LD50 (lethal dose) of A/chicken/Vietnam/NCVD-15A59/2015 (H5N6) (a, c and e) or A/Vietnam/1203/04 (H5N1) (b, d and f) (n = 10 chickens / group). The data for lung virus titer (n = 5 chickens/ group) are presented as the means ± SD. Asterisks indicate significant differences compared to the PBS and L. lactis/pNZ8149 controls (p < 0.05)