Figure 6. Immunogenic activity of HA_63–286-RBD.

(A) Evolution of specific immune response of ferret 4A to intramuscular application of HA_63–286-RBD. Arrows indicate the days at which dosages of the protein were administered. (B) Evolution of a specific immune response of ferret 4C to sub-dermal application of HA_63–286-RBD. Arrows indicate the days at which dosages of the protein were administered. Error bars indicate one standard deviation for three replicates in an ELISA experiment. Specific immune response is expressed in absorbance units (absorbance signal in the assay with ferret serum minus absorbance in negative control). (C and D) Effect of adjuvant on immune response and comparison of immunogenic activity of different doses of HA_63–286-RBD administered to ferrets. Specific immune response is expressed in absorbance units (absorbance signal in the assay with ferret serum minus absorbance in negative control) at days 0 (gray), 3 (yellow), 15 (green), and 20 (blue) after the first vaccination dose. Error bars indicate one standard deviation with respect to the mean value for replicates of the experiment in different ferrets. Arrows indicate days of application of a second dose (if administered).